Culture optimization method for improving microalgae output

Abstract

The invention relates to a culture optimization method for improving microalgae output, equipment of the culture optimization method comprises a transparent culture container, a stirring paddle located in the culture container and an auxiliary light source for forming uniform light supplement on the peripheral surface of the culture container, the speed of the stirring paddle is adjustable, and the illumination intensity of the auxiliary light source is adjustable. The culture optimization method mainly comprises three experimental groups, the first experimental group selects stirring paddle stirring blade types, the second experimental group selects stirring paddle rotating speeds, and the third experimental group selects illumination intensity, so that the culture optimization method is used as an optimization scheme for subsequent microalgae culture, and the yield of microalgae is increased.

Description

Technical Field

[0001] The invention relates to the field of microalgae cultivation, and is a cultivation optimization method for improving microalgae output. Background Art

[0002] When microalgae are cultivated in existing large-scale culture containers, stirring paddles are usually added. In particular, adding stirring paddles to bubbling culture containers can bring about very uniform liquid mixing, fairly high light utilization efficiency and good temperature control. However, it was also found during the cultivation process that the stirring paddle will also generate shear force that damages the microalgae while stirring, and different microalgae have different adaptability to stirring shear force. This makes it difficult to select a specific stirring paddle according to the microalgae in the existing microalgae cultivation process, thereby affecting the efficiency and final output of large-scale microalgae cultivation. The prior art also does not disclose relevant literature on the selection of specific stirring paddles for microalgae cultivation. Therefore, a technical solution for rationally selecting stirring paddles and optimizing microalgae output needs to be designed for microalgae cultivation. Summary of the invention

[0003] In order to overcome the above shortcomings, the purpose of the present invention is to provide a method for optimizing the cultivation of microalgae to improve the output of microalgae, so as to solve the technical problem that the existing microalgae cultivation lacks the reasonable selection and application of stirring paddles, resulting in low microalgae output. The purpose is achieved through the following technical solution.

[0004] A method for optimizing cultivation to improve the output of microalgae, the equipment of the method comprises a transparent cultivation container, a stirring paddle in the cultivation container, an auxiliary light source for uniformly supplementing the surrounding surface of the cultivation container, the stirring paddle has an adjustable speed, and the auxiliary light source has an adjustable light intensity, and the method is characterized in that the method comprises the following steps:

[0005] Step 1: for the first experimental group, a number of stirring paddles with different stirring blade types and culture containers corresponding to the number of stirring paddles are prepared, and each culture container is equipped with an external auxiliary light source;

[0006] Step 2: Put an equal amount of microalgae seed liquid into each culture container, and put each stirring paddle into the culture container;

[0007] Step 3, the rotation speeds of the stirring blades are the same, the illumination intensities of the auxiliary light sources are the same, and each culture container is subjected to a cycle of microalgae culture. During the culture period, the biomass, phycoerythrin content, and polysaccharide content of the microalgae in each culture container are measured regularly, and corresponding graphs are prepared;

[0008] Step 4, according to the results of the chart, select a culture container with the best comprehensive culture results of microalgae biomass, phycoerythrin content and polysaccharide content, and use the stirring paddle of the culture container as the stirring paddle of the second experimental group;

[0009] Step 5, the second experimental group, prepare a number of culture containers and the stirring paddles of the above step 4 corresponding to the number of culture containers, and each culture container is equipped with an external auxiliary light source;

[0010] Step 6, placing an equal amount of microalgae seed solution in each culture container, and placing each stirring paddle in the culture container;

[0011] Step 7, the stirring speed of each culture container is different, and is divided into at least three stirring speeds of low, medium and high. The illumination intensity of each auxiliary light source is the same, and each culture container is subjected to a cycle of microalgae cultivation. During the cultivation period, the microalgae biomass, phycoerythrin content and polysaccharide content in each culture container are measured regularly, and corresponding charts are prepared;

[0012] Step 8, according to the results of the chart, select a culture container with the best comprehensive culture results of microalgae biomass, phycoerythrin amount and polysaccharide amount, and use the stirring paddle speed of the culture container as the stirring paddle speed of the third experimental group;

[0013] Step nine, the third experimental group, prepare a number of culture containers and the stirring paddles of the above step four corresponding to the number of culture containers, and set the auxiliary light source on the circumference of each culture container;

