Journal of Microbiology

Journal Articles

Full-repertoire comparison of the microscopic objects composing the human gut microbiome with sequenced and cultured communities: Edmond Kuete Yimagou , Jean-Pierre Baudoin , Rita Abou Abdallah , Fabrizio Di Pinto , Jacques Yaacoub Bou Khalil , Didier Raoult; J. Microbiol. 2020;58(5):377-386. Published online April 11, 2020; DOI: https://doi.org/10.1007/s12275-020-9365-3

20 View
0 Download
3 Citations

Abstract: The study of the human gut microbiome is essential in microbiology and infectious diseases as specific alterations in the gut microbiome might be associated with various pathologies, such as chronic inflammatory disease, intestinal infection and colorectal cancer. To identify such dysregulations, several strategies are being used to create a repertoire of the microorganisms composing the human gut microbiome. In this study, we used the “microscomics” approach, which consists of creating an ultrastructural repertoire of all the cell-like objects composing stool samples from healthy donors using transmission electron microscopy (TEM). We used TEM to screen ultrathin sections of 8 resin-embedded stool samples. After exploring hundreds of micrographs, we managed to elaborate ultrastructural categories based on morphological criteria or features. This approach explained many inconsistencies observed with other techniques, such as metagenomics and culturomics. We highlighted the value of our cultureindependent approach by comparing our microscopic images to those of cultured bacteria and those reported in the literature. This study helped to detect “minimicrobes” Candidate Phyla Radiation (CPR) for the first time in human stool samples. This “microscomics” approach is non-exhaustive but complements already existing approaches and adds important data to the puzzle of the microbiota.

Antarctic tundra soil metagenome as useful natural resources of cold-active lignocelluolytic enzymes: Han Na Oh , Doyoung Park , Hoon Je Seong , Dockyu Kim , Woo Jun Sul; J. Microbiol. 2019;57(10):865-873. Published online September 30, 2019; DOI: https://doi.org/10.1007/s12275-019-9217-1

9 View
0 Download
19 Citations

Abstract: Lignocellulose composed of complex carbohydrates and aromatic heteropolymers is one of the principal materials for the production of renewable biofuels. Lignocellulose-degrading genes from cold-adapted bacteria have a potential to increase the productivity of biological treatment of lignocellulose biomass by providing a broad range of treatment temperatures. Antarctic soil metagenomes allow to access novel genes encoding for the cold-active lignocellulose-degrading enzymes, for biotechnological and industrial applications. Here, we investigated the metagenome targeting cold-adapted microbes in Antarctic organic matter-rich soil (KS 2-1) to mine lignolytic and celluloytic enzymes by performing single molecule, real-time metagenomic (SMRT) sequencing. In the assembled Antarctic metagenomic contigs with relative long reads, we found that 162 (1.42%) of total 11,436 genes were annotated as carbohydrate-active enzymes (CAZy). Actinobacteria, the dominant phylum in this soil’s metagenome, possessed most of candidates of lignocellulose catabolic genes like glycoside hydrolase families (GH13, GH26, and GH5) and auxiliary activity families (AA7 and AA3). The predicted lignocellulose degradation pathways in Antarctic soil metagenome showed synergistic role of various CAZyme harboring bacterial genera including Streptomyces, Streptosporangium, and Amycolatopsis. From phylogenetic relationships with cellular and environmental enzymes, several genes having potential for participating in overall lignocellulose degradation were also found. The results indicated the presence of lignocellulose-degrading bacteria in Antarctic tundra soil and the potential benefits of the lignocelluolytic enzymes as candidates for cold-active enzymes which will be used for the future biofuel-production industry.

Research Support, Non-U.S. Gov't

Antioxidant Capacity of Novel Pigments from an Antarctic Bacterium: Daniela N. Correa-Llantén , Maximiliano J. Amenábar , Jenny M. Blamey; J. Microbiol. 2012;50(3):374-379. Published online June 30, 2012; DOI: https://doi.org/10.1007/s12275-012-2029-1

15 View
0 Download
51 Citations

Abstract: In Antarctica microorganisms are exposed to several conditions that trigger the generation of reactive oxygen species, such as high UV radiation. Under these conditions they must have an important antioxidant defense system in order to prevent oxidative damage. One of these defenses are pigments which are part of the non-enzymatic antioxidant mechanisms. In this work we focused on the antioxidant capacity of pigments from an Antarctic microorganism belonging to Pedobacter genus. This microorganism produces different types of pigments which belong to the carotenoids group. The antioxidant capacity of a mix of pigments was analyzed by three different methods: 1,1-diphenyl-2-picrylhydrazyl, ROS detection and oxygen electrode. The results obtained from these approaches indicate that the mix of pigments has a strong antioxidant capacity. The oxidative damage induced by UVB exposure to liposomes was also analyzed. Intercalated pigments within the liposomes improved its resistance to lipid peroxidation. Based on the analysis carried out along this research we conclude that the antioxidant properties of the mix of pigments protect this bacterium against oxidative damage. These properties make this mix of pigments a powerful antioxidant mixture with potential biotechnological applications.

Journal Article

Psychroflexus lacisalsi sp. nov., a Moderate Halophilic Bacterium Isolated from a Hypersaline Lake (Hunazoko-Ike) in Antarctica: Hongyan Zhang , Shoko Hosoi-Tanabe , Syuhei Ban , Satoshi Imura; J. Microbiol. 2010;48(2):160-164. Published online May 1, 2010; DOI: https://doi.org/10.1007/s12275-010-0018-9

10 View
0 Download
11 Citations

Abstract: A novel Gram-negative, aerobic, moderate halophilic, and psychrotolerant bacterium, designated as strain H7T, was isolated from a hypersaline lake located in Skarvsnes, Antarctica. Cells were filaments with varying lengths. Coccoid bodies developed in old cultures. Growth occurred with 0.5-15% (w/v) NaCl (optimum, 5.8-7.0%), at pH 6.0-10.0 (optimum, pH 7.0-8.0), and at 10-28°C (optimum, 25°C). The strain had a G+C content of 34.9 mol%, which is within the range of 32-36 mol% reported for the genus Psychroflexus. Chemotaxonomic data (major respiratory quinone: MK-6; major fatty acids: aC15:0, iC16:0 3-OH, and aC15: 1 A) supported the classification of strain H7T within the genus Psychroflexus. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain H7T should be assigned to the genus Psychroflexus and has a homology with Psychroflexus salinarum (98.2%), P. sediminis (96.1%), P. torquis (95.2%), P. tropicus (95.8%), and P. gondwanense (92.2%). Strain H7 is not identified as P. salinarum because that DNA-DNA hybridization data were 8.5% between strain H7T and P. salinarum. The combination of phylogenetic analysis, DNA-DNA hybridization data, phenotypic characteristics, and chemotaxonomic differences supported the view that strain H7T represents a novel species of the genus Psychroflexus. The name Psychroflexus lacisalsi is proposed, and the type strain is H7T (=JCM 16231T =KACC 14089T).

First
Prev
Page of 1
Next
Last

Search