Screening And Identification Of Bacillus Pumilus NDY-10 And Optimization Of Its Antibacterial Activity And Fermentation Conditions

Bacillus sp. is widely distributed in nature. It can produce spores withstanding a variety of adverse conditions for its spores. It can secrete bacteriostatic substances. With the wide application in plant disease control, microbial ecological agents and other fields, more and more people recognized the importance of Bacillus sp.. In the study, a bacteriostatic strain NDY-10 and its inhibited strain were screened from the soil of coal storage. The strain NDY-10 was identified as Bacillus pumilus NDY-10 and tne strain NDD-1 was identified as Bacillus sp. NDD-1.The results of inhabition specture show that B. pumilus NDY-10 can inhibit the growth of the strains of Bacillus sp. NDD-1, E. coli and Staphylococcus aureus by Oxford cup method. Menawhile it has the best inhibitory on Bacillus sp. NDD-1.Select Bacillus sp. NDD-1 as inhibited bacteria to determine the bacteriostatic activity and stability of the supermatant of B. pumilus NDY-10. Conclusions are as follows:(1) The pH of B. pumilus NDY-10 supernatant was 7.8 and its inhibition rate was 78.2%.(2) The high temperature has significant effect on bacteriostatic activity.(3) Stable pH range of the above inhibitory activity are 5-9. Its inhibitory rate is above 69% and its relative antibacterial activity remain above 88%.(4) UV has little influence on bacteriostatic activity.The optimized fermentation conditions for B. pumilus NDY-10 ars Beef extract 0.30%, Sucrose 0.30%, Yeast extract 1.00% and MgSO4·7H2O 0.50%. The best initial pHis 7.0 and the best culture temperature is 37℃.