Nutrition has had a very significant development which has changed its concept in the recent decades. Diet was previously considered as having the role of providing nutrients necessary to maintain the health condition, whereas today this concept has evolved into the idea that diet can contain foods which in addition to providing nutrition, promote health. This is the reason why the food industry has started to develop a large amount of products promoting health and wellbeing. In this area the line of functional foods has had a very significant development, where the consumption of probiotics by the population increases daily. The real challenge is to broaden the knowledge of these foods, among them those containing probiotics have a special interest.
There are very old records relating to the beneficial effects derived from the consumption of foods with high bacterial content, such as in the version of the old testament wherein it is said that Abraham attributes his long life to the consumption of milk, or the Roman historian Plinius who in the year 76 B.C. recommended the use of fermented milk products for treating gastroenteritis (Senmier and De Vrese 2001).
At the beginning of the last century, the Russian microbiologist Elie Metchnikoff (1845-1916) suggested that the consumption of fermented milk modulated the intestinal microbiota producing a positive effect in human health (Metchnikoff 1908). He fixed his attention to the fact that there was an incredible number of centenarians in Bulgaria, despite of it being one of the poorest European countries. He observed that the Bulgarians consumed large amounts of yoghurt. Metchnikoff successfully isolated the bacteria responsible for producing the yoghurt and used it in his researches. It was the start of the probiotic study. Metchnikoff became a strong defender of the concept that diet can protect the body from pathogen invasion and therefore improves and prolongs the quality of life. He was also the first person to develop a preparation using lactobacillus in the form of capsule to be ingested orally, called Lactobacillin.
At the same time, the French microbiologist Tissier observed that the fecal microbiota of breast-feeding newborns have more bacteria from the genus Bifidobacterium than the fecal microbiota of children who have received artificial milk and acknowledged the beneficial role of this microorganism.
Later in 1940, Bifidus Milk appeared to alleviate children nutritional deficiencies during the 1st World War. In 1950, the Degusta factory prepares Biogur and Bio-garde. In 1989, the consumption and production of fermented milk increases in Switzerland. In 1993, two researchers, Modler and Vila-García, developed the first low acidity bio yoghurt.
In 1965, Lilly and Stillwell used the term “probiotic” for the first time to name the products of gastric fermentation. But the more valid and widely used definition of probiotic will be that enunciated much later on by Fuller (Fuller 1992, Fuller 1989). Probiotics are defined as: “supplements of live microorganisms which upon being added to foods exert beneficial effects in the health of the receiver as they condition an improvement in his/her intestinal microbial balance”. For the adult human being, this includes both products derived from fermented milk and preparations lyophilized with these bacteria.
In 1998, the International Life Science Institute (ILSI) in Brussels defined probiotics as live microorganisms, which when ingested in sufficient amounts, have beneficial effects on health, which effect is way above the conventional nutritional effects. They beneficially affect one or several functions of the organism. They provide a better health condition and wellbeing and/or reduce the risk of disease. They can be functional for the general population or for particular groups thereof.
Today there are criteria for the definition of probiotic microorganisms:    1. They are of human origin.    2. They are of non-pathogenic nature.    3. They are resistant to destruction by technical processes.    4. They are resistant to destruction by gastric acid and bile.    5. They adhere to the intestinal epithelium.    6. They are capable of colonizing the gastrointestinal tract.    7. They produce antimicrobial substances.    8. They modulate the immune response.    9. They influence the human metabolic activities (cholesterol assimilation, vitamin production, etc).
The probiotic bacteria can influence all the intestinal cells and the mechanisms of action of these cells including the effects on the microbiota (Backhed and Ley 2005), the modulation of the immune function (Picard et al. 2004; Kalliomaki 2004) and the increase of the epithelial barrier function (Madsen et al. 2001; Isolauri & Salminen 2005).
Among the bacteria with probiotic activity, those from the genus Bifidobacterium are the most abundant in the intestine with 25% of bacteria in the adult colon and 95% in the breast-feeding newborn. There are many food products (yoghurt and milk) today which are supplemented with this type of bacteria. Other strains which also have probiotic activity are those from the genus Lactobacillus, which according to “in vitro” studies inhibit the adhesion of other anaerobic bacteria such as clostridium, bacteroides, bifidobacterium, pseudomonas, staphylococcus, streptococcus and enterobacteriaceas (Silva et al. 1987).
The use of probiotics as medical tool in some pathologies is very well-received and the proof of the effectiveness thereof is strong, mainly as the result of the clinical studies and meta-analysis, for malabsoprtion of lactose, (Adolfsson et al. 2004; Piaia et al. 2003) gastrointestinal infections (Brownlee et al. 2003) and diarrhea associated to the use of antibiotics (D'Souza et al. 2002). Furthermore, the use of probiotic bacteria either bifidobacteria, lactobacillus and/or a mixture thereof have shown beneficial effects on some digestive diseases. There is much proof in the literature on the beneficial effects.
The understanding of the relationship existing between the components of the intestinal microbiota as well as the interaction with the host is very complex. The genome facilitates analyzing the isolated bacteria response to the intestinal conditions, partly revealing the metabolic capacity of the strains, however, the conditions in which these capacities can be expressed, as well as the conditions to enable isolating most of the strains forming the intestinal microbiota is still largely unknown, it being able to be identified only by means of molecular tools identifying their genome partly or completely. Due to this reason the development in the area of the probiotics and functional foods is in full development.
Thus, taking into account that there are different effects between the probiotic strains and that varieties of bacteria belonging to the same species may present different physiological characteristics rendering them different or improved probiotic properties against other bacteria, the identification and characterization of the effects of new prebiotic strains is very important in view of their health and industrial interest.
The general objective of this study is to isolate probiotic microorganisms with improve probiotic properties resistance to an acidic pH, resistance to bile salts and intestinal cell adhesion for a subsequent use in the food and pharmaceutical industry especially for using them in infant formula milk.
The present invention provides and characterizes probiotic microorganisms isolated from faeces of children fed exclusively with breast milk.
The greater resistance of the strains object of the invention to pH and bile salts confers the probiotic microorganisms a greater survivability as they pass through the stomach and intestine and thus increases their colonizing effect and therefore their antagonic effects against other potentially pathogenic bacteria. On the other hand, the greater adherence of the probiotics strains making up the object of the invention to the human intestinal cells enables a greater action on all immune system modulation.