Aerobic Biodegradation of BTX by Halophilic Planococcus sp. Strain TS1 Isolated from Egypt

Abstract

Aims: The purpose of the present study is to isolate pure halophilic bacteria potentially able to degrade BTX compounds as a sole carbon source under aerobic condition. Such these studies are necessary for bioremediation application of hydrocarbons in our ecosystem. Study Design: Isolation of halophilic bacterial strains from hypersaline soil of Wadi An- Natrun, in Egypt. Selected isolates able to utilize BTX compounds as the only carbon and energy source. Efficiency of biodegradation ability will be enhanced via optimizing microbial growth condition. Most potent isolate will be identified through phenotypic and phylogenetic characterizations. Place and Duration of Study: The study was performed in Physiological Lab in Botany and Microbiology Department in Faculty of Science (Boys), Al-Azhar University, Cairo, Egypt from May 2013 until October 2015. Methodology: The halophilic bacterial strains were selected based on its ability to grow in the presence of high salt concentration and undiluted Toluene (~222 μmol) which served as the only source of carbon. Subsequently select the most potent isolate and identify it. Thereafter, study some factors affecting on the biodegradation of toluene and estimated the biodegradation ratio of BTX by Purge-Trap GC-MS. Result: Fifty halophilic bacteria isolates are capable of utilized toluene as the only source of carbon and energy isolated from alkaline soils in Al- Hamra Lake, Wadi An Natrun, Egypt. One isolate was selected as the most potent strain. Based on the 16S rDNA gene sequence and phenotypic characterizations the strain TS1was most closely related to the Planococcus maritimus with similarity 95% which belong to family Planococcaceae. Strain TS1 could grow at temperatures between 20 up to 40ºC, pH 5 to 8 and salt concentrations from 5 to 20%. Its optimal conditions for biodegradation of Toluene were 30ºC, pH 8 and 10% salt concentration. Purge-Trap GC-MS analysis showed that, strain TS1 has the ability to degrade 25.33% of toluene and 46.67% of xylene in addition 47.55% and 46.84% of benzene and toluene mixture respectively, during first 24 h of incubation. This study suggests that strain Planococcus TS1 may play an important role for biodegradation of BTX in different marine contaminated sites.