Leuconostoc mesenteroides subsp. mesenteroides ATCC 8293
   
   
 

Photo: Fred Breidt, North Carolina State University
Leuconostoc species are epiphytic bacteria that are wide spread in the natural environment and play an important role in several industrial and food fermentations. Leuconostoc mesenteroides is a facultative anaerobe requiring complex growth factors and amino acids (Reiter and Oram 1982; Garvie 1986).

Most strains in liquid culture appear as cocci, occurring singly or in pairs and short chains, however, morphology can vary with growth conditions; cells grown in glucose or on solid media may have an elongated or rod shaped morphology. Cells are Gram positive, asporogenous and non-motile.

A variety of lactic acid bacteria (LAB), including Leuconostoc species are commonly found on crop plants (Mundt et al 1967; Mundt 1970). L. mesenteroides is perhaps the most predominant LAB species found on fruits and vegetables and is responsible for initiating the sauerkraut and other vegetable fermentations (Pederson and Albury 1969). L. mesenteroides starter cultures also used in some dairy and bread dough fermentations (Server-Busson et al. 1999).

Under microaerophilic conditions, a heterolactic fermentation is carried out. Glucose and other hexose sugars are converted to equimolar amount of D-lactate, ethanol and CO2 via a combination of the hexose monophosphate and pentose phosphate pathways (Demoss et al 1951; Garvie 1986; Gottschalk 1986). Other metabolic pathways include conversion of citrate to diacetyl and acetoin (Cogan et al 1981) and production of dextrans and levan from sucrose (Alsop 1983; Broker 1977).

Viscous polysaccharides produced by L. mesenteroides are widely recognized as causing product losses and processing problems in the production of sucrose from sugar cane and sugar beets (Tallgren et al. 1999). The first observation of the production of polysaccharide "slime" from sugar, dates to the earliest days of the science of microbiology; Pasteur (1861) attributed this activity to small cocci, presumably Leuconostoc species. Commercial production dextrans and levans by L. mesenteroides, for use in the biochemical and pharmaceutical industry, has been carried out for more than 50 years (Alsop 1983; Sutherland 1996).

Dextrans are used in the manufacture of blood plasma extenders, heparin substitutes for anticoagulant therapy, cosmetics, and other products (Leathers et al 1995; Sutherland 1996; Alsop 1983; Kim and Day 1994). Another use of dextrans is the manufacture of Sephadex gels or beads, which are widely used for industrial and laboratory protein separations (Sutherland 1996). Currently, L. mesenteroides has significant roles in both industrial and food fermentations.

References:

  1. Alsop, R. M. 1983. Industrial Production of Dextrans. Progress in Industrial Microbiology., 1-42. ed. M. E. Bushell. New York: Elseiver.
  2. Broker, B. E. 1977. Ultra structural surface changes associated with dextran synthesis by Leuconostoc mesenteroides. J. Bacteriol. 131: 288-92
  3. Cogan, T. M. 1987. Co-metabolism of citrate and glucose by Leuconostoc spp.: effects on growth, substrates and products. J. Appl. Bacteriol. 63: 551-58.
  4. Cogan, T. M., M. O'Dowd, and D. Mellerick. 1981. Effects of Sugar on Acetoin Production from Citrate by Leuconostoc lactis. Appl. Environ. Microbiol. 41, no. 1: 1-8.
  5. Demoss, R. D., R. C. Bard, and I. C. Gunsalus. 1951. The mechanism of heterolactic fermentation: a new route of ethanol formation. J. Bacteriol. 62: 499-511.
  6. Garvie, E. I. 1986. Genus Leuconostoc. Bergey's Manual of Systematic Bacteriology. eds. P. H. A. Sneath, N. S. Mair, M. E. Sharpe, and J. G. Holt. Baltimore, MD: The Williams and Wilkins Co.
  7. Gottschalk, G. 1986. Bacterial Metabolism. 2nd ed. New York: Springer-Verlag.
  8. Kim, D., and D. F. Day. 1994. A new process for the production of clinical dextran by mixed-culture fermentation of Lipomyces starkeyi and Leuconostoc mesenteroides. Enzyme Microb. Technol. 16: 844-48.
  9. Leathers, T. D., G. T. Hayman, and G. L. Cote. 1995. Rapid Screening of Leuconostoc mesenteroides Mutants for Elevated Proportions of Alternan to Dextran. Current Microbiol. 31: 19-22.
  10. Mundt, J. O. 1970. Lactic Acid Bacteria Associated with Raw Plant Food Material. J. Milk Food Technol. 33: 550-553.
  11. Mundt, J. O., W. F. Graham, and I. E. McCarty. 1967. Spherical Lactic Acid Producing Bacteria of Southern-Grown Raw and Processed Vegetables. Appl. Microbiol. 15: 1303-8.
  12. Pasteur, L. 1861. Sur la Fermentation Visquese et la Fermentation Butyrique. Bull. Soc. Chim., Paris 11: 30-31.
  13. Pederson, C. S., and M. N. Albury. 1969. The Sauerkraut Fermentation. N.Y. State Agr. Expt. Sta. (Geneva, N.Y.) Tech. Bull. Bulletin 824.
  14. Reiter, B., and J. D. Oram. 1982. Nutritional Studies on Cheese Starter. 1. Vitamin and Amino Acid Requirements of Single Strain Starters. J. Dairy Res. 29: 63-68.
  15. Server-Busson, C., C. Foucaud, and J.-Y. Leveau. 1999. Selection of Dairy Leuconostoc Isolates for Important Technological Properties. J. Dairy Res. 66: 245-56.
  16. Sutherland, I. W. 1996. Extracellular Polysaccharides. 2nd ed. Biotechnology, eds. H.-J. Rehm, G. Reed, A. Puhler, and P. Stadler, Vol 6: Products of Primary Metabolism. New York: VCH.
  17. Tallgren, A. H., U. Airaksinen, R. von Weissenberg, H. Ojamo, J. Kuusisto, and M. Leisola. 1999. Exopolysaccharide-Producing Bacteria from Sugar Beets. Appl. Environ. Microbiol. 65, no. 2: 862-64.