Glyoxylate cycle in Mucor racemosus

Area of Science:

• Microbiology
• Biochemistry
• Mycology

Background:

• Mucor racemosus is a dimorphic phycomycete fungus.
• The glyoxylate bypass is a crucial metabolic pathway in microorganisms.
• Carbon source availability influences fungal enzyme expression and metabolic activity.

Purpose of the Study:

• To investigate the presence and activity of glyoxylate bypass enzymes (isocitrate lyase and malate synthase) in Mucor racemosus.
• To determine the effect of different carbon sources (acetate, glutamate, peptone, glucose) on enzyme activity.
• To assess the role of the glyoxylate cycle in M. racemosus metabolism under varying nutritional conditions.

Main Methods:

• Culturing Mucor racemosus in defined media with acetate, glutamate, or peptone as sole carbon sources.
• Measuring specific activities of isocitrate lyase and malate synthase throughout growth cycles.
• Assessing enzyme activity and growth inhibition using glucose and itaconic acid treatments.

Main Results:

• Isocitrate lyase and malate synthase were detected across all tested carbon sources.
• Highest enzyme specific activities were observed in acetate-supplemented media.
• Glucose repressed glyoxylate bypass enzyme activity, which resumed upon glucose depletion; itaconic acid inhibited growth and enzyme activity in acetate-grown cells.

Conclusions:

• The glyoxylate bypass is active in Mucor racemosus, with its expression significantly influenced by the carbon source.
• Acetate supports high glyoxylate bypass activity, suggesting its importance in acetate metabolism.
• Glucose acts as a repressive carbon source for this pathway, and itaconic acid demonstrates inhibitory potential against key enzymes.