| Iamia majanohamensis | 102561T | 
| Idiomarina halophila | 109833T | 
| Idiomarina homiensis | 106395T | 
| Idiomarina piscisalsi | 108617T | 
| Idiomarina sediminum | 109488T | 
| Idriella fertilis | 30445 | 
| Idriella lunata | 7700T, 32041, 100566 | 
| Ignatzschineria cameli | 113042T | 
| Ignavibacterium album | 101810T | 
| Ilumatobacter coccineus | 103263T | 
| Ilumatobacter nonamiensis | 109120T | 
| Ilyomonas limi | 112826T | 
| Inconstantimicrobium mannanitabidum | 112100T | 
| Incrucipulum capitatum | 113938 | 
| Incrucipulum ciliare | 113861, 113940, 113941 | 
| Incrucipulum foliicola | 113942T | 
| Incrucipulum radiatum | 113862, 113933 | 
| Infundibulicybe gibba | 100092 | 
| Inhella inkyongensis | 103252T | 
| Inonotus cuticularis | 9788 | 
| Inonotus dryadeus | 9352 | 
| Inonotus mikadoi | 6517 | 
| Inonotus obliquus | 113406, 113407, 113408, 113409, 114701, 114702 | 
| Insolitispirillum peregrinum subsp. integrum | 13617T | 
| Insolitispirillum peregrinum subsp. peregrinum | 14922T | 
| Interfilum sp. (class: Ulvophyceae) | 113306 | 
| Intestinibaculum porci | 113396T | 
| Intrasporangium calvum | 12989T | 
| Intrasporangium chromatireducens | 113233T | 
| Intrasporangium flavum | 110749T | 
| Intrasporangium oryzae | 101802T | 
| Intrasporangium sp. | 106350, 106456, 106457, 107105, 116604 | 
| Involutiscutellula rubra | 9271, 9272, 9273T, 9274, 9275, 9276, 9277, 9371 | 
| Iodobacter fluviatilis | 102505T | 
| Iodophanus carneus | 7799, 7800, 7801 | 
| Irpex lacteus | 5367, 106829 | 
| Isabelozyma gotoi | 103920T | 
| Isabelozyma rhagii | 10308T | 
| Isaria cateniannulata | 109997 | 
| Isaria cicadae | 33061, 33259 | 
| Isaria nipponica | 108996 | 
| Isaria sp. | 103708, 103709, 104353 | 
| Isochrysis galbana (class: Haptophyceae) | 102813 | 
| Isochrysis sp. (class: Haptophyceae) | 102814, 102815, 102941 | 
| Isoptericola halotolerans | 104116T | 
| Isoptericola hypogeus | 104396T | 
| Isoptericola jiangsuensis | 106522 | 
| Isoptericola sp. | 110988, 110993, 110999, 111000, 111001 | 
| Isoptericola variabilis | 104115T | 
| Issatchenkia occidentalis | 1904T, 105118, 105120, 105179 | 
| Issatchenkia orientalis | 1279T, 105119, 105121, 105122, 105123 | 
| Issatchenkia scutulata var. exigua | 1896T, 10077, 10078 | 
| Issatchenkia scutulata var. scutulata | 1895T | 
| Issatchenkia sp. | 10049, 10050, 10051, 10068, 10069, 10070, 10079, 10080, 10081, 10082, 10083, 10084, 10085, 10086, 10087, 10088, 104879, 105180 | 
| Issatchenkia terricola | 0933T, 1798, 1888, 1907 | 
| Isthmolongispora ampulliformis | 6787T | 
| Isthmolongispora lanceata | 100994T | 
| Isthmolongispora minima | 30075, 111160 | 
| Isthmolongispora quadricellularis | 100995 | 
| Isthmolongispora variabilis | 100996 | 
| Itersonilia perplexans | 31349, 31350, 31655T | 
| Itersonilia pyriformis | 31656T | 
| Ithmotricladia cf. laeensis | 106796 |