Challenges and opportunities in understanding microbial communities with metagenome assembly (accompanied by IPython Notebook tutorial)

Metagenomic investigations hold great promise for informing the genetics, physiology, and ecology of environmental microorganisms. Current challenges for metagenomic analysis are related to our ability to connect the dots between sequencing reads, their population of origin, and their encoding functions. Assembly-based methods reduce dataset size by extending overlapping reads into larger contiguous sequences (contigs), providing contextual information for genetic sequences that does not rely on existing references. These methods, however, tend to be computationally intensive and are again challenged by sequencing errors as well as by genomic repeats While numerous tools have been developed based on these methodological concepts, they present confounding choices and training requirements to metagenomic investigators. To help with accessibility to assembly tools, this review also includes an IPython Notebook metagenomic assembly tutorial. This tutorial has instructions for execution any operating system using Amazon Elastic Cloud Compute and guides users through downloading, assembly, and mapping reads to contigs of a mock microbiome metagenome. Despite its challenges, metagenomic analysis has already revealed novel insights into many environments on Earth. As software, training, and data continue to emerge, metagenomic data access and its discoveries will to grow

Draft Genome Sequence of Sorghum Grain Mold Fungus Epicoccum sorghinum, a Producer of Tenuazonic Acid

The facultative plant pathogen Epicoccum sorghinum is associated with grain mold of sorghum and produces the mycotoxin tenuazonic acid. This fungus can have serious economic impact on sorghum production. Here, we report the draft genome sequence of E. sorghinum (USPMTOX48)

Comparative genome analysis of Burkholderia phytofirmans PsJN reveals a wide spectrum of endophytic lifestyles based on interaction strategies with host plants

Burkholderia phytofirmans PsJN is a naturally occurring plant-associated bacterial endophyte that effectively colonizes a wide range of plants and stimulates their growth and vitality. Here we analyze whole genomes, of PsJN and of eight other endophytic bacteria. This study illustrates that a wide spectrum of endophytic life styles exists. Although we postulate the existence of typical endophytic traits, no unique gene cluster could be exclusively linked to the endophytic lifestyle. Furthermore, our study revealed a high genetic diversity among bacterial endophytes as reflected in their genotypic and phenotypic features. B. phytofirmans PsJN is in many aspects outstanding among the selected endophytes. It has the biggest genome consisting of two chromosomes and one plasmid, well-equipped with genes for the degradation of complex organic compounds and detoxification, e.g., 24 glutathione-S-transferase (GST) genes. Furthermore, strain PsJN has a high number of cell surface signaling and secretion systems and harbors the 3-OH-PAME quorum-sensing system that coordinates the switch of free-living to the symbiotic lifestyle in the plant-pathogen R. solanacearum. The ability of B. phytofirmans PsJN to successfully colonize such a wide variety of plant species might be based on its large genome harboring a broad range of physiological functions

Single-cell and metagenomic analyses indicate a fermentative and saccharolytic lifestyle for members of the OP9 lineage

OP9 is a yet-uncultivated bacterial lineage found in geothermal systems, petroleum reservoirs, anaerobic digesters and wastewater treatment facilities. Here we use single-cell and metagenome sequencing to obtain two distinct, nearly complete OP9 genomes, one constructed from single cells sorted from hot spring sediments and the other derived from binned metagenomic contigs from an in situ-enriched cellulolytic, thermophilic community. Phylogenomic analyses support the designation of OP9 as a candidate phylum for which we propose the name ‘Atribacteria’. Although a plurality of predicted proteins is most similar to those from Firmicutes, the presence of key genes suggests a diderm cell envelope. Metabolic reconstruction from the core genome suggests an anaerobic lifestyle based on sugar fermentation by Embden–Meyerhof glycolysis with production of hydrogen, acetate and ethanol. Putative glycohydrolases and an endoglucanase may enable catabolism of (hemi)cellulose in thermal environments. This study lays a foundation for understanding the physiology and ecological role of the ‘Atribacteria’.United States. National Aeronautics and Space Administration (Exobiology Grant EXO-NNX11AR78G)National Science Foundation (U.S.) (Grant MCB 0546865)National Science Foundation (U.S.) (Grant OISE 0968421)United States. Dept. of Energy (Grant DE-EE-0000716)Nevada Renewable Energy ConsortiumUnited States. Dept. of Energy. Office of Science. Joint Genome Institute (Contract DE-AC02-05CH11231

Draft Genome Sequence of Frankia sp. Strain CN3, an Atypical, Noninfective (Nod–) Ineffective (Fix–) Isolate from Coriaria nepalensis

We report here the genome sequence of Frankia sp. strain CN3, which was isolated from Coriaria nepalensis. This genome sequence is the first from the fourth lineage of Frankia, strains of which are unable to reinfect actinorhizal plants. At 10 Mb, it represents the largest Frankia genome sequenced to date

Draft Genome Sequence of Frankia sp. Strain QA3, a Nitrogen-Fixing Actinobacterium Isolated from the Root Nodule of Alnus nitida

Members of the actinomycete genus Frankia form a nitrogen-fixing symbiosis with 8 different families of actinorhizal plants. We report a high-quality draft genome sequence for Frankia sp. strain QA3, a nitrogen-fixing actinobacterium isolated from root nodules of Alnus nitida