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:Wastewater treatment plants use a variety of bioreactor types and configurations to remove organic matter and nutrients. Little is known regarding the effects of different configurations and within-plant immigration on microbial community dynamics. Previously, we found that the structure of ammonia-oxidizing bacterial (AOB) communities in a full-scale dispersed growth activated sludge bioreactor correlated strongly with levels of NO2- entering the reactor from an upstream trickling filter (Wells et al 2009). Here, to further examine this puzzling association, we profile within-plant microbial biogeography (spatial variation) and test the hypothesis that substantial microbial immigration occurs along a transect (raw influent, trickling filter biofilm, trickling filter effluent, and activated sludge) at the same full-scale wastewater treatment plant. AOB amoA gene abundance increased >30-fold between influent and trickling filter effluent concomitant with NO2- production, indicating unexpected growth and activity of AOB within the trickling filter. Nitrosomonas europaea was the dominant AOB phylotype in trickling filter biofilm and effluent, while a distinct ‘Nitrosomonas-like’ lineage dominated in activated sludge. Prior time series indicated that this ‘Nitrosomonas-like’ lineage was dominant when NO2- levels in the trickling filter effluent (i.e., activated sludge influent) were low, while N. europaea became dominant in the activated sludge when NO2- levels were high. This is consistent with the hypothesis that NO2- production may co-occur with biofilm sloughing, releasing N. europaea from the trickling filter into the activated sludge bioreactor. Phylogenetic microarray (PhyloChip) analyses revealed significant spatial variation in taxonomic diversity, including a large excess of methanogens in the trickling filter relative to activated sludge and attenuation of Enterobacteriaceae across the transect, and demonstrated transport of a highly diverse microbial community via the trickling filter effluent to the activated sludge bioreactor. Our results provide compelling evidence that substantial immigration between coupled process units occurs and may exert significant influence over microbial community dynamics within staged bioreactors.