Microbial degradation of phenol and derivatives using environmental isolates from industrial waste sources.

This study investigates the microbial degradation of phenolic compounds using environmental bacterial isolates obtained from refinery wastewater and petroleum-contaminated soil. Phenolic pollutants are highly toxic and persistent, posing significant challenges for biological wastewater treatment systems. To address this issue, microorganisms were enriched under increasing phenolic loads using Bushnell Haas Yeast (BHY) medium supplemented with phenol and mixed phenolic derivatives as the sole carbon source. Through adaptive passaging, two phenol-tolerant isolates were obtained and identified by 16S rRNA sequencing as Microbacterium arabinogalactanolyticum (PKN7) and Brevundimonas diminuta (VGT4). Time-resolved HPLC analyses demonstrated that both isolates completely degraded phenol within 120 h in BHY medium containing 20 mg/L phenol and 30 mg/L mixed phenolic compounds. While the strains exhibited only partial degradation of chlorophenols and cresols, consortium experiments showed enhanced performance in the mixed culture: the mixed culture achieved complete degradation of 2,4-dinitrophenol within 12 h and complete phenol removal within 60 h, while removing 73-78% of the remaining phenolic derivatives. These results confirm that cooperative metabolic interactions substantially enhance degradation performance under mixed-pollutant conditions. Overall, this study identifies M. arabinogalactanolyticum and B. diminuta as promising non-model phenol degraders, particularly when applied as a defined microbial consortium. Their combined activity highlights the potential for bioaugmentation-based strategies in industrial wastewater treatment systems. Further pilot-scale studies using real refinery effluents are needed to evaluate long-term stability and field applicability.