Whole-cell conversion of L-glutamate to 1,4‑butanediol in Escherichia coli by PPK2 introduction under Mg2+-optimized conditions

초록

The increasing environmental problem of conventional plastics has driven interest in biodegradable alternatives and their sustainable monomer production. 1,4-butanediol (1,4-BDO) is one of the building blocks of polybutylene adipate terephthalate, a biodegradable polymer. In this study, L-glutamate-based whole-cell conversion system for 1,4-BDO production was developed using an engineered Escherichia coli strain. A synthetic metabolic pathway was composed of gadB, gabT, yqhD, and car3/sfp genes. The maximum titer of 1,4-BDO production was 48 mM from 100 mM L-glutamate as a substrate. Polyphosphate kinase 2 (PPK2) was introduced into the system together with polyphosphate (polyP) as a phosphate donor. Under the PPK2-expressing system, the 1,4-BDO titer increased up to 55 mM depending on polyP availability. Further analysis of metal ions identified Mg2+ as the most effective cofactor, and under Mg2+-optimized conditions, a 1,4-BDO titer of approximately 71 mM was obtained from 100 mM L-glutamate. These results suggest that PPK2 introduction combined with Mg2+ optimization is an effective strategy for enhancing 1,4-BDO production in an E. coli whole-cell conversion system. © The Author(s), under exclusive licence to The Korean Society for Biotechnology and Bioengineering 2026.

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