How to calculate Oxygen consumption?
Assuming that you know the amount of NADH and FADH$_2$ produced by glycolysis and TCA cycle, you can determine the reducing equivalent produced: for each NADH or FADH$_2$ produced, two reducing equivalents are produced. It means that the re-oxidation of NADH and FADH$_2$ will release 2 electrons. Here are the corresponding half-reactions:

$\textrm{NADH} = \textrm{NAD}^+ + \textrm{H}^+ + 2~\textrm{e}^-$

$\textrm{FADH}_2 = \textrm{FAD} + 2~\textrm{H}^+ + 2~\textrm{e}^-$

Knowing the total reducing equivalent produced, divide it by four in order to obtain dioxygen consumption: O$_2$ is reduced into 2 H$_2$O by accepting four electrons. Here is the corresponding half-reaction:

$\textrm{O}_2 + 4~\textrm{e}^- + 4~\textrm{H}^+ =  2~\textrm{H}_2\textrm{O}$ 

Of course this only applies to aerobic organisms: some microbes are able to use other electron acceptors than O2.