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Biomedical subjects

A Konopka

Publications and source records attributed to A Konopka.

At least 19 recordsLinked to original sources
PubMed2002

Functional and structural adaptations of bacterial communities growing on particulate substrates under stringent nutrient limitation.

Biomass recycle reactors (BRRs) were used as a model system to study the functional and structural adaptations of mixed bacterial communities in response to the imposition of increasingly severe nutrient limitation. BRRs were fed synthetic media containing either spinach homogenate or autoclaved yeast cells to simulate the complex mixtures of particulate carbon sources that are often present in nature. In the BRRs fed spinach homogenate, the biomass (measured as particulate protein) exhibited a physiological response similar to previous studies as detected by 40-80% reductions in respiratory potential and by relatively stable catabolic ectoenzyme activities. Concomitant adaptations in bacterial community structure were detected by PCR-DGGE and RT-PCR-DGGE of 16S rDNA and 16S rRNA fragments, respectively. The microbial community structure was dynamic even after the biomass had reached a quasi-steady state with respect to physiological measurements. In the BRRs fed yeast cells, respiratory potentials increased 2- to 5-fold during the initial portion of the BRR run and alpha-glucosidase and beta-glucosidase activities increased 2- to 4-fold. Substantial bacterial community shifts were also detected in both the rDNA and rRNA profiles, indicating that this community was also structurally dynamic. These experiments suggest that phylogenetically different bacteria sustained the functional activities in these ecosystems in response to increasingly stringent nutrient limitation.

Bacteria↗
PubMed2002

Effect of starvation length upon microbial activity in a biomass recycle reactor.

The kinetics of substrate degradation and bacterial growth was determined in a microbial community from a biomass recycle reactor that had been deprived of substrate feed for 0-32 days. Starvation caused changes in bacterial numbers, community composition, and physiological state. Substrate starvation for less than 1 day resulted in modest (less than threefold) changes in endogenous respiration rate, ATP content, and biomass level. During a starvation period of 32 days, there were substantial changes in microbial community composition, as assessed by denaturing gradient gel electrophoresis (DGGE) fingerprinting of PCR amplicons of a portion of the 16S rDNA or by phospholipid fatty acid (PLFA) analysis. When the starved communities were stimulated with organic nutrients, the growth kinetics was a function of the length of the starvation period. For starvation periods of 2-8 days prior to nutrient addition, there was a phase of suboptimal exponential growth (S-phase) in which the exponential growth rate was about 30% of the ultimate unrestricted growth rate. S-phase lasted for 2-8 h and then unrestricted growth occurred at rates of 0.3-0.4 h(-1). At starvation times of 12 and 20 days, a lag phase preceded S-phase and the unrestricted growth phase.

Bacteria↗
PubMed2001

Thermophilic aerobic treatment of a synthetic wastewater in a membrane-coupled bioreactor.

Synthetic wastewater containing alpha-lactose and gelatin was treated in a thermophilic membrane-coupled bioreactor (MBR). Thermophilic (>45 degrees C) treatment represents a potentially advantageous process for high-temperature as well as high-strength industrial wastewaters susceptible to reactor autoheating. Thermophilic systems, however, generally support a nonflocculating biomass that resists conventional methods of cell separation from the treated wastewater. MBRs were applied to thermophilic treatment systems because bacterial cells can be retained regardless of cell aggregation. Thermophilic aerobic MBRs were successfully operated at high levels of biocatalyst and produced a better effluent quality than analogous thermophilic bioreactors without cell recycle. At a hydraulic residence time (HRT) of 13.1 h, the chemical oxygen demand (COD) of the membrane eluate improved from 760 mg l(-1) (without cell recycle) to 160 mg l(-1) (with cell recycle). Bacterial community shifts were detected by denaturing gradient gel electrophoresis (DGGE) of polymerase chain reaction (PCR) -amplified 16S rRNA gene fragments - 6 of 13 bands disappeared within 2 days of MBR operation. A concomitant 40-50% reduction in physiological indicators of cell reactivity (RNA:protein; ATP:protein) was also observed. The specific activity of beta-galactosidase and aminopeptidase, however, increased by 10-25%, indicating that there is a definite advantage to MBR operation at the highest biomass level possible. Nucleotide sequence analysis of 16S rDNA clones identified phylotypes from the low-G+C Gram-positive division and the beta- and gamma-subdivisions of Proteobacteria.

Aerobiosis↗
PubMed2000

Microbial physiological state at low growth rate in natural and engineered ecosystems.

Microbes often grow in nature and bioreactors at very low growth rates. However, the physiological consequences at low growth rates have not been explored as completely as at faster growth rates or under starvation conditions. Nutrient flux to (and through) the cell surface and non-growth-dependent energy consumption (maintenance) are important considerations under these conditions. The biomass recycle reactor is a system to explore physiological state at low growth rate, and to optimize certain industrial process rates.

