Biodegradation of Linear Alkylbenzene Sulfonate (LAS) by Immobilized <i>Pseudomonas</i> sp.

Abstract

Anionic surfactants are the most widely exploited chemical surfactants, which are being incorporated into majority of detergents and cleaning products used for household and industrial applications. Linear alkylbenzene sulfonates (LAS) is one of the major xenobiotic anionic surfactants. Biodegradation is an effective process to reduce the amount of surfactants released in the environment. In this study soil samples were collected from detergent contaminated sites to isolate linear alkylbenzene sulphonate degrading bacteria using mineral salt media supplemented with LAS as sole source of carbon. From the twenty isolates selected for the study, two of them (L9 and L12) have exhibited excellent ability to degrade LAS. The LAS degradation ability was determined by using MBAS assay and HPLC. The selected isolates were immobilized in alginate and polyvinyl alcohol to check the suitability of the isolates in onsite LAS removal. The percentage of degradation of LAS by alginate entrapped L9 was 85.155 ± 1.2 and that of PVA immobilized cells was 58.535 ± 2.9. Whereas L12 PVA entrapped were good compared to alginate. L12 exhibited 62.977 ± 1.3 percentage of degradation of LAS when immobilized in PVA and 61.07 ± 0.6 percentage in alginate entrapped condition. In comparison between the organisms alginate entrapped Pseudomonas nitroreducens (L9) was found to be superior to Pseudomonas aeruginosa (L12) in immobilised condition. It was found that immobilized cells performed superiorly than free cells. In particular, calcium alginate immobilised cells were more efficient in LAS removal than polyvinyl alcohol immobilised cells.