**1. Introduction**

As it was reported by Chow (2002), the notion that food could serve as medicine was first conceived thousands of years ago by the Greek philosopher and father of medicine, Hippocrates, who once wrote: 'Let food be thy medicine, and let medicine be thy food'. However, during recent times, the concept of food having medicinal value has been reborn as 'functional foods'. The list of health benefits accredited to functional food continues to increase, and the gut is an obvious target for the development of functional foods, because it acts as an interface between the diet and all other body functions. One of the most promising areas for the development of functional food components lies in the use of probiotics and prebiotics which scientific researches have demonstrated therapeutic evidence. Nowadays, consumers are aware of the link among lifestyle, diet and good health, which explains the emerging demand for products that are able to enhance health beyond providing basic nutrition. Besides the nutritional valaes, ingestion of lactic acid bacteria (LAB) and their fermented foods has been suggested to confer a range of health benefits including immune system modulation, increased resistance to malignancy, and infectious illness (Soccol, et al., 2010). LAB were first isolated from milk. They can be found in fermented products as meat, milk products, vegetables, beverages and bakery products. LAB occur naturally in soil, water, manure, sewage, silage and plants. They are part of the microbiota on mucous membranes, such as the intestines, mouth, skin, urinary and genital organs of both humans and animals, and may have a beneficial influence on these ecosystems. LAB that grow as the adventitious microflora of foods or that are added to foods as cultures are generally considered to be harmless or even an advantage for human

© 2013 Harzallah and Belhadj, licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2013 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

health. Since their discovery, LAB has been gained mush interest in various applications, as starter cultures in food and feed fermentations, pharmaceuticals, probiotics and as biological control agents. In food industry, LAB are widely used as starters to achieve favorable changes in texture, aroma, flavor and acidity (Leory and De Vuyst, 2004). However, there has been an important interest in using bacteriocin and/or other inhibitory substance producing LAB for non-fermentative biopreservation applications. Du to their antimicrobial and antioxidant activities some LAB strains are used in food biopreservation. However, LAB are generally regarded as safe (GRAS) to the consumer and during storage, they naturally dominate the microflora of many foods (Osmanağaoğlu and Beyatli, 1999; Parada et al., 2007). Many of the indications for probiotic activity have been obtained from effects observed in various clinical situations. Even, there are few strains that have officially gained the status of pharmaceutical preparation; each of these effects is gradually being supported by a number of clinical studies or human intervention trials, performed in a way that resembles the traditional pharmacological approach (placebo-controlled, double blind, randomized trials) and the strains used in these studies belong to different microbial species, but are mostly lactic acid bacteria (Mercenier et al, 2003).

Lactic Acid Bacteria as Probiotics:

**Animal model in which benefit is shown** 

*Citrobacter rodentium*-induced

10−/− mice (spontaneous IBD)

IL-10−/− mice (spontaneous

*C. rodentium*-induced colitis

TNBS-induced colitis

chronic stress, and early life

DSS-induced colitis, IL-10−/<sup>−</sup> mice (spontaneous IBD; DNA only), and SAMP mouse model of spontaneous IBD

colitis

enterocolitis

NA

Crohn's disease DSS-induced colitis and IL-

IBD)

–

NA *C. rodentium*-induced colitis,

stress

Characteristics, Selection Criteria and Role in Immunomodulation of Human GI Muccosal Barrier 199

**which benefit is shown** 

Sepsis in very low birth weight infants

associated diarrhea

associated diarrhea

Bacterial infections NA

Pouchitis and pediatric ulcerative

colitis

Abbreviations: DNBS, dinitrobenzene sulfonic acid; DSS, dextran sodium sulfate; IL-10, interleukin 10; NA, not

**Table 1.** Selected organisms that are used as probiotic agents (Gareau et al., 2010).

*Lactobacillus acidophilus* NA Visceral hyperalgesia 40 and

*Lactobacillus casei* NA DNBS-induced colitis *Bacillus polyfermenticus* NA DSS-induced colitis and

infection

*Escherichia coli* Nissle 1917 NA DSS-induced colitis

*Bifidobacteria bifidum* NA Rat model of necrotizing

**Probiotic Human disease in** 

*Saccharomyces boulardii Clostridium difficile*

*Bifidobacteria infantis* IBS29 NA

*Lactobacillus plantarum* 299v Antibiotic-

*Lactobacillus rhamnosus* Pediatric antibiotic-

**Yeast**

**Gram-negative bacteria**

**Gram-positive bacteria**

*Lactobacillus rhamnosus GG*  (used with lactoferrin)

**Combination regimens**

with *Bifidobacterium lactis*

*Lactobacillus helveticus*

*thermophilus*)

*Lactobacillus rhamnosus GG* combined

*Lactobacillus rhamnosus* combined with

VSL#3 (*Lactobacillus casei, Lactobacillus plantarum, Lactobacillus acidophilus, Lactobacillus bulgaricus, Bifidobacterium* 

*Bifidocacterium infantis and Streptococcus* 

available; TNBS, trinitrobenzene sulfonic acid.

*longum, Bifidobacterium breve,* 

*Lactococcus lactis* (engineered to produce IL-10 or trefoil factors)
