Question

4.14 Oxygen requirement for growth on glycerol Klebsiella aerogenes is produced from glycerol in aerobic culture with ammonia as nitrogen source. The biomass contains 8% ash, 0.40 g biomass is produced for each g of glycerol consumed, and no major metabolic products are formed. What is the oxygen requirement for this culture in mass terms

Answer 1

Answer:

0.37 g

Explanation:

The molecular weight for Glycerol = 92

Number of Carbon atoms in glycerol (x)  $C_3H_8O_3$ = 3

Molecular weight of  the Biomass  ( Klebsiella aerogenes )

= $CH_{1.73}O_{0.43}N_{0.24}$

= $\frac{23.97}{0.92}$

= 26.1

From the molecular weight of the Biomass, we can deduce the Degree of reduction for the substrate(glycerol denoted as $\delta _g$) as follows:

= (4×1)+(1×1.73)-(2×0.43)-(3×0.24)

= 4.15

Given that the yield of the Biomass = 0.40 g

However;

C = $Yield of Biomass *\frac{Molecular weight of substrate}{Molecular weight of the Biomass}$

C = $0.40*\frac{92}{26.1}$

C = 1.41 g

Now , the oxygen requirement can be calculated as:

= $\frac{1}{4}*(n*S - C * \delta _{g})$

= $\frac{1}{4}(3*4.7-1.41*4.15)$

= 2.1 g/mol

Hence, we can say that the needed oxygen = 2.1 g/mol of the substrate consumed.

Now converting it to mass terms; we have:

= $2.1*\frac{number of mole of oxygen}{molecular weight of glycerol}$

= $2.1 * \frac{16}{92}$

= 0.3652 g

≅ 0.37 g

∴ The oxygen requirement for this culture in mass terms = 0.37 g