Method for culturing beneficial algae by resource utilization of cyanobacterial bloom

Abstract

The invention provides a method for culturing beneficial algae by resource utilization of cyanobacterial blooms, which comprises the following steps: 1, obtaining cyanobacterial (microcystis) blooms, and concentrating the cyanobacterial (microcystis) blooms until the concentration of chlorophyll a is 80-150mg / L; 2, carrying out continuous hydrodynamic disturbance on the high-concentration cyanobacterial bloom, wherein the disturbance intensity is suitable for preventing the cyanobacterial bloom from blackening and stinking; 3, continuously disturbing for 20-60 days to obtain cyanobacterial bloom which turns light yellow green or white; 4, tap water is used for diluting cyanobacterial blooms with changing colors, the concentration during dilution is 0.5-2.3 mL / cm < 2 >, and beneficial algae such as diatom and green algae are inoculated for culture under the conditions of normal temperature and weak light; and 5, when the culture is performed for 12-30 days, the growth density of the beneficial algae reaches the highest peak, and the cell density of the beneficial algae can reach up to 2.5 * 10 < 6 >-5.6 * 10 < 7 > cells / cm < 2 >. According to the method, algal toxin can be removed, beneficial algae such as diatom and green algae can be cultured through resource utilization of the cyanobacterial bloom, and a new way is provided for control and resource utilization of the cyanobacterial bloom.

Description

Technical Field

[0001] The invention relates to the field of resource utilization of harmful algae, in particular to resource utilization of cyanobacteria blooms and a cultivation method of beneficial algae. Background Art

[0002] At present, cyanobacteria bloom mainly refers to the bloom of Microcystis of the genus Cyanobacteria (referred to as cyanobacteria bloom). Cyanobacteria bloom is a common harmful algae bloom in eutrophic lakes, reservoirs, ponds and other water bodies in my country. After the cyanobacteria bloom occurs, it is easy to float on the water surface. Under the influence of wind direction, it is easy to gather in large quantities at the downwind, and often forms deposits like green paint at the downwind. After the accumulation of cyanobacteria bloom, it is easy to stink in the hot season, and the odor emitted affects the surrounding environment. A large number of cyanobacteria blooms will also consume oxygen in the water body, causing hypoxia in the water body at night, produce algae toxins, destroy the ecological balance, affect drinking water and irrigation water, and affect the output and quality of aquaculture. These problems caused by cyanobacteria blooms seriously threaten the water environment and water body functions. Therefore, the regulation and resource utilization of cyanobacteria blooms have always been an important research direction.

[0003] Compared with cyanobacteria, diatoms have great nutritional value. Diatoms are rich in siliceous shells. The nutritional value of diatoms includes high protein content, moderate fat content, rich vitamins and minerals, and rich unsaturated fatty acids. Diatoms are rich in high-quality protein and are an ideal source of protein. They play an important role in increasing the growth rate and weight gain of aquatic animals such as fish, shrimp, and shellfish. Diatoms contain a moderate amount of fat, which is not only an important source of energy, but also a carrier for the storage and absorption of fat-soluble vitamins. Diatoms are rich in various vitamins and minerals, such as vitamin C, vitamin E, β-carotene, calcium, iron, zinc, etc. These nutrients play an important role in the immunity, antioxidant capacity, bone development and reproductive health of aquaculture organisms. Diatoms are rich in ω-3 series unsaturated fatty acids, such as EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid). These unsaturated fatty acids play an important regulatory role in the growth, immunity and anti-inflammatory ability of aquaculture organisms such as fish and shrimp. Therefore, diatoms are widely used in aquaculture as bait or additives, which can significantly improve the quality and yield of aquaculture. High-density cultivation of diatoms is an important research direction in aquaculture. High-density cultivation of diatoms is even more important in the current context of rising costs of aquatic feed.

[0004] In addition to its important role in aquaculture, diatoms also play an important role in many other aspects. Diatoms are rich in fucoxanthin. Fucoxanthin, also known as fucoxanthin and fucoxanthin, is a natural pigment of the xanthophyll class in carotenoids. It is light yellow to brown in color, which is the main reason why diatoms appear brown or tan. Fucoxanthin has anti-tumor, anti-inflammatory, antioxidant, weight loss, and nerve cell protection effects. It is widely used in the market of medicine, skin care and beauty products, and health care products. In addition, diatoms are widely used in bioremediation, chemical materials, nanotechnology, diatomaceous earth, etc., and have extremely broad research and application prospects.

[0005] There have been many reports on the large-scale cultivation of seawater diatoms. At present, the cultivation technology of diatoms is mainly reflected in the cultivation of seawater diatoms. For example, Shenzhen Zhaokai Bioengineering Research and Development Center Co., Ltd. has developed a large-scale open cultivation method and system for seawater diatoms. The diatoms obtained can have multiple uses, but it is still relatively lacking in diatom cultivation methods and technologies. Generally, diatoms are more likely to grow in nutrient-rich, weak light environments. There are few methods for the natural proliferation and cultivation of diatoms. Other aspects of diatom cultivation technology mainly utilize the characteristics of diatoms that are easy to attach and grow. By using diatom sources, diatoms can be attached to a certain substrate and grow, and serve as high-quality biological live bait for aquaculture objects. The commonly used attached diatom cultivation method for aquaculture is an open cultivation method for shellfish bait. The inventors of this application have discovered a method for cultivating diatoms using microcystis blooms, the main feature of which is to use the substances and energy stored in cyanobacteria blooms to promote the succession of cyanobacteria blooms to diatom advantages under hydrodynamic disturbance conditions. The inventors also provide a method for cultivating attached diatoms using aquatic plants in the process of decay. These diatom cultivation methods are helpful for cultivating high-density diatoms, and are also conducive to the beneficial transformation of natural substances and the large-scale development and utilization of diatoms. In order to further shorten the time for resource utilization of cyanobacteria blooms and improve the utilization rate and effect of substances in cyanobacteria blooms, the applicant continues to optimize and innovate the resource utilization methods of cyanobacteria blooms.

