Organic solvent-tolerant bacteria in mangrove ecosystem

摘要

Organic solvents are known to be extremely toxic to cells. They dissolve and accumulate in the bacterial cell membrane, resulting in changes in structural and functional integrity and cause cell lysis. Organic solventtolerant bacteria are a newly discovered group of micro-organisms with novel tolerance mechanisms, which enable them to thrive in solvent-saturated environments. These bacteria are significant due to their immense potential in non-aqueous bio-catalysis, industrial processes involving biphasic organicaqueous fermentation systems, effluent treatment and bioremediation in hydrocarbon-saturated environments. Inoue and Horikoshi used the parameter log P as a measure of solvent toxicity, where P is the partition coefficient of the given solvent in an equimolar mixture of octanol and water. The greater the polarity of a solvent, the lower its log P value and the greater its toxicity. In general, solvents with log P values below 4 are considered extremely toxic. Solvent tolerance is a strain-specific property and every micro-organism has a limiting log P value below which it is unable to grow. This intrinsic tolerance level is determined genetically and is also influenced by environmental factors. The most toxic solvent to which a given microbial strain is tolerant is called the index solvent and the log P value of the index solvent is called the index value of that particular organism.