Biodegradation potentials of edaphic bacterial isolates cultured on Haloxyfop R Methyl ester herbicide-mineral salt medium

Abstract

The heterotrophic and haloxyfop-R methyl ester utilizing bacterial counts associated with top soil samples was evaluated. Three (3) bacterial isolates; Bacillus sp., Micrococcus sp. and Staphylococcus sp. were cultured and screened for their ability to utilize haloxyfop-R methyl ester as sole source of carbon and energy using the turbidimeteric procedure. The growth profiles of two axenic cultures; Bacillus sp. and Micrococcus sp. were determined using the shake flask test. Parameters which included pH, mean viable bacterial counts, optical density and dissolved CO₂ were determined during growth profiling using relevant procedures and equipment. The pH of the soil samples was 5.08 ± 0.02 for sample A and 4.62 ± 0.02 for sample B. The total heterotrophic bacterial count was 2.8 × 10⁴ cfu/g ± 849 for A and 4.62 × 10⁴ cfu/g ± 989 for B. The mean dissolved CO₂ data for Micrococcus sp. during the growth profile study ranged from 1.1 mg/l ± 0.1 to 6.8 mg/l ± 0.2. Axenic Micrococcus sp. was the most effective amongst the growth profile cultures in mineralizing the herbicide content of the culture medium.