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Role of the Enterococcus faecalis GelE Protease in Determination of Cellular Chain Length, Supernatant Pheromone Levels, and Degradation of Fibrin and Misfolded Surface Proteins. Christopher M. Waters, 2003.Gelatinase (GelE), a secreted Zn-metalloprotease of Enterococcus faecalis, has been implicated as a virulence factor by both epidemiological data and animal model studies . Expression of gelE is induced at a high cell density by the fsr quorum-sensing system . In the present study, GelE was shown to be responsible for the instability of a number of Asc10 (aggregation substance) mutant proteins, implying that GelE functions to clear the bacterial cell surface of misfolded proteins . Disruption of GelE production led to increased cell chain length of E . faecalis, from a typical diplococcus morphology to chains of 5 to 10 cells . This function of GelE was also exhibited when the protein was expressed in Streptococcus pyogenes . GelE-expressing E . faecalis strains were more autolytic, suggesting that GelE affects chain length through activation of an autolysin . GelE was also essential for degradation of polymerized fibrin . GelE expression reduced the titer of cCF10, the peptide pheromone that induces conjugation of pCF10, and pCF10 had increased conjugation into non-GelE-expressing strains . These new functions attributed to GelE suggest that it acts to increase the dissemination of E . faecalis in high-density environments . Comparison of Euryarchaea Strains in the Guts and Food-Soil of the Soil-Feeding Termite Cubitermes fungifaber across Different Soil Types. S. E. Donovan, 2004.Termites are an important component of tropical soil communities and have a significant effect on the structure and nutrient content of soil . Digestion in termites is related to gut structure, gut physicochemical conditions, and gut symbiotic microbiota . Here we describe the use of 16S rRNA gene sequencing and terminal-restriction fragment length polymorphism (T-RFLP) analysis to examine methanogenic archaea (MA) in the guts and food-soil of the soil-feeder Cubitermes fungifaber Sjostedt across a range of soil types . If these MA are strictly vertically inherited, then the MA in guts should be the same in all individuals even if the soils differ across sites . In contrast, gut MA should reflect what is present in soil if populations are merely a reflection of what is ingested as the insects forage . We show clear differences between the euryarchaeal communities in termite guts and in food-soils from five different sites . Analysis of 16S rRNA gene clones indicated little overlap between the gut and soil communities . Gut clones were related to a termite-derived Methanomicrobiales cluster, to Methanobrevibacter and, surprisingly, to the haloalkaliphile Natronococcus . Soil clones clustered with Methanosarcina, Methanomicrococcus, or rice cluster I . T-RFLP analysis indicated that the archaeal communities in the soil samples differed from site to site, whereas those in termite guts were similar between sites . There was some overlap between the gut and soil communities, but these may represent transient populations in either guts or soil . Our data do not support the hypothesis that termite gut MA are derived from their food-soil but also do not support a purely vertical transmission of gut microflora .
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