What is the reason behind the bad odor underarm??

Scientist have discovered the reason behind the armpit releasing pungent odour.

Researchers from the University of York working with Unilever scientist have studied the underarm microbiome who mentioned that our skin of underarm provides a unique niche for bacteria. As, our skin microbes cannot directly produce thioalcohol. However, bacteria ingest odourless compound i.e Cys-Gly-3M3SH released by sweat glands- apocrine gland open into follicles and placed in the armpit as well as nipples, genitals- in the armpit. And the left they spit out as a odour component.

 Moreover, they identified a unique enzyme ( BO enzyme), (C-T lyase) Cysteine- thiol lyase, found in the bacterium Staphylococcus hominis that is effective at breaking down sweat molecules ( Cys-Gly-3M3SH) into compounds known as thioalcohols (3M3SH). This compound is responsible for the characteristics body's armpit odour. So, this molecule is core component released by enzyme present in Staphylococcus hominis for armpit releasing pungent odour.
 

Here are the articles and news published to garner the more information more about this.

https://www.nature.com/articles/s41598-020-68860-z

https://www.google.com/amp/s/amp.theguardian.com/science/2020/jul/27/know-sweat-scientists-solve-mystery-behind-body-odour

https://www.google.com/amp/s/www.examinerlive.co.uk/news/local-news/york-scientists-discover-exact-bacteria-18681477.amp