Question

streptococcus lacks an electronic transport chain. how does this bacteria reside NADH. where is the NADH formed in bacteria

Answer 1

Streptococcus is a gram-positive, facultative anaerobic bacteria. Streptococcus carried out fermentation of sugars and the end product is lactic acid. This fermentation makes ATP in the absence of oxygen by converting glucose to lactic acid. It contains two major steps :-
1) Glycolysis :- During glycolysis, one glucose molecule is converted to two pyruvate molecules, producing two net ATP and two NADH. From each molecule of glucose 2 molecules of ATP and two molecules of NADH are formed.
2) NADH regeneration :- Oxidation of NADH to form NAD+ is carried out in the second step of fermentation. NADH transfers its electrons directly to pyruvate, generating lactate as a byproduct. As electron transport chain is absent , then to regenerate the electron carrier NAD+ from the NADH produced in glycolysis, NADH transfers its electrons to an organic molecule pyruvate. By this way steady supply of NAD+ ( electron carrier ) is maintained in
fermentation.