Defined microbial consortium with bioremediation potential: atrazine removal, phytotoxicity, and detection of genes involved in herbicide catabolism

Abstract

Atrazine is one of the most used herbicides in Argentina. This stable and persistent compound was detected in the environment, even exceeding permitted concentration limits. In this sense, the present work focuses on selecting a defined actinomycetota consortium with atrazine removal abilities, determining the phytotoxicity of the liquid treated systems, and identifying genes involved in the herbicide catabolism. For that, four actinomycetota consortia (C1, C2, C3, and C4) were tested about their ability to grow and remove 25 and 50 mg L-1 of atrazine as the only carbon source. The best growth and removal efficiency were detected for C1, constituted by Streptomyces sp. A2, A5, A11, and M7. This consortium was selected and tested on their ability to use atrazine as a sole nitrogen source, and no statistically significant differences (p > 0.05) were observed between the growth values detected with atrazine as a carbon (2.98 ±0.13 g L-1) or nitrogen source (2.88 ±0.18 g L-1). However, a removal decrease of 13.3% was observed with the herbicide as a nitrogen source. Phytotoxicity tests demonstrated the ability of C1 to reverse the herbicide toxicity, especially with atrazine as a carbon source. Moreover, the presence of at least one of the genes that encode enzymes involved in the herbicide degradation was detected in all C1 members. These results demonstrated the ability of C1 to remove atrazine and use it as a carbon or nitrogen source, revealing their metabolic versatility and potential cooperative work, fundamental for the degradation of xenobiotic compounds