Lactic acid bacteria, often called lactobacillales, lactobacilli, or sour milk bacteria, comprise a family of gram-positive, always anaerobic but usually aerotolerant bacteria. These are characterized by the fact that they convert sugars into lactic acid (lactic acid fermentation): they make the milk sour.
What are lactic acid bacteria?
Lactic acid bacteria describe a large supergroup of different types of bacteria found in the human body. Fundamentally, however, these different types of lactic acid bacteria bear little resemblance to each other. The only similarity is mostly that they convert sugars into lactic acid and rely on carbohydrates for energy. However, while homofermentative bacteria only produce lactic acid (lactate), heterofermentative bacteria also produce other end products in addition to this, such as ethanol and carbon dioxide. Lactobacilli differ from other bacteria, which also produce lactic acid, in that they are only capable of metabolic fermentation. However, they also carry this out when oxygen is added.
Significance and function
Lactic acid bacteria have lost the ability to synthesize many necessary substances, such as amino acids, porphyrins, and cytochromes, due to their specialization in growth in milk and similar substances. As a result, they cannot cleave hydrogen peroxide. Therefore, lactic acid bacteria are found only in the intestines and mucous membranes of mammals, such as humans. Likewise, however, lactic acid bacteria are also found in some living or decomposing plants that come into contact with milk and milk-like substances. Nevertheless, lactic acid bacteria are among the most important representatives of the human intestinal and vaginal flora. Various subspecies (strains) and species of lactic acid bacteria are also used to preserve foods, such as yogurt, cheese, sour milk, kefir and sauerkraut as well as for skin care and caries prophylaxis. Lactic acid bacteria are also used quite frequently as probiotics, which are supposed to strengthen the immune system and positively stimulate, influence and thus regulate digestion. For example, probiotics can be used to intervene in the intestinal, oral but also vaginal flora. This can be thought to restore a disturbed, but also to improve and optimize a healthy flora.
Diseases
Lactic acid bacteria present numerous different species and subspecies. Some of these species are thereby less useful, but represent pathogens. These can, depending on the species, cause disturbances of the body flora. Most often affected here is the vaginal and intestinal flora, which is thrown out of balance by harmful lactic acid bacteria. Symptoms can include dryness in the vaginal area, inflammation, fungal infections, infertility and digestive problems in the intestinal area. The last, of course, refers to the fact that the intestinal flora is affected. By the way, an imbalance can also occur if the natural intestinal flora reaches the weakened vaginal flora in too large a quantity. Therefore, after going to the toilet and during the subsequent cleaning of the abdomen, one should make sure that one always “wipes” away from the vagina. However, the vaginal flora can also become unbalanced due to improper hygiene (too often, but also too rarely) or incorrect use of tampons. However, lactic acid bacteria also come in other subspecies, which, depending on where they occur and by species, can trigger further disorders and thus pose risks. The so-called Streptococcus pneumoniae is a pathogen belonging to the species of lactic acid bacteria that can cause pneumonia. Streptococcus mutans, on the other hand, is involved in the development of caries. This often develops in the oral flora when eating sugary foods, when lactic acid is formed directly in the oral cavity and after consumption. This type of lactobacillus attacks the tooth enamel and, if not prevented from doing so, eats through the underlying tooth structure as well. Another disease that can – but does not have to – be associated with lactic acid bacteria is lactose intolerance. This is known as lactose intolerance when the lactose in the diet is not properly processed. Incidentally, lactose intolerance can remain asymptomatic, but can also result in complaints such as disorders of the gastrointestinal tract.