Design of a Multi-Functional Actinobacteria Consortium for the Reduction of Agrochemicals
In this study Actinobacteria strains isolated from agricultural soil were evaluated for three different attributes: pesticide degraders, plant growth promoting and antimicrobial activity. Eighteen strains were selected as a result of their tolerance to 50 mg L-1 of thiamethoxam (neonicotinoid insecticide) in agar plate. Four of the eighteen strains degraded over 10% of the pesticide in liquid culture after 48 h. Two strains were selected (TM22 and TM24) and the removal for thirty days was evaluated. Our results showed that thiamethoxam removal was close to 80% after thirty days with a removal rate of 0.067 d-1 and0.0529 d-1, and a half-life of 10.3 d-1 and 13.10 d-1. On the other hand, Actinobacteria strains exhibited characteristics of plant growth promoters, which was evidenced through the production of indole acetic acid in concentrations between 3-33 µg L-1. Moreover, some Actinobacteria strains caused the inhibition of the phytopathogenic fungi Gaeumannomyces graminis var. tritici. In this study we select three Actinobacteria strains to construct a multifunctional consortium able to remove thiamethoxam (TM22), present characteristics for plant growth promotion (PM9) and anti-fungal activity (TM7). The compatibility assay performed between the Actinobacteria spp. showed no inhibition between them when they were faced, which suggested that the strains could be cultured together as a mixed culture. Although future assay are required, the designed Actinobaceria consortium could offer great promise to be used as bioinoculant and to reduce the use and presence of pesticides in agricultural activities.
Keywords - Neonicotinoid, Removal Rate, Plant Growth Promoters, Antimicrobial Activity, Consortium.