Renewable nitrogen-containing products by Maillard reaction of sewage sludge and glucose. Part I. Analysis of nitrogen composition and protein model based on AlphaFold2

Abstract

• Composition, content, and structure of protein-N in sludge were investigated. • Distribution and relative content of Maillard reaction-related functional groups. • Trace the origin of protein by microbial community and protein function analysis. • Sludge protein model is predicted by Alphafold2. • Crucial factors of sludge protein model for Maillard reaction are proposed. In order to better understand the nitrogen transformation in Maillard reaction during the co-pyrolysis of sewage sludge (SS) and glucose, analysis of Maillard reaction-related nitrogen-containing compounds (NCCs) and the protein model of SS is proposed. The composition, content, and structure of NCCs, especially protein in SS, are critical for the investigation of nitrogen transformation in Maillard reaction. The distribution and relative content of Maillard reaction-related functional groups, NCCs, and amino acids in SS were studied. Genomes by DNA sequencing are further applied in building a database search for metaproteomic studies, which provide valuable information and insight into the origin of SS protein, such as the taxonomic composition of the underlying microbial community, inferred protein functions, and their relationship with the transformation of NCCs. SS protein model was constructed by Alphafold2, and key factors determining the selection of SS protein model were revealed.