[0006] In addition to diatoms, some species of Chlorophyta also have outstanding nutritional value, such as Haematococcus pluvialis of Chlorophyta, which is a freshwater unicellular green algae belonging to Chlorophyta, Volvoxales, Haematococcus family, Haematococcus genus. The algae can accumulate astaxanthin in large quantities and appear red, also known as Haematococcus. Astaxanthin is a natural pigment widely distributed in aquatic species, such as salmon, shrimp, crab, etc. It has been found that it has extremely strong antioxidant capacity, which is 1000 times that of vitamin E, 200 times that of tea polyphenols, 100 times that of α-tocopherol, 65 times that of vitamin C, 17 times that of grape seeds, and usually 10 times higher than other carotenoids, such as β-carotene, canthaxanthin, zeaxanthin and lutein. The internal structure of astaxanthin makes astaxanthin have strong antioxidant and anti-inflammatory activity. Since it was first isolated from lobster in 1938, it has been widely used in the feed industry. Currently, it and canthaxanthin are the most important and expensive pigments used in aquaculture for pigmentation of salmon, trout and shrimp meat. It is also an essential component of feed for ornamental fish and large ornamental fish. In addition, astaxanthin has a positive effect on the color of egg yolks and the skin and meat tissue of broiler carcasses. Due to its strong antioxidant properties and other health benefits, astaxanthin can also be used in the nutritional supplement and cosmetic industries. In some countries, astaxanthin is also used as a food and beverage additive.

[0007] Haematococcus pluvialis is a unicellular green algae that can synthesize lipids and astaxanthin. Among its carotenoid secondary metabolites, the astaxanthin content exceeds 80%, and the overall astaxanthin accumulation level of algae is 1% to 3%. It is currently one of the main sources of natural astaxanthin. Many studies have described the positive effects of Haematococcus pluvialis powder as an aquatic feed additive, such as improving the growth performance of rainbow trout and large yellow croaker. Among crustaceans, Haematococcus pluvialis also shows excellent application prospects. Studies have found that it can increase the deposition level of carotenoids in various tissues of Chinese mitten crabs and Procambarus clarkii, and enhance antioxidant properties; in addition, it can also improve the anti-hypoxia ability of Procambarus clarkii; at the same time, it was found that adding an appropriate amount of Haematococcus pluvialis powder can regulate the intestinal flora of Procambarus clarkii, alleviate intestinal dysfunction, and thus improve its growth performance; Haematococcus pluvialis was also found to have a positive regulatory effect on the intestinal flora in white shrimp and Chinese mitten crab. Haematococcus pluvialis can accumulate high levels of astaxanthin under environmental stress conditions such as high salinity, high temperature, and high light.

[0008] The culture medium for freshwater algae is generally referred to as BG11, BBM, SE, HUT and other culture media (from the Freshwater Algae Species Bank of the Chinese Academy of Sciences https: / / algae.ihb.ac.cn / MeSearch.aspx?type=00020001), which contains a variety of major elements and some trace elements, which can meet the growth needs of algae, and one culture medium can often meet the growth needs of multiple algae. In order to obtain rapid and large-scale growth of algae, a sufficient supply of nutrients is a basic requirement. The large-scale occurrence of cyanobacterial blooms indicates that there is a rich accumulation of material basis to meet the growth needs of algae, and the nutrients released after decay under appropriate conditions will also become the material basis for the growth of new algae.

[0009] Regulating cyanobacteria blooms into beneficial algae such as diatoms and green algae is one aspect of the resource utilization of cyanobacteria blooms, that is, turning waste into treasure. It also provides an efficient culture medium for the cultivation of high-nutritional algae such as Haematococcus pluvialis of the Chlorophyta. How to improve the purity and density of beneficial algae cells such as diatoms and green algae, reduce the mixed cyanobacterial cells, improve the cultivation efficiency of beneficial algae, and reduce the time and economic costs of cultivation is an important research direction in the resource utilization of cyanobacteria blooms. Summary of the invention

[0010] The technical problem to be solved by the present invention is to provide a method for cultivating beneficial algae by utilizing cyanobacteria blooms as resources, which can enrich the pathways of material and energy transfer in the water environment, enrich the cultivation methods of beneficial algae, and enrich the theoretical research on algae ecology. The cultivated beneficial algae also have many meanings such as high-quality biological live bait for aquatic products, water quality purification, environmental protection, nutritional product development, drug development, and new energy development.

[0011] The technical problem to be solved can be implemented through the following technical solutions.

