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E L Schmidt

Publications and source records attributed to E L Schmidt.

At least 55 records · Page 3Linked to original sources
PubMed1976

Immunofluorescent polar tips of Rhizobium japonicum: possible site of attachment or lectin binding.

Rhizobium japonicum USDA 31 demonstrated marked polarity by binding homologous fluorescent antibody (FA) heavily on one end of the cell. FA prepared against R. japonicum strains 110 and 138, and against R. trifolii TA1 cross-reacted with strain 31 only in the polar tip region. No polar immunofluorescing tips could be seen with FA against two other strains of R. japonicum or with those against several unrelated microorganisms. Common antigens localized only in a polar region were seen in many rhizobia stained with R. japonicum 31 FA: 22 of 23 strains of R. japonicum, 10 of 17 strains of R. trifolii, 3 of 7 strains of R. melitolii, 3 of 6 strains of R. phaseoli, and 3 of 9 strains of R. leguminosarum had some cells with detectable polar tips. The proportion of R. japonicum 31 cells with polar tips was high throughout the growth cycle. Polar tip staining was not affected by drastic cell treatments. A function was proposed for the polar tip region as a site for attachment. R. japonicum 31 cells attached to each other in a tip-to-tip fashion and endwise to fungal hyphae with the polar tip in contact with the hyphal wall. Binding of fluorescein isothiocyanate-labeled soybean lectin to certain strains of R. japonicum gave additional evidence of polarity. Polar binding of both antibody and lectin may provide insights into relationships between rhizobia and roots of host legumes.

Antibodies, Bacterial↗
PubMed1975

Autoradiography and immunofluorescence combined for autecological study of single cell activity with Nitrobacter as a model system.

Specific detection of a particular bacterium by immunofluorescence was combined with estimation of its metabolic activity by autoradiography. The nitrifying bacteria Nitrobacter agilis and N. winogradskyi were used as a model system. Nitrobacter were incubated with NaH14CO3 and 14CO2 prior to study. The same preparations made for autoradiograms were stained with fluorescent antibodies specific for the Nitrobacter species. Examination by epifluorescence and transmitted dark-field microscopy revealed Nitrobacter cells with and without associated silver grains. Direct detection and simultaneous evaluation of metabolic activity of Nitrobacter was demonstrated in pure cultures, in a simple mixed culture, and in a natural soil.

Autoradiography↗
PubMed1974

Autecological study of the chemoautotroph Nitrobacter by immunofluorescence.

Fluorescent antibodies (FA) prepared for Nitrobacter agilis and N. winogradskyi were highly reactive in homologous staining. Low-level cross-reactions between the two species were removed by adsorption. All 15 pure-culture isolates of Nitrobacter tested reacted strongly with either N. agilis FA or N. winogradskyi FA. All pure-culture isolates from soils were determined to be N. winogradskyi; those from Mammoth Cave sediments and a cattle waste oxidation ditch were N. agilis. No cross-reaction was found in extensive tests that included five isolates of Nitrosomonas europaea and 668 heterotrophic aerobic and anaerobic bacteria isolated from soil, sewage, and cave sites. The FA preparations were used to detect Nitrobacter species in Mammoth Cave sediments, in a cattle waste oxidation ditch, and in surface waters and sediments of a river and to observe that N. winogradskyi can outgrow N. agilis in enrichment culture.

Aerobiosis↗
PubMed1971

Nitrification of aspartate by Aspergillus flavus.

Heterotrophic conversion of l-aspartic acid to nitrification products by Aspergillus flavus was studied in a replacement incubation system. Numerous amino acids supported nitrification; aspartate and glutamate were about equivalent as the best sources of nitrate. Addition of sodium bicarbonate to the incubation system substantially enhanced nitrate formation for all nitrifiable amino acids except aspartic acid, but the basis for the bicarbonate effect is obscure. The yield of nitrate from l-aspartate was not approached by forms of aspartic acid resulting from substitution on the beta carbon, the amino nitrogen, or the gamma carboxyl group or by aspartate presented as the d-configuration. There was no relationship between nitrate formation and the occurrence of such possible intermediates as nitrite, bound hydroxylamine, ammonia, aspergillic acid, and beta-nitropropionic acid. Uniformly labeled (14)C-l-aspartate that was nitrified in replacement incubation led to no accumulation of label in possible nitrification products in the culture filtrate. Label was found in components of the mycelium after acid hydrolysis, with heaviest accumulation in what appeared to be glucosamine and an unidentified compound, possibly acetylglucosamine. Detectable label was redistributed into serine, glycine, and threonine.

Amino Acids↗
PubMed1968

Fluorescent-antibody approach to study of rhizobia in soil.

Application of fluorescent-antibody (FA) techniques to the study of rhizobia as free-living soil bacteria was explored. Antiserum to a particular strain of Rhizobium japonicum proved specific in both agglutination and FA tests. Within the R. japonicum group, 2 of 12 strains were stained by the conjugate and these fluoresced brightly; all others were entirely negative. FA tests were negative for 7 strains of R. meliloti, 9 strains of R. leguminosarum, 9 strains of R. trifolii, 6 strains of R. phaseoli, and 65 unidentified bacteria isolated from 12 soils. R. japonicum grew in autoclaved soil and was readily detectable by FA examination of contact slides. The FA technique also detected antibody-reacting bacteria in a field soil whose rhizobial content was unknown. Fluorescent cells were probably R. japonicum, since nodules developed on soybean plants grown in the same soil sample and FA preparations of the crushed nodules proved positive. Autofluorescence was not a problem, but nonspecific adsorption of conjugate restricted observations to microscopic fields free from soil particles. Nonspecific adsorption was substantial, irrespective of the soil used.

