Characterization of the Rothia spp. and their role in human clinical infections.

The genus Rothia are emerging as opportunistic pathogens associated with various infections in immunocompromised and immunocompetent individuals. This review describes the taxonomy, cell wall structure, pathogenesis, phenotypic and molecular characteristics, clinical diseases, treatment and, as well as, the related genera that may be misidentified by Rothia species.

Phenotypic heterogeneity as key factor for growth and survival under oligotrophic conditions.

Productivity-poor oligotrophic environments are plentiful on earth. Yet it is not well understood how organisms maintain population sizes under these extreme conditions. Most scenarios consider the adaptation of a single microorganism (isogenic) at the cellular level, which increases their fitness in such an environment. However, in oligotrophic environments, the adaptation of microorganisms at population level - that is, the ability of living cells to differentiate into subtypes with specialized attributes leading to the coexistence of different phenotypes in isogenic populations - remains a little-explored area of microbiology research. In this study, we performed experiments to demonstrate that an isogenic population differentiated to two subpopulations under low energy-flux in chemostats. Fluorescence cytometry and turnover rates revealed that these subpopulations differ in their nucleic acid content and metabolic activity. A mechanistic modelling framework for the dynamic adaptation of microorganisms with the consideration of their ability to switch between different phenotypes was experimentally calibrated and validated. Simulation of hypothetical scenarios suggests that responsive diversification upon a change in energy availability offers a competitive advantage over homogenous adaptation for maintaining viability and metabolic activity with time.

Nesterenkonia jeotgali sp. nov., isolated from jeotgal, a traditional Korean fermented seafood.

A Gram-positive, non-motile, slightly halophilic actinomycete, strain JG-241T, was isolated from jeotgal, a traditional Korean fermented seafood, and its taxonomic position was investigated by using a polyphasic approach. Strain JG-241T grew optimally at 25-30 degrees C and in the presence of 2-5% (w/v) NaCl. The physiological and biochemical properties of strain JG-241T were distinguishable from those of recognized Nesterenkonia species. Strain JG-241T had a peptidoglycan type based on L-lys-gly-D-Asp. It contained MK-7, MK-8 and MK-9 as the predominant menaquinones and anteiso-C15:0) and anteiso-C17:0 as the major fatty acids. The major polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol and an unidentified glycolipid. The DNA G+C content was 68.0 mol%. Comparative 16S rRNA gene sequence analysis showed that strain JG-241T falls within the radiation of the cluster comprising Nesterenkonia species. Similarity values between the 16S rRNA gene sequence of strain JG-241T and those of the type strains of Nesterenkonia species ranged from 96.7 to 99.7%. DNA-DNA relatedness data and repetitive extragenic palindromic DNA-PCR genomic fingerprinting patterns showed that strain JG-241T differs genetically from recognized Nesterenkonia species. On the basis of its phenotypic properties and phylogenetic and genetic distinctiveness, strain JG-241T represents a novel species of the genus Nesterenkonia, for which the name Nesterenkonia jeotgali sp. nov. is proposed. The type strain is JG-241T (=KCTC 19053T=JCM 12610T).

Rothia dentocariosa: taxonomy and differential diagnosis.

As recent external quality control results have shown, the diagnosis of Rothia dentocariosa infection still presents problems for clinical laboratories. This review describes the taxonomy, as well as the chemotaxonomic, morphological and biochemical characteristics, of this organism, and surveys bacteria that may be confused with Rothia dentocariosa.

Pair-dependent co-aggregation behavior of non-flocculating sludge bacteria.

Two strains of non-flocculating sewage sludge bacteria (Xanthomonas sp. S53 and Microbacterium esteraromaticum S51) showed 91% and 77% co-aggregation, respectively, with Acinetobacter johnsonii S35 using a spectrophometric assay. The co-aggregates in case of Xanthomonas sp. S53 and A. johnsonii S35 were above 100 microm and stable against EDTA (2 mM) and a commercial protease (0.2 mg ml(-1)). Protease/periodate pretreatment of the partners did not affect this co-aggregation. On the other hand, co-aggregates of M. esteraromaticum S51 and A. johnsonii S35 (50-70 microm) were deflocculated by EDTA or protease. Protease pretreatment of M. esteraromaticum S51 and periodate pretreatment of A. johnsonii S35 prevented their co-aggregation with respective untreated partners. The potential co-aggregation mechanisms of A. johnsonii S35 varied depending upon the other partner involved.

Gamma irradiation and cellular damage in Kocuria rosea: investigation by one- and two-dimensional infrared spectroscopy.

Fourier transform infrared (FT-IR) spectroscopy was used to investigate the radiation-induced effects on Kocuria rosea. Bacterial suspensions at the stationary phase were exposed to increasing doses of gamma radiation. In the region 1350-840cm(-1), assigned to phosphodiester backbone, nucleic acids, and sugar rings, the radical damaging effects were dose-dependent, with the first threshold at 2.75kGy and the second at 13.75kGy inducing more striking spectral variations. Postirradiation reincubation did not significantly affect the biomolecular response, except in the spectral range 1100-1000cm(-1). These observations suggest the occurrence of new phylogenetic characteristics for K. rosea following irradiation. Moreover, two-dimensional analysis was used to highlight correlated evolutions of molecular species as radical aggression increased. The results point to an evolutionary scheme during the time course of irradiation. Thus, one- and two-dimensional IR analyses are convenient means of investigating the metabolic events following oxidative stress generated by either chemical or physical agents.