[0012] A method for cultivating beneficial algae by utilizing cyanobacteria blooms as resources, the method comprising the following steps:

[0013] S1. Obtain high-concentration cyanobacteria (Microcystis) blooms from lakes, ponds, reservoirs and other water bodies where cyanobacteria blooms occur, concentrate the cyanobacteria blooms to obtain slurry-like cyanobacteria blooms, and regulate the chlorophyll a concentration of the cyanobacteria blooms to a high concentration of 80 to 150 mg / L;

[0014] S2, accumulating high concentration of cyanobacteria blooms at normal temperature and weak light conditions for 0 to 3 days;

[0015] S3, continuously perturbing the high-concentration cyanobacteria bloom with a hydrodynamic disturbance intensity that is appropriate to prevent the cyanobacteria bloom from turning black and smelly;

[0016] S4. At normal temperature, the disturbance lasts for 20 to 60 days until the green algae bloom turns white or light yellow-green;

[0017] S5. Use the whitish or light yellow-green cyanobacteria bloom mother liquid as a dilution into the culture container with tap water. The dilution concentration of the whitish or light yellow-green cyanobacteria bloom mother liquid should be 0.5-2.3 mL / cm 2 , the water depth should be between 5 and 100 cm;

[0018] S6. Let the diluted cyanobacteria bloom stand for 1 to 3 days. Some cyanobacteria blooms sink to the bottom, while some float on the water surface. Inoculate the cyanobacteria blooms floating on the water surface with beneficial algae, such as diatoms and green algae. The initial density of inoculating beneficial algae should be 1.0×10 3 cells / cm 2 above;

[0019] S7. After inoculating the beneficial algae species, static culture is carried out under normal temperature and weak light conditions. During the 7-15 days of inoculation and culture, high-density growth of the corresponding inoculated algae appears on both the blue algae blooms floating on the water surface and the blue algae blooms sinking to the bottom, and the algae floating on the water surface and the blue algae blooms gradually sink to the bottom, and the beneficial algae gradually grow into high-concentration algae clusters on these sinking substrates;

[0020] S8. The total culture time after inoculation of beneficial algae is 12 to 30 days. The growth density of beneficial algae reaches its peak. The cell density of beneficial algae on the sediment can be as high as 2.7×10 6 ~5.6×10 7 cells / cm 2 .

[0021] In step S1, the concentration of the cyanobacteria bloom can be estimated by using the buoyancy of the cyanobacteria bloom without measuring the concentration of chlorophyll a. That is, the high-concentration cyanobacteria bloom is added with water and stirred, and then allowed to stand for 0.5 to 1 hour to obtain the accumulation layer of cyanobacteria bloom floating on the water surface, thereby obtaining a high-concentration cyanobacteria bloom that meets the requirements, wherein the chlorophyll a concentration satisfies the concentration range of 80 to 150 mg / L.

[0022] In step S2, the normal temperature and weak light conditions are the temperature conditions of the season and the weak light conditions with a shading rate of more than 70%, which can be completely dark conditions without light. The purpose is to promote the formation of a certain anaerobic fermentation process during the accumulation of high-concentration cyanobacteria blooms due to the lack of oxygen caused by the large amount of respiration of cyanobacterial cells.

[0023] In step S3, the disturbance is aeration disturbance, rotation or circulation stirring to increase the dissolved oxygen level in the cyanobacteria bloom and prevent severe anaerobic decay and odor.

[0024] In step S4, a lot of foam will be generated during the continuous disturbance of high-concentration cyanobacteria bloom, and the cyanobacteria bloom gradually changes from green to yellow-green and gradually turns white. When the time is long enough, the cyanobacteria bloom appears obviously white, or even becomes off-white. At this time, the cyanobacteria cells in the cyanobacteria bloom appear to rot or even rot to a round shape where the cells cannot be seen, while the cyanobacteria gel is still relatively intact. The rotten cyanobacteria cells and cyanobacteria gel are still gathered together to maintain a fine particle state. The speed at which the green cyanobacteria bloom gradually turns white is related to the water temperature. In summer, the water temperature is high and the speed of turning white is fast. In summer, it can be obviously white in 20 days under the water temperature of about 30°C during the daytime. Otherwise, the speed of turning white is slow. The green cyanobacteria bloom needs nearly 60 days to turn white when the water temperature is about 15-20°C during the day.

[0025] In step S5, when tap water is added to dilute the whitish blue algae bloom, the degree of dilution is mainly related to the thickness of the whitish blue algae bloom gathered on the water surface, and the water depth is controlled to meet the light and nutrient concentration in the water in the appropriate range for algae growth.

[0026] In step S6, theoretically, the higher the initial density of the inoculated beneficial algae, the faster the algae will multiply.

[0027] In step S7, the culture process is preferably carried out in the warm months of May to October, and the highest culture water temperature during the day is preferably above 18°C.

[0028] In step S8, when the inoculated algae is diatoms, the color of the algae layer is brown or tan; when the dominant algae inoculated is green algae, the color of the algae layer is green. If the color of Haematococcus pluvialis turns brown-red or dark red, the color of the algae layer will also change from green to darker, or even appear brown-red or dark red.

[0029] In the technical scheme of the present invention, three factors, namely, high concentration of cyanobacteria bloom, continuous hydrodynamic disturbance until the cyanobacteria bloom turns white, and diluting the whitish cyanobacteria bloom with tap water at an appropriate ratio, are key conditions for realizing the present invention. Changes in any one of these factors will affect the time and culture concentration required for cultivating beneficial algae. If the concentration of the cyanobacteria bloom is inappropriate during continuous hydrodynamic disturbance, it will affect the decay process of the cyanobacteria cells, and it will not be easy to obtain a cyanobacteria bloom that is obviously whitish, that is, a cyanobacteria bloom in which the cyanobacteria cells decay while the cyanobacteria colony gelatin is still well preserved. When the concentration of the cyanobacteria bloom is too low, both the cyanobacteria cells and the cyanobacteria colony gelatin will decay, and it will not be easy to obtain an obvious cyanobacteria gelatin; when the concentration of the cyanobacteria bloom is too high, a longer aeration disturbance time will be required, and it will easily cause the cyanobacteria bloom to decay and turn brown, forming a bacterial advantage. After the cyanobacteria bloom turns white, the dilution level with tap water also needs to be well controlled. If the tap water dilution concentration is too low, the accumulation concentration of the whitish blue-green algae bloom on the water surface will be too high, causing the blue-green algae bloom to continue to rot, which is not conducive to the growth of inoculated algae; if the tap water dilution concentration is too high, it will cause the accumulation concentration of the whitish blue-green algae bloom to be too low, and the culture concentration of the inoculated beneficial algae will also be low.

