The Propionic-Acid Bacteria-a Review

Abstract

This review, appearing in three parts, is concerned with the growth, metabolism, and miscellaneous metabolic activities of propionibacteria. The first section, presented here, deals primarily with nutritional requirements, substrate and product inhibition, physical factors, associative action of other microorganisms, and enumeration and isolation of propionibacteria. The nutrition of propionic-acid bacteria has been extensively investigated and the absolute requirements for their nutrition are known. Since propionibacteria play an important role in the fermentation of Swiss cheeses, development of a completely selective medium and continued study of agents inhibitory and stimulatory to propionibacteria would be a valuable aid in solving many of the practical problems associated with Swiss cheese manufacture. Part two will discuss formation of propionate and acetate, the carboxylation, decarboxylation, and transcarboxylation reactions, the roles of biotin and vitamin B12, and the enzymes involved in the propionic-acid fermentation. The third and final section concerning miscellaneous metabolic activities will deal with erythritol metabolism, formation of diacetyl-acetoin and vitamin B12, production of previously undiscussed volatile compounds, propionin, lipids and phospholipids, and the production of slime. The third section also will include concluding comments to provide a brief summary of the important points developed in this review.

Screening of a natural biodiversity of lactic and propionic acid bacteria for folate and vitamin B12 production in supplemented whey permeate

“…Cessation of growth and eventually cell death at pH values below 4 and 5 for LAB and PAB, respectively, are reported in literature (Hammes & Hertel, 2009;Hettinga & Reinbold, 1972). We observed that pH decreased below 4 within 24 h for LAB, except for L. brevis strains that did not acidify the medium below pH 6 and belonged to one of the best folate producing species in this study.…”

“…However, yields of the 3 tested strains were very low in a range from 0.058 to 0.115 mg mL À1 . Contrary, the genus Propionibacterium has been known for quite some time for their ability to produce vitamin B12 in large amounts (Hettinga & Reinbold, 1972). We however detected differences in the ability to produce vitamin B12 among different species.…”

“…Berry and Bullerman (1966) adjusted pH of the cultures every 24 h to approximately 7.0, whereas in our screening, pH of the cultures was between 5.0 and 6.0 after 72 h and decreased to less than 5 after 168 h. Control of pH at approximately 7.0 was reviewed as being critical for reaching high vitamin B12 yields (Martens et al, 2002). Moreover, PAB cannot grow below pH 5.0 (Hettinga & Reinbold, 1972). Quesada-Chanto et al (1998) tested significantly higher vitamin B12 yields of 2.7 mg mL À1 after three days anaerobic fermentation at 35 C with pH controlled at 6.5 for P. freudenreichii DSM20271, compared to only 0.9 mg mL À1 for our uncontrolled pH conditions for the same strain.…”

Batch Fermentation Model of Propionic Acid Production by Propionibacterium acidipropionici in Different Carbon Sources

“…The propionibacteria are very sensitive to pH and usually require pH control because little growth occurs below pH 5.0 [3,7]. Lactate as carbon source has a clear advantage over glycerol and over sugarcane molasses when tight pH control cannot be implemented, as previously described [11], once it was shown that pH variation was faster when using BMG and BMSM in comparison to BML.…”

“…Propionic acid is the major product from the dicarboxylic acid pathway, also known as succinate pathway. This organic acid and its salts are able to inhibit microorganisms [1][2][3][4][5]. The prevailing view is that propionic acid disturbs the pH gradient across the cell membrane, an essential motive force for facultative anaerobes to transport nutrients and metabolites.…”