Lactate metabolism by pediococci isolated from cheese

Area of Science:

• Food Microbiology
• Biochemistry

Background:

• Pediococcus pentosaceus is a common bacterium in Cheddar cheese microflora.
• Lactate metabolism by microorganisms is crucial for cheese ripening and flavor development.

Purpose of the Study:

• To investigate the lactate metabolism of Pediococcus pentosaceus under different conditions.
• To determine the activity of the lactate oxidation system in Pediococcus pentosaceus within Cheddar cheese.

Main Methods:

• Incubation of Pediococcus pentosaceus with L-(+)-lactate under anaerobic and aerobic conditions.
• Analysis of lactate isomers, acetate, and CO2 production.
• Monitoring lactate oxidation activity in Pediococcus pentosaceus-inoculated Cheddar cheese over time.

Main Results:

• Anaerobic conditions led to the conversion of L-(+)-lactate to D-(-)-lactate, forming DL-lactate.
• Aerobic conditions resulted in the oxidation of both lactate isomers to acetate and CO2.
• The lactate oxidation system showed optimal activity at pH 5-6 and was enhanced by aerobic growth and sugar depletion.
• Lactate conversion to acetate was observed in Pediococcus pentosaceus-enriched Cheddar cheese, with activity persisting after 6 months of ripening.

Conclusions:

• Pediococcus pentosaceus possesses a versatile lactate oxidation system adaptable to aerobic and anaerobic environments.
• This bacterium contributes to acetate production in Cheddar cheese, influencing its flavor profile during ripening.