Gastrointestinal Microflora: Probiotics
Introduction
The human bacterial gut flora has been the subject of extensive investigation for several years. Its complexity, more than 400 commensal species, inaccessibility, and fastidious growth requirements constitute analysis an extremely painstaking task. The human gut, site of numerous diseases acute and chronic, also plays an important role in health promotion through the activities of the resident microflora. Probiotics have long been recognized as health‐promoting agents. Advances in molecular methodologies and conduction of well‐designed studies performed in the last two decades illustrate the potential of probiotics against a multitude of conditions.
Section snippets
The Human Gastrointestinal Microflora
The human adult colon is the most complex bacterial ecosystem in the human body, harboring more than 400 different culturable bacterial species belonging to more than 50 different genera (Finegold 1983, Gibson 1995). Due to gastric acid in the stomach and rapid washout rates in the small intestine the colon is the main site of bacterial colonization. The average bacterial content of the human colon is 1013 cells, while viable counts are typically in the region of 1012 cells g−1 of colonic
Probiotic History
The protective nature of certain microorganisms, in particular lactic acid bacteria contained in fermented foods and drinks has a long history. Humans have been consuming live bacterial cultures for centuries in the form of fermented milk without any knowledge of the active ingredients or how they work. Among the first reported probiotic intakes was the ingestion of soured milk by nomads over 2000 years ago. In the start of the last century, Metchnikoff attributed the good health and longevity
Definition of Probiotics
The term probiotic is derived from the two Greek words: “πρo” and “βιoς” and literally means “for life.” In 1991 Fuller defined probiotics as:
Live microbial food supplements that beneficially affect the host by improving the intestinal microbial balance. —(Fuller, 1991)
It is difficult to identify with certainty the first time the term probiotic was used, but it is believed that one of the earliest mentions was by Vergin in 1954 when he suggested that the intestinal microbial balance may be
Microorganisms Currently Used as Probiotics
Commercially available probiotics commonly contain strains of the Bifidobacterium, Lactobacillus, and Streptococcus genera as well as yeasts of the Saccharomyces genus. The majority of commercially available probiotic formulations contain lactobacilli as opposed to bifidobacteria as the former are more aerotolerant and thus more stable in food products (Crittenden and Playne, 1996). In Europe, the most common probiotic delivery formats are fermented dairy products, such as milk drinks and
Selection Criteria for Probiotic Bacteria
For a microorganism to be characterized “probiotic,” a number of criteria have to be met (Dunne 2001, Tannock 1998):
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Human origin. Although certain commercially available probiotics are not of human origin, it is believed that if a probiotic is isolated from the human gastrointestinal tract it is safer for human consumption and may be more effective in colonizing the large intestine.
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GRAS (generally regarded as safe) status. GRAS status is granted by the FDA to food/food components that have been
Lactose Intolerance
The term lactose intolerance describes the inability to digest significant amounts of lactose. This inability results from a shortage of the enzyme lactase, which is normally produced by the cells that line the small intestine. Common symptoms include nausea, abdominal cramps, bloating, gas, and diarrhea, which begin about 30 minutes to 2 hours after eating or drinking foods containing lactose. Lactose intolerance is a common disorder that may affect as many as 70% to 75% of the world
Atopic Disorders
During the last two decades a steep increase in the incidence of atopic diseases, such as eczema, asthma, allergic rhinitis, and cow's milk allergy has been observed. The intestinal microflora plays a central role in the immune system regulation in the intestinal mucosa associated lymphoid tissue (MALT), which, in turn, is very important for atopic sensitization. Important features of atopy, the excess formation of IgE to food antigens, for example, unhydrolyzed casein, and the development of T
Antibiotic Associated Diarrhea
Antibiotic associated diarrhea (ADD) is defined as an acute inflammation of the intestinal mucosa caused by the administration of broad‐spectrum antibiotics. It occurs to approximately 20% of patients receiving antibiotic treatment. Antibiotic treatment disturbs the balance between commensal colonic bacteria populations. Overgrowth of C. difficile is the most common etiology of ADD, being responsible for more than 40% of reported ADD cases (Clabots et al., 1992).