[0030] The beneficial algae grown in the present invention mainly float on the water surface and settle at the bottom of the container, which is different from the growth attached to the inside of the container in previous studies, and as the culture time continues, the beneficial algae will be suspended in the water. The beneficial algae such as diatoms and green algae grown in the present invention are based on the nutrients released by the decay of cyanobacteria blooms, that is, the cyanobacteria blooms are used as the source of nutrients, so the purpose of utilizing the cyanobacteria blooms to cultivate beneficial algae is achieved.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] 1. The decay of cyanobacteria blooms is achieved under aerobic conditions formed by hydrodynamic disturbance, especially promoting the decay of cyanobacterial cells, while the gelatinous layer of cyanobacteria colonies is relatively intact. Since the main component of the gelatinous layer of cyanobacteria colonies is polysaccharides, it is equivalent to forming an effective method to maintain the gelatinous layer of cyanobacteria blooms and obtain cyanobacterial polysaccharides.

[0033] 2. It is clarified that the cyanobacterial colony gelatin, especially the dominant cyanobacterial polysaccharide, can be used to efficiently and quickly cultivate beneficial algae such as diatoms and green algae, especially the astaxanthin-producing Haematococcus pluvialis, which provides an efficient and high-quality culture medium for the large-scale cultivation of Haematococcus pluvialis.

[0034] 3. Compared with algae that grow on the inner wall of the container, beneficial algae that float on the water surface and those that grow on the bottom are easier to collect and concentrate, and are conducive to further utilization after concentration.

[0035] 4. After the cyanobacteria bloom turns white, the cyanobacteria cells in the gelatin of the cyanobacteria colony have obviously decayed, and the algae toxins produced by the cyanobacteria are completely decayed and degraded within a few days. When cultivating beneficial algae such as diatoms and green algae, the cyanobacteria cells will not form competition, and there will be no algae toxin residues. The cell purity and density of the beneficial algae are high, which is conducive to the further collection and utilization of these beneficial algae, such as for use in aquaculture live bait, extraction of effective chemical substances, etc.

[0036] 5. This method directly uses high-concentration cyanobacteria bloom slurry for resource utilization, which provides a resource utilization method for the direct treatment of cyanobacteria bloom slurry salvaged from eutrophic lakes. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Other features, purposes and advantages of the present invention will become more apparent by reading the detailed description of the non-limiting embodiments with reference to the following drawings: All the algae photos in the embodiments were taken under an optical microscope after being magnified 400 times, and were taken after the algae were diluted with an appropriate amount of pure water (not indicating the actual algae density).

[0038] Figure 1-1 to Figure 1-30 This is a photo of the algae in Example 1.

[0039] Figure 2-1 to Figure 2-6 This is a photo of algae in Example 2.

[0040] Figure 3-1 to Figure 3-10 This is a photo of algae in Example 3.

[0041] Figure 4-1 to Figure 4-8 This is a photo of algae in Example 4. DETAILED DESCRIPTION

[0042] Based on the current state of the prior art, the inventors of the present application have discovered a method for cultivating beneficial algae by utilizing cyanobacteria blooms as resources. The main feature of the method is that high-concentration cyanobacteria blooms decay under aerobic conditions, and the cyanobacteria blooms become lighter in color, especially whitish. The cyanobacteria cells in the cyanobacteria colony decay before the cyanobacteria colony gelatin, while the cyanobacteria gelatin still maintains a good fine granular state, which is a good culture medium for the growth of beneficial algae. Beneficial algae, such as diatoms and green algae, are inoculated into the cyanobacteria blooms that have decayed aerobically, and the beneficial algae can grow at a high density on the whitish cyanobacteria bloom layer. The gelatin of the whitish cyanobacteria bloom, the main component of which is polysaccharide, is an important material basis for promoting the growth of beneficial algae.

[0043] The present invention will be further described and illustrated in more specific embodiments below in conjunction with specific embodiments and drawings.

[0044] Example 1

[0045] In the warm June, fresh blue algae blooms (Microcystis) floating on the water surface were collected from aquaculture ponds where blue algae blooms occurred. Microcystis colonies were seen in fresh blue algae blooms. Figure 1-1 to Figure 1-4 The cyanobacteria bloom was concentrated. The chlorophyll a (Chl-a) concentration of the high-concentration cyanobacteria bloom was 100.0 mg / L, and the density of Microcystis cells was 3.1×10 11 cells / L, which is about 310 billion Microcystis cells per liter of water. The volume of the resulting high-concentration cyanobacteria bloom was 35L. These high-concentration cyanobacteria blooms were placed in a 60cm high, 80L total volume white plastic bucket, and air aeration was performed continuously using air bubbles. The white plastic bucket was placed in a glass greenhouse. The light conditions in the glass greenhouse were about 30% of the outdoor natural sunlight conditions. During the continuous aeration process, no additional water was added.

