19129
Through construction and analysis of a series of knockout mutants , we identified the genes necessary for A - 74528 biosynthesis .
 Chemical: A - 74528
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
 Entities: A - 74528 
Answer:
 Chemical: A - 74528