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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).

The failure of sludge chlorination to prevent filamentous bulking in wastewater treatment plants may occur because the microbial community in the sludge is resistant to chlorine. Researchers describe two filamentous bacteria that cause bulking in wastewater, one of which is sensitive to chlorine and one of which is resistant.

The addition of the reductive acetogen Peptostreptococcus productus ATCC 35244 and 2-bromoethanesulfonic acid (BES) promotes the production of acetic acid and the consumption of H2 in the ruminal ecosystem. However, this reductive acetogenesis is stimulated only when methanogenesis is selectively suppressed. P. productus ferments C6 units heterotrophically to acetate. The addition of P. productus to BES-treated samples suppresses acetic acid production and promotes volatile fatty acids production. This leads to a gain of 13 to 15% of energy gain.

The isolation and expression of a conjugated bile acid hydrolase gene from a Lactobacillus plantarum strain usinga direct plate assay is discussed. Lactobacillus strains were tested for bile acid hydrolase activity. Nucleotide sequence analysis characterized the conjugated bile acid hydrolase gene and surrounding regions. It was found that the gene was well conserved among the different Lactobacillus specimens tested.