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Influent and effluent samples originating from two wastewater treatment plants (WWTPs) (treating hospital wastewater and domestic wastewater, Belgium) have been analyzed in order to estimate their steroid hormone content. The natural estrogens estrone (E1), 17[beta]-estradiol (E2), and the synthetic 17[alpha]-ethinylestradiol (EE2) together with other steroid hormones progesterone (P) and testosterone (T) metabolites were detected in these samples. The hormone concentrations in both the hospital and the domestic WWTP samples were not significantly different and ranged from 100 ng P/L. E2 was detected once at a concentration of 17 ng/L. In the domestic WWTP which comprises a conventional activated sludge treatment in parallel with a membrane bioreactor, no differences in estrogen removal efficiency could be observed for both treatments. In comparison to chemical analysis data, the Yeast Estrogen Screen (YES) appears to underestimate the influent estrogen concentrations, probably due to influent toxicity for the YES. Effluent estrogen concentrations, on the other hand, were overestimated by the YES test, probably due to the presence of other estrogenic compounds in the effluent. DOI: 10.1061/(ASCE)0733-9372(2008)134:11(933) CE Database subject headings: Wastewater management; Health care facilities; Water treatment plants.

The study examined whether Legionella pneumophila is able to thrive on heat-killed microbial cells (necrotrophy) present in biofilms or heat-treated water systems and quantification by means of plate counting, real-time PCR and flow cytometry demonstrated necrotrophic growth. Techniques aimed at the elimination of protozoa or biofilm from water systems will not necessarily result in a subsequent removal of L. pneumophila unless the formation of dead microbial cells is minimized.

Recent mieroarray experiments suggested that Burkholderia xenovorans LB400, a potent polychlorinated biphenyl (PCB)-degrading bacterium, utilizes up to three apparently redundant benzoate pathways and a [C.sub.1] metabolic pathway during biphenyl and benzoate metabolism. To better characterize the roles of these pathways, we performed quantitative proteome profiling of cells grown on succinate, benzoate, or biphenyl and harvested during either mid-logarithmic growth or the transition between the logarithmic and stationary growth phases. The Bph enzymes, catabolizing biphenyl, were ~16-fold more abundant in biphenyl- versus succinate-grown cells. Moreover, the upper and lower bph pathways were independently regulated. Expression of each benzoate pathway depended on growth substrate and phase. Proteins specifying catabolism via benzoate dihydroxylation and catechol ortho-cleavage (ben-cat pathway) were approximately an order of magnitude more abundant in benzoate- versus biphenyl-grown cells at the same growth phase. The chromosomal copy of the benzoyl-coenzyme A (CoA) ([box.sub.c]) pathway was also expressed during growth on biphenyl: [box.sub.c] proteins were approximately twice as abundant as Ben and Cat proteins under these conditions. By contrast, proteins of the megaplasmid copy of the benzoyl-CoA ([box.sub.M]) pathway were only detected in transition-phase benzoate-grown cells. Other proteins detected at increased levels in benzoate- and biphenyl-grown cells included general stress response proteins potentially induced by reactive oxygen species formed during aerobic aromatic catabolism. Finally, [C.sub.1] metabolic enzymes were present in biphenyl-grown cells during transition phase. This study provides insights into the physiological roles and integration of apparently redundant catabolic pathways in large-genome bacteria and establishes a basis for investigating the PCB-degrading abilities of this strain.

The whole-genome expression patterns were investigated when Burkholderia xenovorans LB400 was grown on biphenyl or benzoate and it was compared to the patterns when the organism was grown on succinate. The microarray results were validated by using the data for a subset of genes measured by quantitative reverse transcription PCR (Q-RT-PCR).