Isolation of an anaerobic bacterial consortium degrading phenolic compounds—Assay in swine waste

A microbial culture able to degrade phenol and p-cresol under anaerobic conditions was isolated from a mixture of swamp water, sewage sludge, swine waste and soil after an acclimation period of 5 weeks. The culture was enriched by periodic transfer in mineral salts medium containing phenol or p-cresol as the sole source of carbon. After several months of enrichment, the degradative activity of some cultures was lost. Addition of proteose peptone to the minimal medium maintained the activity, whereas the addition of acetate, glucose or nitrate or the presence of silica gel as a solid matrix to hold the cells, had no effect. The degradation of the phenolic compounds appeared to be carried out via methanogenic fermentation by a bacterial consortium. Optimal degradation by the enriched culture was at pH between 7 and 8 and at 37°C. The bacterial culture was adapted to grow in swine waste and complete degradation of 100–120 mg liter⁻¹ of phenolic compounds was obtained in swine waste seeded with this culture.