[Respiratory activity of diploid Pullularia pullulans strains].

Area of Science:

• Microbiology
• Biochemistry
• Yeast Physiology

Background:

• Pullularia pullulans is a fungus known for producing the polysaccharide pullulan.
• Understanding the metabolic differences between fungal strains is crucial for optimizing bioprocesses.
• Respiration and substrate utilization efficiency can vary significantly among strains and ploidy levels.

Purpose of the Study:

• To compare the respiration activity of different strains of Pullularia pullulans.
• To investigate the relationship between respiration rates, ploidy, and pullulan synthesis.
• To determine how culture age affects respiratory activity in these strains.

Main Methods:

• Culturing of one haploid and two diploid strains of Pullularia pullulans.
• Measurement of endogenous respiration rates.
• Quantification of oxygen uptake and carbon dioxide evolution during glucose respiration.
• Calculation of respiration quotient (RQ) to assess substrate oxidation.

Main Results:

• Minimal differences in endogenous respiration intensity were observed among the strains.
• The diploid strain P. pullulans 11254(13), a high pullulan producer, exhibited lower oxygen uptake and carbon dioxide evolution per unit biomass during glucose respiration compared to other strains.
• This high-producing diploid strain demonstrated a lower respiration quotient, indicating less substrate oxidation to CO2.

Conclusions:

• The diploid strain P. pullulans 11254(13) exhibits a more efficient metabolic strategy for pullulan production.
• Lower respiration rates in this strain suggest a redirection of carbon flux towards polysaccharide synthesis rather than complete substrate oxidation.
• These findings highlight the potential for strain selection and metabolic engineering to enhance pullulan yields.