Biodegradation of toluene and xylenes under microaerophilic and denitrifying conditions by Pseudomonas maltophilia

Thesis/Dissertation · Sat Jan 01 04:00:00 EST 1994

OSTI ID:6755683

Su, J J

Aerobic biodegradation of aromatic hydrocarbons has been well studied. Under aerobic conditions, aerobes or facultative anaerobes can utilize aromatic hydrocarbons as sole carbon and energy sources by using oxygen as the cosubstrate of oxygenase enzymes for the initial attack of the aromatic ring and as the terminal electron acceptor for aerobic respiration. However, some facultative or obligate anaerobes can degrade these hydrocarbons by using alternate electron acceptors, such as nitrate, sulfate, carbon dioxide, or iron for anaerobic respiration. Among the potential alternate electron acceptors available, nitrate is the most common one used by microorganisms under oxygen-limited conditions. The first objective of this project was to explore hydrocarbon utilization under anoxic or low oxygen conditions. A microorganism that can utilize the petroleum hydrocarbons, toluene and xylene, as sole carbon and energy sources under microaerophilic (2% oxygen) and denitrifying conditions was isolated and characterized. Since oxygen may repress microbial denitrification, it was of interest to monitor the effects of low oxygen levels on aromatic hydrocarbon biodegradation coupled to denitrification. We isolated a Gram-negative rod, Pseudomonas maltophilia from anaerobic sewage digester sludge. The patterns of biodegradations of toluene and two isomers of xylenes, m- and p-xylene, were very similar under either microaerophilic or anaerobic conditions. Nitrate reduction was also observed during time course experiments under aerobic conditions. The final objective was to test the feasibility of an immobilized cell reactor to treat waste streams. Therefore, a bench-scale bioreactor was built to treat a waste stream contaminated with both toluene and nitrate without aeration. The utilization of toluene and nitrate was monitored periodically in a continuous system under anaerobic conditions.

• Research Organization: Rutgers--the State Univ., Newark, NJ (United States). Dept. of Geology
• OSTI ID: 6755683
• Country of Publication: United States
• Language: English

Related Subjects

560300* -- Chemicals Metabolism & Toxicology
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ALKYLATED AROMATICS
ANAEROBIC CONDITIONS
AROMATICS
BACTERIA
BIODEGRADATION
CHEMICAL REACTIONS
DECOMPOSITION
DENITRIFICATION
HYDROCARBONS
MANAGEMENT
MICROORGANISMS
ORGANIC COMPOUNDS
PROCESSING
PSEUDOMONAS
TOLUENE
WASTE MANAGEMENT
WASTE PROCESSING
XYLENES