Biodiversity of human faecal bacteria isolated from phytic acid enriched chemostat fermenters.
BACKGROUND
Myo-inositol hexaphosphate (IP6) or phytic acid is found mostly in cereals and legumes and is thought to possess anti-carcinogenic properties.


OBJECTIVE
To isolate and identify faecal bacteria capable of phytic acid metabolism and to assess the effectiveness of prebiotics (dietary oligosaccharides, metabolised by selective colonic bacteria) in preserving the integrity of phytic acid.


METHODS
Faecal samples from three volunteers were used in continuous culture experiments under varying conditions of pH, substrate concentration and dilution rates, seventy three different isolates cultured at steady state were then screened for phytic acid metabolism and identified through partial sequencing of their 16S rRNA genes (16S ribosomal ribonucleic acid). Utilisation of phytic acid was also assessed in a continuous culture system enriched with prebiotic fructooligosaccharides (FOS).


RESULTS
Bacteroides spp., Clostridium spp. and facultatively anaerobic bacteria generally appeared to maintain viable counts in the presence of phytic acid. Bifidobacterium spp. and Lactobacillus spp. appeared less able to maintain viable counts in the presence of phytic acid. These results were confirmed by an increase in viable counts of Bacteroides spp., Clostridium spp. and a decrease in viable counts of Bifidobacterium spp. and Lactobacillus spp. once phytic acid was introduced to a FOS enriched continuous culture.


CONCLUSIONS
The phytate metabolising biodiversity from the human large intestine does not appear to encompass major bacterial genera associated with beneficial or benign health effects (e.g. Lactobacillus spp. and Bifidobacterium spp).
Steer
Toni E
TE
Food Microbial Sciences Unit, School of Food Biosciences, The University of Reading, Whiteknights, PO Box 226, Reading, RG6 6AP, UK.
Gee
Jenny N
JN
Johnson
Ian T
IT
Gibson
Glenn R
GR
D001419:Bacteria / Q000145:classification* / Q000235:genetics / Q000254:growth & development*; D044822:Biodiversity; D015169:Colony Count, Microbial; D003470:Culture Media; D004275:DNA, Ribosomal / Q000032:analysis; D005243:Feces / Q000382:microbiology*; D005285:Fermentation; D006801:Humans; D009844:Oligosaccharides / Q000378:metabolism; D010833:Phytic Acid / Q000378:metabolism*; D019936:Probiotics; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA
D003470:Culture Media; D004275:DNA, Ribosomal; D009844:Oligosaccharides; D012336:RNA, Ribosomal, 16S; C116580:fructooligosaccharide; D010833:Phytic Acid