Lactobacillus

Characteristics of Lactobacillus

The genus Lactobacillus is the largest and most diverse group among the lactic acid-producing bacteria (LAB), comprising approximately 120 species or more! They are generally gram positive, rod shaped and non-spore-forming. This genus of bacteria is aero tolerant – meaning they can survive in both aerobic and anaerobic conditions.

Lactobacillus and Fermentation

These bacteria are natural inhabitants of the gastrointestinal tract and genitourinary tract. They derive their energy from fermenting lactose, glucose and other sugars, and converting these to lactate, lactic acid, or alcohol as a metabolic by-product. The amount of lactic acid they produce varies from one type of Lactobacilli to the other, and is a distinguishing factor between them. Different species may produce different types of lactic acid: either L-lactate, D-lactate or a combination of both. We can therefore further differentiate Lactobacillus at species level, and sub-divide them into groups according to how they process carbohydrates and the end product of this.

Lactobacilli play a significant role in controlling intestinal pH through the production of these acids, which decrease the intestinal pH (making it more acidic), restricting the growth of many potentially pathogenic and putrefactive bacteria and favouring the growth of further Lactobacilli as they prefer to live in a lower ph. This helps to maintain a balanced intestinal flora, protect from unwanted intruders and protects against leaky gut. This low pH also helps with mineral absorption such as Calcium, Copper, Magnesium and Iron. Only a small number of lactobacilli species produce a small amount of acetic acid.

The Uses of Lactobacillus Bacteria

Lactobacillus bacteria are naturally abundant in both plant and animal environments (such as yogurt and cheese). This is why experts suggest that eating a variety of foods may help support a wide diversity of gut microflora, which are vital to the health of your digestive system. Lactobacillus bacteria are commonly used as part of the fermentation process in yogurt, cider, wine, sauerkraut, pickles, cheese, chocolate, and other fermented foods.

Bibliography

Coeuret V. et al., (2003), ‘Isolation, characterisation and identification of lactobacilli focusing mainly on cheeses and other dairy products’, Lait, 83:269–306.
Conlon M.A. & Bird, A. R., (2015), ‘The Impact of Diet and Lifestyle on Gut Microbiota and Human Health’. Nutrients, 7(1):17-44.
T Jiang, & D.A. Savaiano, (1997), ‘In vitro lactose fermentation by human colonic bacteria is modified by Lactobacillus acidophilus supplementation’. The Journal of Nutrition, 127(8):1489-95.
Lee Y., and Salminen S. (2009). ‘Handbook of Probiotics and Prebiotics’, Hoboken, New Jersey: John Wiley & Sons, pp 7-14.

Last updated - 21st June, 2017