Materials, Methods & Technologies, Volume 14, 2020

Abstract: Phenol and its derivatives are hazardous pollutants being highly toxic even at low concentrations. Biotechnology has been very effective in dealing with major environmental challenges through utilizing different types of bacteria and biocatalysts to develop innovative processes for the biodegradation, biotreatment and biosorption of various contaminants. Many aerobic phenol-degrading microorganisms have been isolated and the pathways for the aerobic degradation of phenol are now firmly established. In many studies the results showed that Bradyrhizobium japonicum produces the most stable enzymes for biodegradation of organic pollutants. In this study we investigate biodegradation of phenol by Bradyrhizobium japonicum 273 cells. We made experiments with poor and rich (with two organic carbon sources) mineral medium. We compare an aerobic biodegradation in shaking flasks of 250 ml in a rotary shaker with various initial concentration of substrate: 0,02; 0,04; 0,06 and 0,08 g dm-3 phenol. The phenol degradation time was 10 days. We investigated the impact of glucose as an additional carbon source on the phenol biodegradation process. The maximum amount of degraded phenol was 1.08 g. It was obtained in an experiment with 0.02 g dm-3 initial phenol concentration when working in poor medium. When using a poor nutrient medium, the amount of degraded phenol is bigger than that in the rich nutrient medium. In experiments with a rich medium, Bradyrhizobium japonicum 273 cells grow and, thanks to the second carbon source, glucose, which causes a smaller amount of phenol to be treated.