Assessment of phenol-degrading ability ofAcinetobactersp. B9 for its application in bioremediation of phenol-contaminated industrial effluents

Abstract

Successful bioremediation of a phenol-contaminated environment requires application of those microbial strains that have acquired phenol tolerance and phenol-degrading abilities. A newly isolated strain B9 of Acinetobacter sp. was adapted to a high phenol concentration by growing sequentially from low-to highstrength phenol. The acclimatised strain was able to grow and completely degrade up to 14 mM of phenol in 136 h. The degradation rates were found to increase with an increase in the phenol concentration from 2.0 to 7.5 mM. The strain preferred neutral to alkaline pH range for growth and phenol degradation, with the optimum being pH 8.0. The optimum temperature for phenol degradation was found to be in the range of 30-35°C. Transmission electron micrographs showed a disorganised and convoluted cell membrane in the case of phenol-stressed cells, showing a major effect of phenol on the membrane. Enzymatic and gas chromatography-mass spectrometry studies show the presence of an ortho-cleavage pathway for phenol degradation. Efficient phenol degradation was observed even in the presence of pyridine and heavy metals as co-toxicants showing the potential of strain in bioremediation of industrial wastes. Application of strain B9 to real tannery wastewater showed 100% removal of initial 0.5 mM phenol within 48 h of treatment.

Analysis of a phenol-adapted microbial community: degradation capacity, taxonomy and metabolic description

“…Different strategies have been used to overcome this problem including acclimatization, encapsulation, supplementation of extra carbon or nitrogen source, and the use of consortia, mixed cultures or novel strains (Bhattacharya et al . ; Bera et al . ).…”

“…However, many micro-organisms are vulnerable to high concentration of this chemical, resulting in substrate inhibition and low specific conversion rates. Different strategies have been used to overcome this problem including acclimatization, encapsulation, supplementation of extra carbon or nitrogen source, and the use of consortia, mixed cultures or novel strains (Bhattacharya et al 2015;Bera et al 2017). The acclimation of cells is a practical method for the treatment of large amounts of wastewater, and the limits of the biological processes depend on the acclimation conditions (Mohseni et al 2016;Bera et al 2017).…”

Seasonal Shift in Physicochemical Factors Revealed the Ecological Variables that Modulate the Density of Acinetobacter Species in Freshwater Resources

“…Public Health 2020, 17, 3606 2 of 19 Some Acinetobacter species have been implicated in wound infection [11], bloodstream infection [12] and meningitis [13]. Additionally, selected strains of Acinetobacter species have shown ecological and economic importance such as in bioremediation of industrial effluents [14], degradation of oil spill [15] production of bioemulsifiers [16][17][18] and secretion of phytohormones [19].…”

“…Understanding the response of Acinetobacter species in freshwater resources to changes in the environment during different seasons could serve as a tool to monitor the stress response of the microorganism when exposed to a sudden shift in environmental conditions. Therefore, given that some Acinetobacter species are potential waterborne pathogens [22] and some are useful bioremediation agents [14], this study was undertaken to evaluate the effect of seasonal peculiarities of the South African environmental conditions on the survival of Acinetobacter species in the freshwater resources.…”