3847
Symbiotic nitrogen-fixing bacteria , such as " Rhizobium " species , detect compounds like flavonoids secreted by the roots of leguminous plants and then produce nod factors that signal to the plant that they are present and will lead to the formation of root nodules .
 location: Rhizobium
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: location, person, organization 
Text: {0} 
 Entities: Rhizobium 
Answer:
 location: Rhizobium