| 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 |