Agglutination Tests↗
PubMed1967

Growth response of Nitrosomonas europaea to amino acids.

Growth responses of Nitrosomonas europaea to individual amino acids or vitamins was observed in log-phase cultures, as was the incorporation of carbon-14 labeled amino acids. Nitrite formation and protein synthesis were increased by l-glutamic acid, l-aspartic acid, l-serine, and l-glutamine. l-Lysine, l-histidine, l-threonine, l-valine, l-methionine, and l-arginine were inhibitory. The other amino acids had no effect on growth. All of the uniformly labeled amino acids added at low concentrations were taken up by growing cells and distributed into cell fractions. From 1 to 12% of the added radioactivity was present in cells analyzed in late log phase, depending on the amino acid; glycine and l-serine caused accumulation of the label to the greatest extent, whereas l-aspartic and l-glutamic acids were among those incorporated to the least extent. Aspartic acid increased both cell protein and nitrite values, but did not alter the ratio of protein to nitrite from that found in controls.

Amino Acids↗
PubMed1967

Uptake and utilization of amino acids by resting cells of Nitrosomonas europaea.

Incorporation of selected amino acids by resting cells was studied with regard to effects of concentration, rate and extent of incorporation, cellular distribution, effect of ammonium ion on uptake, and competitive effects. l-Aspartic acid, l-alanine, l-serine, and glycine presented at trace levels were incorporated at rates ranging from 0.11 to 8.2 mumumoles per mg (dry weight) per minute, and maximal incorporation was 11 to 333 mumumoles per mg (dry weight). When glycine and aspartic acid were supplied at substrate level, the rate of incorporation increased 14- and 109-fold, respectively. The presence of ammonium ion further increased both the rate and extent of uptake of glycine and aspartic acid. The distribution of cellular radioactivity arising from (14)C amino acids indicated that cell pool radioactivity was concentrated from 1.2- to 24.5-fold over the external medium. Aspartic acid pool radioactivity accounted for 50% or more of the total cellular radioactivity, whereas radioactivity in glycine and serine pools dropped from initially high levels to 20 to 25% during incubation. The decrease in pool radioactivity with both glycine and serine was accompanied by an increase in other fractions, especially in the cell residue. The growth-inhibiting amino acid l-valine, supplied at substrate level, contributed more carbon per milligram (dry weight) than any other amino acid studied. l-Leucine, in the presence of l-valine, was observed to decrease valine incorporation.

Amino Acids↗
PubMed1966

Effect of mixed culture on Nitrosomonas europaea simulated by uptake and utilization of pyruvate.

Clark, Connie (University of Minnesota, Minneapolis), and E. L. Schmidt. Effect of mixed culture on Nitrosomonas europaea simulated by uptake and utilization of pyruvate. J. Bacteriol. 91:367-373. 1966.-Contamination of a 5-liter culture of Nitrosomonas europaea resulted in enhanced nitrite formation as compared with pure cultures. The dominant contaminant, a yellow-pigmented, heterotrophic bacterium, was isolated and studied both in pure culture and in deliberate mixture with N. europaea. Growth of N. europaea was stimulated in mixed cultures with the heterotrophic isolate to varying degrees, apparently depending on the age and density of autotrophic inocula. Mixed culture stimulation of N. europaea was evidenced only by a shortened lag phase, since post-lag phase growth of the autotroph was equivalent in both pure and mixed cultures. The heterotrophic component had a nutritional requirement for amino acids when grown on simple media; presumably, in the mixed culture system, the heterotroph was provided with amino acids synthesized by the autotroph. The mixed culture effect was reproduced in all essential features by the addition of sodium pyruvate to the nitrification medium. Pure cultures of N. europaea were shown to incorporate sodium pyruvate-2-C(14) during growth. Labeled carbon was widely distributed in cell fractions. The more pronounced and consistent pyruvate effect was observed on old inocula of N. europaea.

Amino Acids↗
PubMed1965

Specificity of immunofluorescent staining for study of Aspergillus flavus in soil.

Fluorescein-labeled antiserum prepared with Aspergillus flavus strain CS was tested for specificity by staining fungi grown in soil in the vicinity of buried slides. All 14 strains of A. flavus fluoresced as intensely or nearly as intensely as the antigen control. Among 21 isolates of species of Aspergillus other than A. flavus, 17 reacted with moderate to low fluorescence at intensities readily distinguishable from that of A. flavus. The fluorescence of the remaining four cultures, and particularly A. sydowi, was indistinguishable from that of A. flavus. Fungi other than aspergilli were generally nonreactive. Interfering cross-reactions were encountered for one strain of Spicaria and one strain of Stemphylium; three isolates could not be evaluated because of interfering autofluorescence. An additional 22 isolates were either wholly negative or had a low order of fluorescence. Agglutination tests between each of the fungi and A. flavus CS serum revealed close agreement between agglutination titer and fluorescent-staining reaction. Unknown fungi freshly isolated from soil were checked for reaction to the A. flavus labeled antiserum; only one isolate gave a pronounced staining reaction, and that one proved to be a strain of A. flavus. In a simplified ecological model, the fluorescent-antibody technique was used to follow the development of A. flavus in mixed culture in soil with five other soil fungi.

Aspergillus↗