Biotechnological production of chiral acetoin

Acetoin (AC) is an important platform bulk chemical with versatile applications. It exists in two stereoisomeric forms: (3R)-AC and (3S)-AC. Both stereoisomers could be potentially applied in the pharmaceutical industry, agriculture, and in optically active alpha-hydroxyketone derivative synthesis. Chiral AC production has recently become a new research focus in biotechnology. Fermentative and biocatalytic routes that can produce (3R)-AC or (3S)-AC with high optical purity have been developed over the past several years. In this review we summarize recent advances in strain screening, metabolic engineering, and biocatalytic system construction aimed at improving the production of chiral AC. Limiting factors and possible solutions for chiral AC production are discussed.