Ty. Wong et al., DIAUXIC GROWTH OF AZOTOBACTER-VINELANDII ON GALACTOSE AND GLUCOSE - REGULATION OF GLUCOSE-TRANSPORT BY ANOTHER HEXOSE, Applied and environmental microbiology, 61(2), 1995, pp. 430-433
The growth curve of Azotobacter vinelandii was biphasic when the organ
ism was grown in a medium containing a mixture of galactose and glucos
e. Galactose was the primary carbon source; glucose was also consumed,
but the rate at which it was consumed was lower than the rate at whic
h galactose was consumed during the first phase of growth. Metabolic p
athways for both sugars were induced. Cell cultures exhibited a second
lag period as galactose was depleted. The length of this lag phase va
ried from 2 to 10 h depending on the pregrowth history of the cells. T
he second log growth phase occurred at the expense of the remaining gl
ucose in the medium and was accompanied by induction of the high-maxim
um rate of metabolism glucose-induced glucose permease and increases i
n the levels of glucose metabolic enzymes. The second lag phase of dia
uxie may have been due to the time required for induction of the gluco
se-induced glucose permease.