Question

Which one of the following vitamins can be synthesized by gut bacteria?
A. B1​
B. A
C. D
D. K

Answer 1

Bacteria are tiny, single-celled creatures that may be found in large numbers in all environments, both within and outside of other species. Some bacteria are dangerous, but the majority are beneficial. They support many forms of life, both plant, and animal, and they are used in industrial and medicinal processes.

Complete answer:
The microbiota of the human colon is a vast and complicated microbial population. Over 1000 bacterial species have been discovered, many of which remain uncultured, with approximately 160 species present in the stomach of each human. The gut microbiota (gut microbiome) gene set is believed to have over 3 million genes, which is 150 times bigger than the human genome. The metabolic repertoire of this huge and diverse microbial population complements the action of mammalian enzymes in the liver and gastrointestinal mucosa.
The gut microbiota contributes to human metabolism by producing enzymes that are not encoded by the human genome, such as those involved in the breakdown of polysaccharides, polyphenols, and vitamin production. Comparative studies in germ-free and conventional microbiota, or human microbiota-associated animals, as well as in vitro studies using human fecal incubations or more complex continuous culture gut models, provide evidence for the role of the microbiota in dietary component metabolism and its impact on health.
Thiamine is the chemical name for vitamin B1. Bacteria in the intestines can produce it.

Thus, the answer is option A: B1

Note:
Bacteria generate intermediate fermentation products such as fumarate, succinate, and lactate, although they are typically identified at low quantities in healthy people's feces due to other bacteria's significant use of them. Lactate, for example, is generally turned into propionate or butyrate by other bacteria, so it's only found in trace amounts in adult feces. Lactate, on the other hand, may be discovered in considerably greater levels in individuals with ulcerative colitis, suggesting that it could be a disease indication.