Fermentation of glucuronic acid by Lactobacillus brevis.

Certain heterofermentative lactic acid bacteria often encountered in food and beverage fermentations are able to utilize the uronic acids as a sole carbon source for energy (J. R. Stamer and B. O. Stoyla, Bacteriol. Proc., p. 1, 1967). Although the mechanisms of uronic acid degradation by gram-negative or phytopathogenic microorganisms have been extensively studied (W. J. Payne and R. A. McRorie, Biochim. Biophys. Acta 29:466, 1958; W. W. Kilgore and M. P. Starr, J. Biol. Chem. 234:2227, 1959; G. Ashwell et al., J. Biol. Chem. 235:1559, 1960), the fermentation of these acidic substrates by members of the family Lactobacillaceae has not been previously described. Therefore, this report describes the end products of the glucuronic acid fermentation by Lactobacillus brevis B155, a member of the subgenus Betabacterium. The sodium salt of glucuronic acid was prepared from the y-lactone (Mann Research Laboratories, New York, N.Y.). The lactone (1.0%) was hydrolyzed at 45 C with an equivalent amount of 0.2 N sodium hydroxide. A pH of 6.8 was maintained during a 3-hr hydrolysis period. The basal medium (J. R. Stamer, M. N. Albury, and C. S. Pederson, Appl. Microbiol. 12:165, 1964) contained 0.5% sodium glucuronate or glucose and was sterilized by membrane filtration. After 24 hr of incubation at 32 C, the cells were harvested and washed three times with distilled water, and were suspended in 0.25 M phosphate buffer (pH 6.0). The formation of carbon dioxide from glucuronate by glucuronate-grown cells was measured by conventional manometric procedures (W. W. Umbreit et al., Manometric techniques, p. 28, Burgess Publishing Co., Minneapolis, 1959). The glucuronate-grown cells produced 9.3 A moles of C02 from the available substrate (10 lmoles) within 60 min, whereas the glucose-grown cells were inactive (Fig. 1). The utilization of glucuronate by L. brevis apparently is dependent upon the formation of adaptive enzyme systems. The requirement for adaptation prior to the dissimilation of the uronic acid appears to be similar to that of the nonlactic acid bacteria as reported previously (S. Hollmann and E. Thofern, Z. Physiol. Chem. 312:111, 1958). The products arising from the fermentation