Screening And Compound Developing Of Tropical Bacillus For Water Purification And Detecting On Its Functions

A lot of bait, excrement and animal residues generated in mariculture lead to constant high content of COD and nitrogen in the farming water. The subsequent outbreaks of eutrophication and aquaculture diseases frequently caused heavy losses in aquaculture. Bacillus is a class of non-toxic aquaculture probiotic bacteria that could produce a variety of hydrolysis of extracellular enzymes to degrade macromolecular organic matters in aquaculture water. It has been used in aquaculture water purification process widely and obtained significant economic and ecological benefits. However, just as other microorganisms, bacillus exists different geographical populations. Rich and diverse tropical bacillus resources in the Hainan marine environment provides an excellent bacteria repositories for developing better tropical bacillus microbial agents suitable for improving tropical marine aquaculture water.In this study, two tropical bacillus with high protease activity, lipase activity, effective COD, nitrogen removal effect, were isolated and screened from tropical aquaculture systems in Nanshan of Sanya city, Xincun harbour of Lingshui country, Banqiao of Dongfang city and Biugang of Ledong country in hainan. Results of antagonism test showed that8strains of bacillus grew well with each other. Multivariate quadratic regression equation of8strains bacillus was established by using Plackett-Burman experiment design, according to results of water purification significant response and parameter analysis, and3strains of composite bacillus were screened ultimately; the central value on centration of3strains composite bacillus were determined by using steep climbing experiment design; Multivariate quadratic regression equation of3strains bacillus was established by Box-Behnken experiment design finally, and the optimum concentration of compound were determined, providing scientific reference and theoretical data for developing tropical indigenous bacillus compound preparation.sugarcane molasses was used as the main raw materialfor large-scale fermentation of the compound of tropical bacillus. Results show that the viable cells of the preparation reached5×109cfu/mL with stable protease activity and lipase activity. A high activity commercial preparation products were used as the control (control group) tomeasure the purification effect of bacillus preparation(experimental group) for tropical marine aquaculture water in Litopenaeus vannamei farming. Results of the experimental group showed that COD decreased more than97.22%, DO increased more than8.92%, ammonia, nitrite and nitrate ecreased88%,92%and75%, respectively; control group results showed that COD decreased93%, DO increased7%, ammonia, nitrite and nitrate decreased70%,90%and75%, respectively; both the experimental group and control group exhibitedt significant inhibition effect against vibrio. Therefore, tropical bacillus preparation has good prospects in improving tropical aquaculture water effectively.