Daniel R. Noguera

Learn More
DECIPHER is a new method for finding 16S rRNA chimeric sequences by the use of a search-based approach. The method is based upon detecting short fragments that are uncommon in the phylogenetic group where a query sequence is classified but frequently found in another phylogenetic group. The algorithm was calibrated for full sequences (fs_DECIPHER) and short(More)
The microbial community structure of anaerobic biological reactors was evaluated by using oligonucleotide probes complementary to conserved tracts of the 16S rRNAs of phylogenetically defined groups of methanogens. Phylogenetically defined groups of methanogens were quantified and visualized, respectively, by hybridization of 32P- and(More)
The effect of dissolved oxygen (DO) on the communities of ammonia-oxidizing bacteria (AOB) in activated sludge was evaluated in lab-scale and full-scale reactors using the amoA gene as the basis for phylogenetic comparisons. Under controlled laboratory conditions, two chemostats seeded with activated sludge from the same source were operated with high-DO(More)
The enzymatic transformation of 2,4,6-trinitrotoluene (TNT) by purified XenB, an NADPH-dependent flavoprotein oxidoreductase from Pseudomonas fluorescens I-C, was evaluated by using natural abundance and [U-(14)C]TNT preparations. XenB catalyzed the reduction of TNT either by hydride addition to the aromatic ring or by nitro group reduction, with the(More)
Nitrification in drinking water distribution systems is a common operational problem for many utilities that use chloramines for secondary disinfection. The diversity of ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) in the distribution systems of a pilot-scale chloraminated drinking water treatment system was characterized using(More)
The participation of organisms related to Rhodocyclus in full-scale enhanced biological phosphorus removal (EBPR) was investigated. By using fluorescent in situ hybridization techniques, the communities of Rhodocyclus-related organisms in two full-scale wastewater treatment plants were estimated to represent between 13 and 18% of the total bacterial(More)
Chemolithoautotrophic nitrite oxidizers of the genus Nitrospira are a monophyletic but diverse group of organisms, are widely distributed in many natural habitats, and play a key role in nitrogen elimination during biological wastewater treatment. Phylogenetic analyses of cloned 16S rRNA genes and fluorescence in situ hybridization with newly developed(More)
Aerated-anoxic processes operate under the principle that small additions of oxygen to an anoxic reactor induce simultaneous nitrification and denitrification. In these systems, ammonia oxidation in the anoxic zone can easily account for 30-50% of the total nitrification in the reactor, even though the dissolve oxygen concentration is usually below(More)
The objective of this research was to assess the relevance of organisms related to Rhodocyclus in enhanced biological phosphorus removal in full-scale wastewater treatment plants. The presence of these organisms in full-scale plants was first confirmed by fluorescent in situ hybridization. To address which organisms were involved in phosphorus removal, a(More)
AIMS To obtain ammonia-oxidizing bacterial (AOB) strains inhabiting low dissolved oxygen (DO) environments and to characterize them to better understand their function and ecology. METHODS AND RESULTS Using a serial dilution method, two AOB strains (ML1 and NL7) were isolated from chemostat reactors operated with low DO concentrations (0.12-0.24 mg(More)