Ww. Mohn et al., AEROBIC BIODEGRADATION OF BIPHENYL AND POLYCHLORINATED-BIPHENYLS BY ARCTIC SOIL-MICROORGANISMS, Applied and environmental microbiology, 63(9), 1997, pp. 3378-3384
We examined the degradation of biphenyl an the commercial polychlorina
ted biphenyl (PCB) mixture Aroclor 1221 by indigenous Arctic soil micr
oorganisms to assess both the response of the soil microflora to PCB p
ollution and the potential of the microflora for bioremediation. In so
il slurries, Arctic soil microflora and temperature-soil microflora ha
d similar potentials to mineralize [C-14]biphenyl. Mineralization bega
n sooner and was more extensive in slurries of PCB-contaminated Arctic
soils than in slurries of uncontaminated Arctic soils. The maximum mi
neralization rates at 30 and 7 degrees C were typically 1.2 to 1.4 and
0.52 to 1.0 mg of biphenyl g of dry soil(-1) day(-1), respectively. S
lurries of PCB-contaminated Arctic soils degraded Aroclor 1221 more ex
tensively at 30 degrees C (71 to 76% removal) than at 7 degrees C (14
to 40% removal). We isolated from Arctic soils organisms that were cap
able of psychrotolerant (growing at 7 to 30 degrees C) or psychrophili
c (growing at 7 to 15 degrees C) growth on biphenyl. Two psychrotolera
nt isolates extensively degraded Aroclor 1221 at 7 degrees C (54 to 60
% removal). The soil microflora and psychrotolerant isolates degraded
all mono-, most di-, and some trichlorobiphenyl congeners. The results
suggest that PCB pollution selected for biphenyl-mineralizing microor
ganisms in Arctic soils. While low temperatures severely limited Arocl
or 1221 removal in slurries of Arctic soils, results with pure culture
s suggest that more effective PCB biodegradation is possible under app
ropriate conditions.