Peptidoglycan is primarily used in immunological research due to its ability to activate innate immune responses. It is a potent stimulator of pattern recognition receptors such as NOD1 and NOD2, making it valuable in studies related to inflammation, host-pathogen interactions, and vaccine development. In biotechnology, peptidoglycan and its fragments are used to develop adjuvants that enhance the efficacy of vaccines by boosting immune activation. It also serves as a model substance in antibiotic research, particularly for studying the mechanism of action of drugs like penicillin and lysozyme, which target bacterial cell wall synthesis. Additionally, peptidoglycan is employed in microbiology for cell wall studies and bacterial classification, as its structure varies between bacterial species and can influence pathogenicity. Its presence in bacterial cultures is also used as a biomarker in diagnostic assays to detect bacterial contamination.