Acetoin and Diacetyl Production by Homo- and Heterofermentative Lactic Acid Bacteria

Abstract

Eleven strains of homofermentative and heterofermentative lactic acid bacteria were screened for acetoin (A) and diacetyl (D) production from pyruvate and citrate in a peptone-yeast extract-glucose broth. The homofermenters, except Streptococcus faecalis subsp. liquefaciens, produced much more AD from pyruvate than from citrate; the opposite was true for the heterofermenters. Acetoin and diacetyl were produced from pyruvate as soon as growth was initiated. The production was exponential up to 24 h. Destruction of the accumulated AD coincided with entry into the stationary phase. Production of AD from citrate did not begin until 6 h of the logarithmic phase of growth. Formation of gas from citrate by Lactobacillus plantarum did not implicate greater ability to form AD from citrate than from pyruvate. Fifty μmoles ml−1 citrate caused about 50% inhibition of growth of Streptococcus lactis subsp. diacetylactis. All strains examined for ability to use pyruvate as a sole source of carbon were able to do so. Acetate (50 μmoles ml−1 generally stimulated AD formation from pyruvate. With the exception of a Pediococcus sp. and S. faecalis subsp. liquefaciens, acetaldehyde (100 μg ml−1) enhanced AD production but not growth. Concentrations higher than 100 μg ml−1 had different effects.

Citrate Metabolism by Enterococcus faecalis FAIR-E 229

“…On the other hand, it has been shown that growth of L. lactis subsp. lactis biovar diacetylactis strains was not enhanced by citrate (15). Likewise, Palles et al (31) suggested that citrate did not affect the growth rate of Lactobacillus casei or Lactobacillus plantarum when it was cometabolized with glucose or galactose.…”

An overview of formation and roles of acetaldehyde in winemaking with emphasis on microbiological implications

“…mesenteroides subsp. cremoris (Lindsay et al, 1965;Collins & Speckman, 1974;Schmitt & Diviés, 1990), while high levels (Ͼ100 mg L Ϫ1 ) of acetaldehyde inhibit growth of these LAB (El-Gendy et al, 1983). It is thought that acetaldehyde acts as a hydrogen acceptor during heterofermentation with the formation of extra energy (ATP) which stimulates growth (Lindsay et al, 1965;Collins & Speckman, 1974).…”

Diacetyl production by different strains of Lactococcus lactis subsp. lactis var. diacetylactis and Leuconostoc spp.

“…The process of diacetyl formation by lactic acid bacteria is poorly understood and therefore difficult to control during the manufacture of dairy products. Furthermore, a large variation in the activity of and product formation from citrate metabolism has been observed in different aromabacteria (Drinan et al 1976;E1-Gendy et al 1983;Oberman et al 1982). These differences in activity are evident from the different starter cultures that Correspondence to: J. Hugenholtz are used for the production of specific dairy products (Driessen and Puhan 1988;Galesloot 1962;Stadhouders 1974).…”