Identification and characterization of lipopolysaccharide in acetic acid bacteria.

BACKGROUND Lipopolysaccharide (LPS), a major component of the cell walls of Gram-negative bacteria, was one of the main components of Coley's vaccine and is known to have strong adjuvanticity. Though it is known that LPS exists in the digestive tract of organisms, the biological significance for the organism has not been clarified. In this study, the correlation between the structure and function of LPS was determined using acetic acid bacteria. These are Gram-negative bacteria consumed in human diets. MATERIALS AND METHODS Extracts were obtained from a strain of acetic acid bacteria which is used for producing vinegar. Determination of the LPS neutralizing activity was carried out by the Limulus test. Tumor necrosis factor (TNF) and nitric oxide (NO) production were then observed after the addition of the extracts to murine monocyte macrophages (RAW264. 7), with or without Polymyxin B. TNF production in peritoneal macrophages derived from LPS-low responsive mice (C3H/HeJ) was studied after the addition of extracts. RESULTS The extracts were shown to be positive only in LPS-specific Limulus test and were negative in the (1,3)-beta-D-glucan-specific Limulus test. Both extracts induced NO and TNF production in RAW264. 7 cells, but this was inhibited by the presence of Polymyxin B. TNF production was inhibited in peritoneal macrophages from LPS low-responsive mice (C3H/HeJ). CONCLUSION LPS with macrophage-activating activity is present in acetic acid bacteria, routinely consumed by humans.