Table 3.

Antimicrobial substances derived from the bacterial cell.

Antimicrobials	Source	Food bio-preservation	References
Organic acids	Main end products of fermentation.	Decrease the pH of the surrounding environment, creating a selective barrier against nonacidophiles. Lactic acid exerts an antimicrobial effect by disruption of the cytoplasmic membrane and interference with membrane potential.	[55]
Carbon dioxide	Produced by fermentation of sugar by-products using heterofermentative lactic acid bacteria	It creates an anaerobic creation of anaerobic conditions it has antagonistic effects on aerobic bacteria and produces carbonic acid.	[19]
Diacetyl (2,3-butanedione)	A type of low molecular weight compound produced as a metabolic by-product of lactic acid bacteria	Inhibits both Gram-positive and Gram-negative bacterias including Bacillus cereus, Staphylococcus aureus, Escherichia coli, Salmonella anatum, Listeria monocytogenes Yersinia, and Aeromonas.	[19]
Hydrogen peroxide	Produced by LAB in the presence of oxygen and action of flavoprotein oxidases or NADH peroxidase.	The antibacterial effect through oxidative damage of proteins and increase of membrane permeability	[56]
Reuterin	A kind of antimicrobial compound with low molecular weight; it is produced by Lactobacillus reuteri by anaerobic metabolism of glycerol.	Effective against Listeria monocytogenes	[57]
Reutericyclin	Produced and isolated from Lactobacillu reuteri	Antibacterial and it effectively inhibits Gram-positive bacteria including B. cereus, B. subtilis, E. faecalis Listeria innocua S. aureus, and Clostridium difficile.	[58]; [19]
Nisin	Nisin synthesized by some strains of Lactococcus lactis is a heat-stable bacteriocin peptide	Nisin inhibits target cells via specific binding to the cell wall precursor lipid II, followed by the formation of pores in the bacterial cell membrane and subsequent loss of intracellular constituents	[59]