Diacetyl and acetoin production from whey permeate using engineered Lactobacillus casei

Area of Science:

• Microbiology
• Metabolic Engineering
• Food Science

Background:

• Lactobacillus casei is a probiotic bacterium with potential for flavor compound production.
• Whey permeate, a dairy industry by-product, is an underutilized resource.
• Diacetyl and acetoin are key flavor compounds in fermented foods.

Purpose of the Study:

• To engineer Lactobacillus casei for enhanced production of diacetyl and acetoin.
• To utilize whey permeate as a substrate for metabolite synthesis.
• To explore metabolic engineering strategies for dairy by-product valorization.

Main Methods:

• Metabolic engineering of L. casei by expressing ilvBN genes from Lactococcus lactis.
• Gene mutations in lactate dehydrogenase (ldh) and pdhC genes.
• Cultivation in whey permeate and analysis of diacetyl/acetoin production.

Main Results:

• Engineered L. casei demonstrated increased capacity for diacetyl/acetoin synthesis.
• Significant production of 1,400 mg/l diacetyl/acetoin achieved in whey permeate at pH 5.5.
• Successful conversion of lactose in whey permeate into valuable flavor compounds.

Conclusions:

• Lactobacillus casei can be metabolically engineered for efficient production of flavor compounds.
• Dairy industry by-products like whey permeate can be effectively utilized.
• Metabolic engineering offers a viable strategy for synthesizing added-value metabolites.