Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “ESCHERICHIA”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
NASA NTRS1968

The food chain

Mathematical model for calculating food chain of Escherichia-amoeba culture

Drake, J. F.↗
NASA NTRS1971

Bacterial Identification Using Light Scattering Measurements: a Preliminary Report

The light scattering properties of single bacterial cells were examined as a possible means of identification. Three species were studied with streptococcus faecalis exhibiting a unique pattern; the light-scattering traces for staphylococcus aureus and escherichia coli were quite similar although differences existed. Based on preliminary investigations, the light scattering approach appeared promising with additional research needed to include a wide variety of bacterial species, computer capability to handle and analyze data, and expansion of light scattering theory to include bacterial cells.

Wilkins, J. R.↗
NASA NTRS1973

Effects of space environment on T-7 bacteriophage and spores of Bacillus subtilis 168

Two strains of Bacillus subtilis were exposed to components of the ultraviolet spectrum in space. Both strains possess multiple genetic markers, and one of the strains is defective in the ability to repair ultraviolet damage. The T-7 bacteriophage of Escherichia coli was also exposed to selected wavelengths and energy levels of ultraviolet light in space. Preliminary findings do not reveal anomalies in survival rates. Data are not yet available on detailed genetic analyses.

Spizizen, J.↗
NASA NTRS1975

Research and development of an electrochemical biocide reactor

An alternate disinfecting process to chemical agents, heat, or radiation in an aqueous media has been studied. The process is called an electrochemical biocide and employs cyclic, low-level voltages at chemically inert electrodes to pass alternating current through water and, in the process, to destroy microorganisms. The paper describes experimental hardware, methodology, and results with a tracer microorganism (Escherichia coli). The results presented show the effects on microorganism kill of operating parameters, including current density (15 to 55 mA/sq cm (14 to 51 ASF)), waveform of applied electrical signal (square, triangular, sine), frequency of applied electrical signal (0.5 to 1.5 Hz), process water flow rate (100 to 600 cc/min (1.6 to 9.5 gph)), and reactor resident time (0 to 4 min). Comparisons are made between the disinfecting property of the electrochemical biocide and chlorine, bromine, and iodine.

See, G. G.↗
NASA NTRS1975

High Ph, Ammonia Toxicity, and the Search for Life on the Jovian Planets

The effects of pH and ammonia concentration were studied separately, where possible, on a variety of organisms, including some isolated from natural environments of high pH and/or ammonia concentration. Escherichia coli and Bacillus subtilis are both extremely sensitive to ammonia. An aerobic organism (growth up to pH 11.4) from an alkaline spring is more resistant, but exhibits a toxic response to ammonia at a pH much lower than its maximum for growth. The greatest ammonia resistance has been found in an unidentified organism growing at near neutral pH. Even in this case, however, urvival at ammonia concentrations reasonably expected on the Jovian planets is measured in hours. This is two to three orders of magnitude longer than for E. coli. Results support the tentative conclusion that contamination of the Jovian planets with terrestrial organisms that can grow is unlikely. However, the range of toxic response noted, coupled with the observation that terrestrial life has not been exposed to high ammonia concentrations for millions of years, suggests that adaptation to greater ammonia tolerance may be possible.

Deal, P. H.↗
NASA NTRS1977

An ancient divergence among the bacteria

The 16S ribosomal RNZs from two species of met methanogenic bacteria, the mesophile Methanobacterium ruminantium and the thermophile Methanobacterium thermoautotrophicum, have been characterized in terms of the oligonucleotides produced by digestion with T1 ribonuclease. These two organisms are found to be sufficiently related that they can be considered members of the same genus or family. However, they bear only slight resemblance to 'typical' Procaryotic genera; such as Escherichia, Bacillus and Anacystis. The divergence of the methanogenic bacteria from other bacteria may be the most ancient phylogenetic event yet detected - antedating considerably the divergence of the blue green algal line for example, from the main bacterial line.

Balch, W. E.↗
NASA NTRS1979

Beta-galactosidase and selective neutrality

Three hypotheses to explain the amino acid composition of proteins are inconsistent (about 10 to the minus 9th) with the experimental data for beta-galactosidase from Escherichia coli. The exceptional length of this protein, 1021 residues, permits rigorous tests of these hypotheses without complication from statistical artifacts. Either this protein is not at compositional equilibrium, which is unlikely from knowledge about other proteins, or the evolution of this protein and its coding gene have not been selectively neutral. However, the composition of approximately 60% of the molecule is consistent with either a selectively neutral or nonneutral evolutionary process.

