Bioreactor studies on acrylamidase produced from Cupriavidus oxalaticus ICTDB921: Production, kinetic modeling, and purification

Acrylamide and polyacrylamide manufacturing/processing industries generate huge volume of waste containing acrylamide, an environmental pollutant (Group-2A carcinogen) that causes neurotoxicity, teratogenicity, mutagenicity, and reprotoxicity. Some bacteria produce acrylamidase and utilize acrylamide solely as carbon and nitrogen source for their growth and metabolic activities. Acrylamidase is a commercially important enzyme that finds innumerable applications in different industrial sectors. The present work reports the production of acrylamidase by Cupriavidus oxalaticus ICTDB921 in a 5 L bioreactor. The interaction of agitation and aeration on acrylamidase production was verified by response surface methodology (RSM). The results showed that agitation of 200 rpm and aeration of 0.5 vvm gave maximum production of acrylamidase and resulted in 1.25-fold increase in yield of acrylamidase over shake flask study. Kinetic models such as Weibull model, Logistic model, and Luedeking-Piret model were found to be consistent with acrylamide utilization, biomass accumulation, and acrylamidase production, respectively, under optimized conditions. Sequential purification of acrylamidase using ammonium sulfate precipitation followed by thermal treatment and anion-exchange chromatography resulted in 2.79-, 3.75- and 4.16- fold increase in purity, respectively. The purified acrylamidase showed a molecular weight of similar to 60 kDa.