Martinez-Martinez_2014_Microb.Biotechnol_7_184

Herein, we applied a community genomic approach using a naphthalene-enriched community (CN1) to isolate a versatile esterase (CN1E1) from the alpha/beta-hydrolase family. The protein shares low-to-medium identity (</= 57%) with known esterase/lipase-like proteins. The enzyme is most active at 25-30 degrees C and pH 8.5; it retains approximately 55% of its activity at 4 degrees C and less than 8% at >/= 55 degrees C, which indicates that it is a cold-adapted enzyme. CN1E1 has a distinct substrate preference compared with other alpha/beta-hydrolases because it is catalytically most active for hydrolysing polyaromatic hydrocarbon (phenanthrene, anthracene, naphthalene, benzoyl, protocatechuate and phthalate) esters (7200-21 000 units g-1 protein at 40 degrees C and pH 8.0). The enzyme also accepts 44 structurally different common esters with different levels of enantio-selectivity (1.0-55 000 units g-1 protein), including (+/-)-menthyl-acetate, (+/-)-neomenthyl acetate, (+/-)-pantolactone, (+/-)-methyl-mandelate, (+/-)-methyl-lactate and (+/-)-glycidyl 4-nitrobenzoate (in that order). The results provide the first biochemical evidence suggesting that such broad-spectrum esterases may be an ecological advantage for bacteria that mineralize recalcitrant pollutants (including oil refinery products, plasticizers and pesticides) as carbon sources under pollution pressure. They also offer a new tool for the stereo-assembly (i.e. through ester bonds) of multi-aromatic molecules with benzene rings that are useful for biology, chemistry and materials sciences for cases in which enzyme methods are not yet available.