l-Serine and Glycine

Abstract

The biosynthesis of glycine and l-serine is closely connected,\rand both amino acids are produced in industry. However, whereas glycine is made chemically, l-serine\rproduction relies largely on microbial processes. These include conversions of added glycine by C-1 utilizing\rmicroorganisms. But such precursor conversions usually suffer from low yields, as did previous attempts\rto produce l-serine from glucose. As more recent molecular and physiological\rstudies have shown, microorganisms like Corynebacterium glutamicum have\ra high l-serine degradation capacity corresponding to an apparent\rkey position of this amino acid in metabolism. Considering this key position, deletion of a serine\rdehydratase gene and prevention of folate synthesis to reduce serine hydroxymethyltransferase activity together\rwith increased biosynthesis resulted in l-serine producers of C. glutamicum with excellent production characteristics and maximal specific\rproductivities of 1.45 mmol g−1 h−1\raccumulating more than 50 g l−1\rl-serine.