Probiotic consumption has been
Ulcerative Colitis and Pouchitis
Ulcerative colitis is a chronic relapsing inflammatory disease of the large bowel, which has an unknown etiology. It is a primary, often recurrent, and occasionally persistent mucosal inflammatory condition, which mainly affects the rectum but can subsequently spread to a variable length of the colon. It is characterized by diffuse inflammation of the wall of the large bowel, predominantly confined to the mucosa and superficial submucosa, and is usually associated with diarrhea and rectal
Irritable Bowel Syndrome
Irritable bowel syndrome (IBS) is one of the most common gastrointestinal disorders affecting 3% to 15% of the general population (Cremonini and Talley, 2005). It is associated with the manifestation of diarrhea or constipation or both alternating, accompanied by abdominal bloating and pain. The cause is not as yet known and colonic biopsies from IBS patients appear to be normal. Although it is suggested that IBS is a psychosomatic disorder, the colonic microflora has been implicated in its
Probiotics Against Urogenital Tract Infections
More than 300 million women worldwide currently suffer from nonsexually transmitted urogenital infections such as urinary tract infection (UTI), bacterial vaginosis, and yeast vaginitis. Although hygiene standards have improved during the past 40 years, incidence of urogenital infections has tripled (Reid and Bruce, 2003).
The female urogenital tract is populated by a Lactobacillus‐dominated microflora, which similarly to the large intestine, acts as a natural barrier against infection from
Helicobacter pylori Infection
Helicobacter pylori (H. pylori) is the causative agent of chronic gastritis and idiopathic peptic ulcer disease. H. pylori infection has been associated with increased incidence of gastric cancer of which 60–80% is attributable to H. pylori (Asghar and Parsonnet, 2001). Standard treatment for H. pylori infection is 1‐week therapy combining two antibiotics together with acid suppression (triple therapy). Although triple therapy is quite effective, fully eradicating H. pylori from the stomach is
Future Perspectives
In the last few decades, the need to find replacement therapeutic approaches to overcome side effects associated with the current pharmacological treatments, and the need for new antimicrobials due to the overuse of antibiotics has propelled forward research on probiotics against a multitude of disorders of varying severity. The findings are promising in most of the earlier reviewed conditions but the major obstacle that we have yet to overcome is not only the lack of knowledge with regards to
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Streptomyces genus as a source of probiotics and its potential for its use in health
2023, Microbiological ResearchCitation Excerpt :However, determining an optimal strain and using it as a probiotic is an empirical process and should be considered standard criteria for its selection. The common characteristics include host origin, survival under gastric and intestinal barriers, adherence to and colonization of the intestinal epithelium, production of anti-microbial substances, safety, etc. (Kolida et al., 2006; De Melo Pereira et al., 2018; Terpou et al., 2019). For these reasons, reliable in vitro methods are required for selecting new probiotic strains to increase the probability that they can produce the molecules needed to obtain profitable in vivo effects on the host.
Encapsulation, with and without oil, of biofilm forming Lactobacillus fermentum UCO-979C strain in alginate-xanthan gum and its anti-Helicobacter pylori effect
2018, Journal of Functional FoodsCitation Excerpt :Several “in vitro” and “in vivo” experiments have demonstrated their beneficial effect for humans, mainly against gastrointestinal diseases caused by pathogenic bacteria (Kaushik et al., 2009; Vuyst & Leroy, 2007). Bacteria most used as probiotics are lactic acid bacteria (LAB), mainly those belonging to genus Lactobacillus (Kolida, Saulnier, & Gibson, 2006), some of them being able to inhibit Helicobacter pylori. H. pylori is a pathogen able to cause diseases such as chronic gastritis, MALT lymphoma, duodenal ulcer and gastric ulcer and it is the main risk factor to develop gastric cancer (Uemura et al., 2001).
In vitro probiotic profile based selection of indigenous actinobacterial probiont Streptomyces sp. JD9 for enhanced broiler production
2016, Journal of Bioscience and BioengineeringIn vitro evaluation of potential antimicrobial synbiotics using Lactobacillus kefiri isolated from kefir grains
2015, International Dairy JournalAdhesion abilities of dairy Lactobacillus plantarum strains showing an aggregation phenotype
2014, Food Research InternationalCitation Excerpt :Due to their explored health-promoting properties, selected strains are also marketed as probiotics (De-Vries, Vaughan, Kleerebezem, & de Vos, 2006) which have been defined as “live microorganisms, which when administered in adequate amounts, confer a health benefit on the host” (FAO/WHO, 2002). Adhesion to the intestinal mucosa is considered one of the main criteria for the selection of potential probiotics, as it may increase their persistence in the intestine and thus allows the probiotic to exert its effects (Kolida, Saulnier, & Gibson, 2006). Adhesion is also known to be a prerequisite for colonization and infection of the gastrointestinal tract by many pathogens.
Disruption of the intestinal mucosal barrier in Candida albicans infections
2013, Microbiological ResearchCitation Excerpt :The intestinal microbiota includes about 500 different bacteria species belonging to more than 50 different genera. The distribution of this microflora is uneven, with the highest concentration in the colon (Kolida et al. 2006; O’Flaherty and Klaenhammer 2010). Microorganisms, especially Bifidobacterium and Lactobacillus species, are important components of the microbial barrier (Fig. 1d).