Conjugal transfer of a plasmid encoding bacteriocin production and immunity in Pediococcus acidilactici H

Abstract

Previous investigations indicated that curing of a 7.4‐Md plasmid (pSMB74) resulted in concomitant loss of bacteriocin activity and immunity in Pediococcus acidilactici H. Transfer of pSMB74 to a gentamicin‐neomycin resistant (GmrNmr) derivative of P. acidilactici LB42, which was devoid of any plasmid DNA, required cell‐to‐cell contact on a solid mating surface and converted the strain to Bac+Bacr phenotype. Gene transfer processes such as transduction and transformation were ruled out from the experiment. Treatment of donor cells with chloroform did not allow the appearance of recombinant clones, confirming that viable cells were essential for this particular mechanism of genetic transfer. Transconjugants obtained from selective agar surface were subjected to plasmid isolation and agarose gel electrophoresis. Each of them exhibited plasmid size corresponding to pSMB74 of donor strain. All results suggested this genetic transfer similar to conjugation, and provided presumptive evidence for plasmid‐encoded bacteriocin activity and immunity in P. acidilactici H.

Isolation and Characterization of Pediocin NV 5 Producing Pediococcus acidilactici LAB 5 from Vacuum-Packed Fermented Meat Product

“…This plasmid DNA is quite dissimilar in size than other P. acidilactici strains like P. acidilactici CFR K7 which have 7.8 kbp plasmid [19], P. acidilactici H (7.4 MDa) [33], and P. cerevisiae FBB63 (10.5 MDa) [34] and P. pentosaceus FBB61 and L7230 possessed a 13.6-megadalton plasmid (pMD136) [11]. Both the native and the cured strains are sensitive to ampicillin (10 lg), cephalothin (30 lg), cephalexin (30 lg), cephaloridine (30 lg), chloramphenicol (30 lg), clindamycin (2 lg), erythromycin (15 lg), gentamicin (10 lg), kanamycin 30 lg), lincomycin (2 lg), methicillin (5 lg), norfloxacin (10 lg), oleandomycin (15 lg), oxacillin (1 lg), penicillin (2 units), penicillin V (3 lg), penicillin G (10 units), tetracycline (10 lg) and tobramycin (10 lg) antibiotics but the mutant strain in contrast to native strain is sensitive to amoxycillin (10 lg), cloxacillin (5 lg) and vancomycin (30 lg) and both the native and cured mutant strains are resistant to co-trimoxazole (25 lg).…”

Pediocin PA-1, a Wide-Spectrum Bacteriocin from Lactic Acid Bacteria

“…32 Recently, it has been shown that purified pediocin PA-1 stored at 4 and 25°C is stable at pH 5 but not at pH 7, while it remains stable after storage at -20°C at both pH values. 33 Pediocin PA-1 activity is unaffected by treatment with phospholipase C, catalase, lysozyme, Dnases, Rnases, or lipases but is lost after incubation with proteolytic enzymes such as trypsin, papain, ficin, α-chimotrypsin, protease IV, protease XIV, protease XXIV, and proteinase K. 8,10,34 Pediocin activity rapidly decreased when monitored in a culture of Lb. plantarum WHE 92, most probably because of hydrolysis by proteolytic enzymes produced at the end of the exponential growth phase.…”

“…8,11,15,[17][18][19]23,34,98,99 In several strains, the sizes, organization, and restriction profiles of the various pediocin-encoding plasmids are similar. 17,100 It has been shown that the plasmids responsible for production in P. acidilactici H can be transferred intragenerically by conjugation.…”

“…17,100 It has been shown that the plasmids responsible for production in P. acidilactici H can be transferred intragenerically by conjugation. 34 …”

“…Pediocin-producing strains are found in a variety of natural foodstuffs, such as meat products, 8,10,19,34 dairy products, 17 and vegetables. 18 Therefore, they (and most probably pediocin too) have been ingested by human consumers for centuries without apparent adverse effects, which is a first indication of low toxicty of this bacteriocin toward eukaryotic cells.…”