Batch fermentation of glucose to ethanol yields a productivity

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Batch fermentation of glucose to ethanol yields a productivity of 4.5 g1^–1 hl^–1. If the yeast cell concentration in the fermentation brought is 5% (v/v) and the intracellular NAD/NADH concentration in the yeast cells in 10 µM the cycling rate of NAD⁺ ⇔ NADH will be

1. 50,000 cycles hr^–1
2. 20,000 cycles hr^–1
3. 100 cycles hr^–1
4. None of these

Correct Option: B

P = 4.5 gm/l.hr Ethanol production yeast cell conc.(X) = 5% v/v
NAD⁺/NADH ceme in yeast cell = 10 µm (m = ml/lit)
= (me/ωt) the cycling rate of NAD⁺ ⇌ NADH will be.

X =	5	ml in 1 liter of broth
	100

NAD⁺/NADH = 10^–5 ml/lit.

	50	ml/lit = 10^-5 ml/lit	No. of cy dest	= cycle rate
	100		unit time

Total NAD+/NADH conc = 5 × 10^–5(v/v)

Now, cycle rate =		1		cycle / hr = 20,000 cycle/hr.
		5 × 10^-5