Major changes in microbial diversity and community composition across gut sections of a juvenile Panchlora cockroach.

Investigations of gut microbiomes have shed light on the diversity and genetic content of these communities, and helped shape our understanding of how host-associated microorganisms influence host physiology, behavior, and health. Despite the importance of gut microbes to metazoans, our understanding of the changes in diversity and composition across the alimentary tract, and the source of the resident community are limited. Here, using community metagenomics and 16S rRNA gene sequencing, we assess microbial community diversity and coding potential in the foregut, midgut, and hindgut of a juvenile Panchlora cockroach, which resides in the refuse piles of the leaf-cutter ant species Atta colombica.

Biosynthesis of piperazic acid via N5-hydroxy-ornithine in Kutzneria spp. 744.

Which came first? We have investigated the biosynthesis of the piperazic acid (Piz) building blocks in the kutzneride family of metabolites. The flavin-dependent oxygenase KtzI was shown to convert ornithine to N(5)-OH-Orn. LC-MS/MS showed (13)C(5)-labeled versions of these two amino acids to be direct precursors of piperazic acid in vivo.

Significant natural product biosynthetic potential of actinorhizal symbionts of the genus frankia, as revealed by comparative genomic and proteomic analyses.

Bacteria of the genus Frankia are mycelium-forming actinomycetes that are found as nitrogen-fixing facultative symbionts of actinorhizal plants. Although soil-dwelling actinomycetes are well-known producers of bioactive compounds, the genus Frankia has largely gone uninvestigated for this potential. Bioinformatic analysis of the genome sequences of Frankia strains ACN14a, CcI3, and EAN1pec revealed an unexpected number of secondary metabolic biosynthesis gene clusters.

Potassium sensing histidine kinase in Bacillus subtilis.

The soil-dwelling organism Bacillus subtilis is able to form multicellular aggregates known as biofilms. It was recently reported that the process of biofilm formation is activated in response to the presence of various, structurally diverse small-molecule natural products. All of these small-molecule natural products made pores in the membrane of the bacterium, causing the leakage of potassium cations from the cytoplasm of the cell.

Sequence-based analysis of secondary-metabolite biosynthesis in marine actinobacteria.

A diverse collection of 60 marine-sediment-derived Actinobacteria representing 52 operational taxonomic units was screened by PCR for genes associated with secondary-metabolite biosynthesis. Three primer sets were employed to specifically target adenylation domains associated with nonribosomal peptide synthetases (NRPSs) and ketosynthase (KS) domains associated with type I modular, iterative, hybrid, and enediyne polyketide synthases (PKSs). In total, two-thirds of the strains yielded a sequence-verified PCR product for at least one of these biosynthetic types.

Genomic islands link secondary metabolism to functional adaptation in marine Actinobacteria.

Genomic islands have been shown to harbor functional traits that differentiate ecologically distinct populations of environmental bacteria. A comparative analysis of the complete genome sequences of the marine Actinobacteria Salinispora tropica and Salinispora arenicola reveals that 75% of the species-specific genes are located in 21 genomic islands. These islands are enriched in genes associated with secondary metabolite biosynthesis providing evidence that secondary metabolism is linked to functional adaptation.

Salinipyrones and pacificanones, mixed-precursor polyketides from the marine actinomycete Salinispora pacifica.

Chemical examination of a phylogenetically unique strain of the obligate marine actinomycete Salinispora pacifica led to the discovery of four new polyketides, salinipyrones A and B ( 1, 2) and pacificanones A and B ( 3, 4). These compounds appear to be derived from a mixed-precursor polyketide biosynthesis involving acetate, propionate, and butyrate building blocks. Spectral analysis, employing NMR, IR, UV, and CD methods and chemical derivatization, was used to assign the structures and absolute configurations of these new metabolites.

Phylogenetic diversity of gram-positive bacteria cultured from marine sediments.

Major advances in our understanding of marine bacterial diversity have been gained through studies of bacterioplankton, the vast majority of which appear to be gram negative. Less effort has been devoted to studies of bacteria inhabiting marine sediments, yet there is evidence to suggest that gram-positive bacteria comprise a relatively large proportion of these communities. To further expand our understanding of the aerobic gram-positive bacteria present in tropical marine sediments, a culture-dependent approach was applied to sediments collected in the Republic of Palau from the intertidal zone to depths of 500 m.