Abstract
Esterases are widely used in food processing industry, but there is little information concerning enzymes involved in decompositions of esters contributing to pollution of environment. Vinyl acetate (an ester of vinyl alcohol and acetic acid) is a representative of volatile organic compounds (VOCs) in decomposition, of which hydrolyses and oxidoreductases are mainly involved. Their activities under periodically changing conditions of environment are essential for the removal of dangerous VOCs. Esterase and alcohol/aldehyde dehydrogenase activities were determined in crude cell extract from Pseudomonas fluorescens PMC 2123 after vinyl acetate induction. All examined enzymes exhibit their highest activity at 30–35 °C and pH 7.0–7.5. Esterase preferably hydrolyzed ester bonds with short fatty chains without plain differences for C2 or C4. Comparison of Km values for alcohol and aldehyde dehydrogenases for acetaldehyde suggested that this metabolite was preferentially oxidized than reduced. Activity of alcohol dehydrogenase reducing acetaldehyde to ethanol suggested that one mechanism of defense against the elevated concentration of toxic acetaldehyde could be its temporary reduction to ethanol. Esterase activity was inhibited by phenylmethanesulfonyl fluoride, while β-mercaptoethanol, dithiothreitol, and ethylenediaminetetraacetic acid had no inhibitor effect. From among metal ions, only Mg2+ and Fe2+ stimulated the cleavage of ester bond.Electronic supplementary materialThe online version of this article (doi:10.1007/s12223-013-0268-0) contains supplementary material, which is available to authorized users.
Highlights
Vinyl acetate belongs to the group of volatile organic compounds (VOCs)
Vinyl acetate appears in exhaust gases, and it itself is not considered to be highly toxic, it is very hazardous in case of skin and eye contact as well as in case of inhalation (ATSDR 1992)
Enzymes exhibiting stability in high temperatures are supposed to be more proper for harsh conditions of industrial processes, but on the other hand, their activities are relatively low at room temperature, which is sometimes required for chemicals labile in higher temperature like, e.g., vinyl acetate (Zamost et al 1991)
Summary
Vinyl acetate belongs to the group of volatile organic compounds (VOCs). In the industry, it is used for the production of polyvinyl acetate, polyvinyl alcohol, and other polymers which are exploited to manufacture building materials, printing inks, plastics, lacquers, or paints (US EPA 2000). The aim of these studies was to determine the optimal conditions for activities of esterase as the essential enzyme in degradation of vinyl acetate by P. fluorescens PCM 2123. Esterase activity was determined spectrophotometrically using p-nitrophenyl butyrate (pNPB) or p-nitrophenyl acetate (pNPA) as described previously (Greń et al 2011).
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