Author(s): Wei YH, Wang LF, Chang JS
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Abstract Supplement of Fe(2+) into fermentation medium was utilized as a tool to optimize the iron-mediated enhancement of surfactin production from Bacillus subtilis ATCC 21332. Up to 3000 mg L(-)(1) of surfactin was produced using an iron-enriched minimal salt (MS) medium amended with an optimal Fe(2+) dosage of 4.0 mM, leading to 8-fold and 10-fold increase in cell concentration and surfactin yield, respectively, as compared to those without Fe(2+) supplement. In addition to resulting in an optimal production yield of surfactin, a supplement of 4.0 mM of Fe(2+) also propelled maximum overall surfactin production rate to a highest value of 24 mg L(-)(1) h(-)(1). Our results also show that production of surfactin followed a growth-associated kinetic model. The best yield coefficient estimated from the model was ca. 162 mg surfactin (g dry cell)(-)(1). The supernatant of the iron-enriched culture of B. subtilis ATCC 21332 exhibited the ability to emulsify kerosene and achieved a maximum emulsion index (E(24)) of 80\% for culture supplemented with 4.0 mM of Fe(2+). Comparison of emulsion index and the corresponding surfactin production indicates that the emulsification activity was essentially contributed by surfactin.
This article was published in Biotechnol Prog
and referenced in Industrial Engineering & Management