OSMOTOLERANCE AND HYDROCARBON DEGRADATION BY A GENETICALLY-ENGINEEREDMICROBIAL CONSORTIUM

Most bacteria characterized as hydrocarbon degrading are isolated from the terrestrial environment and have very limited or no application u nder estuarine/hyper-saline conditions. The collective efforts of thes e hydrocarbon-degrading bacteria help in the preservation of the envir onment under man-made disasters. However, the process has a long lag p hase, 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, comp osed of four members; strain Pseudomonas NCC.DSS6, P. NCC.DSS8, II NCC .GSS(3) and II putida, which can attack various fractions of crude oil . To extend the capacity of the consortium for degradation of hydrocar bons in marine environments or estuarine conditions the key is the req uirement of an osmotolerance function. Hence, in the present study, to provide osmotolerance to these soil isolates, the E. coli pro U opero n was subcloned into a broad-host range vector and transferred into th e members of the microbial consortium. The non-specific basal expressi on of the pro ii operon, under the control of tac-lac promoter was dem onstrated by the ability of the transformed organisms to grow under hy per-saline conditions. The degradation capacity of the engineered cons ortium was also studied using a designed model petroleum mixture. The study underscores the potential of the osmoregulatory function for deg radation of anthropogenic molecules in marine niches. (C) 1998 Publish ed by Elsevier Science Ltd. All rights reserved.