Statistical evaluation of the bioremediation performance of Ochrobactrum thiophenivorans and Sphingomonas melonis bacteria on Imidacloprid insecticide in artificial agricultural field.

BACKGROUND: Pesticides are applied directly on the soil or on the vegetation, and thus, they can reach the receiving environment easily. In this way, environmental damage that stems from pesticides also affects public health and the natural habitat. Pesticides are one of the most harmful pollutant groups in terms of human health, fauna and the environment. They penetrate the application field and the applicator right after the application and start to show adverse effects.
METHODS: The bioremediation of the Imidacloprid (C9H10ClN5O2) insecticide, which is used commonly in Mediterranean climate, was compared with some soil bacteria in artificially prepared fields. For this purpose, firstly, it was determined whether the soil samples taken from a field where cotton was cultivated in Adana in Turkey was suitable for bioremediation. Then, the bacteria were isolated from these soils with the 16sRNA method. The enhanced microbial consortia of these isolated bacteria were inoculated to the artificial fields, meanwhile, the recommended concentrations of Imidacloprid were added to these agricultural fields. Imidacloprid, Chemical Oxygen Demand (COD), Biochemical Oxygen Demand (BOD5) and Total Organic Carbon (TOC) measurements were performed every day for two weeks on the filtrate samples taken from the artificial fields.
RESULTS: As a result of the monitoring, it was determined that Ochrobactrum thiophenivorans (Ot) and Sphingomonas melonis (Sm) species and their mixtures could eliminate the Imidacloprid pesticide within two weeks' time. The removal efficiencies were 100% for active ingredient for each bacterium and their mixtures while COD were 97% and 96% for Ot. and Sm., respectively. TOC and BOD5 removal rates were 97% for both types and their mixtures in one or two-week period. Mixture of Ot and Sm shows 98.5% for COD, BOD5 parameters and 97.5% for TOC parameter.
CONCLUSIONS: The results that will be obtained will help in the rehabilitation of the receiving environments that are exposed to pesticides in our country and take precautions to avoid the accumulation of pesticides in the body of the humans who are at the top of the food chain. © Springer Nature Switzerland AG 2019.