[0014] Step 10, placing an equal amount of microalgae seed liquid in each culture container, and placing each stirring paddle in the culture container;

[0015] Step 11, the stirring paddles in each culture container adopt the stirring paddle speed of step 8, and the auxiliary light source intensity outside each culture container is different, and is divided into at least three light source intensities of low, medium and high. Each culture container is subjected to a cycle of microalgae cultivation, and the microalgae biomass, phycoerythrin content and polysaccharide content in each culture container are measured regularly during the cultivation period, and corresponding charts are prepared;

[0016] Step 12, according to the results of the chart, select a culture container with the best comprehensive culture results of microalgae biomass, phycoerythrin amount and polysaccharide amount, and use the light intensity of the auxiliary light source outside the culture container as the light intensity for subsequent microalgae culture;

[0017] The above optimizations obtain the type of stirring paddle, stirring speed of the stirring paddle, and intensity of the auxiliary light source required for culturing microalgae, which are used for subsequent microalgae cultivation.

[0018] The microalgae is Porphyridium.

[0019] The types of stirring blades in step one include inclined plate blades, triangular plate blades, circular plate blades and frame plate blades.

[0020] The stirring speeds in step seven include a low speed of 90 RPM, a medium speed of 120 RPM, and a high speed of 150 RPM.

[0021] The light source intensity in step 11 includes a low intensity of 70 μmol·m -2 s -1 , medium intensity 100 μmol·m -2 s -1 , high intensity 130μmol·m -2 s -1 .

[0022] The present invention combines fluid dynamics characteristics and can effectively select reasonable stirring blades, rotation speeds and light intensity for specific microalgae, thereby improving the efficiency and output of microalgae cultivation. It is suitable for use as an optimization method for improving microalgae cultivation output, or an improvement of similar methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is an experimental diagram of the culture container and stirring paddle of the present invention.

[0024] Figure 2 This is the inclined plate blade structure of the present invention.

[0025] Figure 3 This is the frame plate blade structure of the present invention.

[0026] Figure 4 It is the triangular plate blade structure of the present invention.

[0027] Figure 5 This is the circular plate blade structure of the present invention.

[0028] Figure 6 It is a cloud diagram of vertical flow velocity under the stirring paddle of four different stirring blade types in the culture container of the present invention.

[0029] Figure 7 It is the horizontal flow velocity vector diagram under the stirring paddle of four different stirring blade types in the culture container of the present invention.

[0030] Figure 8 It is a horizontal shear rate cloud diagram under the stirring paddle of four different stirring blade types in the culture container of the present invention.

[0031] Fig. 9 This is a graph showing the effects of four different types of stirring blades on the biomass, polysaccharides and phycoerythrin of Porphyridium cruentum in the culture container of the present invention.

[0032] Fig.10 It is a relationship diagram of the average radial velocity of the present invention and the biomass and specific growth rate of Porphyridium.

[0033] Fig.11 It is a vertical flow velocity cloud diagram of different rotation speeds of stirring paddles of the same blade type in the culture container of the present invention.

[0034] Fig.12It is a horizontal flow velocity vector diagram of a stirring paddle of the same blade type at different rotation speeds in the culture container of the present invention.

[0035] Fig.13 It is a horizontal shear rate cloud diagram of a stirring paddle of the same blade type and different rotation speeds in the culture container of the present invention.

[0036] Fig.14 This is a chart showing the effects of different rotation speeds of a stirring paddle of the same blade type in a culture container of the present invention on the biomass, polysaccharide and phycoerythrin of Porphyridium cruentum.

[0037] Fig.15 1 is a relationship diagram between the average radial velocity and the rotation speed of the stirring blade of the present invention.

[0038] Fig.16 The invention discloses the influence of the same stirring paddle and the same rotation speed on the biomass and specific growth rate of Porphyridium cruentum under different light intensities.

[0039] Fig.17 The invention discloses the influence of different light intensities on the concentration and content of phycoerythrin of Porphyridium cruentum under the same stirring paddle and the same rotation speed. Implementation

[0041] Taking the cultivation of Porphyridium cruentum as an example, the specific implementation of the present invention is described as follows.

