Biodegradación microbiana de carbofurano en suelos de cultivos de papa criolla Solanum phureja.

Abstract

The overuse of agrochemicals is one of the main causes of soil contamination, which causes a socio-environmental imbalance due to the deterioration they exert on the biota. One of the biological alternatives to reduce soil contamination is the biodegradation. The development of this research allowed evaluating the degradation capacity of the microbiota present in the soil, compared to the chemical compound carbofuran, which has been used to control pests in ´´papa criolla” crops (Solanum phureja) in the village of San Agustín municipality of Mutiscua, province of Pamplona. The physicochemical and environmental conditions of the soil were evaluated initially since these parameters influence the metabolic activity of the microorganisms, later autochthonous microorganisms were isolated and identified and their ability to grow in three different concentrations of carbofuran was evaluated, the most efficient microorganisms were characterized by Fourier transform infrared spectroscopy (FT-IR) and biodegradation tests were carried out with them. Through the use of biological reactors, the degradation capacity of each microorganism towards carbofuran was determined, the quantification of the compound was performed by UV/Vis spectrophotometry, bacterial growth was controlled by CFU /ml count, while in fungi it was estimated the dry weight. The biodegradation by consortiums of microorganisms was done directly in soils and it was evaluated by gas chromatography coupled to mass spectrometry (GC/MS). It was found that the soil with a fumigation background presents variation in the physicochemical parameters with respect to the control soil, which may affect or favor the activity of the microorganisms. In the isolation and identification process, seven bacteria and seven fungi were found. Due to its ability to tolerate carbofuran, Bacillus mycoides, Pseudomonas sp. Serratia marcescens, and the fungi Aspergillus niger, Mucor sp. and Trichoderma sp. were selected for the degradation tests. It was also found that during fifteen days the removal of carbofuran occurs in percentages of 54%, 71% and 56% in the order of the bacteria described, while the fungi degrade respectively 57%, 73% and 81.6% of the xenobiotic. Furthermore, the degradation on the part of the consortium of microorganisms indicates that in fifteen days they achieve to remove 91, 7% of the pesticide in the soil. The biological degradation of carbofuran is possibly due to the fact that microorganisms use the compound as a source of nutrients (carbon and / or nitrogen), and for this they have adapted their genetic mechanisms to enzymatic metabolic processes that synthesize, hydrolyze and hydroxylase carbofuran, reducing the toxicity of the compound through cometabolic activity or completed mineralization.