Antibacterial activities of bacteriocins: application in foods and pharmaceuticals

Abstract

Bacteriocins are a kind of ribosomal synthesized antimicrobial peptides produced by bacteria, which can kill or inhibit bacterial strains closely-related or non-related to produced bacteria, but will not harm the bacteria themselves by specific immunity proteins. Bacteriocins become one of the weapons against microorganisms due to the specific characteristics of large diversity of structure and function, natural resource, and being stable to heat. Many recent studies have purified and identified bacteriocins for application in food technology, which aims to extend food preservation time, treat pathogen disease and cancer therapy, and maintain human health. Therefore, bacteriocins may become a potential drug candidate for replacing antibiotics in order to treat multiple drugs resistance pathogens in the future. This review article summarizes different types of bacteriocins from bacteria. The latter half of this review focuses on the potential applications in food science and pharmaceutical industry.

Keywords: bacteriocin; cancer treatment; food; natural product; protein.

Figure 1

Bacteriocins function as a natural bacterial immune weapon system. Gram-positive and Gram-negative can produce many kinds of bacteriocins that allow bacteriocin-producing bacteria to have the ability to inhibit the growth of sensitive bacteria. (A) General process of bacteriocins production and antibacterial functions. Bacteriocins are proteins or peptides synthesized by the ribosomal. When released by bacteriocin-producing bacteria, it can become combined with the corresponding receptor on the surface of the sensitive bacteria to kill the bacteria. The sensitive bactericidal mechanisms include the pore-forming type, a nuclease type with DNase and RNase function, and peptidoglycanase type etc. The structure of an unmodified bacteriocin peptide of small molecular weight is subtilisin A (PDB cord 1PXQ). The structure of the modified bacteriocin peptide of small molecular weight is bacteriocin AS-48 (PDB cord 1O83), and the colicin protein structure is colicin Ia (PDB cord 1CII). These structural diagrams are taken from the website of a protein data bank (PDB). (B) When the bacteriocin-producing strains are growing on sensitive bacteria LB soft agar, an inhibition zone will be produced around the bacteriocin-producing strains (right colony). However, there is no inhibition zone around bacteriocin non-producing strains (left colony).

Figure 2

Bacteriocin-producing strains and purified bacteriocins can be applied to food, animals, and medicine. If bacteriocin-producing strains are applied through start culture or co-culture in food, it can extend the preservation of food. Probiotics produced by bacteriocins can balance the bacteria in the digestive tract to reduce gastrointestinal diseases. Purified bacteriocins can be added directly to foods as a natural preservative. Bacteriocins can be added to animal feed as an anti-pathogen additive to protect livestock against pathogen damage. The bacteriocins used in medicine can improve the quality of human life. Bacteriocins have the potential to replace antibiotics as an antibacterial drug, and are a novel anti-cancer drug.