A phylogenetic analysis based on 16S rRNA gene sequences reveals that Alysiella filiformis belongs to the family Neisseriaceae. The genus Simonsiella is phylogenetically separated by the genera Kingella and Neisseria. The species Simonsiella crassa and A. filiformis show a close phylogenetic relationship, with the 16S rDNA sequence similarity and the DNA-DNA hybridization representing 98.7% and 35%, respectively. Therefore, S. crassa should be transferred from the genus Simonsiella to the genus Alysiella as Alysiella crassa comb. nov. Simonsiella steedae and Simonsiella sp. of cat origin show strong genetic affinities and are distantly related with the type species of Simonsiella, S. mulleri. Thus, a new genus, Conchiformibium is proposed; Conchiformibium steedae comb. nov. and Conchiformibium kuhniae sp. nov. are accommodated in this new genus. On the basis of the phylogenetic, phenotypic and chemotaxonomic distinction from the genus Neisseria, N. denitrificans should be reclassified, for which a new genus and new combination Bergeriella denitrificans are proposed.
A PCR-based screening method was used to study the genetic variations of the pgm locus among natural isolates of Yersinia pestis from China. Our results indicate that genetic variations in the pgm locus are well correlated with biovars of Y. pestis and plague foci, suggesting that the pgm locus plays a role in Y. pestis adaptation to its environment. The gene encoding two-component regulatory system sensor kinase became a pseudogene in all strains of biovar Orientalis due to a thymidine deletion, while it is intact in all the strains of the other biovars. Only strains from Foci H and L are the same as Yersinia pseudotuberculosis in that they have an intact transmembrane helix in the sensor kinase protein, which is lost in all the other strains because of the 18 bp in-frame deletion. The IS100 element that flanks the 3′ terminus of the pgm locus was inserted into the chromosome during the within-species microevolution of Y. pestis, which is absent in strains from Foci G, H and L and also in Y. pseudotuberculosis. This fact indicates that the strains from these three foci are of an older lineage of Chinese Y. pestis. It is this IS100 element's absence that maintained high stability of the pgm locus in the Y. pestis strains from these three foci. The IS285 element insertion in the pigmentation segment and the IS100 element insertion in the downstream flanking region of the pgm locus are only present in strains from Foci H and L. The flanking region outside the 5′ terminus of the upstream IS100 element is identical in the strains from these two foci, which is different in the other strains. All of these unique characteristics suggest that they are of a special lineage of Chinese Y. pestis.
In this study, the effect of Carica papaya seed macerate on conjugal R plasmid transfer from Salmonella typhimurium to Escherichia coli was investigated in vitro and in the digestive tract of gnotobiotic mice. Twenty-five micrograms per milliliter and 430 µg (administered intragastrically twice a day) of papaya seed macerate concentrations were used during conjugation for in vitro and in vivo assays, respectively. High frequency of conjugation inhibition by macerate was observed for both in vitro and in vivo experiments, independently of bacterial growth and mating conditions. Papaya seed macerate caused a reduction of the transconjugant population ranging from 71% to about 100%. There was no lethal effect of the seed macerate on donor or recipient cells in the concentrations used. Once the mechanisms and magnitude of resistance gene transfer are clearly understood, strategies to reduce or minimize the dissemination of these genes could be relevant. The data here obtained show a clinical potential use of papaya seed macerate on this transfer.
Anaerobically digested sewage sludge with a variety of moisture content, namely 81%, 86%, 90% and 98%, were anaerobically cultured at 35°C under light. Phototrophic bacteria grew in the 86% moisture sludge (bacteriochlorophyll a, 0.46 g/L), 90% sludge (bacteriochlorophyll a, 0.36 g/L) and 98% sludge (bacteriochlorophyll a, 0.04 g/L) with methane production. Phototrophic bacteria could not grow in the 81% moisture sludge (bacteriochlorophyll a 0.004 g/L). Phototrophic bacteria could assimilate about 46% of the extracellular ammonium in the 90% moisture sludge. Phototrophic bacteria utilized organic compounds competing with methanogens; therefore, methane yield from the 90% moisture sludge under the light conditions was lower than that under the dark conditions. Phototrophic bacteria could grow in anaerobically digested sludge with relatively low moisture content, and assimilated extracellular ammonium in the sludge. The quality of digested sludge with phototrophic bacterial biomass for fertilizer could be improved compared with that without phototrophic bacterial biomass.