#20. Rhizobium Leguminosarum APA format 300 -400 Words minimum. You must discuss your chosen organism to tell us what type of microbe it is, what helpful beneficial actions it performs, and which subfield of microbiology it is involved in. You must discuss only the helpful, beneficial, positive aspects of your chosen organism for your entire main discussion. #20 was chosen and listed on top. reference form textbook 1. microbiology-a system approach (six editions). 2. peer review article used on what is needed. using the article is not madnditory. peer-reviewed article: calcium uptake and nitrogen-fixing ability in the heavy metal resistant laboratory and field strains of rhizobium leguminosarum biovar trifolii.