In situ bioremediation of Chromium contaminated soil using a novel cationic lipopeptide biosurfactant from Alcaligenes aquatilis sp.

Abstract

Biosurfactants are surface-active compounds derived from various microbial sources including bacteria and fungi. They have a wide range of properties and applications in various fields. Alcaligenesaquatilis sp. bacterium was isolated from soil. The cationic nature of the biosurfactant was confirmed by tests such as Blue plate agar test and by determining the amino acid composition of the biosurfactant. The optimized conditions for the production of cationic lipopeptide were found to be 96 h, pH 4 and temperature 370C.The biochemical characteristics of the cationic lipopeptide show that the protein concentration is 26.06 mg/g and lipid concentration is 60 mg/g respectively. The SDS-PAGE revealed that the molecular weight of the biosurfactant is 100.2 KDa. Chromium removal studies were performed to determine the effect of time,pH and temperature on the removal of Cr by the cationic biosurfactant as well as anionic biosurfactant. Adsorption isotherm studies were performed using Langmuir and Freundlich isotherms to determine the extent of adsorption of the biosurfactant onto the soil. The characterization of the Immobilized Cationic Biosurfactant (ICB) was carried out using FTIR, TGA, DSC and XRD. This ICB along with anionic biosurfactant was used for Insitu Bioremediation of Cr from contaminated soil. The initial concentration of Cr in the soil sample collected was found to be 19.5mg/g of soil using standard Cr estimation method.The removal of Cr from the soil was confirmed after estimating the Cr concentration in the soil treated with ICB. Finally seed germination studies were carried out for Cr sensitive seeds such as Zea mays (Maize), Luffa (Ridge Gourd), Trigonellafoenum-graecum (Fenugreek) using the treated and untreated soil and comparisons were made.