Human fecal flora: variation in bacterial composition within individuals and a possible effect of emotional stress

Abstract

Data are presented on the distribution of 101 bacterial species and subspecies among 1,442 isolates from 25 fecal specimens from three men on: (i) their normal diet and normal living conditions, (ii) normal living conditions but eating the controlled metabolic diet designed for use in the Skylab simulation and missions, and (iii) the Skylab diet in simulated Skylab (isolation) conditions. These bacteria represent the most numerous kinds in the fecal flora. Analyses of the kinds of bacteria from each astronaut during the 5-month period showed more variation in the composition of the flora among the individual astronauts than among the eight or nine samples from each person. This observation indicates that the variations in fecal flora reported previously, but based on the study of only one specimen from each person, more certainly reflect real differences (and not daily variation) in the types of bacteria maintained by individual people. The proportions of the predominant fecal species in the astronauts were similar to those reported earlier from a Japanese-Hawaiian population and were generally insensitive to changes from the normal North American diet to the Skylab diet; only two of the most common species were affected by changes in diet. However, one of the predominant species (Bacteroides fragilis subsp. thetaiotaomicron) appeared to be affected during confinement of the men in the Skylab test chamber. Evidence is presented suggesting that an anger stress situation may have been responsible for the increase of this species simultaneously in all of the subjects studied. Phenotypic characteristics of some of the less common isolates are given. The statistical analyses used in interpretation of the results are discussed.

Diversity of the human gastrointestinal tract microbiota revisited

“…Molecular studies showed that members of the phylum Cyanobacteria (one phylotype) can be found in the human gastrointestinal samples (Eckburg et al, 2005), even though isolates from this group have not been reported. Furthermore, six phylotypes of the subphylum of a-Proteobacteria were detected by SSU rRNA gene sequencing, while there is only one known a-proteobacterial gastrointestinal isolate -Gemmiger formicilis (Holdeman et al, 1976;Benno et al, 1986;Moore and Moore, 1995;Macfarlane et al, 2004). Unfortunately, no 16S rRNA gene sequence is available for this species.…”

Assessment of fecal pollution sources in a small northern-plains watershed using PCR and phylogenetic analyses of Bacteroidetes 16S rRNA gene

“…Screening for members of the Bacteroidetes phylum has advantages over screening for traditional indicators, including fecal coliforms and enterococci. For example, Bacteroidetes are more abundant in the feces of warm-blooded animals than Escherichia coli, constituting up to one half of fecal bacterial community (Holdeman et al, 1976;Fiksdal et al, 1985). Additionally, Bacteroidetes might be useful in predicting recent fecal contamination, as they are obligate anaerobes and are assumed to survive for only short periods of time outside the intestinal tract, while E. coli and enterococci are facultative anaerobes able to proliferate in soil, sand and sediments (Duerden, 1980;Allsop & Stickler, 1985;Franks et al, 1998;Suau et al, 1999;Sghir et al, 2000;Hopkins et al, 2001;Hold et al, 2002).…”

Ribosomal DNA Sequence Analysis of Mucosa-Associated Bacteria in Crohn’s Disease

“…It is composed of some 30 genera and hundreds of species making up approximately 100 trillion microorganisms. 8 Most are strict anaerobes that are extremely difficult to isolate and to identify using standard bacteriologic approaches.…”