Application of the bacterium Marivita litorea in improving the heat tolerance of large calcified algae
By adding the seaweed symbiotic bacterium Marivita litorea to the large calcified algae growth system, the problem of inhibited algal growth and calcification function under high temperature was solved, and the effect of improving its high temperature tolerance and growth rate was achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SOUTH CHINA SEA INST OF OCEANOLOGY CHINESE ACAD OF SCI
- Filing Date
- 2025-10-22
- Publication Date
- 2026-07-31
AI Technical Summary
Large calcifying algae experience inhibited growth and calcification under high temperature stress, threatening the stability of coral reef ecosystems. Existing technologies lack effective means of microbial regulation.
By incorporating the seaweed symbiotic bacterium Marivita litorea into a large calcified algae growth system, the negative effects of high temperatures on algae were mitigated, and their high-temperature tolerance was improved.
It effectively enhances the growth rate and photosynthetic efficiency of large calcified algae, maintains their calcification function, and alleviates the inhibitory effect caused by high temperature stress.
Smart Images
Figure CN121465043B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the fields of biotechnology and ecological protection, specifically relating to the application of a seaweed symbiotic bacterium, Marivitaltitorea, in improving the high-temperature tolerance of large calcified algae. Background Technology
[0002] Macrocalcifying algae are a special type of large algae whose cells, during growth, can form calcified deposits, primarily composed of CaCO3, through calcification, thus serving as their supporting framework. As the main calcifying organisms in coral reef ecosystems, macrocalcifying algae have extremely important ecological functions: 1) They can calcify and form calcium carbonate deposits simultaneously with photosynthetic growth, making them the main builders of coral reefs. Studies have shown that macrocalcifying algae are the main contributors to coral islands and reefs in the South my country Sea, accounting for more than 50%; 2) They are important contributors to marine primary productivity, synergistically regulating carbon flux changes in coral reef areas through unique inorganic carbon mineralization and organic carbon metabolism processes, occupying an important position in the marine carbon cycle; 3) They can also induce attachment metamorphosis of coral and other invertebrate larvae, thereby affecting their larval replenishment.
[0003] However, in recent decades, influenced by human activities and global climate change, the frequency and intensity of marine heat waves have increased significantly. Between 1980 and 2020 alone, seawater temperatures rose by 1.1°C, leading to the loss of over 10% of coral reefs worldwide. As important calcifying organisms in coral reef ecosystems, macrocalcifying algae also face severe survival challenges under such high-temperature stress: multiple studies have confirmed that high temperatures inhibit the growth and calcification of macrocalcifying algae, even causing algal bleaching and death, thus threatening the stable development of coral reef ecosystems. Zhang et al. (2025) found that 31°C led to a decrease in the photosynthetic performance of *Halimeda macroloba*, and abnormal expression of proteins related to light capture, photosynthesis, and carbon fixation. Buapet et al. (2023) observed that *H. macroloba* and *H. opuntia* showed decreased photosynthetic carbon fixation and calcification rates at 32-42°C, with even calcium carbonate dissolution observed at 42°C, directly affecting reef stability. Therefore, in the context of global warming, how to improve the temperature tolerance of calcified algae and promote their calcification and growth has become a key scientific and technological problem that urgently needs to be solved.
[0004] Microorganisms have a close relationship with their hosts and play an important role in the host's growth process, offering new directions for solving this problem. For example, Santoro et al. (2021) found that probiotics help corals recover from heat stress-induced bleaching and significantly improve coral survival rates. Doering (2021) found that inoculation with bacteria such as Rhodobacteraceae can alleviate the bleaching response of corals under heat stress, speculating that these bacteria enhance coral heat tolerance through mechanisms such as antioxidant activity, metabolic support, or pathogen inhibition. However, there are currently no reports on the effects of microorganisms on the high-temperature tolerance of large calcified algae. Summary of the Invention
[0005] The purpose of this invention is to provide the application of the bacterium Marivita litorea in improving the heat tolerance of large calcified algae.
[0006] This invention, through experiments, reveals that *M. litorea* can effectively alleviate the negative impact of high temperatures on the growth of *Cymbidium*, mitigating the inhibitory effect of high temperatures on its photosynthesis. The addition of *M. litorea* can effectively alleviate the decrease in calcification rate caused by high-temperature stress through a certain physiological regulatory mechanism, thus playing a positive role in maintaining the calcification function of *Cymbidium*.
