Molecular screening of chlorophenol-degrading bacteria and comparative analysis of bacterial diversity from sewage treatment plant

Abstract

Molecular ecological approaches have detected diverse microorganisms that occur in response to pollution and bioremediation; however, most of these organisms have not been isolated, and their physiological traits are poorly understood. Phenol and chlorophenols are some of the major hazardous compounds in industrial wastewater, and for this reason biodegradation of phenol and chlorophenols has attracted keen attention. However, since most studies of phenol and chlorophenols biodegradation have been carried out under laboratory conditions with arbitrarily selected phenol and chlorophenols-degrading bacteria, the biodegradation in the environment is not well understood yet. The process of enrichment and subsequently isolation of aromatic compound-degrading bacteria has been applied using sewage sludge samples from sewage treatment plant in Gumi industrial complex. The enrichment method used in this study targeted bacteria degrading phenol, mono-chlorinated phenols. Pyrosequencing-based comparative genome analysis of phenol- and monochlorophenol-degrading bacteria diversity was used to compare the structure of bacterial communities at various steps of enrichment. For the easy and fast detection and isolation of bacterial populations capable of degrading aromatic compounds, Functional LmPH, C12O and C23O genes were used as molecular marker to confirm to assess the functional and genetic diversities of phenol- and chlorophenol-degrading bacteria. PCR primer sets were designed which can, respectively, amplify specific fragments from a wide variety of the multi-component phenol hydroxylase (LmPH), catechol l, 2-dioxygenase (C12O) and catechol 2, 3-dioxygenase (C23O) genes. To understand the bacterial diversity from the environment samples, we applied pyrosequencing to investigate bacterial community structure in sewage sludge samples and compared diversity of original sample and enrichment ones. The microbial community response may prove to be a much more comprehensiv...