Matthew W. Fields

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We employed culture-dependent and -independent techniques to study microbial diversity in Lake Chaka, a unique hypersaline lake (32.5% salinity) in northwest China. It is situated at 3,214 m above sea level in a dry climate. The average water depth is 2 to 3 cm. Halophilic isolates were obtained from the lake water, and halotolerant isolates were obtained(More)
Iron-reducing enrichments were obtained from leachate ponds at the U.S. Borax Company in Boron, Calif. Based on partial small-subunit (SSU) rRNA gene sequences (approximately 500 nucleotides), six isolates shared 98.9% nucleotide identity. As a representative, the isolate QYMF was selected for further analysis. QYMF could be grown with Fe(III)-citrate,(More)
There is potential for algal-derived biofuel to help alleviate part of the world’s dependency on petroleum based fuels. However, research must still be done on strain selection, induction of triacylglycerol (TAG) accumulation, and fundamental algal metabolic studies, along with large-scale culturing techniques, harvesting, and biofuel/biomass processing.(More)
BACKGROUND Phaeodactylum tricornutum is a unicellular diatom in the class Bacillariophyceae. The full genome has been sequenced (<30 Mb), and approximately 20 to 30% triacylglyceride (TAG) accumulation on a dry cell basis has been reported under different growth conditions. To elucidate P. tricornutum gene expression profiles during nutrient-deprivation and(More)
Criteria for the design of gene-specific and group-specific oligonucleotide probes were established experimentally via an oligonucleotide array that contained perfect match (PM) and mismatch probes (50-mers and 70-mers) based upon four genes. The effects of probe-target identity, continuous stretch, mismatch position, and hybridization free energy on(More)
Saline lakes at high altitudes represent an important and extreme microbial ecosystem, yet little is known about microbial diversity in such environments. The objective of this study was to examine the change of microbial diversity from the bottom of the lake to sediments of 40 cm in depth in a core from Qinghai Lake. The lake is saline (12.5 g/L salinity)(More)
This study evaluates changes in the microbial community structure and function of a pilot-scale denitrifying fluidized bed reactor during periods of constant operating conditions and periods of perturbation. The perturbations consisted of a shutdown period without feed, two disturbances in which biofilms were mechanically sheared from carrier particles, and(More)
A detailed physiological and molecular analysis of lipid accumulation under a suite of conditions including nitrogen limitation, alkaline pH stress, bicarbonate supplementation, and organic acid supplementation was performed on the marine diatom Phaeodactylum tricornutum. For all tested conditions, nitrogen limitation was a prerequisite for lipid(More)
Nitrate-contaminated groundwater samples were analysed for nirK and nirS gene diversity. The samples differed with respect to nitrate, uranium, heavy metals, organic carbon content, pH and dissolved oxygen levels. A total of 958 nirK and 1162 nirS clones were screened by restriction fragment length polymorphism (RFLP) analysis: 48 and 143 distinct nirK and(More)
Patterns of spatial positioning of individuals within microbial communities are often critical to community function. However, understanding patterning in natural communities is hampered by the multitude of cell-cell and cell-environment interactions as well as environmental variability. Here, through simulations and experiments on communities in defined(More)