Isolation, Molecular Characterization and Screening of Atrazine-Degrading Bacteria from Some Agricultural Soil of Jere Nigeria

Abstract

Atrazine, a major herbicide considered an endocrine disruptor and a potential carcinogen, is widely used in Nigeria; its widespread and long-term use results in high soil residue levels, thus necessitating a continuous search for atrazine biodegradation microorganisms. Microbial degradation of herbicides represents a time- and cost-effective way of eco-restoration. This research aimed to isolate and characterize bacteria capable of degrading and utilizing atrazine as a sole carbon source. Soil samples were collected from four locations, namely Alau, Dusuman, Unimaid Campus, and Zabarmari farmlands of the Jere local government area of Borno State, in November 2022 after the rainy season. The samples were collected and analyzed for pH, organic matter, organic carbon, electrical conductivity, potassium, phosphorus, and nitrogen. Statistical analysis was done to determine the significant difference in the soil parameters. There were no significant (p > 0.05) differences in the parameters of all the soils tested. Serial dilution was followed by the isolation of bacteria in a mineral salt medium (MSM) containing atrazine as the carbon source in the media. Three (3) isolates belonging to three genera (Pseudomonas, Bacillus, and Paenibacillus) exhibited remarkable stimulation in their growth and were considered acclimatized and highly Atrazine-resistant, therefore, they were selected for Atrazine-biodegradation. Pseudomonas aeruginosa had the highest degradation percentage of 93.7%. Bacillus subtilis also had a higher percentage of degradation (89.4%), and Paenibacillus validus had a percentage degradation of 82.2% on atrazine. The isolate with the highest atrazine degradation was isolated from Zabarmari farmland and was identified morphologically, biochemically, and molecularly characterized as Pseudomonas aeruginosa based on a 16S rRNA gene sequence, and a phylogenetic tree was constructed using the NCBI database. Pseudomonas aeruginosa could be a suitable candidate for the biodegradation of atrazine-polluted sites.