TITLE:
Growth Kinetics Study of a Bacterial Consortium Producing Biosurfactants, Constructed with Six Strains Isolated from an Oily Sludge
AUTHORS:
Zohra Sadouk-Hachaïchi, Ammal Tazerouti, Hocine Hacene
KEYWORDS:
Andrews Model; Bacterial Consortium; Biodegradation; Biosurfactants; Diesel Oil; Kinetic Parameters
JOURNAL NAME:
Advances in Bioscience and Biotechnology,
Vol.5 No.5,
April
2,
2014
ABSTRACT: We investigated the ability of a bacterial community constructed with six
strains isolated from an oily sludge, to utilize diesel oil at high
concentrations. The consortium was able to grow at concentrations up to 84 g
diesel oil/L and had produced biosurfactants during its active growth phase;
these compounds, in their crude form, reduced the surface tension of distilled
water from 72 mN/m to 31 mN/m, with a corresponding Critical Micelle Concentration value γCMC = 81 mg/L. The plot of
specific growth rates obtained from the growth curves versus initial
concentrations was found to fit adequately the experimental data by the Andrews
inhibitory model, which resulted in the following kinetic constants: μmax = 0.535d-1 ± 0.063, KS = 18.68 g/L ± 3.59 and KI = 29.02
g/L ± 4.96, reflecting the slow biodegradation rate. At 25.2 g diesel oil/L, close
to the optimal concentration S* = 23.28 g/L ± 4.23, the consortium metabolized diesel oil
faster than each strain did individually, suggesting that the process was
stimulated by a synergistic interaction between the members of the consortium.