[0046] After 15 days of continuous aeration disturbance, the color of the fresh high-density cyanobacteria bloom gradually became lighter and whiter, from green to light yellow-green, and a lot of foam was produced, which overflowed from the bucket. After 30 days of continuous aeration disturbance, the color of the high-density cyanobacteria bloom became lighter and whiter, and the foam produced became less. At this time, when the cyanobacteria bloom was examined under a microscope, it was found that the Microcystis cells in the cyanobacteria group were obviously rotten and reduced, and the shape of the Microcystis cells was incomplete, but the group still maintained a granular state, that is, the group's gelatinous layer was still intact ( Figure 1-5 to Figure 1-8 ). That is, in this case, after the Microcystis cells in the cyanobacteria colony decay, the overall color of the cyanobacteria bloom becomes lighter and whiter, and the transparent colony gelatin is still well maintained.

[0047] Then, the whitish cyanobacteria bloom was allowed to stand for 1 hour, and the cyanobacteria bloom layer floating on the water surface was obtained as the mother liquid. 0.18L, 0.36L, 0.54L and 0.72L of these mother liquids were respectively taken into a colorless transparent glass tank of 30cm×30cm×30cm, and tap water was added to 23L for dilution. The concentration of the whitish cyanobacteria bloom was 0.20mL / cm 2 , 0.40mL / cm 2 , 0.60mL / cm 2 and 0.80mL / cm 2 During the cultivation process, it was found that the main destination of the whitish blue algae bloom in the water was that some of it sank to the bottom and some floated on the surface. The concentration of the aggregate was mainly related to the area of ​​the water body, so the unit representing the concentration of the blue algae bloom was converted to mL / cm 2 The culture was carried out in a glass greenhouse under two conditions: aeration disturbance and no aeration disturbance. The specific treatment conditions are shown in Table 1.

[0048] Table 1: Treatments for algae cultivation using whitish cyanobacteria blooms

[0049]

[0050] After adding tap water to each glass tank, the whitish blue algae bloom was left to stand for 2 days, and then the Nitzschia cells of the diatom phylum were inoculated into each glass tank at a density of 1.2×10 3 cells / cm 2 During the cultivation process, different phenomena occurred in each treatment. In the four treatments without aeration disturbance, some whitish algae particles floated on the water surface, and some whitish algae particles settled at the bottom of the tank. The water column was distributed with rotten whitish algae blooms, and the water column turned light yellow-green as a whole. The cyanobacteria particles floating on the water surface and sinking to the bottom gradually turned brown.

[0051] On the 7th day, the brown color in the floating matter and sediment was the most obvious in the treatment III without aeration disturbance, and under the microscope, it was found that there were very dense cells of Nitzschia ( Figure 1-9 to Figure 1-12 ), and also a small amount of green algae. The density of the growth of Nitzschia algae is as high as 1.2×10 6 cells / cm 2 At the same time, the sediments of treatment III also showed a predominance of Nitzschia algae, mixed with some green algae and filamentous cyanobacteria ( Figure 1-13 to Figure 1-16 ), which is very similar to the algae found in the floating objects on the water surface. On the 7th day, some Nitzschia algae growth appeared in the cyanobacterial bloom on the surface of treatment IV without aeration ( Figure 1-17 to Figure 1-20 ).

[0052] On the 10th day, the surface floating matter of treatment III without aeration was replaced by a large amount of Nitzschia algae ( Figure 1-21 to Figure 1-26 ), the cell density of Nitzschia reached 2.7×10 6 cells / cm 2 A large number of Nitzschia algae also grew in the floating objects and sediments of treatments I and II. The density of Nitzschia algae growing on the surface of treatments I and II reached 0.4×10 6 cells / cm 2 and 1.5×10 6 cells / cm 2 , which was lower than that of treatment III. The growth time of a large number of brown Nitzschia algae in the sediments and floating materials in treatment IV was 3 days later than that in treatment III, and the situation of Nitzschia algae was similar to that in treatment III. However, after the floating materials in treatment IV sank to the bottom, the growth density of Nitzschia algae cells in the sediments of treatment IV was higher, reaching 1.7×10 7 cells / cm 2 .

[0053] On the 10th day, obvious green algae growth appeared in all four aeration-disturbed tanks, especially in treatment VII, where the water color was dark green. Under the microscope, a large amount of green algae growth was found ( Figure 1-27 to Figure 1-30 ), these green algae are mainly of the genus Dictyophagus, mixed with some filamentous cyanobacteria.

[0054] This example shows that after the decayed whitish blue algae bloom is appropriately diluted with tap water, diatoms can be cultured under static conditions to achieve the growth of a large number of diatoms. The appropriate addition concentration for obtaining high-concentration diatom growth is treatment III and IV, that is, the concentration of the whitish blue algae bloom added is 0.60 mL / cm 2 and 0.80mL / cm 2 However, aeration disturbance of diluted cyanobacteria blooms is not conducive to the formation of diatom dominance in them, and green algae are more likely to become dominant under aeration disturbance.