[0042] like Figure 1 As shown, the equipment used in the cultivation optimization method for improving microalgae output includes a transparent culture container 1, a stirring paddle 2 located in the culture container, and an auxiliary light source 3 that forms uniform fill light on the circumference of the culture container, and the stirring paddle has an adjustable speed and the auxiliary light source has an adjustable light intensity.

[0043] The cultivation optimization method specifically includes the following steps.

[0044] Step 1, first experimental group, prepare several stirring blades of different types, such as Figure 2-Figure 5 As shown, the stirring blade types are inclined plate blade (Type-1), triangular plate blade (Type-2), circular plate blade (Type-3) and frame plate blade (Type-4), and culture containers corresponding to the number of stirring paddles are prepared, and the culture container is 50L.

[0045] Step 2: put an equal amount of Porphyridium seed liquid into each culture container. The Porphyridium seed liquid is the pre-prepared Porphyridium seed liquid cultured for about 16 days. It is inoculated into the 50L culture container at a 5% inoculation rate, and each stirring paddle is installed in the culture container.

[0046] Step 3: The speed of each stirring blade is the same, all set to 120RPM, and ventilation is provided to each culture container at the same time, with a ventilation rate of 15L·min -1The environmental conditions were set as follows: temperature 25°C, the intensity of the auxiliary light source was set to 100 μmol·m -2 s -1 , the microalgae were cultured in each culture container for 24 days, and the biomass, phycoerythrin and polysaccharide content of the microalgae in each culture container were measured every four days during the culture period, and corresponding charts were prepared, namely Figure 6-Figure 9 , and as shown in Table 1 and Table 2 below.

[0047] Table 1: Average radial flow velocity under different types of impellers in culture vessels

[0048]

[0049] Table 2: Shear rate under different types of impellers in culture vessels

[0050]

[0051] By the above Figure 6 It can be seen that there is almost no red area around the Type-3 impeller, and the maximum velocity of the fluid in this area is smaller than that of the other three impellers. Compared with the faster flow rate of Type-2, the flow rate in the top area of ​​Type-1 and Type-4 is extremely low, and although the overall fluid velocity of the Type-3 impeller is relatively slow, there is almost no area with extremely low fluid velocity. During the cultivation of microalgae, there may be dead zones at locations where the algae liquid flow rate is low, which can easily lead to algae accumulation and deteriorate the physiological state of algae cells. Therefore, in order to avoid the above phenomenon and improve the energy efficiency of microalgae cultivation, the proportion of dead zones should be minimized. For microalgae cultivation, light utilization efficiency is a key factor in the growth of microalgae. Since the fluid in the culture container is affected by the radial flow of the rotating impeller, there is a vortex in the culture container. The vortex can increase the frequency of cells circulating back and forth between the light and dark areas, thereby reducing the light-dark cycle. Figure 7 The horizontal velocity vector diagrams of the fluid in the culture container under four different types of stirring paddles were simulated. The average fluid velocity along the light gradient direction was introduced to quantitatively describe the degree of fluid mixing in the direction of light attenuation. The light intensity is vertically incident on the surroundings of the culture container, so the radial velocity of the fluid can represent the flow velocity of the fluid in the direction of light attenuation. Figure 7 As shown in Table 1, the radial velocity of the four types of impellers is Type-2, Type-3, Type-4 and Type-1, indicating that the fluid mixing degree is better under the Type-2 impeller. Figure 8 As shown in Table 2, the shear strain rate of the fluid under the Type-2 impeller is also larger, reaching 11.59s -1 , while the shear strain rate of Type-3 is 9.03s -1 , the shear strain rate of Type-1 is 8.84s-1 , the shear strain rate of Type-4 is 6.63s -1 Although the Type-2 has a better mixing degree, the high average shear strain rate is not a good phenomenon, which may cause considerable damage to the biomass productivity of microalgae. Therefore, the Type-3 impeller with better mixing performance and relatively low shear strain rate is more conducive to the growth of Porphyridium cells.

