bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of unsaturated fatty acid deprivation on neutral lipid synthesis in Saccharomyces cerevisiae
Authors: Buttke T M , Pyle A L
Published: June 2021

The effects of unsaturated fatty acid deprivation on lipid synthesis in Saccharomyces cerevisiae strain GL7 were determined by following the incorporation of [14C]acetate. Compared to yeast cells grown with oleic acid, unsaturated fatty acid-deprived cells contained 200 times as much 14C label in squalene, with correspondingly less label in 2,3-oxidosqualene and 2,3;22,23-dioxidosqualene. Cells deprived of either methionine or cholesterol did not accumulate squalene, demonstrating that the effect of unsaturated fatty acid starvation on squalene oxidation was not due to an inhibition of cell growth. Cells deprived of olefinic supplements displayed additional changes in lipid metabolism: (i) an increase in 14C-labeled diacylglycerides, (ii) a decrease in 14C-labeled triacylglycerides, and (iii) increased levels of 14C-labeled decanoic and dodecanoic fatty acids. The changes in squalene oxidation and acylglyceride metabolism in unsaturated fatty acid-deprived cells were readily reversed by adding oleic acid. Pulse-chase studies demonstrated that the [14C]squalene and 14C-labeled diacylglycerides which accumulated during starvation were further metabolized when cells were resupplemented with oleic acid. These results demonstrate that unsaturated fatty acids are essential for normal lipid metabolism in yeasts.
Molecular mapping of glyW, a duplicate gene for tRNA3Gly of Escherichia coli
Authors: Tucker S D , Gopalakrishnan A S , Bollinger R , Dowhan W , Murgola E J
Published: June 2021

By the use of [5'-32P]tRNA3Gly from Escherichia coli as a hybridization probe, glyW was located on cloned fragments of the uvrC pgsA region of the bacterial chromosome. After determination of the sites of action of several restriction enzymes, glyW was found to be within approximately 300 base pairs of pgsA. The order of genes in this region is uvrC, pgsA, glyW, flaI. Comparison of the order of determined restriction sites with the sites predicted from the nucleotide sequence of tRNA3Gly indicates that the direction of transcription of glyW is counterclockwise on the circular E. coli map.
Integration and partial excision of a cryptic plasmid in Pseudomonas syringae pv. phaseolicola
Authors: Curiale M S , Mills D
Published: June 2021

A virulent strain of Pseudomonas syringae pv. phaseolicola, a pathogen of the common bean Phaseolus vulgaris (L.), was shown to harbor a 98-megadalton cryptic plasmid, pMC7105. After exposure of this strain to the plasmid-curing agent mitomycin C, a colony was isolated which had no detectable extrachromosomal DNA. Hybridization of labeled pMC7105 probe to nitrocellulose filters containing Southern-blotted BamHI cleavage products of cellular DNA revealed that pMC7105 was integrated into the chromosome rather than cured from this strain. Imprecise excision of pMC7105 resulted in the formation of three smaller plasmids of 34, 50, and 58 megadaltons. BamHI and EcoRI fingerprint analyses revealed that these plasmids were excised from a common region of pMC7105. The BamHI fragments of pMC7105 which were not present in the excision plasmids remained integrated and could be detected by hybridization of pMC7105 probe to Southern-blotted cellular DNA from these strains. Certain chromosomal fragments also had homology with the pMC7105 probe. The excision plasmids were stably maintained and neither integration nor excision altered the pathogenicity of these strains.
Biological factors affecting enflagellation of Naegleria fowleri
Authors: Woodworth T W , John D T , Bradley S G
Published: June 2021

Naegleria fowleri is a pathogenic amoeboflagellate that can be evoked to transform from amoebae to flagellates by subculture to nonnutrient buffer. More than half of the amoebae of strains KUL, nN68, and Lovell became enflagellated 300 min after subculture to amoeba-saline, whereas no amoebae of strains NF66, NF69, and HB4 did. N. fowleri nN68 enflagellated best when grown at 32 or 37 degrees C and subcultured to amoeba-saline at 37 or 42 degrees C. Amoebae from the stationary phase of growth enflagellated more readily than did actively growing amoebae. Incubation in expended culture medium from stationary-phase cultures enhanced the capability of growing amoebae to enflagellate after subculture to amoebasaline. Enflagellation was more extensive when the population density in amoebasaline did not exceed 2 x 10(5) amoebae per ml. Cycloheximide at 1 microgram/ml and actinomycin D at 25 micrograms/ml inhibited growth of N. fowleri nN68. Cycloheximide at 0.5 microgram/ml and actinomycin D at 25 micrograms/ml completely prevented enflagellation when added at time zero. Cycloheximide at 0.5 microgram/ml, added 120 to 300 min after initiation of enflagellation, prevented further differentiation and caused existing flagellates to revert to amoeboid cells. Similarly, actinomycin D at 25 micrograms/ml, added 90 to 300 min after initiation of enflagellation, retarded differentiation and caused flagellates to revert. Radiolabeled precursors were incorporated into macromolecules during differentiation in nonnutrient buffer. Enflagellation of N. fowleri is a suitable model for studying regulation of a eucaryotic protist.
In vitro membrane association of the F0 polypeptides of the Escherichia coli proton translocating ATPase
Authors: Decker K P , Brusilow W S , Gunsalus R P , Simoni R D
Published: June 2021

