Spatial Microbial Composition Along the Gastrointestinal Tract of Captive Attwater's Prairie Chicken.

Gastrointestinal microbiota is increasingly recognized as an important component of individual health, and therefore, our ability to quantify its diversity accurately is central for exploring different ways to improve health. Non-invasive sampling methods, such as cloaca swabs, are often used to measure gastrointestinal microbiota diversity within an individual. However, few studies have addressed to what degree differences exist in microbial community composition along the gastrointestinal tract, and measures obtained from the cloaca may not actually represent the diversity present elsewhere in the gastrointestinal tract. In this study, we systematically characterized the gastrointestinal microbial community of the critically endangered Attwater's Prairie chicken (Tympanuchus cupido attwateri) by opportunistically sampling four different locations (ileum, cecum, large intestine, and cloaca) along the gastrointestinal tract of eight individuals. Spatial variation of microbial community was observed at different sampling locations within the gastrointestinal tract. The cecum harbored the most diverse and significantly different microbiota from the other locations, while the microbial α- and ß-diversities were similar in the ileum, large intestine, and cloaca. The results of this study provide evidence that microbiota diversity can differ depending on sampling location and metric used to quantify diversity. As shown here, non-invasive cloacal sampling strategies may reflect microbiota diversity elsewhere in the gastrointestinal tract, yet caution is warranted when making generalizations in terms of the microbiota diversity correlations when samples are obtained from a single location within the gastrointestinal tract.

Cluster K mycobacteriophages: insights into the evolutionary origins of mycobacteriophage TM4.

Five newly isolated mycobacteriophages--Angelica, CrimD, Adephagia, Anaya, and Pixie--have similar genomic architectures to mycobacteriophage TM4, a previously characterized phage that is widely used in mycobacterial genetics. The nucleotide sequence similarities warrant grouping these into Cluster K, with subdivision into three subclusters: K1, K2, and K3. Although the overall genome architectures of these phages are similar, TM4 appears to have lost at least two segments of its genome, a central region containing the integration apparatus, and a segment at the right end. This suggests that TM4 is a recent derivative of a temperate parent, resolving a long-standing conundrum about its biology, in that it was reportedly recovered from a lysogenic strain of Mycobacterium avium, but it is not capable of forming lysogens in any mycobacterial host. Like TM4, all of the Cluster K phages infect both fast- and slow-growing mycobacteria, and all of them--with the exception of TM4--form stable lysogens in both Mycobacterium smegmatis and Mycobacterium tuberculosis; immunity assays show that all five of these phages share the same immune specificity. TM4 infects these lysogens suggesting that it was either derived from a heteroimmune temperate parent or that it has acquired a virulent phenotype. We have also characterized a widely-used conditionally replicating derivative of TM4 and identified mutations conferring the temperature-sensitive phenotype. All of the Cluster K phages contain a series of well conserved 13 bp repeats associated with the translation initiation sites of a subset of the genes; approximately one half of these contain an additional sequence feature composed of imperfectly conserved 17 bp inverted repeats separated by a variable spacer. The K1 phages integrate into the host tmRNA and the Cluster K phages represent potential new tools for the genetics of M. tuberculosis and related species.