Antimicrobial activity of lactobacilli: preliminary characterization and optimization of production of acidocin B, a novel bacteriocin produced by Lactobacillus acidophilus M46

Abstract

Approximately 1000 lactobacillus strains were isolated and screened for the production of antimicrobial activity, using a target panel of spoilage organisms and pathogens. Only eight positive strains were found; two of these were studied in more detail. Lactobacillus salivarius M7 produces the new broad spectrum bacteriocin salivaricin B which inhibits the growth of Listeria monocytogenes, Bacillus cereus, Brochothrix thermosphacta, Enterococcus faecalis and many lactobacilli. A new atypical bacteriocin produced by Lact. acidophilus M46, acidocin B, combines the inhibition of Clostridium sporogenes with a very narrow activity spectrum within the genus Lactobacillus and was selected for further characterization. Acidocin B is sensitive to trypsin, heat-stable (80 degrees C for 20 min) and can be extracted from the culture supernatant fluid with butanol. Native acidocin B occurs as a large molecular weight complex (100 kDa), while with SDS-PAGE the partly purified activity migrates as a peptide of 2.4 kDa. Optimization of the cultivation conditions resulted in an eightfold increase of the amount of acidocin B produced during growth. Growth is not necessary for acidocin B production; washed producer cells can synthesize the bacteriocin in a chemically defined production medium. The application potential of acidocin B is discussed.

Isolation and characterization of lactobacilli from some traditional fermented foods and evaluation of the bacteriocins

“…The physico-chemical properties of bacteriocins from the two species were similar to those of the other bacteriocins of lactobacilli belonging to the group II lactic acid bacteria with respect to molecular weight, heat and pH stability, sensitivity to proteolytic enzymes (B. ten Brink et al, 1994). The initial bacteriocin preparations from the cell adsorption-desorption technique showed multiple bands on account of the presence of broth proteins along with the bacteriocins in the electrophoretogram of Tris-tricine SDS-PAGE (data not shown).…”

“…acidophilus) is within the MW range of 2.5-5.0 kDa reported by others for Lb. acidophilus (B. ten Brink et al, 1994;Messens and De Vuyst, 2002;Muriana and Klaenhammer, 1991).…”

Bovicin HJ50, a novel lantibiotic produced by Streptococcus bovis HJ50

“…Like nisin and acidocin B (ten Brink et al, 1994), bovicin HJ50 could be extracted with n-propanol because of its hydrophobic properties. Most bovicin HJ50 remained in solution in n-propanol.…”

Purification and characterization of thermophilin ST-1, a novel bacteriocin produced by Streptococcus thermophilus ACA-DC 0001

“…Their inhibitory spectrum is restricted to Gram-positive bacteria, but several bacteriocins produced by lactic acid bacteria are also active against food spoilage and foodborne pathogenic microorganisms including Bacillus cereus, Clostridium botulinum, C. perfringens, Listeria monocytogenes, Staphylococcus aureus, Escherichia coli, Enterobacteria, etc. [2,3,23,28,31]. The above bacteriocins are the most important with regard to food preservation and the development of probiotics.…”