[0052] Fig. 9 The graphs of the biomass, phycoerythrin and polysaccharide concentrations of Porphyridium cruentum under different types of stirring blades in the reactor are shown. Fig. 9 As shown in A, under four different types of stirring paddles, the biomass of Porphyridium increased rapidly in the first 4 days, and the biomass concentration increased slowly after 4 days. The biomass concentration under the four stirring paddles was not much different, reaching the maximum value on the 20th day. The biomass concentration of Porphyridium under Type-3 stirring paddle was the largest, which was 1.34 g / L -1 , and there is a slow downward trend after 20 days. Fig. 9 As shown in B, under Type-3 impeller, the specific growth rate of Porphyridium cruentum is greater than that of the other three types, which is 0.15d -1 Obviously, the growth of Porphyridium cruentum is better under Type-3 stirring paddle. Fig. 9 C and Fig. 9 D shows the change of phycoerythrin concentration and content of Porphyridium cruentum under different types of stirring paddles in the reactor. As shown in Figure 9C, during the entire culture cycle, the phycoerythrin concentration under Type-1 and Type-2 stirring paddles increased slowly, reached the maximum value on the 20th day, and then slowly decreased. However, under Type-3 and Type-4 stirring paddles, the phycoerythrin concentration increased slowly in the first 4 days, and the increase rate became faster from 4 to 20 days, and also reached the maximum value on the 20th day, and finally decreased rapidly. The maximum phycoerythrin concentration in the entire culture process was achieved under the Type-3 stirring paddle, which was 67.34 mg / L -1 Similarly, the phycoerythrin concentration under Type-4 impeller was 67.22 mg / L -1 In addition, as shown in 9D, the phycoerythrin content under the four types of impellers showed a trend of first increasing and then decreasing, but reached the maximum value of 50.25 mg g under the Type-3 impeller. -1 . Fig. 9 E and Fig. 9 F represents the change of concentration and content of Porphyridium cruentum polysaccharide under different types of stirring blades in the reactor. Fig. 9 As shown in E, during the entire culture cycle, the polysaccharide concentrations under the Type-1, Type-2, Type-3, and Type-4 stirring paddles increased slowly, remained basically unchanged after the 20th day, and reached a maximum value on the 24th day. The polysaccharide concentration under the Type-4 stirring paddle was the highest, at 0.12 g / L-1 , which are 1.14, 1.15 and 1.3 times of those under Type-1, Type-2 and Type-3 stirring paddles, respectively. Fig. 9 As shown in F, the polysaccharide content under the four types of stirring impellers is very low, lower than the content at the initial inoculation.

[0053] Different types of impellers not only changed the flow state in the reactor, but also changed the light level in the reactor. The relationship between the biomass concentration and specific growth rate of Porphyridium cruentum and the radial flow velocity was analyzed. Fig.10 As shown in the figure, it was found that the biomass concentration and specific growth rate of Porphyridium cruentum increased first and then decreased with the increase of radial flow velocity, and reached the maximum value at the radial velocity under the Type-3 impeller. Therefore, the Type-3 impeller in the reactor is more suitable for the growth of Porphyridium cruentum.

[0054] Step 4: According to the results in the chart, select the stirring propeller with triangular plate blades as the stirring propeller for the second experimental group.

[0055] Step 5, second experimental group, prepare three culture containers identical to those in step 1, and stirring paddles from step 4 corresponding to the number of culture containers.

[0056] Step 6: In the same manner as step 2, an equal amount of microalgae seed solution is placed in each culture container, and each stirring paddle is installed in the culture container.

[0057] Step 7: The stirring speed of each culture container is different, which is divided into three stirring speeds: low speed 90RPM, medium speed 120RPM, and high speed 150RPM. At the same time, ventilation is provided to each culture container at a ventilation rate of 15L·min -1 The environmental conditions were set as follows: temperature 25°C, the intensity of the auxiliary light source was set to 100 μmol·m -2 s -1 , the microalgae were cultured in each culture container for 24 days, and the biomass, phycoerythrin and polysaccharide content of the microalgae in each culture container were measured every four days during the culture period, and corresponding charts were prepared, namely Figure 11-Figure 15 , and as shown in Table 3 and Table 4 below.

