Megaplasmid encoding novel sugar utilizing phenotypes, pediocin production and immunity in Pediococcus acidilactici C20.

Plasmid-linked traits in a strain of Pediococcus acidilactici C20, previously isolated from fowl intestine and revealed to harbour a single megaplasmid, were characterized. Curing experiments using novobiocin (1 mug/ml) in combination with high temp. (25C) were conducted to ascertain plasmid-linked functions. Results indicated that the genetic determinants encoding capacity to ferment a wide range of sugars, pediocin production and immunity against pediocin were associated with the megaplasmid. Strain C20 was able to ferment lactose (not previously reported for pediocin-producing P. acidilactici strains), maltose, mannitol, melibiose, raffinose, sorbitol, sucrose and trehalose. Pediocin activities were observed to range from 2500 to 3500 AU/ml when strain C20 was grown in the presence of different C sources. Rapid molecular techniques such as PCR, dot-blot and other biochemical tests revealed that the pediocin produced by strain C20 was similar to pediocin AcH/PA-1 and had high activity against Listeria monocytogenes. It is concluded that the strong antilisterial activity exhibited by strain C20 in combination with its rare ability to ferment lactose make it a likely candidate for the biocontrol of Listeria in dairy, vegetable and meat products.