Bacteriocins, probiotics

Nissen-Meyer, J., Oppegard, C., Rogne, P., et al. (2010). Structure and mode-of-action of the two-peptide (Qass-IIb) bacteriocins. Probiot Antimicrob Prot 2, 52-60. 

FIGURE 1.1 Probiotics may protect against infection by pathogens through (1) Direct antagonism via bacteriocin production. (2) Immunomodulation via immune cell (T-cell, Dendritic cell) activation. (3) Improvement of epithelial barrier function and competitive exclusion via induction of mucus and blocking of epithelial binding receptors. 

Lactic acid bacteria and bifidobacteria are preferred as protective and probiotic cultures, and have been used since the beginning of history as starter cultures. They have a long history of being safely used and consumed. LAB are widely used for fermentation of milk, meat, and vegetable foods. In fermentation of dairy products, lactose is metabolized to lactic acid. Other metabolic products, hydrogen peroxide, diacetyl, and bacteriocins may also play inhibitory roles and contribute to improving the organoleptic attributes of these foods, as well as their preservation (Messens and De Vuyst, 2002). 

Dried powders containing probiotics may be applied to dovmstream processes, e.g., adjimcts for Cheddar cheese manufacture (Gardiner et al., 2002), malted beverages (O Riordan et al., 2001) and the exploitation of bacteriocin... 

There are many scientific evidences, supported by clinical studies, on the efficacy of probiotics in the prevention and treatment of gastrointestinal disorders, respiratory, and urogenital diseases. Many microbial strains with probiotic properties are able not only to restore the intestinal microbial balance, but also to impart other beneficial effects on health, associated with the production of acids, bacteriocins and with the competition with pathogenic microorganisms. Among these, the main effects are the reduction of the level of cholesterol in the blood, the reduction of fecal enzymes, with potentially mutagenic activity that can induce the onset of tumors, the reduction of lactose intolerance, the increase of the response of the immune system, the increase of calcium absorption, and synthesis of vitamins. ... 

The use of probiotic LAB, especially Lactobacillus and Bifidobacterium spp., as starter cultures, alone or in combination with traditional starter cultures in various fermentation processes, has been explored for different fermentation food products. Formulated fermented probiotic food may present consumers with a healthy dietary component at a considerabley low cost (Goldin, 1998). Furthermore, it was reported that LAB may contribute to microbiological safety and/or provide one or more technological, nutritional and organoleptic advantages to a fermented product, through production of ethanol, acetic acid, aroma compounds, exopolysaccharides, bacteriocins and several enzymes (Leroy De Vuyst, 2004). 

However, when considering the use of probiotic strains as functional starters or co-cultures, it is important that they do not enhance acidification and thereby reduce the shelf-life of the product, and that they do not have adverse effects on the aroma or taste of the product (Heller, 2001). Uncertainty still exists as to whether multifunctional strains possessing all desirable metabolic features would result from modem isolation techniques and selection procedures. Therefore, recent studies focus on the improvement of selected strains by the application of recombinant DNA technology. By its application, certain beneficial features, such as health-promoting properties, accelerated acid production, wholesomeness and overproduction of specific enzymes or bacteriocins can be improved (Holzapfel, 2002). Gene dismption may be used to... 

Todorov, S. D., von Mollendorff, J. W., Moelich, E., Muller, N., Witthuhn, R. C., Dicks, L. M. T. (2009). Evaluation of potential probiotic properties of Enterococcus mundtii, its survival in boza and in situ bacteriocin production. Food Technology and Biotechnology, 47, 178-191. 

The replacement effect has also been studied in the oral microbiota. In this case bacteriocin-producing probiotics have been shown to have positive effects replacing the cariogenic bacteria. 

O Shea EF, Cotter PD, Stanton C, Ross RP, Hill C. Production of bioactive substances by intestinal bacteria as a basis for explaining probiotic mechanisms Bacteriocins and conjugated linoleic acid. Int ] Food Microbiol. 2012 152 189-205. 

Nurmi E, Nuotio L, Schneitz C (1992) The competitive exclusion concept development and future. Int J Food Microbiol 15 237-240 Okereke A, Montville TJ (1991) Bacteriocin-mediated inhibition of Clostridium botulinum spores by lactic acid bacteria at refrigeration and abuse temperatures. Appl Environ Microbiol 57 3423-3428 Ouwehand AC, Sondberg Svendsen L, Leyer G (2011) Probiotics from strain to product. In Kniebel W, Salminen S (eds) Probiotics and health claims. Wiley, W. Sussex, pp 37-47... 

Some probiotics produce anti-microbial agents targeting important gastrointestinal pathogens which is a desirable characteristic. Many lactic acid bacteria and bifidobacteria have been shown to produce bacteriocin-like molecules with different spectrums of activity. 

Remarks Some strains are used as probiotics in animals, can produce entero-toxins (bacteriocin 31, enterotoxins A, B, P and 50) ... 

There are several reasons for the limited success in commercial application of bacteriocins. Their physiochemical properties seem to be an obstacle when applied in a chemically complex environment such as food and feed. Being positively charged and hydrophobic/anphiphilic they will attach to negatively charged and/or lipophilic surfaces/molecules that will actually make the bacteriocins less available to reach target bacteria. There have been a great number of excellent works and reviews in recent years that directly deal with applications of bactoiocins in foods, therefore this field will not be treated in this review. We will focus on medical-related applications of bacteriocins and the potential of bacteriocin-producing bacteria as probiotics. 

From the ileal-caecal region of the human GI tract, a probiotic Lact. salivarius subsp. salivarius was isolated and found to produce the two-peptide bacteriocin ABP-118, which is discussed at the... 

In a study with fecal samples from piglets, a Lact. reuteri isolate was shown to produce a bacteriocin-like substance and it was shown that the same type of bacteria were found in porcine milk obtained from the same population of pigs (Bohle et al. 2010). Probiotic bacteria are shown to effectively promote the health status of pigs (Cho 2011), and recently a patent for probiotic supplement for the diet of pigs was filed and one of the strains included in this patent does indeed produce a bacteriocin (Stanton et al. 2012). 

---