Comparative (Meta)genomic Analysis and Ecological Profiling of Human Gut-Specific Bacteriophage φB124-14

Bacteriophage associated with the human gut microbiome are likely to have an important impact on community structure and function, and provide a wealth of biotechnological opportunities. Despite this, knowledge of the ecology and composition of bacteriophage in the gut bacterial community remains poor, with few well characterized gut-associated phage genomes currently available. Here we describe the identification and in-depth (meta)genomic, proteomic, and ecological analysis of a human gut-specific bacteriophage (designated φB124-14). In doing so we illuminate a fraction of the biological dark matter extant in this ecosystem and its surrounding eco-genomic landscape, identifying a novel and uncharted bacteriophage gene-space in this community. φB124-14 infects only a subset of closely related gut-associated Bacteroides fragilis strains, and the circular genome encodes functions previously found to be rare in viral genomes and human gut viral metagenome sequences, including those which potentially confer advantages upon phage and/or host bacteria. Comparative genomic analyses revealed φB124-14 is most closely related to φB40-8, the only other publically available Bacteroides sp. phage genome, whilst comparative metagenomic analysis of both phage failed to identify any homologous sequences in 136 non-human gut metagenomic datasets searched, supporting the human gut-specific nature of this phage. Moreover, a potential geographic variation in the carriage of these and related phage was revealed by analysis of their distribution and prevalence within 151 human gut microbiomes and viromes from Europe, America and Japan. Finally, ecological profiling of φB124-14 and φB40-8, using both gene-centric alignment-driven phylogenetic analyses, as well as alignment-free gene-independent approaches was undertaken. This not only verified the human gut-specific nature of both phage, but also indicated that these phage populate a distinct and unexplored ecological landscape within the human gut microbiome

Effect of pin volume ratio on wear behaviour of friction stir processed LM25AA-5%SiCp metal matrix composites

Friction stir processing (FSP) technique is preferable over other conventional surface modification techniques because of its capability to produce relatively strong and defect free surfaces. However, there are certain parameters in FSP which have to be carefully optimized to obtain defect free surfaces with exceptional properties. From the previous findings, it was understood that the tool pin profile played an important role in determining the characteristics of the processed surfaces. Hence, it was decided to investigate the effect of pin volume ratio (PVR) on various regions of the processed surface. PVR is the ratio of dynamic volume to the static volume of tool pin. Dynamic volume is the volume of the profile generated by the tool pin when it is in motion. Static volume is the volume of the profile produced by the tool pin when it is at rest. The material displaced by the tool has to be in proper proportion with the volume occupied by the pin in static condition, in order to produce optimal surface properties. In this investigation, the tool with Taper cylindrical pin profile produced defect free surfaces with superior micro hardness and wear resistance compared to other tool pin profiles. Keywords: Metal matrix composite, Tool pin profile, Static volume, Dynamic volume, Friction stir processing, Microstructure, Micro hardness and wear resistanc