The F0 polypeptides a, b, and c of the H+-translocating ATPase associated with membranes when synthesized in vitro. This association occurred when the membranes were present either cotranslationally or post-translationally. In addition, the F0 polypeptides associated with liposomes. The membrane association seemed to be an insertion process since there was protection of polypeptides a and c from proteolysis. The in vitro insertion of the F0 polypeptides a, b, and c was independent of the synthesis of each polypeptide and of the F1 polypeptides.
Lipid synthesis during morphogenesis of Mucor racemosus
Authors: Ito E T , Cihlar R L , Inderlied C B
Published: June 2021

Lipid synthesis increases coordinately with protein and RNA synthesis during morphogenesis of Mucor racemosus. The lipid synthesis inhibitor cerulenin can completely block morphogenesis under conditions in which cell growth continues. An increase in phospholipid turnover may be an important correlate to morphogenesis of Mucor spp., especially the turnover of phosphotidyl inositol and phosphatidyl ethanolamine. The increase in ornithine decarboxylase, which occurs during morphogenesis, is inhibited by the addition of cerulenin.
Nitrogen oxide reduction in Wolinella succinogenes and Campylobacter species
Authors: Payne W J , Grant M A , Shapleigh J , Hoffman P
Published: June 2021

Wolinella succinogenes cells and extracts reduced nitric oxide, and cells, but not extracts, reduced nitrous oxide. Formate-reduced W. succinogenes extracts generated the 573-nm peak in difference spectra seen previously in response to nitric oxide in denitrifiers. The type strains of several Campylobacter species did not reduce either gaseous oxide. Cells, but not extracts, of C. fetus subspecies (fetus and venerealis) reduced nitrous oxide; acetylene inhibited reduction. Neither cells nor extracts reduced nitric oxide.
Escherichia coli polypeptide controlled by the lon (capR) ATP hydrolysis-dependent protease and possibly involved in cell division
Authors: Schoemaker J M , Henderson G W , Markovitz A
Published: June 2021

Mutation in the gene lon (capR) of Escherichia coli K-12 causes conditional inhibition of cell division. Two-dimensional gel electrophoresis was used to compare polypeptides from isogenic capR+ and capR strains. One polypeptide was present in the capR strain but absent in the wild-type strain, and it was proteolyzed when the pure capR+ protease was added to the capR extract. This polypeptide could only be detected in the capR strain when cell division was inhibited, and its synthesis was independent of the SOS response.
Expression of the transposable lac operon Tn951 in Rhodopseudomonas sphaeroides
Authors: Nano F E , Kaplan S
Published: June 2021

The transposon Tn951 (lac) was introduced into the photosynthetic bacterium Rhodopseudomonas sphaeroides 2.4.1, which is normally Lac-, via the P-group plasmid RP1. beta-Galactosidase was produced constitutively in both chemotrophically and phototrophically grown cells, and the levels were found to be the same but low. Mutants were isolated, however, that were able to grow on lactose minimal medium and which expressed different levels of beta-galactosidase when grown chemotrophically or phototrophically. The beta-galactosidase levels found in all R. sphaeroides strains were much less than those found in Escherichia coli.
Heme Inhibition of Ferrisiderophore Reductase in
Bacillus subtilis
Authors: Lodge J. S. , Gaines C. G. , Arceneaux J. E. L. , Byers B. R.
Published: June 2021

Heme was a noncompetitive inhibitor (apparent

K
i

and

K′
i

= 0.043 mM) of a ferrisiderophore reductase purified from
Bacillus subtilis
; protoporphyrin IX had no effect. The cellular level of heme may partly regulate the function of this reductase to yield a controlled flow of iron into metabolism.
Hybridization studies reveal homologies between pBF4 and pBFTM10, Two clindamycin-erythromycin resistance transfer plasmids of Bacteroides fragilis
Authors: Shimell M J , Smith C J , Tally F P , Macrina F L , Malamy M H
Published: June 2021

