Bacillus thuringiensis Genome sequencing. Bacillus thuringiensis

[Background] Staphylococcus aureus is a widespread and common foodborne microorganism that can cause pneumonia, pleurisy, endocarditis, sepsis, sepsis and food poisoning. [Objective] To screen out highly effective antagonistic strains of Staphylococcus aureus, analyze its antibacterial mechanism and explore its strain characteristics. [Methods] Oxford Cup method was used to screen the bacteriocin-producing strains against Staphylococcus aureus. The strains were identified by morphological characteristics and 16S rRNA gene sequence analysis. The physicochemical properties of the bacteriostatic substances were further analyzed. [Results] A bacteriocin-producing strain SA41 was isolated and identified as Bacillus thuringiensis. The diameter of inhibitory zone of bacteriocin crude extract against Staphylococcus aureus was >12.3mm; After fermentation optimization (15g/L of peptone, 5g/L of NaCl, 5g/L of soybean peptone, 15g/L of glucose, 40g/L of rapeseed, residual water, pH 7.0), the liquid antibacterial rate of the fermentation supernatant against Staphylococcus aureus was >44.8%, and the antibacterial zone diameter was >16.1mm up to 18.2mm. The crude extract could significantly inhibit the growth of Staphylococcus aureus. At the same time, the second age cotton bollworm was selected as the experimental material, using the fermentation medium diluted 10-6 times and the blank medium as the control, the killing rate could reach 93.3%.[Conclusion] The bacteriocin crude extract produced by Bacillus thuringiensis obtained by the test has good antibacterial effect on Staphylococcus aureus, and has strong insecticidal activity, and has high development and utilization value.