Isolation of alkali-tolerant benzene-degrading bacteria from a contaminated aquifer.
OBJECTIVE
To isolate benzene-degrading strains from neutral and alkaline groundwaters contaminated by benzene, toluene, ethylbenzene, xylenes (BTEX) from the SIReN aquifer, UK, and to test their effective pH range and ability to degrade TEX.


RESULTS
The 14 isolates studied had an optimum pH for growth of 8, and could degrade benzene to below detection level (1 microg l(-1)). Five Rhodococcus erythropolis strains were able to metabolize benzene up to pH 9, two distinct R. erythropolis strains to pH 10, and one Arthrobacter strain to pH 8.5. These Actinobacteria also degraded benzene at least down to pH 5.5. Six other isolates, a Hydrogenophaga and five Pseudomonas strains, had a narrower pH tolerance for benzene degradation (pH 6 to 8.5), and could metabolize toluene; in addition, the Hydrogenophaga and two Pseudomonas strains utilized o-, m- or p-xylenes. None of these strains degraded ethylbenzene.


CONCLUSIONS
Phylogenetically distinct isolates, able to degrade BTX compounds, were obtained, and some degraded benzene at high pH.


CONCLUSIONS
High pH has previously been found to inhibit in situ degradation of benzene, a widespread, carcinogenic groundwater contaminant. These benzene-degrading organisms therefore have potential applications in the remediation or natural attenuation of alkaline waters.
Fahy
A
A
Department of Biological Sciences, University of Essex, Wivenhoe Park, Colchester, UK. afahy@essex.ac.uk
Ball
A S
AS
Lethbridge
G
G
Timmis
K N
KN
McGenity
T J
TJ
D000468:Alkalies / Q000494:pharmacology*; D001419:Bacteria / Q000302:isolation & purification* / Q000378:metabolism; D001420:Bacteria, Aerobic / Q000254:growth & development / Q000378:metabolism; D001554:Benzene / Q000378:metabolism*; D001673:Biodegradation, Environmental; D014871:Water Microbiology; D014992:Xylenes / Q000378:metabolism
D000468:Alkalies; D014992:Xylenes; D001554:Benzene