Two clindamycin-erythromycin resistance transfer factors of Bacteroides fragilis, pBF4 and pBFTM10, were analyzed for regions of DNA homology. Although the plasmids were derived from different clinical isolates of B. fragilis and have different sizes, they showed homology in the clindamycin-erythromycin resistance region; no homology could be detected outside of this region.
Cloning of the trp-1 gene from neurospora crassa by complementation of a trpC mutation in Escherichia coli
Authors: Keesey J K , Demoss J A
Published: June 2021

Studies with a hybrid plasmid containing 4.0 kilobase pairs of Neurospora crassa DNA cloned into plasmid pBR322 indicated that the plasmid restored to prototrophy a trpC mutant of Escherichia coli which lacked phosphoribosyl anthranilate isomerase but not a trpC mutant which lacked indole glycerol phosphate synthetase, that the relevant transcription was initiated at a promoter within the N. crassa DNA, and that the phosphoribosyl anthranilate isomerase could be specified by a subcloned segment of the original DNA.
Derepression of an NAD-linked dehydrogenase that serves an Escherichia coli mutant for growth on glycerol
Authors: Tang J C , St Martin E J , Lin E C
Published: June 2021

An Escherichia coli mutant using an NAD-linked dehydrogenase instead of an ATP-dependent kinase as the first enzyme for glycerol dissimilation excreted dihydroxyacetone during the initial phase of growth. The intermediate was salvaged as growth of the culture advanced. The transient loss of the intermediate into the medium appeared to be partly determined by variation of the level of glycerol dehydrogenase with growth conditions. With up to 2% casein hydrolysate as the carbon and energy source, the cellular level of the dehydrogenase increased 1 order of magnitude at the end of growth. This increase was probably caused by the depletion of certain metabolites and was prevented by the addition of pyruvate or glucose to the growth medium. The repressive effect of these compounds was not lifted by the addition of cyclic AMP. Diminution of oxygen tension in the culture medium with increased cell density was not directly responsible for the increase of the enzyme level. Thus, neither catabolite repression nor respiratory repression was implicated as an important control mechanism in the synthesis of this enzyme. Since increases in the specific activity of the enzyme in cell extracts reflected increases in the concentration of the enzyme protein, post-translational control was also not involved. A novel kind of regulation of gene expression is indicated.
Sequence-specific DNA uptake in transformation of Neisseria gonorrhoeae
Authors: Graves J F , Biswas G D , Sparling P F
Published: June 2021

Piliated, competent gonococci are known to preferentially take up homologous transforming DNA into the cell. We examined the mechanism for DNA uptake with pFA10, a hybrid 11.5-kilobase (kb) penicillin-resistant (Pcr) plasmid composed of heterologous DNA from a 7.2-kb Pcr plasmid and homologous DNA from a 4.2-kb gonococcal cryptic plasmid. The presence of the gonococcal cryptic plasmid DNA in the hybrid resulted in markedly increased transformation efficiencies in isogenic crosses as compared with the parent 7.2-kb Pcr plasmid. Uptake of 32P-end-labeled MspI or TaqI restriction fragments of the hybrid was limited to fragments entirely derived from the 4.2-kb gonococcal cryptic plasmid, indicating that DNA uptake was probably dependent on the presence of a specific DNA sequence. Since Haemophilus DNA did not inhibit transformation by the hybrid Pcr plasmid, the gonococcal DNA uptake sequence is different from the known sequence involved in homologous DNA uptake by Haemophilus spp.
A second function of the S gene of bacteriophage lambda
Authors: Wilson D B , Okabe A
Published: June 2021

Infection of Escherichia coli by bacteriophage lambda caused an immediate inhibition of uptake by members of all three classes of E. coli active transport systems and made the inner membrane permeable to sucrose and glycine; however, infection stimulated alpha-methyl glucoside uptake. Phage infection caused a dramatic drop in the ATP pool of the cell, but the membrane did not become permeable to nucleotides. Infection by only one phage per cell was sufficient to cause transport inhibition. However, adsorption of phage to the lambda receptor did not cause transport inhibition; DNA injection was required. The inhibition of transport caused by lambda phage infection was transient, and by 20 min after infection, transport had returned to its initial level. The recovery of transport activity appeared to require a lambda structural protein with a molecular weight of 5,500. This protein was present in wild-type phage and at a reduced level in S7 mutant phage but was missing in S2 and S4 mutant phage. Cells infected with S7 phage had a partial recovery of active transport, whereas cells infected with S2 or S4 phage did not recover active transport. Neither the inhibition of transport caused by phage infection nor its recovery were affected by the protein synthesis inhibitors chloramphenicol and rifampin.
Identification of membrane anchor polypeptides of Escherichia coli fumarate reductase
Authors: Lemire B D , Robinson J J , Weiner J H
Published: June 2021

