Abstract
Two novel Bacillus sp. were isolated from a soil sample from a bank of the Tamis river in close proximity to a petrochemical facility. They were capable of utilizing a broad range of aromatic compounds as a sole source of carbon and energy (including phenol, benzene, toluene, biphenyl, naphthalene). The isolates were designated as Bacillus sp. TN41 and TN42, based on their 16S rDNA sequence. Their catabolic potential was compared to two Bacillus sp. strains (PS1 and PS11) isolated from the rhizosphere of the endemorelict plant Ramonda serbica. Specific activities of phenol hydroxylase, catechol 1,2-dioxygenase and catechol 2,3-dioxygenase were analyzed from crude cell extracts of the isolates, as well as the temperature and pH effects on enzyme activity. Although all four isolates had the ability to degrade a similar range of aromatic compounds, the specific activities of the enzymes indicative of aromatic compound catabolism of TN isolates were 2 to 90-fold lower compared to the PS isolates. Phenol hydroxylase and catechol dioxygenases exhibited broad temperature (10?C-80?C) and pH (4-9) activity ranges in all four Bacillus isolates. While phenol inhibited both phenol hydroxylase and catechol dioxygenases in the TN strains, it was an inducer for phenol hydroxylase in the PS strains.
Highlights
Soils and groundwater are preferred sinks for complex contamination
Aromatic hydrocarbon-degrading microorganisms have been isolated from various environments, mostly polluted sites, they are widespread in marine, freshwater and soil habitats (Phale et al, 2007)
Plant rhizospheres have proven to be a rich source of these bacteria, as higher plants usually extrude phenolics into the soil providing a suitable niche for the enrichment of phenol degraders (Toyama et al, 2009)
Summary
Different chemical, biological, and biochemical properties of soil can be profoundly altered. Their main effect is the continuous loss of soil functions in sustaining the survival of living organisms. Higher plants under stress conditions synthesize phenolics as reactive oxygen species scavengers and release them into the soil. The majority of these substances are highly persistent in ecosystems in unaltered, less degradable chemical forms because of their low water solubility, their intrinsic chemical stability, and high recalcitrance to degradation (Andreoni and Gianfreda, 2007). Hydrocarbonpolluted sites can represent a long-term source of pollution and pose a severe risk to environmental health
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