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B E Rittmann

Publications and source records attributed to B E Rittmann.

36 records · Page 2Linked to original sources
PubMed1999

Diversity of sulfate-reducing bacteria in oxic and anoxic regions of a microbial mat characterized by comparative analysis of dissimilatory sulfite reductase genes.

Sequence analysis of genes encoding dissimilatory sulfite reductase (DSR) was used to identify sulfate-reducing bacteria in a hypersaline microbial mat and to evaluate their distribution in relation to levels of oxygen. The most highly diverse DSR sequences, most related to those of the Desulfonema-like organisms within the delta-proteobacteria, were recovered from oxic regions of the mat. This observation extends those of previous studies by us and others associating Desulfonema-like organisms with oxic habitats.

Anaerobiosis↗
PubMed1999

Reductive dehalogenation and conversion of 2-chlorophenol to 3-chlorobenzoate in a methanogenic sediment community: implications for predicting the environmental fate of chlorinated pollutants.

Biotransformation of 2-chlorophenol by a methanogenic sediment community resulted in the transient accumulation of phenol and benzoate. 3-Chlorobenzoate was a more persistent product of 2-chlorophenol metabolism. The anaerobic biotransformation of phenol to benzoate presumably occurred via para-carboxylation and dehydroxylation reactions, which may also explain the observed conversion of 2-chlorophenol to 3-chlorobenzoate.

Anaerobiosis↗
PubMed1997

Oligonucleotide microchips as genosensors for determinative and environmental studies in microbiology.

The utility of parallel hybridization of environmental nucleic acids to many oligonucleotides immobilized in a matrix of polyacrylamide gel pads on a glass slide (oligonucleotide microchip) was evaluated. Oligonucleotides complementary to small-subunit rRNA sequences of selected microbial groups, encompassing key genera of nitrifying bacteria, were shown to selectively retain labeled target nucleic acid derived from either DNA or RNA forms of the target sequences. The utility of varying the probe concentration to normalize hybridization signals and the use of multicolor detection for simultaneous quantitation of multiple probe-target populations were demonstrated.

Bacteria↗
PubMed1996

Critical evaluation of membrane supports for use in quantitative hybridizations.

The quantification of 16S rRNA by oligonucleotide probe hybridization was investigated with MagnaGraph (Micron Separation, Inc. [MSI]), Magna Charge (MSI), Magna (MSI), Immobilon-N (Millipore Corporation), and Nytran (Schleicher & Schuell, Inc.) membranes as supports for nucleic acid immobilization. The levels of detectability provided by the Magna Charge and Immobilon-N membranes were 20 to 50 times better than those obtained with the MagnaGraph, Magna, and Nytran membranes. The variability of the signal response for individual membranes ranged from 10 to 50%, with the Magna Charge and Immobilon-N membranes demonstrating the lowest variability.

Journal Article↗
PubMed1996

Competition and coexistence of sulfate-reducing and methanogenic populations in anaerobic biofilms.

The microbial population structure and function of natural anaerobic communities maintained in laboratory fixed-bed biofilm reactors were tracked before and after a major perturbation, which involved the addition of sulfate to the influent of a reactor that had previously been fed only glucose (methanogenic), while sulfate was withheld from a reactor that had been fed both glucose and sulfate (sulfidogenic). The population structure, determined by using phylogenetically based oligonucleotide probes for methanogens and sulfate-reducing bacteria, was linked to the functional performance of the biofilm reactors. Before the perturbation, the methanogenic reactor contained up to 25% methanogens as well as 15% sulfate-reducing bacteria, even though sulfate was not present in the influent of this reactor. Methanobacteriales and Desulfovibrio spp. were the most abundant methanogens and sulfate-reducing bacteria, respectively. The presence of sulfate-reducing bacteria (primarily Desulfovibrio spp. and Desulfobacterium spp.) in the absence of sulfate may be explained by their ability to function as proton-reducing acetogens and/or fermenters. Sulfate reduction began immediately following the addition of sulfate consistent with the presence of significant levels of sulfate-reducing bacteria in the methanogenic reactor, and levels of sulfate-reducing bacteria increased to a new steady-state level of 30 to 40%; coincidentally, effluent acetate concentrations decreased. Notably, some sulfate-reducing bacteria (Desulfococcus/Desulfosarcina/Desulfobotulus group) were more competitive without sulfate. Methane production decreased immediately following the addition of sulfate; this was later followed by a decrease in the relative concentration of methanogens, which reached a new steady-state level of approximately 8%. The changeover to sulfate-free medium in the sulfidogenic reactor did not cause a rapid shift to methanogenesis. Methane production and a substantial increase in the levels of methanogens were observed only after approximately 50 days following the perturbation.

Journal Article↗
PubMed1996

Phylogenetic probes for analyzing abundance and spatial organization of nitrifying bacteria.