Fumarate reductase of Escherichia coli has been shown to be a membrane-bound enzyme composed of a 69,000-dalton catalytic-flavin-containing subunit and a 27,000-dalton nonheme-iron-containing subunit. Using gene cloning and amplification techniques, we have observed two additional polypeptides encoded by the frd operon, with apparent molecular weights of 15,000 and 14,000, which are expressed when E. coli is grown anaerobically on glycerol plus fumarate. Expression of these two small polypeptides is necessary for the two large subunits to associate with the membrane. The four subunits remain associated in Triton X-100 extracts of the membrane, and a holoenzyme form of fumarate reductase containing one copy of each of the four polypeptides has been isolated. Unlike the well-characterized two-subunit form, the holoenzyme is not dependent on anions for activity and is not labile at alkaline pH. In these respects, it more closely resembles the membrane-bound activity.
Levels of cell wall enzymes in endospores and vegetative cells of Bacillus subtilis
Authors: Reusch V M , Hale S G , Hurly B J
Published: June 2021

Vegetative bacilli and refractile endospores of Bacillus subtilis 168 were disrupted by homogenization with glass beads and fractionated by differential centrifugation. Most of the protein of endospores was particulate, whereas for bacilli most was soluble. Alanine racemase activity was sixfold higher in extract of endospores than in extract of bacilli and was particulate, whereas the enzyme from bacilli was soluble. The specific activities of seven other enzymes involved in peptidoglycan and teichoic acid biosynthesis were higher in extracts of bacilli than in those of endospores. The results suggest that restoration of activities of these seven enzymes to vegetative levels occurs during germination and outgrowth.
Temperature-sensitive processing of outer membrane lipoprotein in an Escherichia coli mutant
Authors: Yamagata H , Ippolito C , Inukai M , Inouye M
Published: June 2021

A mutant of Escherichia coli that accumulated prolipoprotein, a secretory precursor of the outer membrane lipoprotein, was isolated. The prolipoprotein accumulated in this mutant was modified by glyceride, but the in vitro cleavage of the signal peptide of the accumulated prolipoprotein was found to be temperature sensitive. The mutation appears to be located outside the gene for the lipoprotein, thus suggesting that the gene for the signal peptidase for the prolipoprotein was mutated.
Pyruvate-dependent diauxic growth of Rhodospirillum rubrum in light
Authors: Solaiman D , Uffen R L
Published: June 2021

When Rhodospirillum rubrum mutant C was first exposed to radiant energy after long-term anaerobic dark growth, the cells often exhibited a diauxic growth response. This happened with pyruvate in the medium and when cultures were exposed to a less-than-growth-saturating white light intensity of about 6,460 lx. Under the growth-saturating light condition, mutant C photometabolized and growth was not affected by Na hypophosphite, an inhibitor of pyruvate fermentation. In lower intensity light, in which diauxie occurred, initial (phase I) growth occurred by fermentation of Na pyruvate and was sensitive to Na hypophosphite inhibition. Once pyruvate was depleted, phase I growth stopped, the bacteriochlorophyll content of the cells began to increase from about 3 nmol/mg of protein, and growth finally resumed phototrophically (phase II). The lag period and phase II growth were influenced by radiant energy. By changing the white light intensity from 2,150 to 753 lx between experiments, the duration of both the lag period and the generation time of cells in phase II growth increased. Diauxic growth was pyruvate dependent. It occurred with pyruvate even if malate, a photometabolizable substrate, was added to the growth medium. Moreover, the biphasic growth response was reversible. It was observed not only with R. rubrum mutant C grown cells photosynthetically, but also when other strains of R. rubrum were placed in pyruvate medium under lowered light conditions. Only R. rubrum S1 did not exhibit the typical pyruvate-dependent diauxic growth response.
A gene between polA and glnA retards growth of Escherichia coli when present in multiple copies: physiological effects of the gene for spot 42 RNA
Authors: Rice P W , Dahlberg J E
Published: June 2021

We have isolated the single gene for spot 42 RNA of Escherichia coli on a 20-kilobase DNA fragment. Physical characterization of this cloned DNA fragment showed that it is homologous to a region at 86 min on the genetic map and extends from the 23S to 5S rRNA coding region of rrnA to the coding region of glnA, the gene for glutamine synthetase. Other genes included on this cloned DNA fragment are polA, ntrC (glnG), and ntrB (glnL). E coli cells transformed with a multicopy plasmid clone of the gene for spot 42 RNA had about a 10-fold increase in the amount of spot 42 RNA they contained. The amount of 6S RNA in these cells was increased about twofold, although the gene for 6S RNA was not located on this plasmid or on the larger 20-kilobase fragment. Presence of this multicopy plasmid also affected the growth of cells. The generation time was increased under a variety of growth conditions, especially when cells were grown in medium with succinate as the carbon source. In addition, some strains of E. coli which have multicopy plasmids carrying the gene for spot 42 RNA were unable to respond normally to a shift into richer medium: upon upshift from minimal glucose to LB broth or minimal glucose plus 1% Casamino Acids, there was a 3- to 4-h lag before the culture adapted to the new medium. More than 90% of the cells in such cultures stopped dividing, although they remained viable. The plating efficiency of minimal-glucose-grown cells was 100-fold less on rich media than on minimal glucose medium. One revertant was isolated which regained the phenotype of pBR322-transformed cells. Analysis of this strain showed that the plasmid it contained had an insertion of an IS1 element into the 5' end of the coding region for the gene for spot 42 RNA.
Improved version of the exoantigen test for identification of Coccidioides immitis and Histoplasma capsulatum cultures
Authors: Kaufman L , Standard P
Published: June 2021

