NAD-specific 6-phosphogluconate dehydrogenase in lactic acid bacteria

Area of Science:

• Biochemistry
• Microbiology
• Enzymology

Background:

• 6-Phosphogluconate dehydrogenase is a key enzyme in carbohydrate metabolism.
• Lactic acid bacteria (LAB) are a diverse group of microorganisms with significant industrial and health applications.
• Understanding enzyme specificity in LAB is crucial for optimizing fermentation processes and metabolic engineering.

Purpose of the Study:

• To classify 6-phosphogluconate dehydrogenase types in lactic acid bacteria based on coenzyme specificity.
• To investigate the relationship between enzyme type and metabolic pathways in LAB.
• To compare the activity and specificity of different 6-phosphogluconate dehydrogenase types.

Main Methods:

• Cell-free extracts were prepared from seventeen strains of lactic acid bacteria.
• 6-Phosphogluconate dehydrogenase activity was screened and characterized.
• Enzyme activity was assayed with different coenzymes (NAD and NADP) to determine specificity.

Main Results:

• Three types of 6-phosphogluconate dehydrogenase were identified: NAD-specific, NADP-specific, and non-specific.
• Heterofermentative LAB strains exclusively possessed the NAD-specific type of the enzyme.
• The NAD-specific 6-phosphogluconate dehydrogenase exhibited higher specific activity and greater specificity for NAD compared to other types.

Conclusions:

• The coenzyme specificity of 6-phosphogluconate dehydrogenase can be used to classify LAB strains.
• The presence of NAD-specific 6-phosphogluconate dehydrogenase is linked to heterofermentative pathways in LAB.
• This enzyme type offers potential for targeted applications in biotechnological processes involving NAD-dependent reactions.