Lactate Metabolism by Veillonella parvula

Abstract

A strain of Veillonella parvula M4, which grows readily in lactate broth without a requirement for carbon dioxide, has been isolated from the oral cavity. Anaerobic, washed cells of this organism fermented sodium lactate to the following products (moles/ 100 moles of lactate): propionate, 66; acetate, 40; carbon dioxide, 40; and hydrogen, 14. Cells grew readily in tryptone-yeast extract broth with pyruvate, oxaloacetate, malate, and fumarate, but poorly with succinate. The fermentation of pyruvate, oxaloacetate, or lactate plus oxaloacetate by washed cells resulted in the formation of propionate and acetate in ratios significantly lower than those observed with lactate as the sole carbon source. This was primarily due to increased acetate production. Cell-free extracts were unable to degrade lactate but metabolized lactate in the presence of oxaloacetate, indicating the presence of malic-lactic transhydrogenase in this organism. Lactic dehydrogenase activity was not observed. Evidence is presented for oxaloacetate decarboxylase and malic dehydrogenase activities in extracts.

Stimulation of glycolysis through lactate consumption in a resting cell mixture of Streptococcus salivarius and Veillonella parvula

“…The isolation, properties and maintenance of S. salivarius 25975 have been previously described [10], as well as those for V. parvula M4 [9]. S. salivarius was grown anaerobically in batch culture in glucose tryptone-yeast extract broth, harvested in the exponential phase and washed in potassium phosphate buffer (50 mM, pH 7.0).…”

“…S. salivarius was grown anaerobically in batch culture in glucose tryptone-yeast extract broth, harvested in the exponential phase and washed in potassium phosphate buffer (50 mM, pH 7.0). V. parvula was grown anaerobically in Rogosa's 1% lactate broth and harvested as previously described [9].…”

“…While the concentration of acetate and propionate in the 'acetate + propionate' fraction ( Fig. 1, Table 1) was not analyzed, estimates from a previously published V. parvula M4 fermentation balance [9] suggests that values of about 14 and 24 mM for acetate and propionate, respectively, would be present in flasks B-E.…”

“…Sodium propionate, on the other hand, was very inhibitory at concentrations less than 50 mM when tested with batch-grown cells. In view of Table 1 Effect of increasing concentrations of V. parvula M4 on the extracellular lactate concentration and glycolytic rate of washed suspensions of S. salivarius 25975 incubated anaerobically with glucose a [9]. c nmol glucose fermented ml-i rain-].…”

“…In accordance with the above observations the absence of a mechanism to remove lactate from the ecosystems would result in the accumulation of lactate which, in turn, would inhibit energy recovery from lactate efflux. Oral ecosystems, such as whole saliva and dental plaque, are known to possess a simple food chain [7,8] whereby the fermentation of sugars by acidogenic bacteria, such as the streptococci, is coupled to lactate utilization by members of the asaccharolytic genus, Veillonella, which utilize lactate for energy with the formation of acetate, propionate, CO 2 and H 2 [9]. Consequently, the combination of a lactate-forming streptococcal organism with a member of the Veillonella would be mutually beneficial since it would maximize the energy gained from lactate efflux, as well as from the metabolism of lactate.…”