A biotechnological process is reported, which enables an enzymatic reduction without the need for addition of an organic co-substrate for in situ-cofactor recycling. The process is based on merging the fields of enzymatic reductive amination with formate dehydrogenase-based in situ-cofactor recycling and algae biotechnology by means of the photoautotrophic microorganism Chlamydomonas reinhardtii, providing the needed formate in situ by formation from carbon dioxide, water and light. This biotransformation has been exemplified for the synthesis of various aliphatic amines known as bulk chemicals.