[0007] Therefore, this invention provides the application of the bacterium Marivita litorea in improving the heat tolerance of large calcified algae.
[0008] Preferably, the large calcified algae can be various large calcified algae, such as *Cymbidium*, *Cymbidium cycloidum*, *Cymbidium macrocarpa*, *Cymbidium porphyria*, etc.
[0009] Preferably, the application of the bacterium Marivita litorea in the preparation of agents that improve the heat tolerance of large calcified algae is preferred.
[0010] A second objective of this invention is to provide a method for improving the high-temperature tolerance of large calcified algae by adding the bacteria Marivita litorea to the growth system of large calcified algae.
[0011] Preferably, the concentration added is 5×10 6 CFU / ml.
[0012] Ideally, it should be added once every seven days.
[0013] Preferably, the bacteria Marivita litorea is the bacteria with accession number GDMCC NO.1.641.
[0014] This invention focuses on the symbiotic bacterium Marivita litorea, and for the first time explores its regulatory role in the high-temperature tolerance of large calcified algae, especially in the calcification and growth processes. This not only fills a research gap in this field, but also provides a new and innovative solution for improving the stress resistance of calcified algae and contributing to the protection and restoration of coral reef ecosystems through microbial regulation technology. It has significant scientific value and application prospects. Attached Figure Description
[0015] Figure 1 These are images of the bacteria Marivita litorea cultured in 2216E solid and liquid media.
[0016] Figure 2 This refers to the growth, photosynthesis, and calcification of *Cactus* under different culture conditions. Detailed Implementation
[0017] The following embodiments are further illustrations of the present invention, but not limitations thereof.
[0018] Example 1:
[0019] 1. Sample collection and temporary holding
[0020] The large calcified algae *Halimeda opuntia* was selected as the experimental material and collected from coral reef areas in the South China Sea at a sampling depth of 4-10 m. After collection, attached debris was removed, and the samples were temporarily incubated for 15 days in an acrylic tank equipped with a filter and an oxygen pump to acclimatize them to the laboratory culture environment. The incubation conditions were: salinity 33-34 ppt, water temperature 26℃, photoperiod 12 L:12 D, and light intensity 60-80 μmol photons / m². -2 s -1 .
[0021] The bacterium *Marivita litorea* (accession number: GDMCC NO.1.641, deposited at Guangdong Provincial Center for Microbial Culture Collection on May 16, 2013) exhibits white, smooth colonies on 2216E solid medium. Figure 1 Left, in 2216 liquid culture medium as follows Figure 1 right).
[0022] 2. Experimental Design
[0023] After temporary rearing, *M. litorea* with good growth was selected as experimental material. After removing attached algae and sediment, the *M. litorea* was placed in an acrylic tank containing 5L of seawater for cultivation. Three groups were set up: a normal temperature group (26℃, no bacterial agent, T1), a high temperature group without bacterial agent (30℃, no bacterial agent, T2), and a high temperature group with bacterial agent (30℃ + *M. litorea*, T3). The inoculum size for the bacterial agent group was 5 × 10⁻⁶. 6 CFU / ml. The entire culture period was 21 days, with 7 ± 0.5 g of *Cypripedium cactus* added to each tank, and a light intensity of approximately 60 μmol photons / ml. -2 s -1 Two-thirds of the seawater was replaced every 3 days, and the entire culture tank and filter cotton were replaced every 6 days. The T3 group was re-inoculated with M. litorea every 7 days. On day 21, samples of M. litorea were collected to determine their growth rate, photosynthetic parameters, and calcification rate.
[0024] 3. Indicator Measurement
[0025] Growth rate: At the beginning and end of the experiment, the seawater on the surface of the algae was dried to constant weight using absorbent paper, and the relative growth rate was calculated according to the formula RGR = (lnW2 - lnW1) / (t2 - t1).
[0026] Maximum photochemical efficiency Fv / Fm: Algae from different groups were treated in the dark for 30 min and the Fv / Fm value of the algae was measured multiple times.