A rapid and simple method for extracting specific cell-free antigens of Coccidioides immitis and Histoplasma capsulatum from agar slant cultures was developed. The extracts were analyzed in immunodiffusion tests for the presence of C. immitis or H. capsulatum specific antigens. These extracts were compared with culture filtrates of brain heart infusion broth subcultures in tests with 32 isolates of C. immitis and H. capsulatum and 13 other fungi which might be morphologically confused with them. The studies showed that the slant extracts were as useful as the culture filtrates and allowed more rapid identification of C. immitis and H. capsulatum. In every case, when an identification was made by conventional morphological methods, the immunological test yielded correlating results. The immunological tests were positive for two isolates that were converted to their yeast forms only after 4 months of study by conventional tests. The new procedure permits the identification of C. immitis and H. capsulatum 2 days after receipt of a pure mycelial-form culture. The test is recommended for the presumptive identification of C. immitis and H. capsulatum cultures.
Rickettsial indirect hemagglutination test: isolation of erythrocyte-sensitizing substance
Authors: Osterman J V , Eisemann C S
Published: June 2021

The erythrocyte-sensitizing substances (ESS) of Rickettsia prowazekii and R. conorii were characterized by biological and chemical criteria. ESS could be derived from either soluble or particulate complement-fixing antigens obtained by ether extraction of rickettsiae. The soluble complement-fixing antigen exhibited two peaks of serological activity in potassium tartrate density gradients. The particulate complement-fixing antigen coincided with the more dense peak but was distinguishable by its sedimentation in rate-zonal sucrose gradients. ESS was obtained from each of the complement-fixing-reactive gradient peaks by extraction with hot alkali and was quantified by a modified indirect hemagglutination test. These ESS preparations sedimented similarly in potassium tartrate gradients and were shown to contain protein and carbohydrate, both by colorimetric tests and by incorporation of radioactive precursors. The serological activity of ESS was unaffected by trypsin, but both antigenicity and erythrocyte-binding capacity were reduced after exposure to sodium metaperiodate. Highly purified ESS was rapidly inactivated by potassium tartrate and required stabilization with bovine plasma albumin.
Simple Device for Indicating Atmospheric Status of Anaerobic Chamber Entry Locks
Authors: Holland Joseph W.
Published: June 2021

A simple, inexpensive device is described that indicates which door of an anerobic chamber entry lock was last opened.
New hemolytic method for determination of antistreptolysin O in whole blood
Authors: Ricci A , Berti B , Moauro C , Porro M , Neri P , Tarli P
Published: June 2021

A new method is proposed for the determination of antistreptolysin O, based on the properties of streptolysin O. The reduced form of the toxin is hemolytic, whereas the oxidized form is not; this activity can be restored, however, by a reducing agent. Both forms maintain the capacity to bind specific antibodies. Unlike the classical method, the assay is performed on whole blood, using the patient's own erythrocytes as revealing agents. A procedure is proposed which limits the operation to a single dilution of a microvolume of blood (0.05 ml brought to 2 ml) and to the distribution of constant quantities in test tubes prefilled with different amounts of oxidized streptolysin O. After a few minutes, a reducing agent is added, and the reading is performed as in the classical technique after sedimentation of the erythrocytes. Correlation with the traditional method (r = 0.987) is evaluated on the basis of the results of samples from hospitalized patients.
Evaluation of Twenty-Three Blood Culture Media
Authors: Babu Jegdish P. , Schell Ronald F. , Le Frock Jack L.
Published: June 2021

