Yc. Cho et al., Biotransformation of polychlorinated biphenyls in St. Lawrence River sediments: reductive dechlorination and dechlorinating microbial populations, CAN J FISH, 57, 2000, pp. 95-100
Citations number
21
Categorie Soggetti
Aquatic Sciences
Journal title
CANADIAN JOURNAL OF FISHERIES AND AQUATIC SCIENCES
Polychlorinated biphenyl dechlorinating microbial populations in St. Lawren
ce River sediments were fractionated and estimated based on the dechlorinat
ion pattern using a combination of serial dilution and most probable number
techniques. Two distinctive dechlorination patterns were found in most pro
bable number sediments spiked with Aroclor 1248. A high-dilution inoculum d
ecreased the average number of chlorines per biphenyl from 4.0 to 3.4 but w
as unable to dechlorinate meta-substituted congeners consisting mainly of 2
,5,2',5'-, 2,4,2',5'-, and 2,5,2'-chlorobiphenyl (pattern B). On the other
hand, a low-dilution inoculum did dechlorinate the meta-rich congeners and
reduced the average number of chlorines to 2.9 (pattern A). These results i
ndicate that there are at least two populations. While pattern B was produc
ed by pattern B producing dechlorinators, pattern A was produced by a combi
nation of pattern B producers plus another population that dechlorinates th
e meta-substituted congeners. When the population size was calculated based
on the frequency of respective dechlorination patterns, the populations yi
elding pattern B were approximately 2.4 x 10(6) cells . g dry weight sedime
nt(-1) whereas the dechlorinators of the meta-rich congeners were two order
s of magnitude less at 3.5 x 10(4) cells . g dry weight sediment(-1). Despi
te lower numbers, these meta-dechlorinators in pattern A increased the over
all dechlorination by almost twofold.