Question

Time (minutes)	no sugar	glucose	sucrose	maltose	lactose	galactose
0	0	0	0	0	0	0
5	0	3	0	0	2.8	3.1
10	0	6	0	0	5.6	6.2
15	0	9	0	0	8.8	9.3
20	0	12	0	0	11.5	12.5
25	0	15	0	0	13.9	15.7
30	0	18	0	0	17.2	18.9
35	0	21	0	0	20	22
40	0	24	0	0	23.5	25
45	0	27	0	0	26.5	28.5
50	0	30	0	0	29.5	31.6
55	0	33	0	0	32.3	34.8
60	0	36	0	0	35.2	37.8

a) What do you notice immediately about sugar utilization in M. tuberculosis?

b) Consider each sugar carefully, and provide a possible explanation for each of them. You may want to refer back to the structures of the sugars provided at the beginning.

Answer 1

A) It is seen that carbondioxide evolution occurs in case of glucose only. This suggests that only glucose is utilised by the M. tuberculosis.

b) When there is not found any sugar in the surrounding of bacteria, then M. tuberculosis does not utilise sugar and no CO2 is produced. Similarly sucrose can not be utilised by this bacteria. Hence no CO2 is evolved. Because this bacteria can not break down sucrose into glucose and fructose.

The preferable substrate for this bacteria is glucose. This will break down glucose into CO2 and energy. Hence the energy is obtained by the break down of glucose.