Papers by Timothy Hovanec
Applied and Environmental Microbiology, 1998
Oxidation of nitrite to nitrate in aquaria is typically attributed to bacteria belonging to the g... more Oxidation of nitrite to nitrate in aquaria is typically attributed to bacteria belonging to the genus Nitrobacter which are members of the ␣ subdivision of the class Proteobacteria. In order to identify bacteria responsible for nitrite oxidation in aquaria, clone libraries of rRNA genes were developed from biofilms of several freshwater aquaria. Analysis of the rDNA libraries, along with results from denaturing gradient gel electrophoresis (DGGE) on frequently sampled biofilms, indicated the presence of putative nitrite-oxidizing bacteria closely related to other members of the genus Nitrospira. Nucleic acid hybridization experiments with rRNA from biofilms of freshwater aquaria demonstrated that Nitrospira-like rRNA comprised nearly 5% of the rRNA extracted from the biofilms during the establishment of nitrification. Nitrite-oxidizing bacteria belonging to the ␣ subdivision of the class Proteobacteria (e.g., Nitrobacter spp.) were not detected in these samples. Aquaria which received a commercial preparation containing Nitrobacter species did not show evidence of Nitrobacter growth and development but did develop substantial populations of Nitrospira-like species. Time series analysis of rDNA phylotypes on aquaria biofilms by DGGE, combined with nitrite and nitrate analysis, showed a correspondence between the appearance of Nitrospira-like bacterial ribosomal DNA and the initiation of nitrite oxidation. In total, the data suggest that Nitrobacter winogradskyi and close relatives were not the dominant nitrite-oxidizing bacteria in freshwater aquaria. Instead, nitrite oxidation in freshwater aquaria appeared to be mediated by bacteria closely related to Nitrospira moscoviensis and Nitrospira marina.
La presente invention porte sur une souche bacterienne isolee capable d'oxyder le nitrite en ... more La presente invention porte sur une souche bacterienne isolee capable d'oxyder le nitrite en nitrate, et sur son procede d'utilisation visant a prevenir ou attenuer l'accumulation de nitrite dans un milieu aqueux.
Journal of the World Mariculture Society, 2009
Applied and Environmental Microbiology, 2001
Culture enrichments and culture-independent molecular methods were employed to identify and confi... more Culture enrichments and culture-independent molecular methods were employed to identify and confirm the presence of novel ammonia-oxidizing bacteria (AOB) in nitrifying freshwater aquaria. Reactors were seeded with biomass from freshwater nitrifying systems and enriched for AOB under various conditions of ammonia concentration. Surveys of cloned rRNA genes from the enrichments revealed four major strains of AOB which were phylogenetically related to theNitrosomonas marina cluster, theNitrosospira cluster, or the Nitrosomonas europaea-Nitrosococcus mobilis cluster of the β subdivision of the class Proteobacteria. Ammonia concentration in the reactors determined which AOB strain dominated in an enrichment. Oligonucleotide probes and PCR primer sets specific for the four AOB strains were developed and used to confirm the presence of the AOB strains in the enrichments. Enrichments of the AOB strains were added to newly established aquaria to determine their ability to accelerate the est...
Oxidation of nitrite to nitrate in aquaria is typically attributed to bacteria belonging to the g... more Oxidation of nitrite to nitrate in aquaria is typically attributed to bacteria belonging to the genus Nitrobacter which are members of the a subdivision of the class Proteobacteria. In order to identify bacteria responsible for nitrite oxidation in aquaria, clone libraries of rRNA genes were developed from biofilms of several freshwater aquaria. Analysis of the rDNA libraries, along with results from denaturing gradient gel electrophoresis (DGGE) on frequently sampled biofilms, indicated the presence of putative nitrite-oxidizing bacteria closely related to other members of the genus Nitrospira. Nucleic acid hybridization experiments with rRNA from biofilms of freshwater aquaria demonstrated that Nitrospira-like rRNA comprised nearly 5 % of the rRNA extracted from the biofilms during the establishment of nitrification. Nitrite-oxidizing bacteria belonging to the a subdivision of the class Proteobacteria (e.g., Nitrobacter spp.) were not detected in these samples. Aquaria which recei...
These include: This article cites 14 articles, 10 of which can be accessed free at:
aquaria.associated with freshwater and marine Comparative analysis of nitrifying bacteria
Transactions of the Western Section of the Wildlife Society, 1983
The striped bass, Mopone 8axatili8, x white bass, Mopone ChrySOp8, hybrid was first created in 19... more The striped bass, Mopone 8axatili8, x white bass, Mopone ChrySOp8, hybrid was first created in 1965 as an effort to develop a fish with the desirable qualities of a striped bass, but with the added ability to reproduce and sustain its populations in inland lakes and reser voirs. While not successful in the latter respect, the hybrid striped bass has surpassed its other expectations, exhibiting several improvements over its parental species. Anglers are enthusiastic about its recreational value while fishery managers have stocked it to provide controlled management of forage species such as threadfin shad. Recently the, hybrid has been examined as a candidate for commercial aquaculture, and studies have shown excellent survival, growth, and production capabilities in several different culture environments.
Introduction Chemical elements in seawater are commonly grouped into three general categories: ma... more Introduction Chemical elements in seawater are commonly grouped into three general categories: major, minor and trace. Pilson (1998) defines the major elements, of which there are eleven, as those that occur in concentrations greater than 1 ppm (1 mg/kg), admittedly an arbitrary value (Table 1). The distinction between minor and trace elements is even more arbitrary and different authors will use different concentrations for the dividing line. Morel and Price (2003) define trace as <0.1 μM while Kennish (1994) states that the average concentration of 22 trace elements ranged between 0.05 and 50 μmol/kg.Table 2 lists some common trace elements, their mean concentration in the ocean. An important difference between major and minor or trace elements is that higher concentrations for many minor or trace elements may be toxic to much life in the ocean at various trophic levels and/or life stages. This can be especially important when maintaining aquatic life in closed aquatic systems ...
Attached are two articles I have written regarding my research on nitrification and the nitrif~~g... more Attached are two articles I have written regarding my research on nitrification and the nitrif~~g bacteria in culture systems. One is a summary of two papers I have published on the phylogenetics of nit~kg bacteria, The . original papers are copyrighted by the American Society for Mcrobiology but can be freely accessed at their web site www.asm.org! under Journals and. using the search term "Hovanec".
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Papers by Timothy Hovanec