Germ-free animals retards in wound healing to their counterparts with normal intestinal flora. Intestinal microflora modify the wound healing process via activating cellular immune reactions of the host. Gnotobiota with either Lactobacilli or Bifidobacteria could restore the healing potential of germ-free animals to the control levels. Supportive effects of probiotics on wound healing may be modified by their nutritional actions as well. Intestinal flora are also implicated in carcinogenesis of various organs. Their effects on colorectal carcinogenesis has attracted deep interests naturally. In spite of some promizing findings, no definite bacterial metabolites surely capable of inducing human colorectal cancer have not been demonstrated yet. Many studies have confirmed promoting effects of intestinal microflora on developing cancer of the large intestine. Normal intestinal microflora modify mammary carcinogenesis via the route of metabolizing phytoestrogens or manipulating the enterohepatic circulation of estrogen. Heated debates on Helicobacter pylori and gastric cancer problem have not been settled down yet, although the agreement that this microorganism can induce gastritis has been obtained. Cancer of the urinary bladder, bile ducts, etc., induced by parasitic infection can be explained by the deconjugating action of contaminating bacteria to liberate masked carcinogens. Intestinal microflora are also implicated in miscellaneous metabolic fields which are intimately related with clinical medicine offering endless interests.
Lactobacillus kefiranofaciens is known to produce an exopolysaccharide (kefiran) that is either excreted in the growth medium or attaches to the cell wall. In order to achieve high exopolysaccharide production, we devel oped a new rice hydrolyzate (RH) medium using rice starch hydrolyzate as the carbon source and rice protein hydrolyzate as the peptone source. In this study, three fermentation experiments using RH medium, PYG10 medium and PYL10 medium were carried out, respectively. The highest amount of exopolysaccharide production was obtained from the culture grown in RH medium. Among the three various media compositions compared, rice protein hydrolyzate in the RH medium demonstrated the ability to significantly enhance exopolysaccharide production by L. kefiranofaciens. In addition, the cultivation of L. kefiranofaciens in a 500l tank was also experimentally conducted, and the maximum yield of exopolysaccharide from the RH culture was 2.5 g/l after a seven-day culture period at pH 5.0 and 33°C. This result indicates that it is possible to produce exopolysaccharide (OSKC) at the level required for large-scale industrial production through the cultivation of L. kefiranofaciens in RH medium.
The influence of pH on buffers with and without sodium deoxycholate on the activities of the cancer-associated enzymes of intestinal bacteria was investigated. There were differences in the influence of pH between the buffers with and without sodium deoxycholate on the activities of β-glucuronidase and β-glucosidase on intact cells of intestinal bacteria. These findings suggest that detergent activity of sodium deoxycholate is influenced by pH.
In this study, 1, 602 bacterial strains were isolated from various sources and 18 isolates including 12 strains of Lactobacillus, five of Lactococcus lactis and one of Pseudomonas fluorescens, showed bacteriocin-like activity. These isolates were all from Kimchi and Tsukemono. Five strains of Lc. lactis inhibited Listeria monocytogenes, Clostridium difficile, C. perfringens and vancomycin resistant Enterococcus, while P. fluorescens inhibited methicillin resistant Staphylococcus aureus and Salmonella Enteritidis. However, Lactobacillus strains showed no activity against pathogens among these isolates.