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Archives of Microbiology (v.195, #5)

Molecular analysis of red wine yeast diversity in the Ribera del Duero D.O. (Spain) area by Eugenia Muñoz-Bernal; María Esther Rodríguez; Patricia Benítez; Francisco Javier Fernández-Acero; Laureana Rebordinos; Jesús Manuel Cantoral (pp. 297-302).

Molecular characterization of wine yeast population during spontaneous fermentation in biodynamic wines from Ribera del Duero D.O. located at northern plateau of Spain has been carried out during two consecutive years. A total of 829 yeast strains were isolated from the samples and characterized by electrophoretic karyotype. The results show the presence of three population of yeast differentiated by their electrophoretic karyotypes, (1) non-Saccharomyces yeast dominant in the initial phase of the fermentations (NS); (2) Saccharomyces bayanus var uvarum detected mainly mid-way through the fermentation process at 20–25 °C; and (3) Saccharomyces cerevisiae which remained dominant until the end of the fermentation. This is the first study showing the population dynamic of S. bayanus var. uvarum in red wines produced in Ribera del Duero that could represent an important source of autochthonous wine yeasts with novel oenological properties.

Keywords: Biodynamic wines; Spontaneous fermentation; S. bayanus var. uvarum ; PFGE; 5.8S-ITS region

Dominance of green sulfur bacteria in the chemocline of the meromictic Lake Suigetsu, Japan, as revealed by dissimilatory sulfite reductase gene analysis by Yumi Mori; Takafumi Kataoka; Takahiko Okamura; Ryuji Kondo (pp. 303-312).

This study investigated the spatiotemporal abundance and diversity of the α-subunit of the dissimilatory sulfite reductase gene (dsrA) in the meromictic Lake Suigetsu for assessing the sulfur-oxidizing bacterial community. The density of dsrA in the chemocline reached up to 3.1 × 10⁶ copies ml⁻¹ in summer by means of quantitative real-time PCR and it was generally higher than deeper layers. Most of the dsrA clones sequenced were related to green sulfur bacteria such as Chlorobium phaeovibrioides, C. limicola, and C. luteolum. Below the chemocline of the lake, we also detected other dsrA clones related to the purple sulfur bacterium Halochromatium salexigens and some branching lineages of diverse sequences that were related to chemotrophic sulfur bacterial species such as Magnetospirillum gryphiswaldense, Candidatus Ruthia magnifica, and Candidatus Thiobios zoothamnicoli. The abundance and community compositions of sulfur-oxidizing bacteria changed depending on the water depth and season. This study indicated that the green sulfur bacteria dominated among sulfur-oxidizing bacterial population in the chemocline of Lake Suigetsu and that certain abiotic environmental variables were important factors that determined sulfur bacterial abundance and community structure.

Keywords: Dissimilatory sulfite reductase gene; Meromictic lake; Phototrophic sulfur bacteria; qPCR

Diversity of bacteria in surface ice of Austre Lovénbreen glacier, Svalbard by Yin-Xin Zeng; Ming Yan; Yong Yu; Hui-Rong Li; Jian-Feng He; Kun Sun; Fang Zhang (pp. 313-322).

Two 16S rRNA gene clone libraries Cores 1U and 2U were constructed using two ice core samples collected from Austre Lovénbreen glacier in Svalbard. The two libraries yielded a total of 262 clones belonging to 59 phylotypes. Sequences fell into 10 major lineages of the domain Bacteria, including Proteobacteria (alpha, beta, gamma and delta subdivisions), Bacteroidetes, Actinobacteria, Firmicutes, Acidobacteria, Deinococcus-Thermus, Chloroflexi, Planctomycetes, Cyanobacteria and candidate division TM7. Among them, Bacteroidetes, Actinobacteria, Alphaproteobacteria and Cyanobacteria were most abundant. UniFrac data showed no significant differences in community composition between the two ice cores. A total of nineteen bacterial strains from the genera Pseudoalteromonas and Psychrobacter were isolated from the ice cores. Phylogenetic and phenotypic analyses revealed a close relationship between the ice core isolates and bacteria in marine environments, indicating a wide distribution of some bacterial phylotypes in both terrestrial and marine ecosystems.

Keywords: Bacterial diversity; Distribution; Austre Lovénbreen glacier; Marine environment

Identification of a novel gene cluster in the upstream region of the S-layer gene sbpA involved in cell wall metabolism of Lysinibacillus sphaericus CCM 2177 and characterization of the recombinantly produced autolysin and pyruvyl transferase by Magdalena Pleschberger; Florian Hildner; Dominik Rünzler; Nicola Gelbmann; Harald F. Mayer; Uwe B. Sleytr; Eva M. Egelseer (pp. 323-337).

The S-layer protein SbpA of Lysinibacillus sphaericus CCM 2177 assembles into a square (p4) lattice structure and recognizes a pyruvylated secondary cell wall polymer (SCWP) as the proper anchoring structure to the rigid cell wall layer. Sequencing of 8,004 bp in the 5′-upstream region of the S-layer gene sbpA led to five ORFs-encoding proteins involved in cell wall metabolism. After cloning and heterologous expression of ORF1 and ORF5 in Escherichia coli, the recombinant autolysin rAbpA and the recombinant pyruvyl transferase rCsaB were isolated, purified, and correct folding was confirmed by circular dichroism. Although rAbpA encoded by ORF1 showed amidase activity, it could attack whole cells of Ly. sphaericus CCM 2177 only after complete extraction of the S-layer lattice. Despite the presence of three S-layer-homology motifs on the N-terminal part, rAbpA did not show detectable affinity to peptidoglycan-containing sacculi, nor to isolated SCWP. As the molecular mass of the autolysin lies above the molecular exclusion limit of the S-layer, AbpA is obviously trapped within the rigid cell wall layer by the isoporous protein lattice. Immunogold-labeling of ultrathin-sectioned whole cells of Ly. sphaericus CCM 2177 with a polyclonal rabbit antiserum raised against rCsaB encoded by ORF5, and cell fractionation experiments demonstrated that the pyruvyl transferase was located in the cytoplasm, but not associated with cell envelope components including the plasma membrane. In enzymatic assays, rCsaB clearly showed pyruvyl transferase activity. By using RT-PCR, specific transcripts for each ORF could be detected. Cotranscription could be confirmed for ORF2 and ORF3.

