Circular use of food residues by microbial fermentation

A method for producing microbial lipids, said method comprising the steps:

• a) providing a first substrate, wherein said first substrate is a food residue(s);
• b) cultivating a first microorganism selected from filamentous fungi and bacteria with said first substrate, and thereby allowing said first microorganism to produce at least one enzyme and an enzymatically treated first substrate;
• c) optionally, obtaining said at least one enzyme and pretreating a second substrate with said at least one enzyme, and thereby providing an enzymatically treated second substrate;
• wherein said second substrate is a food residue(s);
• d) cultivating a second microorganism, wherein said second microorganism is an oleaginous microorganism, with a medium comprising said enzymatically treated first substrate and/or, if the step c) is present, with a medium comprising said enzymatically treated second substrate, and thereby allowing said oleaginous microorganism to produce microbial lipids;
• e) performing a purely enzymatic treatment of said cultivated second microorganism without any solvent-based extraction or chemicals-based demulsification, to make said microbial lipids produced in the step d) amenable for subsequent harvesting;
• and
• f) harvesting said microbial lipids produced in the step d).