Mode of action of acidocin D20079, a bacteriocin produced by the potential probiotic strain, <Emphasis Type="Italic">Lactobacillus acidophilus</Emphasis> DSM 20079

Lactobacillus acidophilus DSM 20079 is the producer of a novel bacteriocin termed acidocin D20079. In this paper, mode of action using three various concentrations of acidocin D20079 (2,048, 128 and 11.3 AU/ml) was determined against an indicator strain L. delbrueckii subsp. lactis DSM 20076. These concentrations all led to marked decreases in both the number of viable cells and in optical density, indicating that the activity of the acidocin D20079 was bactericidal with concomitant cell lysis. Moreover, the probiotic potential of L. acidophilus DSM 20079 was analyzed for its ability to survive and retain viability at conditions (acid and bile concentrations) mimicking the gastrointestinal (GI) tract, under which it survived exposure to pH 2.0 with a 1.2 log cycle reduction in viability and where 45% of the original population survived in a medium containing 0.3% bile for 3 h.