Enhancement of surfactin production in iron-enriched media by bacillus subtilis ATCC 21332 |
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Authors: | Yu-Hong Wei I-Ming Chu |
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Affiliation: | a Department of Chemical Engineering, National Tsing Hua University Hsinchu, Taiwan Republic of China |
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Abstract: | Production of a lipopeptide surfactant, surfactin, by Bacillus subtilis ATCC 21332 was highly enhanced when iron concentration in the medium was raised from 4 μ to the few m level. This iron enrichment of the medium also resulted in increased biomass concentration. With 1.7 m iron sulfate added to the media of different initial iron concentrations or at different stages of growth, surfactin concentration can be raised to levels of several hundred mg l−1 in general. Acidification of the broth was usually observed following the iron addition, and surfactin in the broth disappeared rapidly due to precipitate as soon as the pH level dropped below 5.0; however, if this acidification phenomenon was delayed, avoided (for reasons still unknown), or reversed (by alkaline addition), surfactin production was highly enhanced to as high as 3,500 mg l−1 which was almost ten times over the previously reported level for this strain and higher than most reported values for genetically improved strains. |
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Keywords: | Biosurfactant surfactin iron Bacillus subtilis |
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