Maltose metabolism in involves the conversion of β-glucose 1-phosphate to glucose 6-phosphate, a reaction which is reversibly catalysed by a maltose-inducible and glucose-repressible β-phosphoglucomutase (β-PGM). The gene encoding β-PGM () was cloned from a genomic library of using antibodies. The nucleotide sequence of a 5695 bp fragment was determined and six ORFs, including the gene, were found. The gene expressed a polypeptide with a calculated molecular mass of 24210 Da, which is in agreement with the molecular mass of the purified β-PGM (25 kDa). A short sequence at the N-terminus was found to be similar to known metal-binding domains. The expression of β-PGM in was found to be induced also by trehalose and sucrose, and repressed by lactose in the growth medium. This indicates that β-PGM does not serve solely to degrade maltose, but that it is also involved in the metabolism of other carbohydrates. The specific activity of α-PGM during fermentation was dependent on the maltose concentration in the medium. The maximum specific activity of β-PGM increased by a factor of 4.6, and the specific growth rate by a factor of 7, when the maltose concentration was raised from 0.8 to 11.0 g I. Furthermore, a higher amount of lactate produced relative to formate, acetate and ethanol was observed when the initial maltose concentration in the medium was increased. The specific activity of β-PGM responded similarly to β-PGM, but the magnitude of the response was lower. Preferential sugar utilization and α- and β-PGM suppression was observed when was grown on the substrate combinations glucose and maltose, or lactose and maltose; maltose was the least-preferred sugar. In contrast, galactose and maltose were utilized concurrently and both PGM activities were high throughout the fermentation.


Article metrics loading...

Loading full text...

Full text loading...


Most cited this month

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error