When the term ‘probiotic’ is mentioned, most people think of Lactobacillus acidophilus, as this is believed to be the most commonly known species of bacteria. The species is typically found in the intestine, vagina and urinary tract, as it is exceptionally good at adhering to the mucosal cells in these areas. Lactobacillus acidophilus belongs to a group of gram-positive non-sporulating (non-spore-forming), anaerobic, rod-shaped bacterium. These bacteria typically ferment glucose, with the primary end products of the fermentation being lactic acid, acetic acid and H2O2. All of these substances entering their environment make it more acidic and less favourable for the growth of harmful bacteria, which prefer a more alkaline environment. This action aids the survival of the Lactobacillus acidophilus bacteria, but also benefits their host by discouraging pathogens.
Because they use sugars as their preferred substrate for fermentation, the gastro-intestinal tract in humans makes a perfect home for Lactobacillus acidophilus, as sugars are available there in abundance. This species is known to break down lactose, the primary sugar found in milk and dairy products; this action offers another useful benefit to their hosts as many people are intolerant to lactose. Lactobacillus acidophilus is also found in fermented dairy product such as yoghurts, and it is actually the bacteria which gives the yoghurt its classic tangy flavour.
The properties & benefits of probiotics are strain-specific, so you will find that this database provides even more detailed information about potential benefits at the level of the strain.
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Lee Y. and Salminen S., (2009), Handbook of Probiotic and Prebiotics. 2nd edition, Hoboken: John Wiley & Sons.
Reid G., (1999), ‘The Scientific Basis for Probiotic Strains of Lactobacillus’. Appl. Environ. Microbiol,. 65:93763-3766.