The Role of Facultative Anaerobic Micro-Organisms in Anaerobic Biodegradation of Chlorophenols

Pure cultures of facultative anaerobic bacteria and yeasts were isolated from anaerobic reactors fed synthetic wastewater which contained eight different chlorophenolic compounds. The concentration of facultative anaerobic micro-organisms was followed in the reactor throughout the experimental period, during which the chlorophenol concentrations were increased and many of the chloronated phenols were removed nearly completely. The most common species were Klebsiella spp. and K. Pneumoniae. Some of the common colonies were tentatively identified as Pseudomonas-like organisms and Aeromonas hydrofila. Methanogenic bacteria in the reactor were mainly acetate users. When the total chlorophenol concentration in the feed was increased from zero to 2.4 or 5.3 mg/1, the concentration of Pseudomonas-like organisms increased, as did the concentration of yeasts. Pure and mixed cultures were tested for use of 2,4,6-trichlorophenol (246-TCP) as a sole carbon and energy source under anaerobic conditions. None of the isolates were able to degrade 246-TCP under anaerobic conditions in pure culture. However, mixed cultures containing only P. aeruginosa and K. oxytoca were able to degrade 246-TCP.