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蜡样芽孢杆菌TC

花匠小妙招
2024-11-06 18:45

Abstract:

Saline-alkaline water resources in China are widely distributed. Saline-alkaline water is characterized by a high pH value, carbonate alkalinity, and ion coefficient. Therefore, regulating water quality has become a key challenge and focus of saline-alkaline aquaculture. Frequent outbreaks of harmful Cyanobacteria in saline-alkaline ponds severely affect the healthy growth of aquaculture organisms. Microcystis spp. is one among the major harmful Cyanobacteria. Currently, the primary methods for controlling harmful Cyanobacteria include physical, chemical, and biological methods. However, physical or chemical methods for preventing and controlling algal blooms have certain limitations, such as being time-consuming, labor-intensive, heavy pollutants, and prone to recurrence. Biological methods, such as the use of algicidal bacteria, are highly efficient and safe, making them a hot research topic. In the aquaculture industry, Bacillus species with algicidal properties, such as Bacillus subtilis, Bacillus cereus, Lysinibacillus fusiformis, and Brevibacillus laterosporus are receiving increasing attention from researchers. However, a few reports are available on algicidal bacteria against harmful Cyanobacteria in saline-alkaline ponds. The Ningxia Hui Autonomous Region, located in the northwest of China, has several northwest sulfate-type saline-alkaline ponds. In this study, we selected a strain of B. cereus TC-1, which was isolated and screened from the microalgae environment in saline-alkaline ponds of Ningxia Hui Autonomous Region. The growth adaptability of this strain was studied under different conditions of salinity (5, 15, 25, and 35), pH (4.0, 6.0, 8.0, and 10.0), temperature (10 ℃, 20 ℃, 30 ℃, and 40 ℃), and alkalinity (4.0 mmol/L, 8.0 mmol/L, 12.0 mmol/L, and 16.0 mmol/L). Additionally, its algal solubilization effects on two kinds of Microcystis were explored. Using nutrient agar culture medium, the bacterial density of each experimental group was determined on days 0, 2, 4, 6, and 8. The results showed that strain TC-1 grew well under conditions of salinity of 5–35, pH 6.0–10.0, temperature of 20 ℃–40 ℃, and alkalinity of 4.0–16.0 mmol/L. The best growth was observed under conditions of salinity of 15, pH 8.0, temperature of 30 ℃, and alkalinity of 12.0 mmol/L, with a bacterial density of (1.14±0.16)×108 CFU/mL. In the co-cultivation system of saline-alkaline water with alkalinity of 4.0 mmol/L and 12.0 mmol/L, the algicidal effects of strain TC-1 on Microcystis aeruginosa and Microcystis sp. were significant. After the action of B. cereus strain TC-1, phenomena, such as fading, cell wall rupture, blurred and deformed edges, and protoplast efflux were observed, resulting in a significant decrease in the algal density. On the 6th day, the algicidal rate of strain TC-1 reached (82.83±0.03)% to (91.67±0.10)%. The results indicate that strain TC-1 has good adaptability to environmental factors, such as salinity, pH, temperature, and alkalinity which is generally consistent with the variation range of salinity, temperature, and pH in most saline-alkaline pond water. It has a good algicidal effect on Microcystis spp. and can be used as a candidate strain for the prevention and control of Microcystis blooms in saline-alkaline ponds.