Genetic and metabolic profiling of pentachlorophenol utilizing bacteria from agricultural soil irrigated with pulp and paper mill effluent

Abstract

Pulp and paper mill is a source of major environmental pollutants generating industries which include pentachlorophenol a highly chlorinated aromatic compound. PCP degrading bacterial isolates obtained from pulp and paper mill effluent contaminated site were characterised using amplified ribosomal DNA restriction analysis of 16S rRNA gene. Based on cluster analysis the representative 13 isolates were identified by partial 16S rRNA gene sequencing. These PCP degrading bacterial isolates were classified into four major bacterial lineages, α, β, ϒ-Proteobacteria and Firmicutes. The PCPmax and IC50 values of these isolates ranged from 100 to 300 mg PCP/l and 125 to 375 mg PCP/l respectively. Pseudomonas aeruginosa (PCP1) and Pseudomonas sp (PCP42) exhibited maximum PCPmax and IC50 value. Degradation of PCP by these isolates at their respective PCPmax ranged from 67.25% to 72.98% as analysed by the HPLC. Metabolic substrate usage of the isolates was evaluated using the BIOLOGTM ECO plates and unique carbon substrate usage profiles were observed. PCP degrading isolates, Azospirillum (PCP13 and PCP16) and Inquilinus limosus (PCP 27) were reported for the first time, these might represent new chlorophenol-degrading taxa.