| Origin | Code | Comment | Supplementary Taxo |
| Nakamurella multipartita | ISNml | | |
| Natranaerobius thermophilus | ISNth | | |
| Natrialba aegyptia | ISNae | | |
| Natrialba asiatica | ISNasi | | |
| Natrialba chahannaoensis | ISNch | | |
| Natrialba hulunbeirensis | ISNhu | | |
| Natrialba magadii | ISNma | | |
| Natrialba sp. | ISNasp | | |
| Natrialba taiwanensis | ISNta | | |
| Natrialbaceae archaeon | ISNarch | | |
| Natrinema pallidum | ISNpa | | |
| Natrinema pellirubrum | ISNpe | | |
| Natronobacterium gregoryi | ISNagr | | |
| Natronococcus jeotgali | ISNje | | |
| Natronococcus occultus | ISNaoc | | |
| Natronolimnobius innermongolicus | ISNin | | |
| Natronomonas moolapensis | ISNamo | | |
| Natronomonas pharaonis | ISNph | | |
| Natronorubrum tibetense | ISNti | | |
| Neisseria gonorrhoeae | ISNgo | | |
| Neisseria meningitidis | ISNme | | |
| Neisseria mucosa | ISNemu | | |
| Neisseria shayeganii | ISNsh | | |
| Neisseria sp. | ISNesp | | |
| Neisseria wadsworthii | ISNwa | | |
| Niabella sp. | ISNia | | |
| Nitrobacter hamburgensis | ISNha | | |
| Nitrobacter sp. | ISNisp | | |
| Nitrobacter winogradskyi | ISNwi | | |
| Nitrococcus mobilis | ISNmo | | |
| Nitrosococcus halophilus | ISNhal | | |
| Nitrosococcus mobilis | ISNimo | | |
| Nitrosococcus oceani | ISNoc | | |
| Nitrosomonas communis | ISNco | | |
| Nitrosomonas europaea | ISNeu | | |
| Nitrosomonas eutropha | ISNieu | | |
| Nitrosomonas halophila | ISNiha | | |
| Nitrosomonas oligotropha | ISNol | | |
| Nitrosomonas sp. | ISNtsp | | |
| Nitrosomonas ureae | ISNur | | |
| Nitrosospira multiformis | ISNmu | | |
| Nitrospira sp. | ISNitsp | | |
| Nitrospirae bacterium | ISNiba | | |
| Nitrospirillum amazonense | ISNam | | |
| Nocardia asteroides | ISNas | | |
| Nocardia farcinica | ISNfa | | |
| Nocardia seriolae | ISNse | | |
| Nocardioides sp. | ISNosp | | |
| Nodularia spumigena | ISNspu | | |
| Nomurabacteria bacterium | ISNba | | |
| Nostoc flagelliforme | ISNfl | | |
| Nostoc punctiforme | ISNpu | | |
| Nostoc sp. | ISNsp | | |
| Noviherbaspirillum sp. | ISNvsp | | |
| Novosphingobium sp. | ISNov | | |