A practical approach to biosurfactant production using nonaseptic fermentation of mixed cultures

Abstract

Non‐aseptic production of biosurfactant from molasses by a mixed culture was investigated in stirred batch reactors. Biosurfactant production was quantified by surface tension reduction, critical micelle dilution (CMD), and emulsification capacity (EC). Biosurfactant production was directly correlated with biomass production, and was improved by pH control and addition of yeast extract. Centrifugation of the whole broth increased emulsifying capacity and reduced surface tension. Acidification of the whole broth increased the emulsification capacity but reduced the apparent biosurfactant concentration (CMD), without affecting the surface tension. The emulsification capacity of the cell‐free broth was equivalent to that of a 100 mg/L solution of sodium dodecyl sulfate. The emulsification capacity of the whole broth and cell‐free broth were reduced by about 50% at and above NaCl concentrations of 100mM. Preliminary characterization suggests that the biosurfactant activity is primarily associated with one or more protease‐sensitive species, released from cells in larger quantities after more vigorous centrifugation. © 1994 John Wiley & Sons, Inc.

Study of the biosurfactant-producing profile in a newly isolatedRhodococcus ruber strain

“…The optimal biomass and biosurfactant production were achieved when the strain grew at NaCl concentration of 2.5% with the mean difference of the 0.05 level. Our results also suggested that the biosurfactant production by R. ruber Z25 was primarily cell-growth associated when the bacteria grew on hydrocarbon, similar to that reported by other investigators (Ghurye and Vipulanandan, 1994;Rodrigues et al, 2006). The optimal growth conditions from this experiment were adopted for further study.…”

Media optimization for biosurfactant production by Rhodococcus erythropolis MTCC 2794: artificial intelligence versus a statistical approach

“…The glycolipid biosynthesis is predominantly cell-growth associated [32,33]. Therefore initial attempts were made to increase the cell mass based on a one-factor-at-a-time strategy.…”

A new biosurfactant produced by Candida glabrata UCP 1002: characteristics of stability and application in oil recovery

“…Desai and Banat (1997), reported that concentrations above 2% of NaCl were enough to inactivate a synthetic surfactant. Reductions were also observed in the emulsification activity of the surfactant produced by C. lipolytica cultivated in n-hexadecane (Cirigliano and Carman, 1984) and of the surfactant from mixed cultures cultivated in molasses (Ghurye et al, 1994). Regarding the influence of the temperature on the surface tension of the cell-free broth containing the biosurfactant (Fig.4), it was observed that the same stable front stayed to the studied temperatures.…”