[0058] Table 3: Average radial flow velocity at different speeds under the same impeller in the culture vessel

[0059]

[0060] Table 4: Shear rate at different speeds of the same impeller in the culture vessel

[0061]

[0062] like Fig.11As shown in the figure, at three different rotational speeds, the main fluid flow is mainly near the two impellers, but two extremes are formed at low and high rotational speeds. At a high rotational speed of 150RPM, the fluid flow rate around the agitator is very fast, and there is more red in this area. The fluid flow in this area is mainly affected by the high rotational speed and bubbling. At a low rotational speed of 90RPM, the fluid flow rate around the agitator is slower, and there is almost no red area in this area. At an intermediate rotational speed of 120RPM, the fluid flow rate around the agitator is between the flow rates at low and high rotational speeds. In addition, as the distance from the agitator increases, the speed of the fluid is relatively slower, and the corresponding color is bluer. Similarly, under different rotational speed conditions, the radial flow rate of the fluid in the reactor is different due to the different rotational speeds of the agitator. As shown Fig.12 As shown in Table 3, the radial velocity of the fluid at three different speeds is related to the speed of the stirring blade, and the speed is positively correlated with the radial velocity of the fluid. At high speeds, the flow velocity near the reactor wall is larger, while at low speeds, the closer to the reactor wall, the smaller the speed. Since the average radial velocity of the fluid is proportional to the light-dark cycle of the cell, the degree of mixing of the fluid is better under the condition of a speed of 150RPM.

[0063] But accordingly, Fig.13 As shown in Table 4, when the radial velocity of the fluid in the reactor is large, the shear strain rate generated is also large. At a high stirring speed of 150RPM, the shear strain rate in the entire reactor area is very high. At a low stirring speed of 90RPM and a medium speed of 120RPM, the high shear strain rate mainly exists around the stirring paddle. When the stirring paddle speed is 150RPM, the average shear strain rate reaches 10.6s -1 , which are 1.46 and 1.17 times of those at 90RPM and 120RPM, respectively. Therefore, when only the mixing degree inside the reactor is considered, a stirring paddle speed of 150RPM is more conducive to cell growth. On the contrary, when considering the damage of shear force to cells, a stirring paddle at a low speed is more conducive to cell growth.

[0064] like Fig.14 As shown, Fig.14 A and Fig.14 B shows the changes in the biomass and specific growth rate of Porphyridium cruentum at different speeds of the Type-3 impeller in the reactor. Fig.14 As shown in A, from 0 to 12 days, the biomass concentration of Porphyridium increased rapidly under the three different rotation speeds, reaching the maximum value of 0.95 g L-1 at 90 RPM, 120 RPM, and 150 RPM on the 12th day, respectively. -1 , 1.01gL -1 and 1.37 gL -1, the biomass concentration remained almost unchanged or showed a slight downward trend from 12 to 20 days, and then dropped rapidly after 20 days. Fig.14 As shown in B, the specific growth rate of Porphyridium cruentum at 150 RPM was significantly greater than that of the other two groups, which was 0.09d -1 . Fig.14 C and Fig.14 D respectively represents the change of the concentration and content of phycoerythrin in Porphyridium cruentum at different speeds of the Type-3 stirring paddle in the reactor. Fig.14 As shown in C, during the entire culture period, the phycoerythrin content of Porphyridium cruentum at 90 RPM, 120 RPM, and 150 RPM first increased slowly and then decreased slightly, and reached the maximum value on the 20th day, which was 50.09 mg / L -1 45.05mgL -1 and 66.29mgL -1 In addition, if Fig.14 As shown in D, the phycoerythrin content was higher when the stirring speed of the impeller was 120 RPM between 4-12 days, and the phycoerythrin content was higher when the stirring speed of the impeller was 90 RPM between 16-24 days. Fig.14 E and Fig.14 F represents the change of concentration and content of Porphyridium crucianum polysaccharide at different speeds of Type-3 stirring paddle in the reactor. Fig.14 As shown in E, between 0 and 12 days, the polysaccharide concentration increased rapidly at the three rotation speeds of 90 RPM, 120 RPM, and 150 RPM, reaching a maximum value of 0.129 g L at a rotation speed of 150 RPM on the 12th day. -1 After 12-24 days, the trend remained unchanged or slowly decreased, which was similar to the trend of phycoerythrin in the late culture period. Fig.14 As shown in F, within 4-24 days, the overall trend is first decreasing and then increasing.

[0065] like Fig.15 As shown in the figure, as the speed of the stirring blade in the reactor increases, the average radial velocity of the fluid also increases. This means that, to a certain extent, the speed and radial velocity are directly proportional. Through the optimization experiment of Porphyridium cruentum, it was found that as the speed of the stirring blade increases, the biomass concentration, specific growth rate and phycoerythrin concentration of Porphyridium cruentum also increase, reaching the maximum value when the stirring blade speed is 150RPM. Therefore, Porphyridium cruentum grows better when the stirring blade speed is 150RPM.

