Arch Microbiol (1990) 154:192-198 Archives of Hicrnbinlngy © Springer-Verlag 1990 Microbial degradation of acrylamide monomer Rishi Shanker*, Cherla Ramakrishna, and Prahlad K. Seth Industrial Toxicology Research Centre (Gheru Campus), Post Box 80, Mahatma Gandhi Marg, Lucknow - 226001, India Received October 17, 1989/Accepted March 8, 1990 Abstract. Acrylamide, a neurotoxic monomer with exten- sive industrial applications was found to be degraded by the microorganisms present in a tropical garden soil. A bacterium capable of degrading acrylamide was isolated from this soil by enrichment. It was found to be aerobic, gram-negative, motile, short rod and identified as Pseudomonas sp. The bacterium degraded high concen- trations of acrylamide (4 g/l) to acrylic acid and ammonia which were utilized as sole carbon and nitrogen source for growth. An amidase was involved in the hydrolysis of acrylamide, which could act on other short chain am- ides like formamide and acetamide but not on acrylamide analogues: methacrylamide and N,N-methylene bis- acrylamide. The enzyme was sensitive to catabolite re- pression by succinate both in presence as well as absence of nitrogen source. Key words: Aerobic degradation - Soil - Acrylamide - Acrylic acid - Ammonia - Pseudomonas - Amidase Acrylamide (ACR, CH 2 =CHCONH2) , a widely used monomer in polymer industry is a potent neurotoxin. Man and animals exposed to this neurotoxin show be- havioural disorders and "dying back" type of central and peripheral neuropathy (Tilson 1981; Shanker and Seth 1986). Acrylamide has also been observed to induce ab- normalities in mitotic and meiotic cells in animals and plants (Shairashi 1978; Shanker et al. 1987). Acrylamide has a variety of industrial applications, including its use as a grouting agent, soil stabilizer and strengthener in the manufacture of paper and cardboards. Polyacrylamide * Presentaddress:DepartmentofChemistry, 207ChandleeLabora- tory, The Pennsylvania State University, University Park, PA 16802, USA Offprint requests to: R. Shanker Abbreviations: Acrylamide (ACR), High Performance Liquid Chro- matography (HPLC) are used as flocculents in water treatment (Prasad 1982), disposal of industrial waste and as a pusher-fluid for increasing secondary recovery from oil wells (Tilson 1981). Unregulated commercial polyacrylamides may contain 0.3 to 5 % monomeric acrylamide as contaminant and industries using polyacrylamide or acrylamide- acrylic acid copolymers discharge effluents containing acrylamide monomer into environment (Croll et al. 1974). The widespread application of acrylamide and its polymers, has led to contamination of soil and water (Cherry et al. 1956; Igisu et al. 1975). The unreacted acrylamide from polymers has been found to migrate into soil and subsequently into plants (Nishikawa et al. 1978, 1979) and water supplies (Igisu et al. 1975). Cases of acute acrylamide poisoning as a result of contamination of water supply have been reported in Japan (Igisu et al. 1975). The monomer was found to remain stable for more than 2 months in tap water (Brown et al. 1980). In spite of numerous reports about the microbial degradation of acrylamide in river water (Cherry et al. 1956; Croll et al. 1974; Brown et al. 1982) and soil (Lande et al. 1979) little is known about the nature of micro- organisms involved in transformation of acrylamide. The chemical nature and fate of intermediate(s) formed on transformation of acrylamide has not been demonstrated. In view of the toxicity of acrylamide, the present investi- gation aimed to examine the detoxication of acrylamide in a tropical soil as well as in bacterial culture. Materials and methods Chemicals Acrylamide of analytical grade was obtained from Sigma, USA and acrylic acid from BDH, England. All other chemicals used were of highest purity available commercially.