A hierarchical set of five 16S rRNA-targeted oligonucleotide DNA probes for phylogenetically defined groups of autotrophic ammonia- and nitrite-oxidizing bacteria was developed for environmental and determinative studies. Hybridization conditions were established for each probe by using temperature dissociation profiles of target and closely related nontarget organisms to document specificity. Environmental application was demonstrated by quantitative slot blot hybridization and whole-cell hybridization of nitrifying activated sludge and biofilm samples. Results obtained with both techniques suggested the occurrence of novel populations of ammonia oxidizers. In situ hybridization experiments revealed that Nitrobacter and Nitrosomonas species occurred in clusters and frequently were in contact with each other within sludge flocs.

Ammonia↗
PubMed1995

Quantification of the effect of substrate concentration on the conjugal transfer rate of the TOL plasmid in short-term batch mating experiments.

Batch mating experiments with Pseudomonas putida PAW 1 (TOL) as a donor and Pseudomonas aeruginosa PAO 1162 as a recipient strain were performed to quantify the effect of the substrate concentration in the mating medium on the observed plasmid transfer rate coefficient. The impact of the substrate concentration in the mating medium was highly correlated with the growth history of the donor strain. When the donor strain was harvested in exponential growth phase, no impact was observed; when the donor strain was taken from the stationary phase, however, a strong impact of the substrate concentration was measured: a 10-fold reduction in the substrate concentration decreased the observed plasmid transfer rate by 55%.

Conjugation, Genetic↗
PubMed1995

Plasmid transfer for enhancing degradation capabilities.

The kinetics of plasmid conjugation for the TOL and RP4 plasmids depend strongly on the donor cells' specific growth rate and substrate concentration, both of which determine the cells' energy availability. Although transfer rates can be large when energy availability is high, normal biological processes have low energy availability. Therefore, we propose and evaluate preliminarily a simple scheme to create a small zone of high energy availability.

Bacteria↗
PubMed1994

Group-specific 16S rRNA hybridization probes to describe natural communities of methanogens.

Eight oligonucleotides which are complementary to conserved tracts of 16S rRNA from phylogenetically defined groups of methanogens were designed and characterized for use as hybridization probes for studies in environmental and determinative microbiology. The target-group specificity and temperature of dissociation for each probe were characterized. In general, the probes were very specific for the target methanogens and did not hybridize to the rRNAs of nontarget methanogens. Together, the eight probes circumscribe methanogens now represented in pure culture (with the exception of members of the family Methanothermaceae). Three probes are order specific; two identify members of the order Methanobacteriales, and one is specific for the order Methanococcales. The fourth probe encompasses three families belonging to the order Methanomicrobiales, the third order within the current classification. The fifth probe is specific for the remaining family within this order (Methanosarcinaceae). Three additional probes encompass different genera within the Methanosarcinaceae.

Ecology↗
PubMed1994

Quantification of methanogenic groups in anaerobic biological reactors by oligonucleotide probe hybridization.

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 fluorescent-dye-labeled probes to the 16S rRNAs from samples taken from laboratory acetate-fed chemostats, laboratory municipal solid waste digestors, and full-scale sewage sludge digestors. Methanosarcina species, members of the order Methanobacteriales, and Methanosaeta species were the most abundant methanogens present in the chemostats, the solid-waste digestors, and the sewage sludge digestors, respectively.

Anaerobiosis↗
PubMed1994

Evolutionary relationships among ammonia- and nitrite-oxidizing bacteria.

Comparative 16S rRNA sequencing was used to evaluate phylogenetic relationships among selected strains of ammonia- and nitrite-oxidizing bacteria. All characterized strains were shown to be affiliated with the proteobacteria. The study extended recent 16S rRNA-based studies of phylogenetic diversity among nitrifiers by the comparison of eight strains of the genus Nitrobacter and representatives of the genera Nitrospira and Nitrospina. The later genera were shown to be affiliated with the delta subdivision of the proteobacteria but did not share a specific relationship to each other or to other members of the delta subdivision. All characterized Nitrobacter strains constituted a closely related assemblage within the alpha subdivision of the proteobacteria. As previously observed, all ammonia-oxidizing genera except Nitrosococcus oceanus constitute a monophyletic assemblage within the beta subdivision of the proteobacteria. Errors in the 16S rRNA sequences for two strains previously deposited in the databases by other investigators (Nitrosolobus multiformis C-71 and Nitrospira briensis C-128) were corrected. Consideration of physiology and phylogenetic distribution suggested that nitrite-oxidizing bacteria of the alpha and gamma subdivisions are derived from immediate photosynthetic ancestry. Each nitrifier retains the general structural features of the specific ancestor's photosynthetic membrane complex. Thus, the nitrifiers, as a group, apparently are not derived from an ancestral nitrifying phenotype.

Ammonia↗
PubMed1993

Biodegradation kinetics of a mixture containing a primary substrate (phenol) and an inhibitory co-metabolite (4-chlorophenol).

