11562
The aim of this study was to investigate host pathways affected by L . johnsonii , with specific focus on the rate - limiting enzyme of tryptophan catabolism , indoleamine 2 , 3 - dioxygenase ( IDO ) .
 Chemical: tryptophan; Chemical: indoleamine
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 Chemical: tryptophan; Chemical: indoleamine