A homofermentative Lactobacillus strain

A homofermentative Lactobacillus strain is grown in milk at 37 ^oC; the milk contains 40 g/l of lactose. After 6h of incubation, the lactose concentration is measured as 25 g/l. Answer the following questions:

1. Calculate the expected lactic acid concertation after 6 h of incubation assuming that 50% of the lactose consumed is converted to lactic acid, as the bacterium is able to utilise glucose but not galactose.

(30 marks)

1. The lactic acid concentration was measured after 6 h of incubation and was found to be 7 g/l. How does the expected yield of lactic acid from lactose (expressed as g of lactic acid produced per g of lactose consumed) compares with the actual experimental yield? Give reasonings regarding the difference.

(30 marks)

A heterofermentative Lactobacillus strain is grown at 37 ^oC in a medium containing 10 g/l of glucose. Assuming complete consumption of glucose, calculate the concentrations of the expected metabolic products.

(40 marks)