Development Of New Type Of Bacillus Probiotics And Its Application In Eutrophic Water

Water pollution has a direct or potential threat to human survival and development. Implementation of bioremediation by microorganisms is becoming an important method for water treatment. Key to get excellent microbiol agent is to find efficient formulations of bacterial strains or combinations thereof used to treat polluted water.Bacillus species are commonly used microorganism to decontaminate aquaculture water. But few studies are associated with its application in the degradation of contaminated water both at home and abroad. In this paper, the cultivating characteristics of Bacillus, optimized conditions of spore production, conducted small scale laboratory biodegaration experiments of creek water were studied, aim to give reference to the development of new microbial agents. The results showed that:(1) The enzymatic activity of extracellular protease, cellulose and amylase of 4 bacillus strains (B. subtilis BL1003, B. laterosporus BL2002, B. lichenniformis BL1103 and P. polymyxa PP1004) under the conditions of plate culture and liquid fermentation were tested. Among them, P. polymyxa PP1004 has showed best enzyme activity, and H/C of amylase, cellulase, protease respectively achieved 7.12,6.09,3.71, and activities of amylase, cellulase, protease respectively achieved 31.31 MMU,1500U,320U respectively under the conditions of liquid fermentation.Comprehensive studies on inhibition effect of 4 bacillus against 7 kinds of pathogenic germs (E.coli, Enterococcus, Listeria monocytogenes, Yersinia intestinal colon bacteria, Pseudomonas, Salmonella, Staphylococcus aureus)with cross-crossed incubating method have showed that 4 bacillus species can effectively inhibit against pathogenic bacteria, and the inhibition against selected pathogenic bacteria showed accumulated effect with time.The inhibition function was: PP1004>BL2002>BL1103>BS1003, in which PP1004 showed best inhibitory effect on the pathogen.The medium elements and cultivating conditions of spore production of 4 bacillus species were optimized by flask culture, followed by conducting experiments with 30L fermentor based on the optimized results. The results showed that spore numbers of BS1003, PP1004, BL2002, BL1103 after fermentation have reached to 1.95×109,1.86×109,2.39×109 and 2.62×109 cfu/ml respectively after fermentation.(2) Four bacillus strains were thrown into the polluted creek water under laboratory conditions, results showed that water quality had significantly improved. BL1103 showed best water quality improvement, in which the removal rate of CODcr, N-NH4, T-P and turbidity were up to 80%, 94%,82%,81%; dead algae sediment appeared in experimental group, the agents added into the creek water may inhibit the growth of some dominant algae. Aeration showed a better degradation effect to polluted water.Single factor test of inoculation of BL1103 were conducted. Results showed the appropriate amount of inoculation was 108cfu/L, more microbial agent suppressed degradation; small-scale lab experiment with different combination way of bacillus was conducted to creek water, best degration efficiency to water appeared when using 4 bacillus species together, CODcr, N-NH4, T-P removal rate achieved 90%,92% and 85% respectively.Salmonella, E.coli, Bacillus were inoculated into creek water with different ratio. Results showed that bacillus exerted obvious inhibition to Salmonella. However, no results demonstrated its'inhibition to E.coli, since the tested E.coli strain can hardly survive in creek water. Meanwhile, the changes of the microbial community diversity in treated water were analyzed using PCR-DGGE method and results showed that the diversity of microbial communities was reduced in the bacillus- treated water.This study has demonstrated those 4 bacillus strains have perfect enzyme production,antibacterial properties, can treat serious polluted creek water quality in the laboratory-scale condition, and inhibit aquagenic germ such as salmonella.4 bacillus strains have the potential to be microecological modulator for wastewater treatment. Pilotscale experiment and further study need to be continued.