Degradation kinetics of carbendazim by Klebsiella oxytoca, Flavobacterium johnsoniae, and Stenotrophomonas maltophilia strains

Abstract

The fungicide carbendazim is an ecotoxic pollutant frequently found in water reservoirs. The ability of microorganisms to remove pollutants found in diverse environments, soil, water, or air is well documented. Although microbial communities have many advantages in bioremediation processes, in many cases, those with the desired capabilities may be slow-growing or have low pollutant degradation rates. In these cases, the manipulation of the microbial community through enrichment with specialized microbial strains showing high specific growth rates and high rates and efficiencies of pollutant degradation is desirable. In this work, bacteria of the genera Klebsiella, Flavobacterium, and Stenotrophomonas, isolated from the biofilm attached to the packed zones of a biofilm reactor, were able to grow individually in selective medium containing carbendazim. In the three bacteria studied, the mheI gene encoding the first enzyme involved in the degradation of the fungicide carbendazim was found. Studying the dynamics of growth and carbendazim degradation of the three bacteria, the effect of co-formulants was also evaluated. The pure compound and a commercial formulation of carbendazim were used as substrates. Finally, the study made it possible to define the biokinetic advantages of these strains for amendment of microbial communities.