Several investigators have evaluated clinically a variety of commercially available blood culture media. No agreement has been reached as to which of these media is optimal for detection of bacteremia. The purpose of this study was to determine the rate of recovery of microorganisms from various blood culture media. A total of 23 blood culture media were inoculated with 7 to 15 microorganisms per bottle in the presence or absence of an erythrocyte-serum mixture. The results demonstrated that blood culture media differed in their ability to support the growth of microorganisms. At 4 days after inoculation, only 10 of the 23 blood culture media supported the growth of 91% (10 of the 11) or more of the test microorganisms. The recovery rate of microorganisms depended not only upon the type of medium but also upon the manufacturer of the type of blood culture medium. The addition of an erythrocyte-serum mixture to the blood culture media did not influence the difference in the recovery rate of microorganisms among media and the same type of medium prepared by different manufacturers. The majority (15 of the 23) of the blood culture media supplemented with the erythrocyte-serum mixture failed to support the growth of 91% or more of the test microorganisms at 4 days after inoculation. These results have demonstrated that blood culture media need to be improved. Better quality control measures should also be implemented to evaluate commercial blood culture media.
Microtitration agglutination for detection of Treponema hyodysenteriae antibody
Authors: Joens L A , Harris D L , Kinyon J M , Kaeberle M L
Published: June 2021

A microtitration agglutination test for the detection of Treponema hyodysenteriae antibody in swine and rabbit sera is described. The following methods provided the best test results: antigen produced from the spirochete after a culturing period of 36 to 44 h at 38 degrees C, washed antigen inactivated with 0.01% Merthiolate at 4 degrees C for 24 to 36 h, sera heated at 56 degrees C for 30 min, a diluent of phosphate-buffered saline (0.01 M, pH 7.2), and test results read macroscopically after 18 to 24 h of incubation at 38 degrees C. The test enabled detection of antibody against pathogenic T. hyodysenteriae with a high level of consistency and sensitivity. Sera against nonpathogenic T. hyodysenteriae produced low agglutinating titers (less than or equal to 1:8) when reacted against antigen from pathogenic isolates. Inactivated antigen remained stable for 7 to 10 days. Specificity of the reaction in the agglutination test was shown by absorption studies.
Carbon substrate utilization studies of some cultures of Alcaligenes denitrificans, Alcaligenes faecalis, and Alcaligenes odorans isolated from clinical specimens
Authors: Rarick H R , Riley P S , Martin R
Published: June 2021

One hundred and sixty-two cultures of Alcaligenes species (A. denitrificans, A. faecalis, and A. odorans) of clinical origin were characterized by routine diagnostic and carbon substrate utilization techniques. The microorganisms were tested for their ability to utilize a total of 188 substrates. Substrate utilization was assayed by (i) growth stimulation and (ii) substrate alkalinization. The A. denitrificans and A. odorans cultures had unique substrate utilization profiles for each species. The A. faecalis isolates were redefined by colonial morphology into two biotypes: (i) biotype I, morphologically and biochemically similar to the A. denitrificans cultures and (ii) biotype II, morphologically similar to the A. odorans cultures.
Urease production from clinical isolates of beta-hemolytic Escherichia coli
Authors: Lesher R J , Jones W H
Published: June 2021

Twenty-four lactose-fermenting, urease-producing strains of beta-hemolytic Escherichia coli were isolated from a variety of clinical material. All isolates were indole positive, citrate negative, and produced the characteristic green metallic sheen on eosin-methylene blue agar.
Specificity of exoantigens for identifying cultures of Coccidioides immitis
Authors: Huppert M , Sun S H , Rice E H
Published: June 2021

Forty-nine isolates of arthroconidial fungi other than Coccidioides immitis did not produce immunodiffusion lines of identity with the reference system for that fungus.
Third Component, HB
e
Ag/3, of Hepatitis B e Antigen System, Identified by Three Different Double-Diffusion Techniques
Authors: Murphy B. , Tabor E. , McAuliffe V. , Williams A. , Maynard J. , Gerety R. , Purcell R.
Published: June 2021

A third component, HB
e
AG/3, of the hepatitis B e antigen system has been detected, and it was consistently detected in three variations of the double-diffusion technique.
Center for Disease Control Diagnostic Immunology Proficiency Testing Program results for 1977
Authors: Taylor R N , Fulford K M , Przybyszewski V A , Pope V
Published: June 2021

A summary of the yearly data accumulated and analyzed in the diagnostic immunology portion of the Center for Disease Control 1977 Proficiency Testing Program provides information on the trends in testing protocols from over 900 participating laboratories. One hundred and fourteen specimens prepared by the Center for the Disease Control were distributed quarterly or in special surveys. The specimens chosen provided feedback from a broad range of tests commonly performed in diagnostic immunology laboratories and included those for rubella antibodies, hepatitis B surface antigen, bacterial antibodies, rheumatoid factor, immunoglobulins and other serum-specific proteins, syphilis serology, and carcinoembryonic antigen. This summary provides an overview of the trends observed since last year's report.
Enzyme-linked immunosorbent assay determination of specific rubella antibody levels in micrograms of immunoglobulin G per milliliter of serum in clinical samples
Authors: Leinikki P O , Shekarchi I , Dorsett P , Sever J L
Published: June 2021

