# Actinomycetota

| Actinomycetota |
| --- |
|  |
| *Actinomyces israelii*. |
| Klasifikasi ilmiah  |
| Domain: | Bacteria |
| Kerajaan: | Bacillati |
| Filum: | Actinomycetota Goodfellow 2021 |
| Genus tipe |
| *Actinomyces* Harz 1877 (Approved Lists 1980) |
| Kelas |
| * Acidimicrobiia
* Actinomycetes
* "Aquicultoria"
* Coriobacteriia
* "Geothermincolia"
* "Humimicrobiia"
* Nitriliruptoria
* Rubrobacteria
* ?"Syntrophaliphaticia"
* Thermoleophilia
 |
| Sinonim |
| * "Actinobacteraeota" Oren *et al*. 2015
* "Actinobacteria" Goodfellow 2012
* "Actinobacteria" Margulis 1974 *ex* Cavalier-Smith 2020
* "Actinobacteria" Stackebrandt, Rainey & Ward-Rainey 1997
* "Actinobacteriota" Whitman *et al*. 2018
* "Actinomycetes" Krasil'nikov 1949
 |

**Actinomycetota** dulu disebut **Actinobacteria**, atau **Actinomycetes** adalah filum bakteri yang beranggotakan bakteri Gram positif. Bakteri ini pernah diklasifikasi sebagai fungi (jamur, *Mycota*) karena ada anggotanya yang membentuk berkas-berkas mirip hifa serta menghasilkan antibiotik. Ketika diketahui memiliki sejumlah ciri bakteri (ukurannya kecil dan dapat diserang virus bakteriofag), kelompok ini pernah dianggap bukan fungi maupun bakteri. Baru setelah pengujian DNA dimungkinkan, kelompok ini diketahui sebagai bakteri.

## Karakteristik

Anggota Actinobacteria kebanyakan aerob, tetapi beberapa, seperti *Actinomyces israelii*, dapat tumbuh dalam kondisi anaerob. Tidak seperti Firmicutes, kelompok utama lain bakteri Gram positif, Actinobacteria memiliki DNA dengan *GC-content* yang tinggi (sekitar 75%) dan beberapa jenis Actinobacteria memproduksi spora eksternal.

Pembentukan spora pada actinomycetes memungkinkan sel bertahan dalam kondisi lingkungan yang buruk. Selain itu, sifat berfilamen dan kemampuan untuk membentuk spora mendukung mikroba ini untuk beradaptasi dan bersaing dengan mikroba lain yang terdapat di daerah rizosfer.

Secara struktural, actinomycetes mampu membentuk miselia vegetatif dan aerial. Miselium tidak selalu stabil dan dapat pecah menjadi fragmen berbentuk batang atau coccus. Bakteri ini juga membentuk struktur reproduksi berupa konidia atau sporangia. Kemampuan ini menyebabkan penampakan koloninya menyerupai jamur. Meskipun demikian, profil genetik dan seluler actinomycetes adalah karakteristik bakteri, seperti kromosom yang dibungkus dengan nukleoid prokariotik. Struktur dinding selnya yang kaku terbentuk dari senyawa kompleks seperti polisakarida, peptidoglikan, asam teikoat, dan teichuronic.

## Habitat

Actinomycetes tersebar di berbagai wilayah, mulai dari daerah tropis hingga beriklim sedang. Mikroorganisme ini dapat ditemukan pada beragam habitat, termasuk lingkungan darat, air tawar, dan laut. Hal ini dikarenakan bakteri umumnya bersifat mesofilik, dengan suhu pertumbuhan optimal berkisar antara 25–30 °C. Namun, beberapa strain ditemukan tumbuh optimal pada suhu lebih tinggi (termofilik), yaitu sekitar 55–65 °C .

Kebanyakan Actinobacteria ditemukan di tanah. Ketersediaan mikroba ini pada tanah mewakili lebih dari 30% dari seluruh populasi mikroba. Sebagian yang lain tinggal di dalam tumbuhan dan hewan, termasuk beberapa patogen seberti *Mycobacterium*. Mereka memainkan peranan yang penting dalam dekomposisi materi organik seperti selulosa dan kitin. Aktivitas ini menambah cadangan hara di dalam tanah dan merupakan bagian penting dari pembentukan humus. Kemampuan Actinobacteria untuk hidup di lingkungan bernutrisi rendah dan untuk mengonsumsi lognoselulosa (lignin dan selulosa, zat-zat penyusun kayu, biasanya sukar dicerna kebanyakan bakteri tanah) menyebabkan Actinobacteria mendominasi kawasan bebatuan karst. Pemberian pupuk kandang yang kaya selulosa akan meningkatkan populasi Aktinobakteri di tanah. Pemupukan amonium atau nitrat yang terus-menerus menekan populasi karena Aktinobakteri tidak suka pH di bawah 6; sebaliknya, pengapuran untuk menaikkan pH juga menaikkan populasinya.

## Peran ekonomis

Beberapa aktinobakteri menyebabkan gangguan kesehatan pada manusia, hewan, dan tumbuhan. *Streptomyces* ada yang menyebabkan penyakit skabies (kudis) pada umbi kentang. *S. griceus* menghasilkan antibiotik streptomisin. Jenis-jenis *Frankia* membentuk simbiosis mutualisme dengan akar tumbuhan sehingga membantu pertumbuhan tanaman. Beberapa aktinobakteria menghasilkan geosmin, suatu senyawa organik yang bertanggung jawab atas bau tanah/lumpur pada tambak atau perairan diam lainnya.

## Filogeni

Filogeni didasarkan pada LTP rilis 123 berdasarkan RNA ribosomal 16s oleh 'The All-Species Living Tree' Project.

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|  | *Rubrobacter* Suzuki *et al*. 1989 |
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| Thermoleophilidae |

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|  | *Gaiella occulta* Albuquerque *et al*. 2012 |
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|  | *Thermoleophilum* Zarilla and Perry 1986 |
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Solirubrobacterales |
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Coriobacteriia |
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Acidimicrobiales |
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| Nitriliruptoridae |

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|  | *Euzebya tangerina* Kurahashi *et al*. 2010 |
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|  | *Nitriliruptor alkaliphilus* Sorokin *et al*. 2009 |
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| **Actinobacteria** |

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|  | *Acidothermus cellulolyticus* Mohagheghi *et al*. 1986 |
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Catenulisporineae |
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|  | *Motilibacter peucedani* Lee 2012 |
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|  | *Streptomyces* Waksman and Henrici 1943 emend. Witt and Stackebrandt 1991 [incl. *Kitasatospora* & *Streptacidiphilus*] |
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Geodermatophilaceae |
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Frankineae |
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Nakamurellaceae |
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|  | *Kineococcus* Yokota *et al*. 1993 |
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Kineosporiaceae |
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|  | *Angustibacter luteus* Tamura *et al*. 2010 |
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Micrococcineae [incl. Actinomycetaceae & Bifidobacteriaceae] |
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Propionibacterineae |
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Nocardioidaceae 2 |
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|  | *Thermobispora bispora* (Henssen 1957) Wang et al. 1996 |
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Streptosporangineae |
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| Arabobacteria |

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Pseudonocardiaceae [incl. *Actinopolyspora*] |
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Corynebacterineae |
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Jiangellaceae |
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Micromonosporaceae |
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|  | *Actinocatenispora* Thawai *et al*. 2006 emend. Seo and Lee 2009 |
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|  | *Phytomonospora endophytica* Li et al. 2011 |
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Glycomycetaceae |
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## Referensi