Production, mode of action and sequencing of the corresponding gene of a bacteriocin produced by Lactococcus lactis 19.3

Abstract

Summary Lactococcus lactis 19.3 produces a bacteriocin with a wide inhibitory spectrum, including the food pathogen Listeria monocytogenes. The producing strain was able to grow and produce similar amounts of bacteriocin in MRS medium, cow's milk and soya milk, respectively. The mode of action of this bacteriocin was further investigated using two indicator strains, Lactobacillus delbrueckii subsp. bulgaricus LMG 6901T and Listeria monocytogenes ATCC 1911‐1. The bacteriocin displayed a bactericidal effect, causing a rapid decrease of the cell viability. Bacteriocin treatment of the sensitive strains resulted in major morphological changes, including pore formation, as shown by scanning electron microscopy. Finally, the bacteriocin‐encoding gene was identified by sequencing. The presence of nisin gene was confirmed. Based on all our data gathered so far, L. lactis 19.3 is a good candidate for a starter or protective culture in the manufacturing of both fermented dairy and vegetarian food products.

Isolation and Characterization of an Anti-listerial Bacteriocin from Leuconostoc lactis SD501

“…Anti-listerial activity was first detected at 3 h, when the culture was in the early logarithmic phase. Anti-listerial activity reached a maximum (735 AU/mL) during the early stationary phase (9 h) and then decreased gradually, as previously reported for most bacteriocins from LAB ( Arakawa et al, 2016 ; Chen et al, 2018 ; Makhloufi et al, 2013 ; Wulijideligen et al, 2012 ; Zamfir et al, 2016 ). Decreased antimicrobial activity after prolonged incubation of the bacteria could be attributed to processes such as proteolytic degradation by extracellular proteases, re-adsorption by the surface of the producing cell, or protein aggregation ( Papagianni and Papamichae, 2011 ).…”

The Biological Role of the S-Layer Produced by Lactobacillus helveticus 34.9 in Cell Protection and Its Probiotic Properties

“…For this, three functional LAB strains, namely Lc. lactis 19.3-a nisin producing strain [18], the potential probiotic L. plantarum BR9 [19], and the S-layer and acidophilin 801 producing strain, L. acidophilus IBB 801 [20,21], were used. The assay was also performed with pathogenic/potential pathogenic strains: Staph.…”

Purification and characterization of a broad spectrum bacteriocin produced by a selected Lactococcus lactis strain 63 isolated from Indian dairy products

“…However, bacteriocin activity started decreasing after 24 h of bacterial growth. This is a common phenomenon that is observed towards the end of the fermentation period and has been attributed to many factors such as proteolytic degradation of the bacteriocin, instability at low pH, bacteriocins self-aggregation or adsorption of bacteriocins to bacterial cell surface (Zamfir et al 2016).…”

“…Many factors such as media composition, growth rate, temperature of incubation, initial pH, aeration etc. have been reported to influence bacteriocin production by L. lactis strains (Guerra and Pastrana 2002;Zamfir et al 2016). In this study we tried to check the influence of different media (composition) on bacteriocin production by isolate 63 keeping all the other factors at optimum level.…”

“…These commercial media are also relatively richer in some of the amino acids such as serine, threonine and cysteine that have been reported to strongly stimulate nisin production, hence favoring better nisin biosynthesis (Guerra and Pastrana 2002). Amongst the 4 tested media, lowest activity was observed in enriched skim milk broth, since food components like proteins and traces of fat in skim milk can interact with the bacteriocins due to its amphipathic nature and lower its activity (Zamfir et al 2016). Also lack of essential nutrient such as free amino acids (required for bacteriocins production) may also be one of the reasons for poor bacteriocin production in skim milk broth media.…”