high-resolution-comparison-of-bacterial-conjugation-frequencies

High-Resolution Comparison of Bacterial Conjugation Frequencies

Bacterial conjugation is an important step in the horizontal transfer of antibiotic resistance genes via a conjugative DNA element. In-depth comparisons ...

RIKEN BioResource Research Center

[Symbiotic complex in the termite gut microbial community].

Haloalkaliphilic strains JCM 19037, JCM 19038, JCM 19039, and JCM 19055, closely related to Geomicrobium sediminis, were isolated from aquatic samples, and their draft genome sequences were determined. The genome information of these four strains will be useful for studies of their physiology and ecology. 

Draft Genome Sequences of Geomicrobium sp. Strains JCM 19037, JCM 19038, JCM 19039, and JCM 19055, Isolated from Aquatic Samples.

Vibrio sp. strains JCM 18905 and JCM 19053 were isolated from a tetrodotoxin (TTX)-bearing scavenging gastropod, and Vibrio sp. strain JCM 18904 was isolated from a sea cucumber. All these are closely related to Vibrio alginolyticus. Their comparative genome information is useful for studies of TTX production in bacteria. 

Draft Genome Sequences of Vibrio sp. Strains Isolated from Tetrodotoxin-Bearing Scavenging Gastropod.

Symbiotic associations of cellulolytic eukaryotic protists and diverse bacteria are common in the gut microbial communities of termites. Besides cellulose degradation by the gut protists, reductive acetogenesis from H2 plus CO2 and nitrogen fixation by gut bacteria play crucial roles in the host termites' nutrition by contributing to the energy demand of termites and supplying nitrogen poor in their diet, respectively. Fractionation of these activities and the identification of key genes from the gut community of the wood-feeding termite Hodotermopsis sjoestedti revealed that substantial activities in the gut--nearly 60% of reductive acetogenesis and almost exclusively for nitrogen fixation--were uniquely attributed to the endosymbiotic bacteria of the cellulolytic protist in the genus Eucomonympha. The rod-shaped endosymbionts were surprisingly identified as a spirochete species in the genus Treponema, which usually exhibits a characteristic spiral morphology. The endosymbionts likely use H2 produced by the protist for these dual functions. Although H2 is known to inhibit nitrogen fixation in some bacteria, it seemed to rather stimulate this important mutualistic process. In addition, the single-cell genome analyses revealed the endosymbiont's potentials of the utilization of sugars for its energy requirement, and of the biosynthesis of valuable nutrients such as amino acids from the fixed nitrogen. These metabolic interactions are suitable for the dual functions of the endosymbiont and reconcile its substantial contributions in the gut.

Article	Year
[Symbiotic complex in the termite gut microbial community]. Tanpakushitsu kakusan koso. Protein, nucleic acid, enzyme\| PubMed ID: 19044020	2008
Draft Genome Sequences of Geomicrobium sp. Strains JCM 19037, JCM 19038, JCM 19039, and JCM 19055, Isolated from Aquatic Samples. Genome announcements\| PubMed ID: 24948772	2014
Draft Genome Sequences of Vibrio sp. Strains Isolated from Tetrodotoxin-Bearing Scavenging Gastropod. Genome announcements\| PubMed ID: 24948773	2014
Acetogenesis from H2 plus CO2 and nitrogen fixation by an endosymbiotic spirochete of a termite-gut cellulolytic protist. Proceedings of the National Academy of Sciences of the United States of America\| PubMed ID: 25979941	2015

Moriya Ohkuma

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