1. As a nitrogen source: 
 (1) instead of peptone, yeast extract used for microbiological culture; 
 (2) for avermectin, erythromycin, rifampicin, oxytetracycline, spiramycin, gentamicin, lincomycin and tetracycline fermentation; 
 (3) for enzymes, steroids, organic acids, amino acids, vitamins, soy sauce and other food making solid-state fermentation and liquid fermentation;