The Benzene, Toluene and Xylene Tolerant Marine Bacteria from Seawater of Karachi Coastline

Abstract

Marine bacteria are highly diverse and have been found to possess a unique system of enzymes that enable them to thrive effectively in a complex mixture of organic and inorganic pollutants present in the marine environment. The microorganisms harnessed from the marine environment are eco-friendly and economical, hence they could be effectively integrated with physico-chemical methods for pollution control. During the present investigation, several bacteria isolated from marine environment of Karachi coast were found Benzene, Toluene and Xylene (BTX) tolerant Gram-positive marine bacteria included, primarily Bacillus sp., and Gram-negative bacteria of the genus Pseudomonas were identified.  The 31% of the bacterial isolates  showed tolerance to BTX in NB supplemented with 3 % NaCl, comprised of 59 % Gram-positive and 40 % Gram-negative isolates. In contrast, BTX tolerant isolates in NB without 3 % NaCl were 25%, included 57 % Gram-positive and 43 % Gram-negative bacterial isolates. Among Gram-negative isolates, the isolate CMG556 (Pseudomonas sp. accession # DQ410039), tolerated 10-15 % v/v of three isomers of xylene (m-, p-, o-), produced hydrophobic mass in the presence of xylene, showed enhanced protease activity, and produced biosurfactant rhamnolipid. CMG556 is a suitable microorganism for further exploration in bioremediation and industrial applications.