Isolation, Characterization and Evaluation of Pseudomonas aeruginosa in the Biodegradation of Propanil Contaminated Rice Farms

Abstract

Propanil are herbicide commonly used on rice farm for the control of weeds and pests. Like other herbicides, tendencies to persists in the soil and impact on the microbial flora of rice farm soils does exists although study finds that propanil is not recalcitrant. This work aimed to isolate, characterize, and evaluate Pseudomonas aeruginosa from Enugu propanil contaminated rice farm. A total of nine [9], contaminated soil samples {three each from Nenwe, Ugbawka and Akpuoga-Nike} were collected and analyzed for presence of P.aeruginosa. The average total count were 3.8x106 [Ugbawka], 3.5x106 (Nenwe) and 2.8x106 (Akpuoga-Nike). Out of nine samples collected, 7 samples were positive for P.aeruginosa. Nine soil samples yielded 13 Pseudomonas aeruginosa isolates. Out of 13 P.aeruginosa isolated 4(30.8%) from Nenwe, 6(46.1%) from Ugbawka and 3(23.1%) from Akpuoga –Nike soil samples. P.aeruginosa were more in Ugbawka followed by Nenwe. The ability to utilize propanil was tested with other isolates based on their growth. It was observed that Pseudomonas aeruginosa and mixed culture showed heavy growth in mineral salt propanil media than in the media without propanil. The results of molecular identification revealed that Pseudomonas aeruginosa from two different strains utilized propanil heavily than other isolates. The result of the varying concentration of propanil showed that Pseudomonas aeruginosa (S1) had increased growth with increase in concentration of propanil from 0.8 at 1ml to 1.2 at 2ml. S2 showed 0.3 at 1ml to 1.0 at 2ml and mixed culture showed 0.6 at 1ml to 0.9 at 2ml. The result showed that P.aeruginosa is an efficient propanil degrader. Application of P.aeruginosa through fertilizer or soil amendment could be used to manage propanil pollution in the agricultural system.