Osmotolerance and hydrocarbon degradation by a genetically engineered microbial consortium

Most bacteria characterized as hydrocarbon degrading are isolated from the terrestrial environment and have very limited or no application under estuarine/hyper-saline conditions. The collective efforts of these hydrocarbon-degrading bacteria help in the preservation of the environment under man-made disasters. However, the process has a long lag phase, since the contaminated ecosystem undergoes a process of natural selection of efficient hydrocarbon degrading bacteria. This paper uses a microbial consortium designed from a library of soil isolates, composed of four members; strain Pseudomonas NCC.DSS6, P. NCC.DSS8, P. NCC.GSS3 and P. putida, which can attack various fractions of crude oil. To extend the capacity of the consortium for degradation of hydrocarbons in marine environments or estuarine conditions the key is the requirement of an osmotolerance function. Hence, in the present study, to provide osmotolerance to these soil isolates, the E.coli pro U operon was subcloned into a broad-host range vector and transferred into the members of the microbial consortium. The non-specific basal expression of the pro U operon, under the control of tac-lac promoter was demonstrated by the ability of the transformed organisms to grow under hyper-saline conditions. The degradation capacity of the engineered consortium was also studied using a designed model petroleum mixture. The study underscores the potential of the osmoregulatory function for degradation of anthropogenic molecules in marine niches.