Publications

4492

ABSTRACT We report the draft genome sequence of “ Candidatus Methanomethylophilus alvus” Mx1201, a methanogen present in the human gut. It was enriched from human feces under anaerobic conditions with methanol as the substrate. Its circular genome, of around 1.7 Mb, contains genes needed for methylotrophic methanogenesis from methanol and tri-, di-, and monomethylamine.

ABSTRACT The recently described bacterium “ Candidatus Methylomirabilis oxyfera” couples the oxidation of the important greenhouse gas methane to the reduction of nitrite. The ecological significance of “ Ca . Methylomirabilis oxyfera” is still underexplored, as our ability to identify the presence of this bacterium is thus far limited to DNA-based techniques. Here, we investigated the lipid composition of “ Ca . Methylomirabilis oxyfera” to identify new, gene-independent biomarkers for the environmental detection of this bacterium. Multiple “ Ca . Methylomirabilis oxyfera” enrichment cultures were investigated. In all cultures, the lipid profile was dominated up to 46% by the fatty acid (FA) 10-methylhexadecanoic acid (10MeC 16:0 ). Furthermore, a unique FA was identified that has not been reported elsewhere: the monounsaturated 10-methylhexadecenoic acid with a double bond at the Δ7 position (10MeC 16:1Δ7 ), which comprised up to 10% of the total FA profile. We propose that the typical branched fatty acids 10MeC 16:0 and 10MeC 16:1Δ7 are key and characteristic components of the lipid profile of “ Ca . Methylomirabilis oxyfera.” The successful detection of these fatty acids in a peatland from which one of the enrichment cultures originated supports the potential of these unique lipids as biomarkers for the process of nitrite-dependent methane oxidation in the environment.

Secondary metabolites are ubiquitous in bacteria, but by definition, they are thought to be nonessential. Highly toxic secondary metabolites such as patellazoles have been isolated from marine tunicates, where their exceptional potency and abundance implies a role in chemical defense, but their biological source is unknown. Here, we describe the association of the tunicate Lissoclinum patella with a symbiotic α-proteobacterium, Candidatus Endolissoclinum faulkneri, and present chemical and biological evidence that the bacterium synthesizes patellazoles. We sequenced and assembled the complete Ca . E. faulkneri genome, directly from metagenomic DNA obtained from the tunicate, where it accounted for 0.6% of sequence data. We show that the large patellazoles biosynthetic pathway is maintained, whereas the remainder of the genome is undergoing extensive streamlining to eliminate unneeded genes. The preservation of this pathway in streamlined bacteria demonstrates that secondary metabolism is an essential component of the symbiotic interaction.

ABSTRACT The genome of “ Candidatus Portiera aleyrodidarum,” the primary endosymbiont of the whitefly Bemisia tabaci (Mediterranean species), is reported. It presents a reduced genome (357 kb) encoding the capability to synthetize, or participate in the synthesis of, several amino acids and carotenoids, being the first insect endosymbiont capable of supplying carotenoids.

ABSTRACT “ Candidatus Portiera aleyrodidarum” is the obligate primary endosymbiotic bacterium of whiteflies, including the sweet potato whitefly Bemisia tabaci , and provides essential nutrients to its host. Here we report two complete genome sequences of this bacterium from the B and Q biotypes of B. tabaci .