Isolation and characterization of phenol degrading Bacillus species from a Southeast Brazilian mangrove sediment

Phenolic compounds are common pollutants in industrial effluents and pose a significant risk to the environment. The microbial capacity to degrade these molecules makes the prospection of bacteria with this ability very strategic for bioremediation processes in contaminated areas. This study was carried out to isolate bacteria with phenol degrading capacity from Brazilian mangrove soil. Microorganisms were evaluated for tolerance and the ability to use this substance as a single source of carbon. Two bacterial isolates were obtained: MF-1 and MF-2. The microorganisms were identified, respectively, as Bacillus cereus and Bacillus circulans by sequencing the 16S rRNA gene. The isolates exhibited tolerance to phenol at concentrations up to 600 mg.L-1 when grown in Bushnell-Haas Agar (BHA) and 1,500 mg.L-1 in nutrient agar (NA). As for the use of phenol as a single carbon source, the microorganisms were grown in concentrations of 100, 200 and 300 mg.L-1 of the compound. The isolate MF-1 presented a percentage consumption of 22.43, 11.52 and 3.33%, respectively, for each tested concentration. Although there was a decrease in phenol consumption in response to the increased concentration of this substance, bacterial growth was not affected. The best results were obtained for the isolate MF-2, in which consumption of phenol was, respectively, 21.54, 20.54 and 28.85% for these concentrations. Likewise, the increase in phenol concentration caused no reduction in the growth of this isolate.