A Novel Efficient L-Lysine Exporter Identified by Functional Metagenomics

Area of Science:

• Microbiology
• Biotechnology
• Metagenomics

Background:

• Industrial bioprocesses for products like L-lysine are often limited by intracellular accumulation due to inefficient export systems.
• This necessitates complex purification steps and hinders high-titer production.

Purpose of the Study:

• To identify novel L-lysine exporter candidates to overcome limitations in L-lysine bio-production.
• To enhance L-lysine tolerance and production efficiency in industrial microbial hosts.

Main Methods:

• Functional screening of a cow gut microbiome metagenomic library to identify genes conferring L-lysine tolerance.
• In vivo characterization of a novel L-lysine transporter using Xenopus oocyte and Escherichia coli expression systems.
• Evaluation of the exporter's impact on L-lysine production in Corynebacterium glutamicum.

Main Results:

• Identified 58 genes from 28 metagenomic fragments that improve L-lysine tolerance.
• Discovered and characterized a novel L-lysine exporter belonging to the EamA superfamily.
• The novel exporter increased L-lysine tolerance in E. coli by 40% and enhanced yield (7.8%), titer (9.5%), and specific production (12%) in Corynebacterium glutamicum.

Conclusions:

• A novel, sequence-independent method for discovering microbial exporters was developed.
• The identified L-lysine exporter significantly improves L-lysine production metrics in an industrial strain.
• This approach can be applied to enhance productivity in other toxicity-limited bioprocesses.