[0055] Example 2

[0056] The inventor's existing experimental studies have found that hydrodynamic disturbance cultivation of cyanobacteria blooms at an appropriate concentration can achieve succession to diatom dominance, but if the concentration continues to increase to a certain extent, the cyanobacteria bloom will rot and turn brown. If the concentration is further increased, more types of changes will occur. In order to further study the degree to which cyanobacteria blooms need to be concentrated, so as to facilitate the cyanobacteria blooms to achieve the whitish phenomenon under hydrodynamic disturbance, and also prevent the cyanobacteria blooms from completely rotting and decomposing into dissolved nutrients under hydrodynamic disturbance, fresh cyanobacteria blooms floating on the water surface were fished out from aquaculture ponds where cyanobacteria (Microcystis) blooms occurred in the hot July, and concentrated to different degrees. The concentrated cyanobacteria (Microcystis) blooms were divided into five concentration gradients according to the Chl-a concentration: 60 mg / L, 80 mg / L, 120 mg / L, 150 mg / L and 170 mg / L. The volume of each concentration of cyanobacteria (Microcystis) blooms was 25 L, which were placed in five white round plastic barrels with a height of 60 cm and a total volume of 80 L, and air aeration was performed continuously using air stones. In the cyanobacteria (Microcystis) blooms with Chl-a concentrations of 60 mg / L, 80 mg / L, 120 mg / L, 150 mg / L and 170 mg / L, the density of Microcystis cells was 1.9×10 11 cells / L、2.5×10 11 cells / L、3.7×10 11 cells / L、4.7×10 11 cells / L and 5.3×10 11 cells / L. White plastic buckets were placed in the glass greenhouse. During continuous aeration, no additional water was added.

[0057] In order to obtain the required concentration of cyanobacteria bloom intuitively and quickly, the inventors found that the cyanobacteria bloom and water were stirred evenly and then left to stand for 1 hour, and the cyanobacteria bloom floated to the water surface and formed a distinct stratification with the water. The Chl-a concentration in the cyanobacteria bloom slurry floating on the water surface was exactly 100 mg / L. This formed a method for quickly and accurately obtaining high-concentration cyanobacteria blooms.

[0058] During the aeration disturbance, the color of the fresh green high-density cyanobacteria bloom gradually turned yellow-green, and a lot of foam was produced. The most foam was produced in 10 to 20 days, and it overflowed out of the barrel. After 20 days of continuous aeration disturbance, the color of the foam produced changed. From low concentration to high concentration treatment, the color of the foam gradually deepened, especially in the high concentration of 150 mg / L and 170 mg / L treatment, the foam gradually turned brown-orange, and the cyanobacteria bloom gradually changed from yellow-green to brown-brown. In the treatments with lower Chl-a concentrations of 60 mg / L and 80 mg / L, the water color gradually turned whitish. After 30 days of continuous aeration disturbance, the colors of the cyanobacteria blooms were light white, light white mixed with light green, light white mixed with yellow-green, light yellow-green, brown-yellow and brown in the treatments with Chl-a concentrations of 60 mg / L, 80 mg / L, 120 mg / L, 150 mg / L and 170 mg / L, respectively. In the treatment with 170 mg / L, the cyanobacteria colonies were basically decayed into brown bacteria, and there were no obvious colony particles. The different colors of cyanobacteria blooms in each treatment were observed under a microscope. They were basically the same as those in Example 1, except that the cyanobacteria colonies in the treatment with 60 mg / L were relatively small. The decay of representative cyanobacteria colonies in the treatments with 80 mg / L, 120 mg / L, and 150 mg / L were shown in Figure 1. Figure 2-1 to Figure 2-6 .

[0059] This example shows that the change of the high-concentration cyanobacteria bloom obtained after the cyanobacteria (Microcystis) bloom is concentrated under the condition of aeration disturbance is related to the concentration of the cyanobacteria bloom. It is speculated that the aeration disturbance increases the dissolved oxygen concentration in the cyanobacteria bloom. Although the cyanobacteria cells will decay and be damaged during the decay process of the cyanobacteria bloom under aerobic conditions, it is not easy to release odorous substances and it is easy to retain obvious colony gelatin. In particular, in the treatment of the Chl-a concentration in the cyanobacteria bloom of 80 to 150 mg / L, a relatively obvious colony gelatin can be retained.

[0060] Example 3

[0061] In September when the temperature was still relatively hot, the cyanobacteria bloom with a concentration of 80 mg / L of Chl-a in Example 2 that turned white after 40 days of aeration disturbance was used for diatom culture. During the culture, the whitish cyanobacteria bloom was first allowed to stand for 0.5 h, and then the whitish cyanobacteria bloom slurry floating on the water surface was taken as the mother liquor. Tap water was added to dilute these cyanobacteria bloom mother liquors. The culture container was a colorless transparent glass tank of 30 cm × 30 cm × 30 cm, and tap water was added to 8.5 L, with a water depth of 10 cm. It was placed in a glass greenhouse for culture. The lighting conditions in the glass greenhouse were about 30% of the outdoor natural sunlight conditions. It was divided into 6 treatments in total, and the specific treatment conditions are shown in Table 2.

[0062] Table 2: Specific conditions for algae cultivation using whitish cyanobacteria blooms

[0063]

[0064] In the three aeration treatment tanks, the water was light white and turbid; in the three non-aeration treatment tanks, some of the whitened blue algae bloom particles gradually floated up, while others sank, forming a light white material layer on the water surface and bottom. Each tank was inoculated with Nitzschia species, and the initial inoculation density was 1.8×10 3 cells / cm 2 .

[0065] On the 4th day, brown spots appeared on the light white floating objects and sinking materials in the water of treatment IV without aeration. Under the microscope, they were found to be cells of Nitzschia. There were no obvious changes in other treatments. On the 6th day, more and larger brown spots appeared on the floating objects and sinking materials in treatment IV without aeration.

