Effect of model sorptive phases on phenanthrene biodegradation: Different enrichment conditions influence bioavailability and selection of phenanthrene-degrading isolates
Rj. Grosser et al., Effect of model sorptive phases on phenanthrene biodegradation: Different enrichment conditions influence bioavailability and selection of phenanthrene-degrading isolates, APPL ENVIR, 66(7), 2000, pp. 2695-2702
The sorption of organic contaminants by natural organic matter (NOM) often
limits substrate bioavailability and is an important factor affecting micro
bial degradation rates in soils and sediments. We hypothesized that reduced
substrate bioavailability might influence which microbial assemblages are
responsible for contaminant degradation under enrichment culture conditions
. Our primary goal was to characterize enrichments in which different model
organic solid phases were used to establish a range of phenanthrene bioava
ilabilities for soil microorganisms, Phenanthrene sorption coefficients (ex
pressed as log K-D values) ranged from 3.0 liters kg(-1) for Amberlite carb
oxylic acid cation-exchange resin (AMB) to 3.5 liters kg(-1) for Biobeads p
olyacrylic resin (SM7) and 4.2 liters kg(-1) for Biobeads divinyl benzene r
esin (SM2), Enrichment cultures were established for control (no sorptive p
hase), sand, AMB, SM7, and SM2 treatments by using two contaminated soils (
from Dover, Ohio, and Libby, Mont,) as the initial inocula, The effects of
sorption by model phases on the degradation of phenanthrene were evaluated
for numerous transfers in order to obtain stable microbial assemblages repr
esentative of sorptive and nonsorptive enrichment cultures and to eliminate
the effects of the NOM present in the initial inoculum. Phenanthrene degra
dation rates were similar for each soil inoculum and ranged from 4 to 5 mu
mol day(-1) for control and sand treatments to approximately 0.4 ymol day(-
1) in the presence of the SM7 sorptive phase. The rates of phenanthrene deg
radation in the highly sorptive SM2 enrichment culture were insignificant;
consequently, stable microbial populations could not be obtained. Bacterial
isolates obtained from serial dilutions of enrichment culture samples exhi
bited significant differences in rates of phenanthrene degradation performe
d in the presence of SM7, suggesting that enrichments performed in the pres
ence of a sorptive phase selected for different microbial assemblages than
control treatments containing solid phase phenanthrene.