Bacteria↗
PubMed1999

Bacterioplankton Community Diversity in a Series of Thermally Stratified Lakes.

> Abstract The dominant members of the bacterioplankton community in a set of 10 small, thermally stratified lakes in northeastern Indiana were determined by denaturing gradient gel electrophoresis (DGGE) of a polymerase chain reaction amplified fragment of 16S rDNA. The variability in community composition was analyzed as function of vertical stratification (epilimnion vs metalimnion), time (July vs August samples), and geographical location. In 58 discrete samples, a range of 8-23 bands were detected (mean = 14, s.d. = 4). For all variables, sample pairs shared about 40-70% of bands. In comparisons between depth strata, pairs of oxic samples shared more bands than an oxic-anoxic pair. There was no obvious relationship between the geographical location of lakes (or their physical connection) and band sharing.http://link.springer-ny.com/link/service/journals/00248/bibs/38n2p126.html

Journal Article↗
PubMed1999

Theoretical Analysis of the Starvation Response under Substrate Pulses.

A simulation model was constructed in which two model bacteria competed with each other in a closed system to which periodic substrate additions were made. One bacterium responded to starvation by entering into a dormant state characterized by a decreased death rate; the other bacterium did not make this transition. The periodicity of substrate addition was varied, and the magnitude of selection for one bacterial type was calculated. For model parameters typical of those measured in Escherichia coli, positive selection for the bacterium capable of the starvation response only occurred if the time interval of substrate addition exceeded 54 times the minimum doubling time of the bacterium. The magnitude of the selection coefficient was most sensitive to two model parameters: the time constant for conversion of dormant cells back to actively growing ones, and the magnitude of the death rate of cells which did not undergo the starvation response.

Journal Article↗
PubMed1999

Quantification of bacterial lead resistance via activity assays.

The level of microbial resistance to heavy metals is an important issue for the microbial ecology of heavy metal-contaminated habitats. However, assays based upon growth in nutrient media will overestimate the resistance level due to metal ion interactions with inorganic and organic components. The analysis of Pb-resistant bacteria isolated from soils containing up to 38 mmol total Pb x kg(-1) indicated that PYT80B medium which did not contain inorganic salts, contained low amounts of organic matter, and was buffered with a molecule that did not interact with metal ions (2-N-morpholinoethanesulfonic acid (MES)) provided the lowest estimates of lead resistance. However, better results were obtained by assaying metabolic activity (aerobic respiration) of resting cells suspended in 10 mM MES. By this criterion, 50% inhibition of Arthrobacter JS7 was found at 37 microM Pb(NO3)2. The effects of Pb+2 concentrations upon respiration of resting cells and growth rate in PYT80B medium were similar. The activity assay also showed that metal resistance was induced to higher levels when Arthrobacter JS7 was grown in the presence of Pb.

Arthrobacter↗
PubMed1999

Bacterial function and community structure in reactors treating biopolymers and surfactants at mesophilic and thermophilic temperatures.

Microbial communities capable of degrading biopolymers and surfactants typically found in graywater were selected in continuous-flow bioreactors operated at 30, 44, 53, or 62 degrees C. The effect of temperature upon microbial activity and community composition was determined. Microbial respiration of the organic components of the medium (including linear alkylbenzene sulfonate) was detected in samples from each reactor. The microbial community in each reactor was adapted to the operating temperature. Nucleic acid-based analyses of community composition showed that distinct consortia were present at each temperature. Community complexity was inversely related to temperature. The specific maintenance rate was twofold higher at 62 degrees C than at the lower temperatures. Under starvation conditions, microbes in the 62 degrees C system lost membrane integrity 30- to 100-fold faster than microbes at lower temperatures.

Journal Article↗
PubMed1999

Microbial biomass and activity in lead-contaminated soil

Microbial community diversity, potential microbial activity, and metal resistance were determined in three soils whose lead contents ranged from 0.00039 to 48 mmol of Pb kg of soil-1. Biomass levels were directly related to lead content. A molecular analysis of 16S rRNAs suggested that each soil contained a complex, diverse microbial community. A statistical analysis of the phospholipid fatty acids indicated that the community in the soil having the highest lead content was not related to the communities in the other soils. All of the soils contained active microbial populations that mineralized [14C]glucose. In all samples, 10 to 15% of the total culturable bacteria were Pb resistant and had MIC of Pb for growth of 100 to 150 &mgr;M.

Journal Article↗
PubMed1998

[A case of dilated cardiomyopathy caused by myocardial microinfarcts in the course of polycythemia vera].

