A microorganism is transformed to be capable of producing guanidinoacetic acid (GAA). A method can be used for the fermentative production of GAA using such microorganism. A corresponding method can also be used for the fermentative production of creatine.

The present invention discloses an L-arginine-glycine amidinotransferase and use thereof in the production of guanidinoacetic acid. In the present invention, through combined multi-site amino acid mutation, a technical effect of significantly improved enzyme activity of the mutant AkAGAT.sub.T225Q/A258P/L278K than that of the wild-type strain is achieved, providing an application value for large-scale production of guanidinoacetic acid in industry. When the L-arginine-glycine amidinotransferase mutant constructed in the present invention is used in the production of guanidinoacetic acid, by optimizing the conversion conditions, the yield of guanidinoacetic acid is up to 21.4 g/L and the conversion rate is 90.4%, after 24 hrs of reaction in a 1 L reaction system. Compared with the production of guanidinoacetic acid with the raw enzyme, the yield is increased by 49.6%.

The present disclosure relates to the production of oligosaccharides, especially Human milk Oligosaccharides (HMOs) using a genetically engineered cell which has decreased or total loss of function of phosphoglycerol transferase I and II and/or phosphoethanolamine transferase and/or glucans biosynthesis protein C to reduce oligosaccharide by-products and/or increase oligosaccharide production.

Herein is reported a nucleic acid comprising in operably linked form a nucleic acid encoding a selection marker, a nucleic acid encoding a self-cleaving peptide sequence, and a nucleic acid encoding a proteinaceous protease inhibitor. Further reported are methods for the recombinant production of a heterologous polypeptide using said nucleic acid as well as a cell comprising said nucleic acid according to the invention. Likewise reported is the use of the nucleic acid according to the invention for increasing the amount of the recombinantly produced heterologous polypeptide by reducing protease cleavage.