[0066] On the 9th day, the brown spots on the floating and sinking materials in the non-aerated treatment IV were more numerous and larger. The foam on the surface of the water in the three aerated treatments turned yellow-green. There were no significant changes in the other treatments.

[0067] On the 11th day, all the floating objects on the surface of the water in the non-aerated treatment IV turned brown, and the sediment turned light brown-yellow. Under the microscope, it was found that these brown, brown-yellow or tan-brown objects were all diatoms. Figure 3-1 to Figure 3-6 , which are basically Nitzschia, with a cell length of about 30 μm and a width of about 5 μm at the widest point. The density of Nitzschia cells in the floating objects on the water surface reached 4.9×10 6 cells / cm 2 The floating objects on the water surface of treatments V and VI without aeration also showed brown spots. The foam on the water surface of the three aerated treatments turned yellow-green, and the water was still turbid, with a light brown-green color. After the 12th day, the floating objects in treatment VI sank a lot, and the sediment gradually turned green, and it was found that there was mixed growth of green algae.

[0068] On the 13th to 16th day, the brown substance in the floating matter and sediment of treatments IV and V without aeration reached the highest peak. Microscopic observation showed that it was a high concentration of Nitzschia. The cell density of Nitzschia in the sediment of treatments IV and V was as high as 3.5×10 7 cells / cm 2 and 5.6×10 7 cells / cm 2 The water color in the three aerated treatments became greener. Under the microscope, the green substances were dominated by green algae, mainly colloid algae, star algae, and a small amount of filamentous cyanobacteria. Figure 3-7 to Figure 3-10 .

[0069] From this example, it can be obtained that the addition concentration of the whitened cyanobacteria bloom mother liquid is 1.11 mL / cm 2 , 2.22mL / cm 2 When the concentration of cyanobacteria blooms was higher, diatom growth was less likely to occur, but green algae growth was more likely to occur.

[0070] Example 4

[0071] In late September when the temperature was relatively hot, the cyanobacteria bloom with a Chl-a concentration of 80 mg / L in Example 2 was used to culture Haematococcus pluvialis. The Haematococcus pluvialis species came from the freshwater algae species bank of the Institute of Hydrobiology, Chinese Academy of Sciences, and was continuously cultured until the concentration of the Haematococcus pluvialis species was about 1.0×10 5 cells / mL. During cultivation, the milky white cyanobacteria bloom was first allowed to stand for 0.5h, and then the milky white cyanobacteria bloom slurry floating on the water surface was taken as the mother liquor. Tap water was added to dilute these cyanobacteria bloom mother liquors. The culture container was a 500mL conical flask, and each bottle was filled with tap water to 400mL. The water depth was 6cm, and cultured under normal temperature conditions in the laboratory. Compared with the outdoor natural sunlight conditions, the lighting conditions in the laboratory are about 2% of the outdoor natural light intensity. There are 6 treatments in total. The specific treatment conditions are shown in Table 3. When calculating the concentration of the milky white cyanobacteria bloom, a volume of 400mL (mL / cm 2 Each bottle was inoculated with 2 mL of Haematococcus pluvialis algae solution, and the initial inoculation density was 5.3×10 3 cells / cm 2 Each bottle was not aerated and was only shaken once a day for about 20 seconds each time.

[0072] Table 3 Specific situation of using milky white cyanobacteria bloom to cultivate Haematococcus pluvialis

[0073]

[0074]

[0075] There were no obvious changes in the bottles in the first three days. The water was turbid and milky white. There were some milky white cyanobacteria blooms floating on the water surface and some milky white cyanobacteria blooms precipitated on the bottom of the water. Starting from the fourth day, the milky white cyanobacteria blooms that sank to the bottom of each bottle gradually showed some light green. As time went on, the milky white cyanobacteria blooms basically sank to the bottom of the water, and the water color remained turbid. The milky white cyanobacteria blooms gradually grew into flocs, and these flocs gradually turned light green. On the 12th day of cultivation, the light green color in culture bottle IV was the most obvious, so the flocs in culture bottle IV were taken for observation under a microscope, and it was found that the Haematococcus pluvialis cells were growing together with the filamentous cyanobacteria. Figure 4-1 to Figure 4-8 As the culture continued, the amount of light green flocs in each bottle gradually increased and sank to the bottom and gathered loosely together.

[0076] On the 28th day, a large number of green flocculent cultures appeared in all the culture bottles, especially in culture bottle VI, where the most flocculent cultures were found, and in culture bottle I, where the least flocculent cultures were found. Therefore, the flocculent cultures in culture bottles I and VI were shaken as much as possible, and 50 mL was taken out from each for cell counting, and the rest was continued to be cultured. By calculation, the total cell density of Haematococcus pluvialis in the flocculent cultures of culture bottles I and VI on the 28th day was 3.9×10 5 cells / mL and 6.5×10 5 cells / mL, and the bottom area of ​​a 500mL conical flask is 63cm 2 After conversion, the average cell density of Haematococcus pluvialis on the bottom surface was 2.5×10 6 cells / cm 2 and 4.1×10 6 cells / cm 2 .

[0077] During the continued cultivation process, the green silky flocculent culture in each treatment bottle did not increase significantly compared with the 30th day. Therefore, it is inferred that the growth density of Haematococcus pluvialis reached its peak around 30 days.

[0078] Relatively speaking, the growth rate of the inoculated Haematococcus pluvialis was slower than that of the diatoms in Examples 1 and 3, and filamentous cyanobacteria grew between cells of the Haematococcus pluvialis, which showed filamentous growth during the culture process, affecting the purity of the Haematococcus pluvialis.