This article presents a case of 45-year-old man with polycythemia vera non diagnosed before. The first symptom of polycythemia vera was acute congestive heart failure which suggested diagnosis of myocarditis. Polycythemia vera was confirmed by raised hematocrit, significantly increased platelet count, normal oxygen saturation, score for leukocyte alkaline phosphatase (LAP)-130 and splemomegaly. Echocardiography revealed left ventricular histological. Coronary arteriography showed normal coronary arteries. Finding of histological examination of the endomyocardial biopsy were described as necrosis of myocytes and abnormal blood flow in very small coronary vessels. It was the main reason of dilated cardiomyopathy caused by microinfarcts in polycythemia vera. Hematological parameters were reduced to normal levels after hydroxyurea treatment. Digitalis and ACE-inhibitor therapy quickly improved cardiovascular status from III to II NYHA class.

Biopsy↗
PubMed1997

Microbial biodegradation of organic wastes containing surfactants in a continuous-flow reactor.

In a continuous flow bioreactor seeded with microbes from municipal activated sludge, complete organic carbon oxidation of simulated graywater (wastewater produced in human residences, excluding toilet wastes) was achieved at dilution rates up to 0.36 h-1 in the presence of 64.1 microM linear alkylbenzenesulfonate (LAS) L-1. At LAS concentrations of 187 microM, the system functioned only at dilution rates up to 0.23 h-1, and the biomass yield was two-fold lower. There were physiological changes in the microbial communities under different operating conditions, as measured by specific contents of ATP and extracellular hydrolases as well as the respiratory potential of the biomass. LAS inhibited the activity of LAS-degrading microbes at >150 microM LAS, and the activity of other microbes at >75 microM LAS. Chemical analysis of graywater indicated that samples consisted primarily of biological polymers (proteins and polysaccharides) and lower concentrations of surfactants. Biological remediation of graywater is possible, although treatment efficiency is influenced by the operating conditions and wastestream composition.

Alkanesulfonates↗
PubMed1997

Feed intake, body weight, body condition score, musculation, and immunocompetence in aged mares given equine somatotropin.

Sixteen 20- to 26-yr-old mares were given 0, 6.25, or 12.5 mg/d equine somatotropin (eST) to determine whether aged mares respond to ST with changes in feed intake, body weight, body condition score (based mostly on fat cover), or immunocompetence. Neither dry matter intake, body weight, nor body condition scores were altered during the 6 wk of eST injection. However, based on photographs taken to evaluate musculation before and after treatment (scores 0 to 4), mares given eST developed greater (P < .07) muscle definition (1.8 +/- .6 and 2.5 +/- .6 for 6.25 and 12.5 mg eST/d, respectively) than control mares (.7 +/- .4). Total circulating leukocytes increased (P < .05) in both of the eST-treated groups during the 6-wk injection period, caused by an increase (P < .05) in granulocytes. Lymphocyte numbers were not altered. Granulocyte oxidative burst activity was not altered by eST treatment. Although lymphocyte proliferative responses to phytohemagglutinin, pokeweed mitogen, or lipopolysaccharide were not altered during the treatment period, lymphocyte proliferation in response to phytohemagglutinin and pokeweed mitogen increased twofold in eST-treated horses at 2 wk after eST treatment. In overview, the increased musculation and the increase in granulocyte numbers in mares given eST suggest that eST supplementation may improve the health and well-being of aged mares.

Aging↗
PubMed1996

Biodegradation of organic wastes containing surfactants in a biomass recycle reactor.

The microbial biodegradation of simulated graywater, containing 21.5 mg of linear alkylbenzene sulfonate liter-1, was investigated with a continuous-flow bioreactor with 100% biomass recycle. Low concentrations of organic matter in the ultrafiltration eluate were achieved by hydraulic residence times as short as 1.6 h and for periods of up to 74 days at a hydraulic residence time of 6 h. Upon a shift from the chemostat to the biomass recycle mode, the increase in biomass with time approximated a linear rather than an exponential function. Biomass densities as high as 6.8 g of cell protein liter-1 were reached; this was 50-fold higher than the steady-state biomass level in chemostats fed the same medium. We assessed physiological changes in the microbial community after a switch from the chemostat to the biomass recycle mode. Over 150 h, there was a two- to fourfold decrease in the respiratory potential of the microbes. After this decrease, respiratory potentials were relatively constant up to 74 days of operation. A decline in reactivity was also indicated by increasing lag periods before growth in response to organic nutrient inputs and by a decrease in the proportion of cells able to reduce tetrazolium dye. However, the bioreactor system was still capable of rapidly metabolizing inputs of organic matter, because of the very high biomass concentrations. It appears that < 10% of the organic carbon inputs accumulate as biomass.

