Phosphoroclastic split

When grown in alkaline media, certain species of lactic acid bacteria decrease production of LDH, resulting in increased formation of formate, acetate, and ethanol as end products. This phenomenon has been observed in S. faecalis subsp. liquefaciens (Gunsalus and Niven 1942), Streptococcus durans, S. thermophilus, (Platt and Foster 1958), and Lactobacillus bulgaricus (Rhee and Pack 1980). Data of Rhee and Pack (1980) indicate that a phosphoroclastic split of pyruvate occurs under alkaline conditions to yield ATP. The enzymes involved in this reaction (pyruvate formate-lyase and acetate kinase) require alkaline conditions for optimum activity. A shift from homo- to heterofermentation because of increased pH has not been observed for Group N streptococci. 

Fig. 21.4 Fate of pyruvic acid in Escherichia strains. Involves a phosphoroclastic split of pyruvic acid in which inorganic phosphate and ADP give rise to ATP.

Bacteria can make formate in many ways. A preliminary note by Chin et al. (1957) reports that the phosphoroclastic splitting of pyruvate to HCOOH -h CH3COOH by Escherichia coli was stimulated by FH4. Huen-nekens et al. (1958) refer to similar unpublished results (Whitely, 1958) with Micrococcus aerogenes and M, lactilyticus-, serine was not an intermediate. If the reaction HCOOH H2 + CO2, also carried out by E. coli, turns out to be folic-catalyzed, the presumption would be greatly strengthened that all formate-C02 reactions require FA, as might perhaps also formate-oxalate reactions. 

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