Enzyme Studies of Bacillus Stearothermophilus NU 10 During Growth at 45 and 65 C

This study found that significant differences exist in the relative levels of the HMP and EMP pathways in Bacillus Stearothermophilus NU 10 grown at 45 and 65 C.Enzyme studies of mid-log phase cells showed that levels of two HMP pathway enzymes were more than two-fold greater at 45 than 65 C, while the inverse was true for both EMP pathway activities. Second, when cells were grown at either 45 or 65 C and shifted rapidly to the other temperature, enzyme levels changed.6-Phosphogluconate dehydrogenase activity increased in cells shifted from 65 to 45 C, while phosphofructokinase activity increased when the shift was from 45 to 65 C, indicating adaptation to temperature variation. During normal growth in trypticase medium, oxygen per cent saturation is drastically reduced at both 45 and 65 C, the effect being greater at 65 C.This drop in dissolved oxygen does not appear to change the growth rate, but may affect the level of at least on key enzyme, phosphorfructokinase.The levels of all enzymes tested fluctuated widely during growth, underscoring the need for carefully controlled growth conditions during any study of bacterial metabolism. Advisor:Carl E. Georgi and Walter E. Militze