In two sentences or so why is oxygen toxic to obligate anaer

In two sentences or so, why is oxygen toxic to obligate anaerobes? Be sure to site your source, including a URL if appropriate.

Solution

Oxygen is toxic to anaerobes for various reasons.

The superoxide radicals and hydrogen peroxide are formed from oxygen when flavins are oxidised. They react and form hydroxyl radicals and singlet oxygen causing intracellular damage, killing the cells which is mainly due to the absence of catalase, superoxide dismutase and peroxidase enzymes.

Another reason is most of the enzymes found in anaerobes are dioxygen sensitive as many of them possess metal cofactors such as W, Mo which react with oxygen and make unstable proteins. These enzymes are important for their survival as they participate in alternate pathways helping in anaerobic respiration and fermentation.

for more information read this papers:

https://www.ncbi.nlm.nih.gov/pubmed/12073652.

http://aem.asm.org/content/36/2/306.full.pdf