[0066] Step 8. According to the results in the chart, select a stirring blade speed of 150 RPM as the stirring blade speed for the third experimental group.

[0067] Step nine, the third experimental group, prepare three culture containers identical to those in step one, and stirring paddles from step four corresponding to the number of culture containers, and set auxiliary light sources around the periphery of each culture container.

[0068] Step 10: In the same manner as step 2, an equal amount of microalgae seed liquid is placed in each culture container, and each stirring paddle is installed in the culture container.

[0069] Step 11: The stirring paddles in each culture container adopt the stirring paddle speed of step 8, i.e., 150 RPM, and the auxiliary light intensity of each culture container is different, including low light intensity of 70 μmol·m -2 s -1 , medium light intensity 100 μmol·m -2 s -1 , high light intensity 130μmol·m -2 s -1 Three light intensities, ventilation to each culture container at the same time, ventilation rate of 15L·min -1 The environmental conditions were set as follows: temperature 25°C, the intensity of the auxiliary light source was set to 100 μmol·m -2 s -1 , the microalgae were cultured in each culture container for 24 days, and the biomass, phycoerythrin and polysaccharide content of the microalgae in each culture container were measured every four days during the culture period, and corresponding charts were prepared, namely Figure 15-17 .

[0070] Depend on Fig.16 As shown in the figure, the changes in biomass and specific growth rate of Porphyridium crucianum under different incident light intensities at a Type-3 stirring impeller and a rotation speed of 150RPM in the culture container. Fig.16 As shown in the left figure, the biomass concentration increased slowly from 0 to 4 days, and from 4 to 24 days, the biomass concentration increased rapidly first and then decreased slowly, and reached the maximum value on the 20th day. -2 s -1 , 100 μmol·m -2 s -1 and 130 μmol·m -2 s -1 The biomass concentrations were 1.16, 1.44 and 1.26 gL -1 In addition, if Fig.15 As shown in the figure on the right, when the light intensity is 100 μmol m -2 s -1 The specific growth rate of Porphyridium cruentum was significantly greater than that of the other two light intensities, which was 0.14d -1 .

[0071] like Fig.17As shown in the figure, the concentration and content of phycoerythrin in Porphyridium cruentum are changed by different incident light intensities under the Type-3 stirring impeller and the rotation speed of 150RPM in the culture container. Fig.17 As shown in the left figure, during the entire culture period, the concentration of phycoerythrin increased first and then decreased, reaching a maximum on the 20th day. On the 20th day, when the incident light intensity was 100 μmol·m -2 s -1 The concentration of phycoerythrin in Porphyridium cruentum was the highest at 59.54 mg / L -1 , is the incident light intensity of 70 μmol·m -2 s -1 and 100 μmol·m -2 s -1 However, as shown in the right figure of Figure 17, at a low light intensity of 70 μmol·m -2 s -1 The phycoerythrin content is higher.

[0072] The changes of the concentration and content of polysaccharides in Porphyridium crucium under different incident light intensities at a Type-3 stirring paddle and a rotation speed of 150 RPM in the culture container are as follows: During the entire culture period, when the incident light intensity was 70 μmol·m -2 s -1 and 130 μmol·m -2 s -1 When the incident light intensity was 100 μmol·m -2 s -1 The polysaccharide concentration also showed a trend of increasing first and then slowly decreasing, reaching a maximum of 0.16 g / L on the 20th day. -1 , which was higher than the other two groups. However, the changes in polysaccharide content did not change much among the three groups of incident light intensities in the late culture period.

[0073] From the above, we can know that the culture container has a light intensity of 100 μmol·m -2 s -1 When the biomass, phycoerythrin and polysaccharide concentrations of Porphyridium cruentum reached their maximum values, which were 1.43 g / L -1 、59.54mgL -1 and 0.16 gL -1 .

[0074] Step 12: According to the results of the chart, select the auxiliary light source with an intensity of 100 μmol·m -2 s -1 As the light source intensity for subsequent microalgae cultivation.

