Question

Lactobacillus is commonly found in
A) Cake
B) Curd
C) Bread
D) All of the above

Answer 1

Lactobacillus are generally immobile and can survive in both aerobic and anaerobic environments Lactobacillus is a of a grouping of rod shaped, gram-positive, non-spore forming bacteria of the family Lactobacillaceae.

Complete answer:
Like other genera in the family, Lactobacillus are characterized by their capacity to produce lactic acid as a by-product of glucose metabolism. The organisms are extensively disseminated in animal feeds, silage, manure and milk and milk products.
A variety of species of Lactobacillus are used commercially throughout the production of sour milks, cheeses, and yogurt, and they have an important function in the manufacture of fermented vegetables ,beverages ,sourdough breads, and some sausages.
The amount of lactic acid produced by diverse Lactobacillus organisms varies. In a number of species, including Lactobacillus acidophilus, Lactobacillus casei, and Lactobacillus plantarum, glucose metabolism is described as homo fermentative. While lactic acid is the primary byproduct.
Though in other species, glucose metabolism is hetero fermentative. Certain other heterofermentative Lactobacillus organisms are comparatively inefficient in their metabolism of glucose and must obtain energy from other types of organic compounds, including galactose, malate, or fructose.
Lactobacillus are the commensal population of animal and human gastrointestinal tracts, in addition to the human mouth and the vagina. Commercial arrangements of lactobacilli are used as probiotics to return normal flora after the imbalance created by antibiotic therapy.
Lactobacillus generally belongs to the group of bacteria which perform fermentation and convert the sugars into lactic acid in the absence of oxygen. This bacterium is usually present in the raw milk. This bacterium is also capable of being added to the milk in the form of previously synthesized curd where it multiplies and lactose sugar into lactic acid. The lactic acid which is produced gives a sour taste and the milk is converted to curd. These organisms are seen in very high numbers in curd.

Hence , the correct answer is option B.

Note: Lactobacillus are generally widely used in the food preservation, fermented products etc. they also have been proposed as probiotics and also considered as the microbial cell factories of the production of nutraceuticals.