21173
Novel - type serine - synthesizing enzymes , termed metal - independent phosphoserine phosphatases ( iPSPs ) , were recently identified and characterized from Hydrogenobacter thermophilus , a chemolithoautotrophic bacterium belonging to the order Aquificales .
 Chemical: serine; Chemical: phosphoserine
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: serine; Chemical: phosphoserine