A "microgram assay" is described in which solid-phase enzyme-linked immunosorbent assay is used for the determination of specific rubella immunoglobulin G (IgG) antibody levels in micrograms per milliliter of serum. The quantitation was based on a standard curve obtained by using a reference serum, for which the specific IgG content was assayed by immunochemical purification. IgG was first purified and specific rubella antibodies were separated by an immunoadsorbent prepared by linking rubella virus antigens to Sepharose 4B. By using IgG-specific conjugate, the levels of specific rubella IgG antibodies could then be determined from clinical samples. Seronegative samples showed antibody levels less than 1 microgram/ml, whereas levels up to several hundred micrograms per milliliter were detected in some postinfection sera. The correlation between microgram antibody levels and hemagglutination inhibition titers was linear. The method offers a simple and sensitive antibody assay which could be used both for the laboratory diagnosis of acute rubella and for the evaluation of immunity.
Selective medium for isolation of Eikenella corrodens from periodontal lesions
Authors: Slee A M , Tanzer J M
Published: June 2021

The addition of 5 microgram of clindamycin per ml to a modified Todd-Hewitt growth medium permitted the ready enumeration of Eikenella corrodens from deep periodontal lesions because it allowed differential growth amongst the periodontal pocket gram-negative microaerophilic-anaerobic flora, maximized the numbers of E. corrodens in such culture, and inhibited the growth of most of the other confounding microorganisms.
Direct use of counterimmunoelectrophoresis in detection of group B streptococci in specimens containing mixed flora
Authors: Fenton L J , Harper M H
Published: June 2021

Isolation procedures for the group B streptococci were bypassed by applying counterimmunoelectrophoresis (CIE) directly to the broth containing the initial inoculum. A total of 458 tests were performed on 389 specimens received from 93 mothers and 81 babies. Of all tests, 19.4% were positive group B streptococci by the Lancefield precipitin method. Twenty hours of incubation were required to produce a positive CIE result in 54% of those specimens which were eventually proven a contain group B streptococci by Lancefield technique. There were no false positive CIE results. It is recommended that the initial broth culture be sampled and tested with CIE after an overnight incubation in those cases where another 24 h may be critical in terms of identifying the group B streptococci. A positive result with CIE can be clinically relied upon, but a negative result is indeterminate, and routine isolation procedures would need to be followed in that case.
Micromethod for biochemical identification of coagulase-negative staphylococci
Authors: Brun Y , Fleurette J , Forey F
Published: June 2021

We have endeavored to elaborate a suitable method for easy and rapid identification in clinical microbiology laboratories of the different species of infection-inducing, coagulase-negative staphylococci. Ten type strains described by Kloos and Schleifer and 269 strains isolated from 95 patients were tested; the classical tests were used for determination of Staphylococcus species. Strains were identified by using the Kloos-Schleifer reference method and the micromethod simultaneously. After preliminary tests on 77 substrates, 19 were retained, 15 for determination of species and 4 to reveal biotypes. The substrates were placed in wells in a rigid strip of inert plastic. Inoculation of wells was carried out with rich microbial suspensions in a special medium; reading of substrate reactions was done after incubation for 48 h at 35 degree C. The intrasystem reproducibility was excellent, from 91 to 100% for the 19 substrates. It was in excellent agreement with the reference method, 100% for type strains and 97.9% for hospital-isolated strains. Because it is simple and easy to reproduce, the micromethod will be most useful in clinical and ecological microbiology laboratories.
Neisseria confirmation by an enriched, bicarbonate-containing carbohydrate medium
Authors: Graves J O , Magee L A
Published: June 2021

A sugar fermentation medium for the confirmation of Neisseria and related species was developed. The medium contained a commercial supplement and a hemoglobin source prepared from lysed sheep erythrocytes. Bicarbonate in the medium substituted for a CO2-supplemented atmosphere. The medium was dispensed into screw-capped tubes. This medium was compared to cystine-Trypticase agar and the modified rapid fermentation test in the confirmation of Neisseria species. Performance of the new medium was equivalent to that of the modified rapid fermentation test, but cystine-Trypticase agar failed to confirm a significant number of clinical isolates of Neisseria gonorrhoeae.
Comparison of pseudorabies virus inactivated by bromo-ethylene-imine, 60Co irradiation, and acridine dye in immune assay systems
Authors: Sun I L , Gustafson D P , Scherba G
Published: June 2021

