Pediococcus pentosaceus ATCC 25745

Photo: Jeff Broadbent, Utah State University
Pediococcus pentosaceus are Gram-positive, facultatively anaerobic, non-motile and non-spore-forming, members of the industrially important lactic acid bacteria. Like other lactic acid bacteria, P. pentosaceus are acid tolerant, cannot synthesize porphyrins, and possess a strictly fermentative metabolism with lactic acid as the major metabolic end product (Axelsson, 1998; Garvie, 1986). Phylogenetically Pediococcus and Lactobacillus form a super-cluster that can be divided in to two sub-clusters, all species of Pediococcus fall within the Lactobacillus casei – Pediococcus sub-cluster. Morphologically, pediococci (cocci; 0.6-1.0 mm in diameter) and lactobacilli (rods) are distinct. The formation of tetrads via cell division in two perpendicular directions in a single plane is a distinctive characteristic of pediococci. Pediococcus can be described as “the only acidophilic, homofermentative, lactic acid bacteria that divide alternatively in two perpendicular directions to form tetrads” (Simpson and Taguchi, 1995). Lactic acid is produced from hexose sugars via the Embden-Meyerhof pathway and from pentoses by the 6-phosphogluconate/phosphoketolase pathway (Axelsson, 1998). P. pentosaceus grow at 40 but not 50oC, between pH 4.5 an 8.0, in 9-10% NaCl, hydrolyzes arginine, can utilize maltose and some strains produce a “pseudo-catalase” (Garvie, 1986, Simpson and Taguchi, 1995).

Strains of P. pentosaceus have been reported to contain between three and five resident plasmids (Graham and McKay, 1985). Plasmid-linked traits include the ability to ferment raffinose, melibiose, and sucrose, as well as, the production of bacteriocins (Daeschel and Klaenhammer, 1985;Gonzalez and Kunka, 1986). Plasmids can be conjugally transferred between Pediococcus and Enterococcus, Streptococcus, or Lactococcus (Gonzalez and Kunka, 1983). Electroporation has been utilized to introduce plasmids into pediococci, including P. pentosaceus (Kim et al, 1992; Caldwell, 1996).

P. pentosaceus can be isolated from a variety of plant materials and bacterial ripened cheeses. This organism is used as an acid producing starter culture in sausage fermentations, cucumber and green bean fermentations, soya milk fermentations, and silage (Simpson and Taguchi, 1995). P. pentosaceus are also a typical component of the adventitious or non-starter microflora of most cheese varieties during ripening (Beresford et al., 2001). In addition, it has been suggested that this organism may have value as an acid-producing starter culture in the dairy fermentations (Caldwell et al, 1996 and 1998).

Genetic studies of P. pentosaceus have generated a limited quantity of information (1 plasmid sequenced and 8 unique chromosomal sequences) on plasmid and chromosomal encoded genes; however, the vast majority of genes encoding industrially important attributes have yet to be described. Genomic sequence analysis of P. pentosaceus genome will help fill key knowledge gaps by providing a comprehensive view of the enzymes and metabolic pathways related to: 1) acid and flavor production in fermented meat and vegetable foods; 2) mechanisms by which by P. pentosaceus and other nonstarter LAB grow and direct flavor development in ripening cheese; and 3) mechanisms by which P. pentosaceus and related lactic acid bacteria spoil wine and other alcoholic beverages. In addition, improved knowledge of global gene regulation and integrative metabolism in P. pentosaceus will also help to identify rational strategies for metabolic and genetic improvements to industrial strains of lactic acid bacteria.


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  2. Beresford, T.P., N.A. Fitzsimons, N.L. Brennan, T.M. Cogan. 2001. Recent advances in cheese microbiology. Int. Dairy J. 11:259-274.
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