High-level acetaldehyde production in Lactococcus lactis by metabolic engineering

Area of Science:

• Biotechnology
• Metabolic Engineering
• Microbial Fermentation

Background:

• Lactic acid bacteria (LAB) like Lactococcus lactis are widely used in food fermentation.
• Efficient production of valuable compounds from simple sugars is a key goal in industrial biotechnology.
• Modifying LAB metabolism can enable the synthesis of non-native products.

Purpose of the Study:

• To engineer Lactococcus lactis for efficient conversion of glucose to acetaldehyde.
• To investigate the combined effect of pyruvate decarboxylase (pdc) and NADH oxidase (nox) overexpression.
• To assess the feasibility of this approach under anaerobic conditions.

Main Methods:

• Nisin-controlled gene expression system used for enzyme overexpression in L. lactis.
• Overexpression of Zymomonas mobilis pyruvate decarboxylase (pdc) and Lactococcus lactis NADH oxidase (nox).
• Cultivation of engineered L. lactis under anaerobic conditions with glucose as substrate.

Main Results:

• Achieved efficient conversion of glucose to acetaldehyde in engineered L. lactis.
• Combined overexpression of pdc and nox successfully redirected metabolic flux.
• Resting cells demonstrated redirection of almost 50% of consumed glucose towards acetaldehyde production.

Conclusions:

• Nisin-controlled co-overexpression of pdc and nox is an effective strategy for acetaldehyde production in L. lactis.
• This metabolic engineering approach offers a promising route for producing acetaldehyde from glucose.
• The engineered L. lactis strain shows potential for biotechnological applications requiring acetaldehyde synthesis.