Thiomargarita magnifica, bakteria wakubwa zaidi wameibuka na kupata uchangamano, na kuwa wa seli za yukariyoti. Hii inaonekana kupinga wazo la jadi la prokaryote.
It was in 2009 when scientists had a strange encounter with microbial diversity that exists in the nature. While looking for sulfur-oxidising symbionts in sulfur-rich mangrove sediments in Guandeloupe , an island group in the southern Caribbean Sea, the research team came across some white filaments attached to sediments. They were big with lot of filaments so the researcher initially thought them to be a eukaryote, some unknown filamentous fungi. However, microscopy studies indicated they were single cells, some sulfar-oxidising, ‘macro’ microbes. If they were fungi then phylogenetic typing should reveal 18S rRNA gene sequence (a marker for yukariyoti) Hata hivyo, mpangilio wa jeni ulibaini kuwepo kwa alama ya prokariyoti 16S rRNA ikimaanisha kuwa sampuli hiyo ilikuwa bakteria, mwanachama wa jenasi Thiomargarita. Ilipewa jina Thiomargarite ya ajabu (magnifica kwa sababu ilionekana kuwa nzuri).
Hivi ndivyo bakteria T. magnifica iligunduliwa huko nyuma mnamo 2009 lakini muundo wa kina wa seli na habari zinazohusiana hazikupatikana hadi hivi majuzi wakati karatasi iliyopewa jina ''Bakteria yenye urefu wa sentimeta yenye DNA iliyomo katika viungo amilifu vinavyofanya kazi kwenye utando.'' na Volland et al ilichapishwa-tarehe 23 Juni 2022 (toleo la awali lilichapishwa tarehe 22 Februari 2022).
Kulingana na utafiti huu, Thiomargarita magnifica ni seli moja ya bakteria yenye urefu wa sentimita. tofauti na bakteria wengi ambao urefu wao ni kama mikromita 2 (baadhi ya bakteria wanaweza kuwa na urefu wa mikromita 750), wastani wa urefu wa seli Thiomargarite ya ajabu ni zaidi ya mikromita 9000. Hii inawafanya kuwa bakteria kubwa zaidi inayojulikana. Kwa wazi, inaonekana wazi kwa jicho la uchi. Ukubwa wa seli ya utaratibu huu ni uncharacteristic sana ya prokaryotes.
zaidi ya hayo, T. magnifica DNA is contained in a novel type of membrane-bound bacterial cell organelle. This is significant because the packing of DNA inside a membrane-bound compartment in the cell is considered to be important feature of eukaryoti. Waandishi wamependekeza jina mbegu kwa organelle hii ya seli ya bakteria iliyo na nyenzo za urithi. Pia, T. magnifica onyesha kiwango cha juu cha polyploidy na jenomu kubwa. Kwa kawaida, prokariyoti hazina viungo vya ndani vilivyofunga utando ndani ya seli na zina kiasi kidogo cha nyenzo za kijeni. Pia hazionyeshi mzunguko wa maendeleo wa dimorphic ambao T. magnifica gani.
Prokariyoti (bakteria na archaea) kwa kawaida ni viumbe vidogo, vyenye seli moja. Hawana kiini kilichoelezwa vizuri na organelles nyingine katika seli. Wana muundo rahisi. Kama inavyoonekana kutokana na vipengele vilivyotajwa hapo juu, T. magnifica seems to have evolved to acquire high level of complexity becoming of a eukaryotiki cell. This seems to challenge the traditional idea of prokaryote.
***
Marejeo:
- Volland JM, et al 2022. Bakteria ya urefu wa sentimita yenye DNA iliyo katika viungo vilivyo na utando amilifu amilifu. SAYANSI. Ilichapishwa tarehe 23 Juni 2022. Vol 376, Toleo la 6600 uk. 1453-1458. DOI: https://doi.org/10.1126/science.abb3634 (Chapisha awali katika bioRxiv. Bakteria ya urefu wa sentimita na DNA iliyounganishwa katika viungo vinavyofungamana na utando. Ilichapishwa Februari 18, 2022. DOI: https://doi.org/10.1101/2022.02.16.480423)
- Berkeley Lab 2022. Bakteria Kubwa Imepatikana katika Mikoko ya Guadeloupe Changamoto Dhana za Jadi. Taarifa ya Habari Mahusiano ya Vyombo vya Habari (510) 486-5183. Tarehe 23 Juni 2022. Inapatikana mtandaoni kwa https://newscenter.lbl.gov/2022/06/23/giant-bacteria-found-in-guadeloupe-mangroves-challenge-traditional-concepts/
***
(Shukrani: Prof K. Vasdev kwa mchango muhimu juu ya sifa za filojenetiki ya bakteria)
