Bacillus subtilis plays a key role in aquaculture, especially in shrimp farming, mainly including core functions such as water quality control, disease prevention and control, growth promotion and digestion enhancement. The specific functions are as follows:
1. Water quality control and bottom quality improvement Degradation of organic pollutants
Secreting extracellular enzymes such as protease, amylase, lipase, etc., efficiently decompose organic matter such as leftover bait, feces, dead algae, and reduce the chemical oxygen demand (COD) of water bodies. Studies have shown that after use, ammonia nitrogen (reduced by more than 50%) and nitrite (reduced by more than 60%) can be significantly reduced, and water transparency and dissolved oxygen levels can be improved.
Regulation of nitrogen cycle :
Through nitrification and denitrification, toxic ammonia nitrogen and nitrite are converted into low-toxic nitrates or nitrogen gas, reducing the risk of poisoning shrimp.
Inhibition of harmful algae :
Competitive consumption of eutrophic substances (such as nitrogen and phosphorus), effectively controlling the outbreak of harmful algae such as cyanobacteria and moss, and maintaining algae phase balance.
2. Disease prevention and control and immune enhancement
Direct inhibition of pathogens :
Metabolism produces antimicrobial peptides such as subtilisin and polymyxin, specifically inhibits common shrimp pathogens such as Vibrio (such as Vibrio parahaemolyticus) and Aeromonas, and reduces the incidence of diseases such as enteritis and gill rot by 34.
Improve shrimp immunity :
Stimulate the development of shrimp immune organs, promote the expression of immune-related genes, enhance nonspecific immunity, and reduce stress response.
Competitive occupation protection :
Rapidly reproduce in the intestines and water bodies to form dominant flora, and inhibit the colonization of pathogens through space and nutrient competition.
3. Promote growth and nutrient absorption
Improve intestinal health :
After colonization in the intestines, it secretes vitamins B1, B2 and organic acids, promotes the development of intestinal villi, and maintains microecological balance.
Enhance digestive efficiency :
The digestive enzymes (such as proteases and amylases) produced cooperate with shrimp endogenous enzymes to improve feed conversion rate and reduce feed coefficient (experiments show that the reduction can reach 18%). Improve the utilization rate of nutrients:
Promote the absorption of minerals such as calcium, phosphorus, and iron and the synthesis of vitamin D, and accelerate the growth and molting of shrimp.
4. precautions for use
Application conditions:
It should be used in the morning on a sunny day (9-11 am), and the water temperature should be ≥25℃ for the best effect; when it is below 15℃, the dosage should be doubled or the use of 1112 should be suspended.
When activated, aerate for more than 2 hours according to the ratio of bacteria: brown sugar: water ≈ 0.5:1.5:25 to ensure sufficient dissolved oxygen.
Contraindications:
Avoid using it with disinfectants and antibiotics at the same time, and use it with lactic acid bacteria at an interval of 24 hours.
When the total alkalinity of the water body is less than 80mg/L, sprinkle quicklime to adjust it before applying it.
Dosage control:
The recommended bacterial concentration in the white shrimp pond is 10^6 CFU/mL (slightly lower for fish), and excessive use can easily cause bacterial imbalance.
Summary
Bacillus subtilis has become the core tool for the green transformation of shrimp farming through the trinity mechanism of "water purification-disease suppression-growth promotion" Short-term benefits: rapid degradation of pollutants, relief of ammonia nitrogen/salt poisoning, and reduction of mortality rate; Long-term value: stabilization of water microecology, improvement of feed utilization and growth rate, and reduction of antibiotic dependence. Scientific application can significantly optimize the breeding environment and achieve a win-win situation of ecological and economic benefits.