Isolation and Characterization of Antibiotic-Resistant Bacteria from Pesticide-Contaminated Agricultural Soils in Edo State, Nigeria.

Abstract

Antibiotic-resistant bacteria from pesticide-contaminated soils in Benin City, Nigeria, were isolated and characterized using standard microbiological methods. The heterotrophic bacterial count ranged from 3.20 x 10 4 ±
0.63 cfu/g to 1.26 x 10 5 ± 0.17 cfu/g. The pesticide-degrading bacterial count ranged from 1.40 x 10 4 ± 0.07 cfu/g to 5.85 x 10 4 ± 0.53 cfu/g. The different bacterial species isolated were: Enterobacter aerogenes, Arthrobacter sp., Bacillus pumilus, Micrococcus roseus, Pseudomonas aeruginosa and Micrococcus loteus. In assessing the antibiotic
susceptibility pattern of the isolates before curing, E. aerogenes was resistant to 6 (60 %) and susceptible to 4 (40 %) of the antibiotics. P. aeruginosa was resistant to 9 (90 %) and susceptible to 1 (10 %) of the antibiotics. Arthrobacter sp. was resistant to 9 (90 %) and susceptible to 1 (10 %) of the antibiotics, while B. pumilus was resistant to 7 (70 %) and susceptible to 3 (30 %) of the antibiotics. M. roseus was resistant to 6 (60 %) and susceptible to 4 (40 %) of the antibiotics, while M. loteus was resistant to 8 (80 %) and susceptible to 2 (20 %) of the antibiotics. After curing, E. aerogenes was resistant to 3 (30 %) and susceptible to 7 (70 %) of the antibiotics. P. aeruginosa was resistant to 4 (40 %) and susceptible to 6 (60 %) of the antibiotics. Arthrobacter sp. was resistant to 6 (60 %) and susceptible to 4 (40 %) of the antibiotics, while B. pumilus was resistant to 5 (50 %) and susceptible to 5 (50 %) of the antibiotics. M. roseus was resistant to 3 (30 %) and susceptible to 7 (70 %) of the antibiotics, while M. loteus was resistant to 5 (50 %) and susceptible to 5 (50 %) of the antibiotics. The isolates were resistant to more than one antibiotic, hence they were multi-drug resistant.