132. In a bioprocess, assume that only cell mass is formed. Due to a variation in process conditions, if the
microbial cell yield has halved, what would be the rate of substrate consumption to maintain the same rate
of cell mass production?
(1) It would be doubled
(2) It would be halved
(3) It would be unchanged
(4) It would increase four folds

Detailed Explanation:

Question:
In a bioprocess, assume that only cell mass is formed. Due to a variation in process conditions, if the microbial cell yield has halved, what would be the rate of substrate consumption to maintain the same rate of cell mass production?

• (1) It would be doubled

• (2) It would be halved

• (3) It would be unchanged

• (4) It would increase fourfold

Correct Answer:

(1) It would be doubled

Explanation:

In bioprocesses, microbial cell yield refers to the amount of biomass produced per unit of substrate consumed. This is typically expressed as the ratio of cell mass produced to substrate consumed, which is often denoted as Y_x/s.

When microbial cell yield halves, the efficiency of converting substrate into cell mass decreases. This means that for the same amount of cell mass production, more substrate will be required.

Understanding the Effect on Substrate Consumption:

If the microbial cell yield is halved, the process is now less efficient at converting the substrate into cell mass. To maintain the same rate of cell mass production, the substrate consumption needs to be increased to compensate for the reduced yield.

Since the yield has halved, the amount of substrate required to produce the same amount of cell mass will be doubled. This is because with a reduced yield, it now takes twice as much substrate to produce the same biomass.

Why the Other Options are Incorrect:

• Option (2) It would be halved: This would only be true if the cell yield were to double, which is not the case here.

• Option (3) It would be unchanged: If the yield decreases, the substrate consumption must increase to maintain the same biomass production rate, so this is not the case.

• Option (4) It would increase fourfold: This is an overestimation. The doubling of substrate consumption is directly related to halving the microbial cell yield, not increasing it by a factor of four.

Conclusion:

When the microbial cell yield in a bioprocess is halved, the rate of substrate consumption must double to maintain the same rate of cell mass production. This highlights the importance of process optimization to balance efficiency in both cell yield and substrate consumption.

Let me know if you’d like more information on optimizing bioprocess conditions or related topics!