Bacillus cereus Strain 10-L-2 Produces Two Arylamine N-Acetyltransferases That Transform 4-Phenylenediamine into 4-Aminoacetanilide

摘要

A bacterium,strain 10-L-2,that was isolated from soil and identified as Bacillus cereus grew well on medium containing 4-phenylenediamine and Polypepton.Strain 10-L-2 converted a wide variety of anilines,including 4-phenylenediamine,to their corresponding acetanilides.Growing cells acetylated a single amino group of 4-phenylenediamine to form 4-aminoacetanilide with a 97% molar yield,as shown by mass spectrometry and HPLC.Cell extracts exhibited arylamine N-acetyltransferase (NAT) activity toward 4-phenylenediamine.Two NATs,namely,NAT-a and NAT-b,were separated by DE52 column chromatography and were further purified and characterized.The subunit molecular masses of NAT-a and NAT-b were 31.0 and 27.5 kDa,respectively,as determined by SDS-PAGE analysis.The two enzymes had similar pH- and thermo-stabilities and were similarly affected by pH,temperature,and several reagents.The enzymes showed peak activity toward 5-aminosalicylic acid of the substrates tested,but they differed in substrate specificity.Only NAT-a had activity toward sulfamethazine.Although other wild-type bacterial cultures also synthesize NAT,the ability of strain 10-L-2 to convert and detoxify 4-phenylenediamine is much higher.This report provides the first evidence of two NATs in a eubacterium.