The strategy of transesterification and degradation improved the resistance of Microbacterium sp. S1037 to antiseptic parabens.

Microorganisms are constantly evolving to resist the toxicity of artificial antibiotics and preservatives released into the environment. Parabens, a group of alkyl and aryl esters of p-hydroxybenzoate, are a class of widely used antimicrobial preservatives, particularly effective against Gram-positive bacteria and fungi. Previous studies have reported the degradation of parabens by numerous Gram-negative strains and activated sludge, with degradation processes often involving transesterification. However, the physiological significance of transesterification has received little attention. Here, a Gram-positive bacterium, Microbacterium sp. S1037 was isolated and characterized for its ability to degrade eight parabens and completely mineralize them through p-hydroxybenzoate and protocatechuate (β-ketoadipate pathway). Moreover, strain S1037 also possesses the ability of paraben-transesterification. Alcohols compete with water molecules for the active center of enzymes, accelerating the transesterification of parabens and inhibiting hydrolysis. Considering that the fate of the transesterification product is still hydrolysis, we speculated and proved that such a "superfluous" mechanism is a detoxification strategy, and could be used in the bioremediation of parabens in wastewater. Microbial transesterification of parabens has been reported worldwide, and we speculated that it might be a common detoxification choice in the evolution of microorganisms worldwide.