[0079] From this example, it can be seen that when the concentration of the whitened blue algae bloom is 0.5-1.0 mL / cm 2When inoculated with Haematococcus pluvialis, filamentous growing Haematococcus pluvialis can be obtained, that is, the aerobic conditions formed by hydrodynamic disturbance cause the blue algae bloom to turn white and can be used to cultivate Haematococcus pluvialis.

Claims

1. A method for cultivating beneficial algae by utilizing cyanobacteria blooms, characterized in that: The processing steps include: S1. obtaining a high-concentration cyanobacteria bloom from a water body where cyanobacteria bloom occurs, concentrating the cyanobacteria bloom to obtain a slurry-like cyanobacteria bloom, and regulating the chlorophyll a concentration of the cyanobacteria bloom to a high concentration of 80 to 150 mg / L; S2, accumulating high-concentration cyanobacteria blooms at room temperature and under weak or no light conditions to form anaerobic fermentation of cyanobacteria cells under anoxic conditions; S3, continuously perturbing the high-concentration cyanobacteria bloom with a hydrodynamic disturbance intensity that is appropriate to prevent the cyanobacteria bloom from turning black and smelly; S4. Under normal temperature, the disturbance continues until the green algae bloom turns whitish or light yellow-green; S5. Take the whitish or light yellow-green cyanobacteria bloom mother liquid and dilute it with water into the culture container. The dilution concentration of the whitish or light yellow-green cyanobacteria bloom mother liquid is 0.5-2.3mL / cm 2 , water depth is 5 to 100 cm; S6. The diluted cyanobacteria blooms were allowed to stand until some of them sank to the bottom and some floated on the water surface. The cyanobacteria blooms floating on the water surface were inoculated with beneficial algae. The initial density of the inoculated beneficial algae was 1.0×10 3 cells / cm 2 above; S7. After inoculating the beneficial algae species, static cultivation is carried out under normal temperature and weak light conditions. During this period, high-density growth of the corresponding inoculated algae occurs on both the cyanobacterial blooms floating on the water surface and the cyanobacterial blooms sinking to the bottom, and the algae floating on the water surface and the cyanobacterial blooms gradually sink to the bottom, and the beneficial algae gradually grow into high-concentration algae clusters on these sinking substrates; S8. Continue culturing until the cell density of beneficial algae on the sediment reaches 2.7×10 6 ~5.6×10 7 cells / cm 2 .

2. The method for cultivating beneficial algae by utilizing cyanobacteria blooms as resources according to claim 1, characterized in that: In step S1, without measuring the concentration of chlorophyll a, the concentration of cyanobacteria bloom is estimated by utilizing the floatation of cyanobacteria bloom.

3. The method for cultivating beneficial algae by utilizing cyanobacteria blooms as resources according to claim 2, characterized in that: During the estimation, water is added to the high-concentration cyanobacteria bloom and the mixture is stirred, and then allowed to stand for 0.5 to 1 hour to obtain the accumulation layer of cyanobacteria bloom floating on the water surface, thereby obtaining a high-concentration cyanobacteria bloom that meets the chlorophyll a concentration requirement.

4. The method for cultivating beneficial algae by utilizing cyanobacteria blooms as resources according to claim 1, characterized in that: In step S2, the normal temperature and weak light conditions refer to the temperature conditions of the season and the weak light conditions with a shading rate of more than 70%, and the no light conditions refer to the no light conditions of complete darkness.

5. The method for cultivating beneficial algae by utilizing cyanobacteria blooms as resources according to claim 1, characterized in that: In step S2, the stacking time is 3 days or less; In step S3, the disturbance is aeration disturbance, rotation or circulation stirring, and the disturbance increases the dissolved oxygen level in the cyanobacteria bloom to prevent severe anaerobic decay and odor; In step S4, the duration of the disturbance is 20 to 60 days; In step S6, the standing time is 1 to 3 days; In step S7, the inoculation and culturing time is 7 to 15 days; In step S8, the total culture time after inoculation of beneficial algae species is 12 to 30 days.

6. The method for cultivating beneficial algae by utilizing cyanobacteria blooms as resources according to claim 1, characterized in that: In step S5, when water is added for dilution, the degree of dilution is mainly related to the thickness of the whitish blue algae bloom gathered on the water surface, and the water depth is controlled to meet the appropriate range of light and nutrient concentration in the water for algae growth.

7. The method for cultivating beneficial algae by utilizing cyanobacteria blooms as resources according to claim 1, characterized in that: In step S6, the beneficial algae are diatoms or green algae, and the higher the initial density of the inoculated beneficial algae, the faster the algae reproduces.

8. The method for cultivating beneficial algae by utilizing cyanobacteria blooms as resources according to claim 1, characterized in that: In step S7, the culture process is carried out in the warm months of May to October, and the culture water temperature during the day is above 18°C.

9. The method for cultivating beneficial algae by utilizing cyanobacteria blooms as resources according to claim 1 or 7, characterized in that: In step S8, when the beneficial algae inoculated and grown are diatoms, the color of the algae layer is brown or tan; when the beneficial algae inoculated and grown are green algae, the color of the algae layer is green; among them, when the color of Haematococcus pluvialis turns brown-red or dark red, the color of the algae layer will also change from green to darker, and even appear brown-red or dark red.

10. The method for cultivating beneficial algae by utilizing cyanobacteria blooms as resources according to claim 1, characterized in that: The cyanobacteria bloom is a bloom of the genus Microcystis of the phylum Cyanobacteria; and the water body is a lake, a pond or a reservoir.

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