[0027] Calcification rate: The net calcification rate of *Cypripedium cactus* was determined using the total alkalinity (TA) differential method. The total alkalinity of the seawater was measured using an automated potentiometric titrator (ZDJ-4B, Leici, China). The *Cypripedium cactus* in the tank was placed in a beaker containing 1 L of 0.45 μM filtered seawater and cultured for 4 h under the same conditions as the experimental setup. The seawater was stirred every half hour to ensure homogeneity. The calculation formula is as follows:
[0028] G = 1000 × 0.5ρ × (TA0 - TA n ) × V / (F W × t)
[0029] In the formula, G represents the calcification rate (μmol gF). W -1 h -1 ); TA0 represents the alkalinity of seawater before the experiment; TA n The value represents the alkalinity of seawater after 4 hours; ρ represents the density of seawater (1.0305 g / cm³). -3 V represents the volume of seawater used for cultivation (1 L); F WThe fresh weight (g) of *Cymbidium goeringii* was determined by a culture time of t of 4 h.
[0030] 4. Test Results
[0031] The effects of the bacterium *Marivita litorea* on the growth and photosynthesis of *Cactus spp.* under high temperature conditions: (e.g.) Figure 2 As shown, compared with the normal temperature control group (T1 group), the relative growth rate of *Cymbidium cactus* in the high-temperature treatment group (T2 group) decreased significantly, by 87%, indicating that high temperature has a significant inhibitory effect on the growth of *Cymbidium cactus*. However, in the high-temperature treatment group with the addition of *M. litorea* bacteria (T3 group), the growth rate of *Cymbidium cactus* was significantly improved, increasing by 84.4% compared with T2 group; at the same time, observation of the algal state showed that some algae in the T2 group exhibited bleaching and death, while the bleaching rate of the algae in the *M. litorea*-treated group was significantly reduced. These results indicate that *M. litorea* can effectively alleviate the negative impact of high temperature on the growth of *Cymbidium cactus*.
[0032] Consistent with the trend in growth rate, high temperature led to a decrease in the photosynthetic efficiency (Fv / Fm) of *Cymbidium cactus*. However, the addition of *M. litorea* significantly increased the Fv / Fm value, with no significant difference compared to the control group at room temperature. This result indicates that *M. litorea* can alleviate the inhibitory effect of high temperature on the photosynthesis of *Cymbidium cactus*.
[0033] Effects of the bacterium *Marivita litorea* on the calcification of *Cypripedium cactus* under high-temperature conditions: Throughout the culture process, the pH of the seawater in each group was maintained within the range of 7.8-8.1, with no significant differences between groups. Regarding calcification, the calcification rate of *Cypripedium cactus* showed a significant decreasing trend under high-temperature conditions, but the decrease was less than that of the growth rate. Specifically, the calcification rate of the room-temperature control group (T1 group) was 5.9 μmol gFW. -1 h -1 The calcification rate of the high-temperature treatment group (T2 group) decreased by 38.2% compared to the T1 group, indicating that high temperature has a certain inhibitory effect on the calcification of *Cypripedium cactus*. Notably, in the treatment group (T3 group) with the addition of *M. litorea* bacteria under high-temperature conditions, the calcification rate of *Cypripedium cactus* was increased to approximately 5 μmol g FW. -1 h -1 The levels were close to those of the control group at room temperature, indicating that the addition of M. litorea can effectively alleviate the decrease in calcification rate caused by high temperature stress through some physiological regulation mechanism, and has a positive effect on maintaining the calcification function of M. litorea.
Claims
1. Bacteria Sea life on the coast The bacteria are used in improving the high-temperature tolerance of large calcified algae. Sea life on the coast It is a bacterium with accession number GDMCC NO.1.641, and the large calcified algae mentioned are *Cymbidium*, *Cymbidium cycloidum*, and *Cymbidium macrocarpa*.
2. The application according to claim 1, characterized in that, It is bacteria Sea life on the coast Application in the preparation of agents to improve the high-temperature tolerance of large calcified algae.
3. A method for improving the high-temperature tolerance of large calcified algae, characterized in that, It is bacteria Sea life on the coast The bacteria are added to the growth system of large calcified algae. Sea life on the coast It is a bacterium with accession number GDMCCNO.1.
641. Sea life on the coast The added concentration is 5×10 6 CFU / ml, bacteria Sea life beach You join once every seven days.