Batch experiments on the simultaneous utilization of phenol (primary substrate) and 4-chlorophenol (cometabolic secondary substrate) demonstrated two critical substrate interactions. First, the cometabolic degradation of 4-chlorophenol was proportional to the rate of phenol oxidation, which provided the electrons for the initial monooxygenase reaction. Second, 4-chlorophenol inhibited the oxidation of the primary substrate, phenol. Modeling analyses of the degradation of phenol alone and of phenol and 4-chlorophenol together showed that the proportionality between phenol and 4-chlorophenol degradation rates averaged 0.1 mg 4-CP/mg phenol, which corresponds to 0.5% of the electrons generated by phenol oxidation being used as a cosubstrate for the monooxygenase reaction of 4-chlorophenol. In addition, modeling analyses suggest that 4-chlorophenol was a noncompetitive inhibitor of phenol oxidation for high phenol concentrations, but a competitive inhibitor for low phenol concentrations.

Biotechnology↗
PubMed1993

The specific growth rate of Pseudomonas putida PAW1 influences the conjugal transfer rate of the TOL plasmid.

The kinetics of the conjugal transfer of a TOL plasmid were investigated by using Pseudomonas putida PAW1 as the donor strain and P. aeruginosa PAO 1162 as the recipient strain. Short-term batch mating experiments were performed in a nonselective medium, while the evolution of the different cell types was determined by selective plating techniques. The experimental data were analyzed by using a mass action model that describes plasmid transfer kinetics. This method allowed analysis of the mating experiments by a single intrinsic kinetic parameter for conjugal plasmid transfer. Further results indicated that the specific growth rate of the donor strain antecedent to the mating experiment had a strong impact on the measured intrinsic plasmid transfer rate coefficient, which ranged from 1 x 10(-14) to 5 x 10(-13) ml per cell per min. Preliminary analysis suggested that the transfer rates of the TOL plasmid are large enough to maintain the TOL plasmid in a dense microbial community without selective pressures.

Conjugation, Genetic↗
PubMed1984

Needs and strategies for genetic control: municipal wastes.

Municipal wastewater, sludge, and refuse constitute major material flows and area of public concern. Substantial lists of desired improvements in the biological treatment of each waste can be formulated. Many improvements can be brought about by better application of biological and process fundamentals; widespread application of good process control and existing microorganisms is still not a reality. Nevertheless, several improvements seem amenable to genetic control techniques. Whether the genetic control technique involves selection of a novel microorganism or genetic manipulation of conventional or novel microorganisms, two key requirements stand out. First, we must recognize the physiological factor that provides the desired function. Second, we must recombine the genes for the desired function into a microorganism that can thrive in a treatment process. For environmental applications, identifying the physiological effect and an appropriate microorganism are the most critical steps. However, they are probably the least well developed, as biochemists and genetic engineers have concentrated mainly on isolating, recombining, and expressing relatively well known genes into convenient laboratory strains. Because of the many different steps associated with applications of genetic control to municipal-waste treatment, the successful application requires coordination of biochemistry, microbiology, and process engineering. No one discipline has all the requisite tools and insight to do the whole job.

Bacterial Physiological Phenomena↗
PubMedDate not supplied

Biological fate of a polydisperse acrylate polymer in anaerobic sand-medium transport.

Soluble polyacrylate (PA), a polydisperse mixture of polyacrylate polymers, is strongly adsorbed and biodegradable. Biotic fate studies were carried out with once-through columns containing sand colonized with anaerobic biomass previously grown in a methanogenic fluidized bed. A fraction of soluble PA having a weight-average molecular weight of 16,700 and a range of molecular weight from 10(3) to 10(5) was biologically removed and mineralized to CO2. Due to its polydisperse nature, the breakthrough curve had a gradual increase to an apparent steady-state removal of approximately 60% near one day when the liquid detention time was 21 minutes. Modeling successfully explained the observed breakthrough result when the fraction was divided into components having a wide range of retardation factors (R): about 25% was strongly adsorbed (R = 200 and 500), 45% was moderately adsorbed (R = 50 and 100), and 30% was weakly adsorbed (R = 1-10). In this study, in which active biomass already was present from utilization of a primary substrate (glucose here), equilibrium adsorption increased the time to breakthrough, which also reduced the exiting concentration by increasing the substrate contact time.

Acrylic Resins↗
PubMedDate not supplied

Biodegradation and sorption properties of polydisperse acrylate polymers.

Polyacrylate (PA), which is widely used in disposable diapers, is synthesized by polymerization and cross-linking of acrylate. During the synthesis, 3-6% of the polyacrylate polymers is not incorporated into the absorbent material, but remains soluble. If the soluble PA is mobilized from a landfill, it could enter the groundwater. Therefore, the biodegradation and adsorption properties of soluble polymers contained in PA are determined in this study. The soluble PA is highly polydisperse, and the fraction tested has a weight-average molecular-weight of 16,700 and a range extending from 10(3) to 10(5). Sand-column tracer tests show that about 1% of the polyacrylate is unadsorbed, but the remainder has a retardation factor that averages at least 58. Biodegradation kinetics are determined in completely mixed biofilm reactors having a methanogenic consortium grown on glucose. The polyacrylate fraction, as well as glucose and acrylate, are removed and mineralized to CO2. The Monod parameters for the polyacrylate are: maximum specific rate of substrate utilization = 0.0016 gC/g biomass-day, and half-maximum-rate concentration = 0.79 gC/m3. Although these kinetics are much slower than for glucose and acrylate, significant degradation and mineralization are observed.

Acrylic Resins↗