Time‐dependent dosing of Fe²⁺ for improved lipopeptide production by marine <i>Bacillus megaterium</i>

Abstract

Abstract BACKGROUND: Lipopeptide production is strongly influenced by trace metals. The availability of free Fe 2+ in the media throughout the process of fermentation was found to be very critical. Since free Fe 2+ was reported to be sequestered by the lipopeptide as it was produced, intermittent feeding of Fe 2+ was strategized and optimized for enhanced lipopeptide production by marine Bacillus megaterium in glucose mineral salts medium (GMSM). RESULTS: Studies with the single‐dose Fe 2+ (0.48 mmol L −1 ) supplementation after 8 h of fermentation resulted in lipopeptide concentration of 3.3 ± 0.1 g L −1 . Lipopeptide production was further enhanced to 4.2 ± 0.15 g L −1 by adopting a multi‐dose Fe 2+ feeding strategy. The maximum product yield ( Y P / S ) of 0.24 ± 0.02 g g −1 with specific product formation rate ( q p ) of 0.124 ± 0.01 g g −1 h −1 was achieved when 0.48 mmol L −1 Fe 2+ was fed intermittently at different times as per the designed strategy. CONCLUSION: Lipopeptide concentration was improved 4.7‐fold by single‐dosing and 5.8‐fold by multiple dosing of Fe 2+ , when compared with GMSM without Fe 2+ supplementation. Copyright © 2012 Society of Chemical Industry