Biofilm formation and lipopeptide antibiotic iturin A production in different peptone media

Abstract

Biofilm fermentation is a newly developed promising technique in fermentation technology. In this study no.3 and no.3S media have been used for the lipopeptide antibiotic iturin A production by Bacillus subtilis RB14. The main component of no.3 and no.3S media is Polypepton and Polypepton S, respectively. B. subtilis RB14 produces thick stable biofilm and high amount of iturin A in no.3S medium. Whereas, impaired biofilm formation and lower iturin A production was observed in no.3 medium. From the analytical information it was observed that the amounts of metal ions, such as K +, Ca 2+ and Mn 2+, cysteine and cellulose are lower in Polypepton compared to the Polypepton S. To investigate their effect on biofilm formation and iturin A production cysteine, cellulose, K +, Ca 2+ and Mn 2+ were added respectively into the no.3 medium at similar amount that Polypepton S contains. It was observed that individual addition of K +, Ca 2+, cysteine and cellulose had no effect on biofilm formation, cellular growth induction or iturin A production. However, when Mn 2+ was supplemented in no.3 medium, biofilm development was restored with an improved production of iturin A. Finally, combined addition of investigated substances into the no.3 medium resulted with highly folded, thick biofilm with high cellular growth and iturin A production compared to the original no.3 medium.