Holmquist, R.↗
NASA NTRS1981

The nucleotide sequence of Beneckea harveyi 5S rRNA

The primary sequence of the 5S ribosomal RNA isolated from the free-living bioluminescent marine bacterium Beneckea harveyi is reported and discussed in regard to indications of phylogenetic relationships with the bacteria Escherichia coli and Photobacterium phosphoreum. Sequences were determined for oligonucleotide products generated by digestion with ribonuclease T1, pancreatic ribonuclease and ribonuclease T2. The presence of heterogeneity is indicated for two sites. The B. harveyi sequence can be arranged into the same four helix secondary structures as E. coli and other prokaryotic 5S rRNAs. Examination of the 5S-RNS sequences of the three bacteria indicates that B. harveyi and P. phosphoreum are specifically related and share a common ancestor which diverged from an ancestor of E. coli at a somewhat earlier time, consistent with previous studies.

Luehrsen, K. R.↗
NASA NTRS1985

Carbon isotopic fractionation in heterotrophic microbial metabolism

Differences in the natural-abundance carbon stable isotopic compositions between products from aerobic cultures of Escherichia coli K-12 were measured. Respired CO2 was 3.4 percent depleted in C-13 relative to the glucose used as the carbon source, whereas the acetate was 12.3 percent enriched in C-13. The acetate C-13 enrichment was solely in the carboxyl group. Even though the total cellular carbon was only 0.6 percent depleted in C-13, intracellular components exhibited a significant isotopic heterogeneity. The protein and lipid fractions were -1.1 and -2.7 percent, respectively. Aspartic and glutamic acids were -1.6 and +2.7 percent, respectively, yet citrate was isotopically identical to the glucose. Probable sites of carbon isotopic fractionation include the enzyme, phosphotransacetylase, and the Krebs cycle.

Blair, N.↗
NASA NTRS1991

Use of T7 RNA polymerase to direct expression of outer Surface Protein A (OspA) from the Lyme disease Spirochete, Borrelia burgdorferi

The OspA gene from a North American strain of the Lyme disease Spirochete, Borrelia burgdorferi, was cloned under the control of transciption and translation signals from bacteriophage T7. Full-length OspA protein, a 273 amino acid (31kD) lipoprotein, is expressed poorly in Escherichia coli and is associated with the insoluble membrane fraction. In contrast, a truncated form of OspA lacking the amino-terminal signal sequence which normally would direct localization of the protein to the outer membrane is expressed at very high levels (less than or equal to 100 mg/liter) and is soluble. The truncated protein was purified to homogeneity and is being tested to see if it will be useful as an immunogen in a vaccine against Lyme disease. Circular dichroism and fluorescence spectroscopy was used to characterize the secondary structure and study conformational changes in the protein. Studies underway with other surface proteins from B burgdorferi and a related spirochete, B. hermsii, which causes relapsing fever, leads us to conclude that a strategy similar to that used to express the truncated OspA can provide a facile method for producing variations of Borrelia lipoproteins which are highly expressed in E. coli and soluble without exposure to detergents.

Dunn, John J.↗
NASA NTRS1993

The evolution of energy-transducing systems: Studies with archaebacteria

N-ethylmaleimide (NEM) inhibits the ATPase of H. saccharovorum in a nucleotide protectable manner. The bulk of 14C-NEM is incorporated into subunit 1. Inhibition kinetics indicated a single binding site. To determine the sequence around this site, cyanogen bromide peptides of NEM-labeled ATPase enzyme were prepared and separated on Tris-Tricine gels. Autoradiography indicated that the NEM binding site is probably located in a fragment of Mr 10-12 K. This result will be confirmed by N-terminal sequencing of the peptide. Since the cysteinyl residue, to which NEM is bound, may be located at the C-terminal end, purification and proteolytic treatment of the 10 K peptide will be required. One inhibitor of V-type ATPases, fluoresceinisothiocyanate (FITC) inhibited also the ATPase of H. saccharovorum. Preliminary results indicated protection against inhibition by nucleotides. Localization of the binding sited to the major subunits is in progress. An extraction procedure for the membrane sector of the ATPase complex of H. saccharovorum yielded a preparation which was enriched in a peptide of Mr 5 500. Experiments to test the immunological crossreaction with subunit c from the Escherichia coli F-type ATPase and the labeling with 14C-DCCD are currently carried out. Polyclonal antiserum to the smaller of the major subunits of the ATPase from H. saccharovorum (subunit ll) reacts in Western blots strongly with the alpha and beta subunits of the F1 ATPase of E. coli, suggesting highly conserved regions on both types of ATPases. To elucidate further the regions of homology, cyanogen bromide peptides of the beta subunits were prepared for sequence analysis.

Stan-Lotter, Helga↗