Keywords: Lysinibacillus sphaericus ; S-layer protein; Secondary cell wall polymer; Autolysin; Pyruvyl transferase CsaB; Heterologous expression

Different assembly of acid and salt tolerance response in two dairy Listeria monocytogenes wild strains by Jessie Melo; Peter William Andrew; Maria Leonor Faleiro (pp. 339-348).

A lack on the association between acid tolerance response (ATR) and osmotolerance response (OTR) among Listeria monocytogenes dairy isolates was found. In order to evaluate how wild L. monocytogenes isolates mount tolerance responses under a sub-lethal pH and a low sodium chloride concentration (pH 5.5 and 3.5 % [w/v] NaCl), a proteomic approach was used. The ATR and OTR of two L. monocytogenes cheese dairy isolates (strain T8, serotype 4b and A9, serotype 1/2b or 3b) were determined. The proteomes of the adapted and non-adapted cultures were evaluated by 2-DE. One strain displayed an ATR, but not an OTR and the other displayed an OTR, but not an ATR. The ATR positive strain showed the over-production of proteins related with protein synthesis, protein folding, attainment of reduction power, ribose production and cell wall. In contrast, in the OTR-positive-strain proteins related with glycolysis, general stress and detoxification were identified.

Keywords: Listeria monocytogenes ; Stress response; Acid adaptation; Salt adaptation; Proteome

Probiotic Bacillus amyloliquefaciens mediate M1 macrophage polarization in mouse bone marrow-derived macrophages by Jian Ji; Sheng-Lan Hu; Zhi-Wen Cui; Wei-Fen Li (pp. 349-356).

Depending on the microenvironment, macrophages can acquire distinct functional phenotypes, referred to as classically activated M1 and M2. M1 macrophages are considered potent effector cells that kill intracellular pathogens, and M2 macrophages promote the resolution of wound healing. In this study, we are interested to know whether probiotic Bacillus amyloliquefaciens (Ba) can induce macrophages polarization. Real-time fluorescence PCR analysis demonstrated that the expression of IL-1β, iNOS, TNF-α and IL-6 genes for M1 macrophages was significantly increased at 1.5 h after probiotic Ba treatment compared to the probiotic Ba-free treatment (P < 0.01), whereas the expression of M2 macrophage marker genes (Arg1, Fizz1, MR, Ym1) was decreased (P < 0.05). Furthermore, the phagocytic activity was dramatically increased in the Ba-treated BMDMs using a FITC-dextran endocytosis assay. Together, these findings indicated that probiotic Ba facilitated polarization of M1 macrophages and enhanced its phagocytic capacity. The results expanded our knowledge about probiotic function-involved macrophage polarization.

Keywords: Mouse bone marrow-derived macrophages; M1 macrophages; M2 macrophage; Probiotic Bacillus amyloliquefaciens

Plant growth promoting traits of phosphate-solubilizing rhizobacteria isolated from apple trees in trans Himalayan region of Himachal Pradesh by Preeti Mehta; Abhishek Walia; Anjali Chauhan; C. K. Shirkot (pp. 357-369).

Two hundred and six phosphate-solubilizing rhizobacteria (PSB) were isolated from rhizosphere soil (RS) and root endosphere (ER) of apple trees from different sites of four locations viz., Chamba, Shimla, Kinnaur and Kullu of Himachal Pradesh, Northern India, and were screened for plant growth promoting traits (PGPTs) by using culture dependent procedures. Indole acetic acid (IAA) production was detected in 50 isolates (24.2 %), siderophore synthesis in 53 isolates (25.7 %), hydrocyanic acid (HCN) in 40 isolates (19.4 %) and percentage growth inhibition against Dematophora necatrix in 61 isolates (29.6 %). Overall, 54.3 % of PSB isolates from RS and 64.4 % from ER showed none of the PGPTs tested. Among the PSB showing PGPTs, 10.6 % had single trait and 30.6 % had multiple traits showing two (10.7 %), three (14.1 %) and four (5.8 %) types of PGPTs. The Shannon–Weaver diversity index (H′) revealed that PGPT-possessing PSBs in RS were more abundant than ER. Clustering analysis by principal component analysis showed that ER was most important factor influencing the ecological distribution and physiological characterization of PGPT-possessing PSB. There was a positive correlation (0.94, p < 0.05) between HCN and antifungal activity producers, and IAA and antifungal activity producers (0.99, p < 0.05). Significant positive correlation (0.42, p < 0.05) between HCN producers and altitude was also noted.

Keywords: P-solubilizing rhizobacteria; Plant growth promoting traits; Indole acetic acid (IAA); Siderophore; Antifungal activity against Dematophora necatrix ; HCN production

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Archives of Microbiology (v.195, #5)

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Archives of Microbiology (v.195, #5)