A Novel Alkaline Esterase from Sporosarcina sp. nov. Strain eSP04 Catalyzing the Hydrolysis of a Wide Variety of Aryl-carboxylic Acid Esters

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A novel esterase showing activity specific for esters of aryl-carboxylic acids was discovered in Sporosarcina sp. nov., which was identified by the 16S rDNA sequencing method in addition to morphological and physiological analyses. The aryl-carboxylesterase (named EstAC) was purified 780-fold from crude cell extracts by a 5-step procedure. EstAC was characterized as a monomeric protein with a molecular weight of 43,000, an optimum pH of around 9.0, and an optimum temperature of 40 °C. The pH optimum and the effects of inhibitors together with an internal amino acid sequence suggested that EstAC is a member of family VIII esterases. EstAC was found to be highly active on a wide variety of substrates such as alkyl benzoates, alkyl phenylacetates, ethyl α- or β-substituted phenylpropionates, dialkyl terephthalates, dimethyl isophthalate, and ethylene glycol dibenzoate. However, monomethyl terephthalate was not hydrolyzed. It was suggested that EstAC had 4-hydroxybenzoyl and cinnamoyl esterase activities as well.