Die ondersoek na spesifieke bakteriegroepe in die feses van geselekteerde proefpersone

Abstract

Micro-organisms play an important role in the gastrointestinal tract of humans. These organisms are mainly aerobic and anaerobic bacteria. This study was limited to the isolation and cultivation of specific groups of bacteria in the human gastrointestinal tract. Eight faecal samples were examined for the presence of the following bacteria, viz ., lactobacilli, methane producing- and sulphate reducing bacteria. Total aerobic and anaerobic counts as well as the number of enterobacteria were determined. These bacteria were quantified employing different isolation media. The lactobacilli, methane producing- and sulphate reducing bacteria were identified and classified using different phenotypic tests. Quantitative analyses revealed that the composition of the bacterial populations differ from person to person. The total percentage anaerobes was 97,96%, while 2,04% were anaerobic and facultative anaerobic bacteria. Of the fifty Lactobacillus isolates that were isolated, 64% were identified as L. plantarum, 24% as L. casei, 8% as L. acidophilus and 4% as L. salivarius subspecies saiivarius. These organisms characteristically use acetate as cellular carbon source. Gaschromatographic analyses were done on the methane producing bacteria to confirm the presence of methane. Methane was detected in most of the faecal samples. Anaerobic isolation of methane producing bacteria in the laboratory was successful. A limited number of methanogens was identified but it seems as if all the isolates belong to the genus Methanobrevibacter. No sulphate reducing bacteria were isolated from the faecal samples which confirms that methanogens and sulphate reducing bacteria compete for available substrates in the same ecological niche.