Project description:We applied numerical ecology methods to data produced with a human intestinal tract-specific phylogenetic microarray (the Aus-HIT Chip) to examine the biogeography of mucosa-associated bacteria along the human colon. The microbial DNA associated with matched biopsy tissue samples taken from the cecum, transverse colon, sigmoid colon and rectum of 10 healthy patients was examined. Consistent with previous studies, the profiles revealed a marked inter-subject variability; however, the numerical ecology methods of analysis allowed the subtraction of the subject effect from the data and revealed, for the first time, evidence of a longitudinal gradient for specific microbes along the colorectum: with Streptococcus, Comamonadaceae, Enterococcus and Lactobacillus in greatest abundance at the cecum, with a gradual decline in their relative abundance through to the rectum. Conversely, the analyses suggest that members of the Enterobacteriaceae increase in relative abundance towards the rectum. These differences were validated by quantitative PCR. We were also able to identify significant differences in the profiles, especially for the Streptococci, on the basis of gender. The results derived by these multivariate analyses are biologically intuitive, and suggestive that the biogeography of the colonic mucosa can be monitored for changes via cross-sectional and/or inception cohort studies.
Project description:We applied numerical ecology methods to data produced with a human intestinal tract-specific phylogenetic microarray (the Aus-HIT Chip) to examine the biogeography of mucosa-associated bacteria along the human colon. The microbial DNA associated with matched biopsy tissue samples taken from the cecum, transverse colon, sigmoid colon and rectum of 10 healthy patients was examined. Consistent with previous studies, the profiles revealed a marked inter-subject variability; however, the numerical ecology methods of analysis allowed the subtraction of the subject effect from the data and revealed, for the first time, evidence of a longitudinal gradient for specific microbes along the colorectum: with Streptococcus, Comamonadaceae, Enterococcus and Lactobacillus in greatest abundance at the cecum, with a gradual decline in their relative abundance through to the rectum. Conversely, the analyses suggest that members of the Enterobacteriaceae increase in relative abundance towards the rectum. These differences were validated by quantitative PCR. We were also able to identify significant differences in the profiles, especially for the Streptococci, on the basis of gender. The results derived by these multivariate analyses are biologically intuitive, and suggestive that the biogeography of the colonic mucosa can be monitored for changes via cross-sectional and/or inception cohort studies. 10 patients, 5 males and 5 females. Four different locations along the colorectum.
Project description:Supplementary raw metabolomics files for "Ecological stochasticity and phage induction diversify bacterioplankton communities at the microscale," Rachel E. Szabo et al.
Project description:Seamounts, often rising hundreds of metres above the surrounding seafloor, obstruct the flow of deep-ocean water. While the resultant entrainment of deep-water by seamounts is predicted from ocean circulation models, its empirical validation has been hampered by the large scale and slow rate of the interaction. To overcome these limitations we use the growth of planktonic bacteria to assess the interaction rate. The selected study site, Tropic Seamount, in the North-Eastern Atlantic represents the majority of isolated seamounts, which do not affect the surface ocean waters. We prove deep-water is entrained by the seamount by measuring 2.3 times higher bacterial concentrations in the seamount-associated or ‘sheath’ water than in deep-ocean water unaffected by seamounts. Genomic analyses of the dominant sheath-water bacteria confirm their planktonic origin, whilst proteomic analyses indicate their slow growth. According to our radiotracer experiments, the doubling time of sheath-water bacterioplankton is 1.5 years. Therefore, for bacterioplankton concentration to reach 2.3 times higher in the ambient seawater, the seamount would need to retain deep-ocean water for more than 3.5 years. We propose that turbulent mixing of the retained sheath-water could stimulate bacterioplankton growth by increasing the cell encounter rate with the ambient dissolved organic molecules. If some of these molecules chelate hydroxides of iron and manganese, bacterioplankton consumption of the organic chelators would result in precipitation of insoluble hydroxides. Hence precipitated hydroxides would form ferromanganese deposits as a result of the bacterioplankton-mediated deep-water seamount interaction.