Highly-efficient co-production of microbial lipid and magnesium ammonium phosphate from N-acetyl-D-glucosamine

The valorization of chitin-rich wastes into chemicals and biofuels holds immense economic and environmental benefits. Here, N-acetyl-D-glucosamine (GlcNAc), the basic structural unit of chitin, was firstly described for co-producing microbial lipid and magnesium ammonium phosphate (MAP). Due to the strong substrate inhibition of GlcNAc, a fed-batch culture mode was successfully adopted to achieve high cell density by Cutaneotrichosporon oleaginosum. When a phosphate limitation strategy was applied, cell mass, lipid titer, content, yield, and productivity were 102.7 g/L, 74.2 g/L, 72.2 %, 21.4 g/100 g, and 0.69 g/L/h, respectively. The ammonium ion was efficiently precipitated by forming MAP with a removal rate around 95.4 %. The lipid samples showed high similarity to vegetable oil, which emerged as high-quality precursor for biodiesel production. This study offers a promising strategy for full conversion of GlcNAc into lipid and slow-release fertilizer, which provides an attractive technical route for turning the chitin-rich materials into valuable products.