[0075] The above optimizations are used to obtain the type of stirring blade, stirring speed of the stirring blade, and the intensity of the auxiliary light source required for the cultivation of Porphyridium cruentum, so as to facilitate the large-scale cultivation of Porphyridium cruentum in the later stage. When it is necessary to optimize the cultivation of other microalgae, the same method can also be used.

Claims

1. A method for optimizing the cultivation of microalgae to improve its yield, wherein the equipment of the method comprises a transparent cultivation container, a stirring paddle in the cultivation container, an auxiliary light source for uniformly supplementing the surrounding surface of the cultivation container, wherein the stirring paddle has an adjustable speed, and the auxiliary light source has an adjustable light intensity, wherein the equipment comprises: The cultivation optimization method comprises the following steps: Step 1: for the first experimental group, a number of stirring paddles with different stirring blade types and culture containers corresponding to the number of stirring paddles are prepared, and each culture container is equipped with an external auxiliary light source; Step 2: Put an equal amount of microalgae seed liquid into each culture container, and put each stirring paddle into the culture container; Step 3, the rotation speeds of the stirring blades are the same, the illumination intensities of the auxiliary light sources are the same, and each culture container is subjected to a cycle of microalgae culture. During the culture period, the biomass, phycoerythrin content, and polysaccharide content of the microalgae in each culture container are measured regularly, and corresponding graphs are prepared; Step 4, according to the results of the chart, select a culture container with the best comprehensive culture results of microalgae biomass, phycoerythrin content and polysaccharide content, and use the stirring paddle of the culture container as the stirring paddle of the second experimental group; Step 5, the second experimental group, prepare a number of culture containers and the stirring paddles of the above step 4 corresponding to the number of culture containers, and each culture container is equipped with an external auxiliary light source; Step 6, placing an equal amount of microalgae seed solution in each culture container, and placing each stirring paddle in the culture container; Step 7, the stirring speed of each culture container is different, and is divided into at least three stirring speeds of low, medium and high. The illumination intensity of each auxiliary light source is the same, and each culture container is subjected to a cycle of microalgae cultivation. During the cultivation period, the microalgae biomass, phycoerythrin content and polysaccharide content in each culture container are measured regularly, and corresponding charts are prepared; Step 8, according to the results of the chart, select a culture container with the best comprehensive culture results of microalgae biomass, phycoerythrin amount and polysaccharide amount, and use the stirring paddle speed of the culture container as the stirring paddle speed of the third experimental group; Step nine, the third experimental group, prepare a number of culture containers and the stirring paddles of the above step four corresponding to the number of culture containers, and set the auxiliary light source on the periphery of each culture container; Step 10, placing an equal amount of microalgae seed liquid in each culture container, and placing each stirring paddle in the culture container; Step 11, the stirring paddles in each culture container adopt the stirring paddle speed of step 8, and the auxiliary light source intensity outside each culture container is different, and is divided into at least three light source intensities of low, medium and high. Each culture container is subjected to a cycle of microalgae cultivation, and the microalgae biomass, phycoerythrin content and polysaccharide content in each culture container are measured regularly during the cultivation period, and corresponding charts are prepared; Step 12, according to the results of the chart, select a culture container with the best comprehensive culture results of microalgae biomass, phycoerythrin amount and polysaccharide amount, and use the light intensity of the auxiliary light source outside the culture container as the light intensity for subsequent microalgae culture; The above optimizations obtain the type of stirring paddle, stirring speed of the stirring paddle, and intensity of the auxiliary light source required for culturing microalgae, which are used for subsequent microalgae cultivation.

2. The method for optimizing the cultivation of microalgae according to claim 1, characterized in that The microalgae is Porphyridium.

3. The method for optimizing the cultivation of microalgae according to claim 1, characterized in that The types of stirring blades in step 1 include inclined plate blades, triangular plate blades, circular plate blades and frame plate blades.

4. The method for optimizing the cultivation of microalgae according to claim 1, characterized in that The stirring speeds in step seven include a low speed of 90 RPM, a medium speed of 120 RPM, and a high speed of 150 RPM.

5. The method for optimizing the cultivation of microalgae according to claim 1, characterized in that The light source intensity in step 11 includes a low intensity of 70 μmol·m -2 s -1 , medium intensity 100 μmol·m -2 s -1 , high intensity 130μmol·m -2 s -1 .

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