Advances in microbial production of feed amino acid.

Feed amino acids have numerous applications, and the market demand for them is likely to grow. Microbial cell factories promise the sustainable production of feed amino acids; however, their performance is significantly affected by the availability of precursors, carbon metabolic flux, and transporter systems. To circumvent these potential roadblocks, high-performance microbial cell factories have been constructed by strengthening the supply of precursors, increasing metabolic pathway flux, and engineering transporters. In this review, limiting factors and recent technical advances affecting the production of feed amino acids in microbial cell factories are discussed. In addition, existing challenges and potential strategies for increasing the output of these amino acids are described.