Sunday, July 26, 2009
P85

Enhanced production of surfactin by natural isolate Bacillus subtilis MB5

Mariusz Bikowski and Michal Obuchowski. Laboratory of Molecular Bacteriology, Intercollegiate Faculty of Biotechnology UG-MUG, Medical University of Gdansk, Debinki 1, Gdansk, 80-211, Poland

Surfactin, cyclic lipopeptide produced by Bacillus subtilis is one of the most powerful biosurfactants ever known exhibiting also strong antimicrobial properties. Those factors make it important for the biocontrol.  Two strains of B. subtilis isolated from soil are able to control the phytopathogenic bacterium Dickeya dianthicola (Erwinia chrysanthemi), cause of blackleg in potato plants.

1. Comparison of methods enabling the surfactin production screening

2. Determination of levels of surfactin excretion in strains of B. subtilis

Detection of biosurfactant production was determined by oil spreading method. Quantitative analysis of surfactin in culture supernatants was performed by Reverse Phase HPLC.

Natural isolate MB5 produces two times more surfactin as compared to the laboratory strain B. subtilis 3610. Chromatographic peaks of isoforms are in equal retention times, but their levels are different. Analysis indicates, that B. subtilis laboratory strain 168 does not excrete such compound.

1. Oil spreading method is simple and easy and allows screening and preliminary quantification of biosurfactant production. Selected cultures are then more precisely investigated by the HPLC analysis.

2. Surfactin is of great industrial interest, however it is not widely available because of low strain productivity and high recovery expenses. The enhanced production of surfactin by MB5 strain described here, connected with nutritional factors manipulation might result in more optimized yields of the lipopeptide.


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