Bacteria↗
PubMed1994

A structure-activity study with aryl acylamidases.

We examined the relationship between chemical structure and biodegradability of acylanilide herbicides by using a set of model compounds. Four bacterial isolates (one gram-negative and three gram-positive) that grew on acetanilide were used. These soil isolates cleaved the amide bond of acetanilide via an aryl acylamidase reaction, producing aniline and the organic acid acetate. A series of acetanilide analogs with alkyl substitutions on the nitrogen atom or the aromatic ring were tested for their ability to induce aryl acylamidase activity and act as substrates for the enzyme. The substrate range, in general, was limited to those analogs not disubstituted in the ortho position of the benzene ring or which did not contain an alkyl group on the nitrogen atom. These same N-substituted compounds did not induce enzyme activity either, whereas the ortho-substituted compounds could in some cases.

Journal Article↗
PubMed1991

Propachlor degradation by a soil bacterial community.

Soil from a pesticide disposal site was used to enrich for microorganisms that degraded the acylanilide herbicide propachlor (2-chloro-N-isopropylacetanilide). After seven transfers of the enrichment, the culture contained about six strains. The highest yield of microbial biomass occurred if just two of these isolates, strains DAK3 and MAB2, were inoculated into a mineral salts medium containing propachlor. When only strain DAK3 was grown on propachlor, a metabolite (2-chloro-N-isopropylacetamide) was released into the medium. Strain MAB2 could grow on this metabolite. The results of morphological and physiological tests suggest that strains DAK3 and MAB2 most closely resemble species belonging to the genera Moraxella and Xanthobacter, respectively. Strain DAK3 can respire and grow on N-substituted acylanilides containing methyl, ethyl, or isopropyl substitutions, but is incapable of respiration or growth on acetanilide, aniline, or the acylanilide herbicides alachlor and metolachlor. Strain DAK3 appears to use the aromatic C atoms of propachlor for growth, as suggested by the growth yield on propachlor and the induction of catechol 2,3-oxygenase activity in acylanilide-grown cells.

Acetamides↗
PubMed1991

Biodegradation of organic compounds in vadose zone and aquifer sediments.

The microbial processes that occur in the subsurface under a typical Midwest agricultural soil were studied. A 26-m bore was installed in November of 1988 at a site of the Purdue University Agronomy Research Center. Aseptic collections of soil materials were made at 17 different depths. Physical analysis indicated that the site contained up to 14 different strata. The site materials were primarily glacial tills with a high carbonate content. The N, P, and organic C contents of sediments tended to decrease with depth. Ambient water content was generally less than the water content, which corresponds to a -0.3-bar equivalent. No pesticides were detected in the samples, and degradation of added 14C-labeled pesticides (atrazine and metolachlor) was not detected in slurry incubations of up to 128 days. The sorption of atrazine and metolachlor was correlated with the clay content of the sediments. Microbial biomass (determined by direct microscopic count, viable count, and phospholipid assay) in the tills was lower than in either the surface materials or the aquifer located at 25 m. The biodegradation of glucose and phenol occurred rapidly and without a lag in samples from the aquifer capillary fringe, saturated zone, and surface soils. In contrast, lag periods and smaller biodegradation rates were found in the till samples. Subsurface sediments are rich in microbial numbers and activity. The most active strata appear to be transmissive layers in the saturated zone. This implies that the availability of water may limit activity in the profile.

Aniline Compounds↗
PubMed1991

[Indications for emergency cardiovascular surgery at the Institute of Cardiology].

Between 1981 and 1989 73 patients (46 males, 27 females aged 15-69; mean 42) underwent emergency cardiac operation in the I Clinic of Cardiosurgery. There were 39 (53%) patients with valvular disease, 18 (25%) with prosthetic valve dysfunction and endocarditis, 9 (12%) with acute aortic dissection (2 of them had Marfan's syndrome), 5 (7%) with atrial myxoma and 2 (3%) with malignant pericardial mesothelioma. All of them were treated in C.C.U. before surgery. 27 urgent operations were performed within the first 24 hours after the admission to C.C.U. 30 of 73 patients died (41%). The IV NYHA functional class was stated as the most significant predictive factor for in-hospital mortality. The greatest mortality was observed in the group of patients with valvular disease (53%). In hospital survival rate reached 50% after reoperations as a procedure of choice in prosthetic valve dysfunction. Good early results were observed in patients with aortic dissection (survival rate--66%). The presence of Marfan's syndrome was associated with a poor surgical prognosis. There were no deaths after atrial myxoma removal, but all patients with malignant mesothelioma died. The most common cause of all deaths was congestive heart failure.

Adolescent↗