21547
FixK2 is an important regulatory protein that helps activating a large number of genes for the anoxic and microoxic , endosymbiotic and nitrogen - fixing life styles of the alpha - proteobacterium Bradyrhizobium japonicum .
 Chemical: nitrogen
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: nitrogen