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Geomicrobiology of caves.

Northup, Diana Eleanor.

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Geomicrobiology of caves.

紀錄類型:	書目-語言資料,印刷品 : Monograph/item
正題名/作者:	Geomicrobiology of caves./
作者:	Northup, Diana Eleanor.
面頁冊數:	144 p.
附註:	Director: Clifford N. Dahm.
Contained By:	Dissertation Abstracts International63-06B.
標題:	Biogeochemistry. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3056911
ISBN:	0493720626

Geomicrobiology of caves.
Northup, Diana Eleanor.

Geomicrobiology of caves. - 144 p.

Director: Clifford N. Dahm.

Thesis (Ph.D.)--The University of New Mexico, 2002.

Caves in the Guadalupe Mountains of New Mexico contain several secondary mineral deposits (speleothems) that may be biogenic, including moonmilk, pool precipitates, and low-density ferromanganese deposits termed “corrosion residues.” Following a review of the literature on geomicrobiological investigations in caves, I present the results of studies on the corrosion residues in Lechuguilla and Spider Caves, which contain an abundance of corrosion residues that may be formed in part by microbial processes. To assess this possibility and to investigate the structure of the microbial community in these materials, we carried out scanning electron microscopy (SEM), metabolic activity studies, chemical analyses, and a culture-independent, small subunit ribosomal RNA (SSU rRNA) sequence-based study. SEM studies revealed the presence of a variety of morphologies of iron and manganese oxides and cocci, filaments, segmented ribbon-like filaments with protrusions, and “beads-on-a-string” cell morphologies. Incubation of samples with a redox dye confirmed that numerous metabolically active cells are present in the corrosion residues and in the underlying punk rock layer. For the small subunit ribosomal RNA study, DNA was extracted from two sites approximately 300 m and 228 m below the surface and 16S rRNA genes were amplified by PCR, cloned, and sequenced. To expand our knowledge of possible manganese- and iron-oxidizing bacteria, additional 16S rRNA gene studies were carried out on manganese and iron enrichment cultures inoculated with corrosion residues. An analysis of the resultant clones revealed that the dominant clone-types in one site originated from mesophilic Archaea in both the Crenarchaeota and Euryarchaeota. The second site was dominated almost entirely by lactobacilli. Other clone sequences were most closely related to those of nitrite-oxidizing bacteria, nitrogen-fixing bacteria, actinomycetes, γ-Proteobacteria, and iron- and manganese-oxidizing bacteria. Sequence analysis of enrichment culture clones showed the presence of putative iron- and manganese-oxidizing bacteria, further supporting the presence of these microbes in corrosion residues. Evidence from microscopy studies, enrichment cultures, and community DNA provides support for our hypothesis that microorganisms contribute to the dissolution of limestone walls and the formation of manganese and iron oxide-rich corrosion residues. A rich and diverse microbial community in these unusual secondary mineral formations was revealed.

ISBN: 0493720626Subjects--Topical Terms:

545717
Biogeochemistry.

Geomicrobiology of caves.
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502 $a Thesis (Ph.D.)--The University of New Mexico, 2002.
520 $a Caves in the Guadalupe Mountains of New Mexico contain several secondary mineral deposits (speleothems) that may be biogenic, including moonmilk, pool precipitates, and low-density ferromanganese deposits termed “corrosion residues.” Following a review of the literature on geomicrobiological investigations in caves, I present the results of studies on the corrosion residues in Lechuguilla and Spider Caves, which contain an abundance of corrosion residues that may be formed in part by microbial processes. To assess this possibility and to investigate the structure of the microbial community in these materials, we carried out scanning electron microscopy (SEM), metabolic activity studies, chemical analyses, and a culture-independent, small subunit ribosomal RNA (SSU rRNA) sequence-based study. SEM studies revealed the presence of a variety of morphologies of iron and manganese oxides and cocci, filaments, segmented ribbon-like filaments with protrusions, and “beads-on-a-string” cell morphologies. Incubation of samples with a redox dye confirmed that numerous metabolically active cells are present in the corrosion residues and in the underlying punk rock layer. For the small subunit ribosomal RNA study, DNA was extracted from two sites approximately 300 m and 228 m below the surface and 16S rRNA genes were amplified by PCR, cloned, and sequenced. To expand our knowledge of possible manganese- and iron-oxidizing bacteria, additional 16S rRNA gene studies were carried out on manganese and iron enrichment cultures inoculated with corrosion residues. An analysis of the resultant clones revealed that the dominant clone-types in one site originated from mesophilic Archaea in both the Crenarchaeota and Euryarchaeota. The second site was dominated almost entirely by lactobacilli. Other clone sequences were most closely related to those of nitrite-oxidizing bacteria, nitrogen-fixing bacteria, actinomycetes, γ-Proteobacteria, and iron- and manganese-oxidizing bacteria. Sequence analysis of enrichment culture clones showed the presence of putative iron- and manganese-oxidizing bacteria, further supporting the presence of these microbes in corrosion residues. Evidence from microscopy studies, enrichment cultures, and community DNA provides support for our hypothesis that microorganisms contribute to the dissolution of limestone walls and the formation of manganese and iron oxide-rich corrosion residues. A rich and diverse microbial community in these unusual secondary mineral formations was revealed.
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