Enterococcus faecalis is a commensal bacterium of the mammalian intestine that can persist in soil and aquatic systems and can be a nosocomial pathogen to humans. It employs multiple stress adaptation strategies in order to survive such a wide range of environments. Within this study, we sought to elucidate whether membrane fatty acid composition changes are an important component for stress adaptation. We noted that E. faecalis OG1RF was capable of changing its membrane composition depending upon growth phase and temperature. The organism also readily incorporated fatty acids from bile, serum, and medium supplemented with individual fatty acids, often dramatically changing the membrane composition such that a single fatty acid was predominant. Growth in either low levels of bile or specific individual fatty acids was found to protect the organism from membrane challenges such as high bile exposure. In particular, we observed that when grown in low levels of bile, serum, or the host-derived fatty acids oleic acid and linoleic acid, E. faecalis was better able to survive the antibiotic daptomycin. Interestingly, the degree of membrane saturation did not appear to be important for protection from the stressors examined here; instead, it appears that a specific fatty acid or combination of fatty acids is critical for stress resistance.

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Incorporation of Exogenous Fatty Acids Protects Enterococcus faecalis from Membrane-Damaging Agents

A nitrogen-fixing bacterium, designated strain X19-5(T), was isolated from rhizosphere soil of Sonchus oleraceus. Phylogenetic analysis based on a fragment of the nifH gene and the full-length 16S rRNA gene sequence revealed that strain X19-5(T) was a member of the genus Paenibacillus. Strain X19-5(T) showed the highest 16S rRNA gene sequence similarity (98.8 %) with Paenibacillus graminis RSA19(T) and below 97 % similarity with other recognized members of the genus. The level of DNA-DNA relatedness between strain X19-5(T) and P. graminis RSA19(T) was 45.7 %. The DNA G+C content of strain X19-5(T) was 46.8 mol%. The major fatty acids were anteiso-C(15 : 0), C(16 : 0) and iso-C(16 : 0). On the basis of its phenotypic characteristics and the level of DNA-DNA hybridization, strain X19-5(T) is considered to represent a novel species of the genus Paenibacillus, for which the name Paenibacillus sonchi sp. nov. is proposed. The type strain is X19-5(T) (=CCBAU 83901(T)=LMG 24727(T)).

Paenibacillus sonchi sp. nov., a nitrogen-fixing species isolated from the rhizosphere of Sonchus oleraceus

A nitrogen-fixing bacterium, designated strain S27T, was isolated from rhizosphere soil of Sophora japonica. Phylogenetic analysis based on a fragment of the nifH gene and the full-length 16S rRNA gene sequence revealed that strain S27T is a member of the genus Paenibacillus. High levels of 16S rRNA gene sequence similarity were found between strain S27T and Paenibacillus durus DSM 1735T (97.3 %), Paenibacillus sabinae DSM 17841T (96.9 %), Paenibacillus forsythiae DSM 17842T (96.7 %) and Paenibacillus zanthoxyli DSM 18202T (96.6 %). However, DNA–DNA hybridization values between strain S27T and the four type strains were 37.64 %, 23.12 %, 25.6 % and 34.99 %, respectively. Levels of 16S rRNA gene sequence similarity between strain S27T and the type strains of other recognized members of the genus Paenibacillus were below 96.5 %. The DNA G+C content of strain S27T was 46.0 mol%. The major fatty acids were anteiso-C15 : 0, C16 : 0 and iso-C16 : 0. The major isoprenoid quinone was MK-7. On the basis of its phenotypic characteristics and DNA–DNA hybridization results, strain S27T is considered to represent a novel species of the genus Paenibacillus, for which the name Paenibacillus sophorae sp. nov. is proposed. The type strain is S27T ( = CGMCC 1.10238T  = DSM 23020T).

Paenibacillus sophorae sp. nov., a nitrogen-fixing species isolated from the rhizosphere of Sophora japonica.

Analysis of survival rates and cellular fatty acid profiles of Listeria monocytogenes treated with supercritical carbon dioxide under the influence of cosolvents.

A nitrogen-fixing bacterium, designated strain T98(T), was isolated from rhizosphere soil of Forsythia mira. Phylogenetic analysis based on a fragment of the nifH gene and the full-length 16S rRNA gene sequence revealed that strain T98(T) was a member of the genus Paenibacillus. High levels of 16S rRNA gene similarity were found between strain T98(T) and Paenibacillus durus ATCC 35681(T) (97.0 %), Paenibacillus sabinae DSM 17841(T) (98.3 %) and Paenibacillus zanthoxyli DSM 18202(T) (96.8 %). Levels of 16S rRNA gene sequence similarity between strain T98(T) and the type strains of other recognized members of the genus Paenibacillus were below 97.0 %. Levels of DNA-DNA relatedness between strain T98(T) and P. durus ATCC 35681(T), P. sabinae DSM 17841(T) and P. zanthoxyli DSM 18202(T) were 27.6, 30.0 and 32.1 %, respectively. The DNA G+C content of strain T98(T) was 50.4 mol%. The major fatty acids were anteiso-C(15 : 0), C(16 : 0) and iso-C(16 : 0). On the basis of its phenotypic characteristics and levels of DNA-DNA hybridization, strain T98(T) is considered to represent a novel species of the genus Paenibacillus, for which the name Paenibacillus forsythiae sp. nov. is proposed. The type strain is T98(T) (=CCBAU 10203(T) =DSM 17842(T)).

Paenibacillus forsythiae sp. nov., a nitrogen-fixing species isolated from rhizosphere soil of Forsythia mira.

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Tang J

Papers

Identification of Bacillus anthracis from culture using gas chromatographic analysis of fatty acid methyl esters.