Eylem Seç
Trace Metal Uptake and Use in Soil Diazotrophs and Marine Vibrios: Alternative Nitrogenases, Siderophores, and Quorum Sensing or Efforts of the Very Small to Acquire the Very Scarce
Başlık:
Trace Metal Uptake and Use in Soil Diazotrophs and Marine Vibrios: Alternative Nitrogenases, Siderophores, and Quorum Sensing or Efforts of the Very Small to Acquire the Very Scarce
Yazar:
McRose, Darcy, author.
ISBN:
9780438047594
Yazar Ek Girişi:
Fiziksel Tanımlama:
1 electronic resource (269 pages)
Genel Not:
Source: Dissertation Abstracts International, Volume: 79-10(E), Section: B.
Advisors: François M. M. Morel Committee members: Bonnie L. Bassler; Anne ML Kraepiel; Mohammad R. Seyedsayamdost; Bess B. Ward.
Özet:
The need for living things to obtain trace elements creates a fundamental interaction between Life and Earth. Iron (Fe), and a handful of other metals, are used ubiquitously in biochemistry, yet must be extracted from insoluble minerals. The major biogeochemical cycles occurring at the Earth's surface are also catalyzed by metalloenzymes. Trace elements therefore form one of the strongest links in the coupling of geologic and biologic processes and their use is key to understanding the co-evolution of Life and Earth. This thesis explores two microbial solutions to the problem of trace metal scarcity: the substitution of different trace elements in enzymes and the production of siderophores or small molecules that aid in trace metal uptake. I use high-throughput sequencing and newly developed isotopic techniques to determine that 'alternative' nitrogenases -- containing vanadium (V) or Fe-only instead of molybdenum (Mo) -- can make substantial (>20%) contributions to nitrogen fixation and nitrogenase diversity in coastal sediments, raising questions about their overall role in nitrogen cycling. My experiments with nitrogen-fixing Azotobacter vinelandii cultures show that the siderophore protochelin is co-regulated by limitation for both Fe and the nitrogenase cofactor Mo. Protochelin complexes Mo, and up-regulation under Mo-limitation is consistent with its long hypothesized role as a molybdophore. Additionally, I report that A. vinelandii can invest > 30% of fixed nitrogen in siderophores and that this nitrogen is isotopically distinct from biomass. Under conditions of iron-limitation siderophore production changes the isotopic composition (delta15N) of A. vinelandii biomass, a result that may help to explain variations in delta15 N from laboratory and field studies of diazotrophs. Finally, I investigate the regulation of siderophore production by Fe and quorum sensing (QS, a microbial counting technique that allows bacteria to tailor their gene expression to their cell density). I find that the marine bacterium Vibrio harveyi uses a single gene cluster to produce both strong, cell-bound siderophores as well as weak soluble siderophores and that QS allows V. harveyi to calibrate its siderophore production to its cellular iron uptake capacity. This final chapter highlights 'biotic' and 'abiotic' controls on siderophore production and the potential importance of microbial interactions in geobiological processes.
Notlar:
School code: 0181
Tüzel Kişi Ek Girişi:
Mevcut:*
Yer Numarası | Demirbaş Numarası | Shelf Location | Lokasyon / Statüsü / İade Tarihi |
---|---|---|---|
XX(680909.1) | 680909-1001 | Proquest E-Tez Koleksiyonu | Arıyor... |
On Order
Liste seç
Bunu varsayılan liste yap.
Öğeler başarıyla eklendi
Öğeler eklenirken hata oldu. Lütfen tekrar deneyiniz.
:
Select An Item
Data usage warning: You will receive one text message for each title you selected.
Standard text messaging rates apply.