Identification and acclimatization of the most potential 4‐chlorophenol degrading bacterial strain isolated from hazardous soil and observing its performance in various process parameters

Abstract

Abstract4‐Chlorophenol is present as an essential compound of various organic compounds found in different kinds of hazardous waste. It can be easily eliminated from the industrial effluents by different physical and chemical treatment methods although best technique is bioremediation. To separate a potent bacterial strain from the soil that can dispose of 4‐chlorophenol from contaminated water, soil sample was collected from a hospital zone. Isolated bacterial colonies were segregated by the technique of soil enrichment with 500 mg/L 4‐chlorophenol and after that the enriched soil sample was serially diluted and transferred to petri plates with agar media. Twenty‐seven colonies were isolated and the most potent strain was selected in 50 mL liquid medium that was enriched previously with 500 mg/L of 4‐chlorophenol. C19 was found to be the most potent strain and it had the ability to reduce almost 99.97% of 4‐chlorophenol within 24 h, 37°C temperatures as well as in shaking condition (140–150 rpm) and pH 6.8–7.2. After the isolation, the strain was acclimatized in mineral salt medium (MSM) from lower concentration to higher concentration of 4‐chlorophenol to increase its removal capacity as well as to prepare the inoculums. Then parameter optimization study was performed where optimum temperature and pH was found to be 25°C and 6.5°C, respectively, 400 mL media volume and 8% inoculums were found to be most effective and finally 24 h time period was optimized. All these five optimum parameters were applied together to remove higher conc. of 4‐chlorophenol where almost 99.3% removals were obtained when the conc. was 600 mg/L. Moreover, more than 90% removals were obtained in case of 700, 800, and 900 mg/L concentration. Morphological, biochemical, nucleotide homology, and phylogenetic investigation of the strain was made which revealed that it was a rod shaped (Bacillus type), gram +ve, spore forming and motile bacterial strain and therefore, the selected strain was found to exhibit most extreme similarities (91.73%) with Bacillus cereus strain MK789657.