Question

Lactobacilli are harmful bacteria.
A) True
B) False

Answer 1

Hint: Lactobacillus is a bacterial genus. There are many Lactobacillus species. They are a significant part of the group of lactic acid bacteria (i.e. they convert sugars into lactic acid).

Complete answer:

These are "friendly" bacteria which normally live without causing disease in our digestive , urinary, and genital systems. In some fermented foods, such as yoghurt and dietary supplements, Lactobacillus is also present. Lactobacillus, including infectious diarrhoea and diarrhoea linked to the use of antibiotics, is most commonly taken by mouth to treat and prevent diarrhoea.

In both aerobic and anaerobic environments, Lactobacillus is generally non-motile and can survive. Lactobacillus, similar to other genera in the family, is characterised by its capacity to produce lactic acid as a by-product of the metabolism of glucose. In animal feed, silage, manure and milk and milk products, organisms are widely distributed.

During the production of sour milk, cheese and yoghurt, various species of Lactobacillus are commercially used and play an important role in the manufacture of fermented vegetables (pickles and sauerkraut), drinks (wine and juices), sourdough breads and certain sausages.

They produce lactic acid and derive energy via homofermentative metabolism from the fermentation of lactose, glucose and other sugars to lactate, as their name implies. Approximately 85-90% of the sugar used in the fermentative process is converted into lactic acid. However, in addition to lactic acid from sugars, there are some heterofermentative lactobacilli which produce alcohol.

Thus the correct answer is option (B) False.

Note: Lactobacillus is a commensal inhabitant of the gastrointestinal tracts of animals and humans, as well as of the human mouth and vagina. After the imbalance created by antibiotic therapy, commercial lactobacilli preparations are used as probiotics to restore normal flora.