What is meaning of oxidation of microorganisms what is meaning of oxidation of microorganisms I am confused meaning of oxidation as per biology kindly help

Dear Student, 
The oxidation process caused by the microorganism in which the value metal remains in its phase. For eg. Bacterial oxidation is Biohydrometallurgical developed for pre cyanidation treatment of gold ores. Bacteria here used is acidithiobacillus  ferrooxidans. 
REGARDS