Lactostrepcins--acid bacteriocins produced by lactic streptococci

Area of Science:

• Microbiology
• Bacteriology

Background:

• Bacteriocins are antimicrobial peptides produced by bacteria.
• Streptococcus lactis and related species are known producers of bacteriocins.

Purpose of the Study:

• To investigate bacteriocin production in Streptococcus lactis and related species.
• To characterize the properties and spectrum of activity of these bacteriocins, termed lactostrepcins.

Main Methods:

• Testing non-nisin producing strains of Streptococcus lactis and Str. lactis subsp. diacetylactis for bacteriocin production.
• Characterizing lactostrepcins using enzymatic, dialysis, and pH stability assays.
• Assessing the activity spectrum against indicator strains, including beta-hemolytic streptococci, Lactobacillus helveticus, and Leuconostoc species.

Main Results:

• 47/47 non-nisin producing Streptococcus lactis and 12/13 Str. lactis subsp. diacetylactis strains produced lactostrepcins.
• Seven Str. cremoris strains produced no active bacteriocins against the tested indicators.
• Lactostrepcins were sensitive to proteolytic enzymes and phospholipase D, stable after dialysis, active between pH 4.2-5.0, and inactivated at pH 7.0-8.0.
• Four different lactostrepcins were suggested, with variations in group II strains.
• Lactostrepcins showed activity against some beta-hemolytic streptococci, Lactobacillus helveticus, and certain Leuconostoc strains.

Conclusions:

• Streptococcus lactis and Str. lactis subsp. diacetylactis are significant sources of bacteriocins (lactostrepcins).
• Lactostrepcins exhibit diverse properties and a spectrum of activity against other bacteria.
• Further research into lactostrepcins could reveal their potential applications.