Bio-degradation of acetamiprid from wetland wastewater using indigenous Micrococcus luteus strain SC 1204: Optimization, evaluation of kinetic parameter and toxicity

The fundamental objective of this study is to investigate the feasibility of microbes in removing toxic substances from environment and hopeful consideration that microbial bioremediation can be a cost effective tool for the detoxification of insecticides. Therefore, efforts were made to isolate and characterize indigenous bacteria, capable of degrading the neonicotinoid insecticide acetamiprid (ACE) and to optimize different process parameters in order to effectively treat the Wetland waste water. The enrichment and isolation was done in minimal salts media enhanced with 50 mg L−1 of ACE as sole carbon, nitrogen and energy source, incubated at 40 °C on a rotary shaker at 100 rpm for about 7 days. The Face centered central composite design (FCCD) was performed to check the significance of the degradation process in a quadratic model. The mathematical model fitting of growth curve of the isolated bacteria was also studied. The indigenous bacterium capable of degrading ACE was observed to be Micrococcus luteus strain SC 1204, having a maximum consumption of 69.84% of ACE in 24 h, quantified using GC–MS. The rate kinetic analysis was investigated using zero-order and three half- order kinetic models. Among the identified metabolites, benzothiazole, 2-(2-hydroxyethylthio) with a prominent peak at RT 6.99 was found to be the end product of ACE bio-degradation. Further, toxicological analysis on Pseudomonas aeruginosa exhibited no inhibition zone, suggesting the eco-friendly nature of the degraded metabolite.