13788
Importantly , O antigen production enables laboratory strains of E . coli to enter the gut of the Caenorhabditis elegans worm and to kill C . elegans at rates similar to pathogenic bacterial species .
 None
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:  
Answer:
 None