Mechanism of action of lactostrepcin 5, a bacteriocin produced by Streptococcus cremoris 202

Abstract

The mechanism of bactericidal activity of lactostrepcin 5 (Las 5), a bacteriocin produced by Streptococcus cremoris 202, was investigated. Las 5 did not kill protoplasts of sensitive cells, and its activity was decreased about 10-fold after pretreatment of the cells with trypsin, suggesting the involvement of the cell wall in the activity of this bacteriocin. In susceptible cells, the bacteriocin slowed down and then stopped synthesis of DNA, RNA, and protein, although this did not appear to be the primary effect of Las 5 action. Las 5 also inhibited uridine transport in susceptible cells and induced leakage of K' ions and ATP. Survival of cells treated with Las 5 in phosphate buffer was higher in the presence of K', Ca2+, or Mg2+ ions.

Genetics of bacteriocins produced by lactic acid bacteria

“…Hybridization experiments with a hhJ-specific probe defined an RNA transcript of 1600 nt in the Lb. helreticus 481-Hlv + producer, 69 the size expected if the operon was transcribed between these initiation and termination signals.…”

“…One group of bacteriocins produced by lactococci remains unique among the LAB because their activity is restricted to acidic pH environments. The lactostrepcins (Las) are proteinaceous antagonists which are purported to be active at acidic pH ranges between 4.5-5.0, but inactive at pH 7 [34,[67][68][69][70]. After treatment at pH 7, lactostrepcin activity can be restored if the pH is again lowered.…”

“…Las compounds were sensitive to various proteases and phospholipase D, and were stable at 100-121°C for 10 min. Action of Las5, which is inhibitory to a more general group of LAB and Bacillus cereus, was suggested to occur at the cytoplasmic membrane [69]. Inhibition of protein, DNA, and RNA synthesis occurred along with significant leakage of ATP, K +, Ca 2+, and Mg 2+.…”

“…Inhibition of protein, DNA, and RNA synthesis occurred along with significant leakage of ATP, K +, Ca 2+, and Mg 2+. Las5 action was not dependent on an energized membrane, but required a trypsin-sensitive protein 'receptor' to elicit bactericidal action on protoplasted cells [39,69].…”

Activity of plantaricin SA6, a bacteriocin produced by Lactobacillus plantarum SA6 isolated from fermented sausage

“…Bacteriocins of lactic acid bacteria (LAB) are potent biopreservative agents and, in recent years, there has been much interest in these substances synthesized by LAB (Klaenhammer 1988;Piard and Desmazeaud 1992;Ray 1992a). Although some bacteriocins of LAB have been well characterized, purified and genetically studied, little data about their modes of action have been reported (Upreti and Hinsdill 1975;Zajdel et al 1985;Gonzalez and Kunka 1987;Bhunia et al 1991;Piard and Desmazeaud 1992;Ray 1992a, b ;Nettles and Barefoot 1993;Abee et al 1994).…”