Influence of pH and temperature on the expression of sboA and ituD genes in Bacillus sp. P11.

Temperature and pH are key factors influencing the production of antimicrobial peptides. In this work, qRT-PCR methodology was used to demonstrate the effect of these two variables on sboA (subtilosin A) and ituD (iturin A) expression in Bacillus sp. P11, an isolate from aquatic environment of the Amazon. Bacillus sp. P11 was incubated in BHI broth for 36 h at 30, 37 and 42 °C, and the pH values were 6.0, 7.4 and 8.0. The production of subtilosin A and iturin A was confirmed by mass spectrometry. The sboA expression increased 200-fold when the initial pH was 8.0. In contrast, ituD expression was maximum at pH 6.0. Increased temperature (42 °C) was adverse for both genes, but ituD expression increased at 37 °C. Expression of sboA and ituD was strongly affected by pH and temperature and qRT-PCR proved to be a powerful tool to investigate the potential of Bacillus strains to produce subtilosin A and iturin A.