Pseudorabies virus infections among animals, especially swine, have become prevalent in the United States in the past few years. The disease in swine is now economically important. Test systems and antigens are being developed for use in control and disease suppression efforts. Pseudorabies virus was inactivated by three methods: chemically, with bromo-ethylene-imine; physically, with 60Co irradiation; and chemically and physically, with 3,9-diaminoacridine dye followed by exposure to white visible light. The antigenicities of the preparations were determined in the presence of specific antibody in immunodiffusion tests and through immunoelectrophoresis. The latter technique permitted quantitation of either antigen or antibody. In the electrophoretic patterns, the antigenic mass in bromo-ethylene-imine preparations was estimated to be 42 mg/ml, the same as in the untreated control material. After 60Co irradiation, 22 mg/ml was present, in comparison with 50 mg/ml in the untreated control antigen. In contrast, 67 mg/ml was present in the acridine dye-light-treated preparation, in comparison with 58 mg/ml in the untreated control material. A possible explanation for the acridine dye-light-treated preparation values is that photodynamic inactivation interferes with viral maturation during the replicative cycle within cells, with a resulting production of a greater amount of antigen, at least some of which is in the form of defective particles.
Differentiation of Bacteroides fragilis species by gas chromatographic detection of phenylacetic acid
Authors: van Assche P F
Published: June 2021

Of 382 strains tested, 261 strains of the species Bacteroides fragilis, B. thetaiotaomicron, B. ovatus, and B. distasonis produced phenylacetic acid; the remaining strains, belonging exclusively to the species B. vulgatus, failed to do so. This differentiation characteristic may be useful in routine clinical bacteriology.
Assessment of expectorated sputum for bacteriological analysis based on polymorphs and squamous epithelial cells: six-month study
Authors: Martin R S , Sumarah R K , Robart E M
Published: June 2021

Samples of sputum were examined microscopically to determine their suitability for routine culture. When the number of squamous epithelial cells per field was less than 10, the number of bacterial species generally fell within the range of one to four. Squamous epithelial cells were not always a true indication because some unmarked transtracheal specimens showing more than 10 squamous epithelial cells also gave a range of isolation falling between one and four. When the presence of 25 or more polymorphs was used as the parameter, the number of bacterial isolates generally fell within the range of one to three, but this resulted in positive overbiasing with consequent rejection of valid specimens. Later it was found that when a differential system using both polymorphonuclear cells and squamous epithelial cells was applied, a significant number of specimens could be salvaged which would otherwise have been discarded.
Comparison of bacteriophage typing, serotyping, and biotyping as aids in epidemiological surveillance of Klebsiella infections
Authors: Rennie R P , Nord C E , Sjoberg L , Duncan I B
Published: June 2021

Bacteriophage typing was used to subdivide Klebsiella obtained from patients in a surgical intensive care unit during a 2-year period. The 15 phages employed to type the strains were propagated by a soft-agar layer technique. In all, 23 phage types were found among the 120 clinical strains. The phage types of repeat isolates were reproducible. Only 70% of the strains tested were phage typable, but when used in conjunction with capsular serotyping and biotyping, a much greater subdivision of the Klebsiella strains was achieved. The addition of phage typing to serobiotyping for epidemiological analysis suggested that the number of cross-infecting Klebsiella strains in the intensive care unit was few, but that these strains persisted in the unit for long periods of time and could infect different body sites.
Rapid diagnosis of septic arthritis by quantitative analysis of joint fluid lactic acid with a monotest lactate kit
Authors: Brook I , Controni G
Published: June 2021

The Monotest Lactate Kit (MLT) was compared with gas-liquid chromatography (GLC) for the rapid detection of septic arthritis. A total of 36 joint fluids were tested. Specimens were obtained from patients with septic arthritis (17 cases), inflammatory arthritis (18 cases), and degenerative arthritis (1 case). Specimens from 15 patients with bacterial arthritis had lactate levels above 65 mg/dl (mean, 318 mg/dl with the GLC method and 378 mg/dl with the MLT method). Three specimens from patients with gonococcal arthritis had levels that were not above 30 mg/dl (mean, 21 mg/dl with either the GLC or the MLT methods). Patients with inflammatory or degenerative disease yielded levels lower than 65 mg/dl (mean, 48 mg/dl with the GLC method and 46 mg/dl with the MLT method). Both methods proved to be equallly reliable in detecting septic arthritis, except for the gonococcal cases. Both methods are fast and easily adaptable to clinical laboratories; however, MLT was more definitive when quantitation was needed, required less fluid per speciment, and could be readily done at the bedside.
Effect of atypical antibiotic resistance on microorganism identification by pattern recognition
Authors: Boyd J C , Lewis J W , Marr J J , Harper A M , Kowalski B R
Published: June 2021

We classified microorganisms from the clinical laboratory by using information provided by the Gram stain and antibiotic sensitivity profiles obtained with the Bauer-Kirby technique. Approximately 4,000 microorganisms, routinely identified and tested for antibiotic sensitivities in a large hospital microbiology laboratory, were used as a data set for several pattern recognition classification methods: K--nearest-neighbor analysis, statistical isolinear multicomponent analysis, Bayesian inference, and linear discriminant analysis. K--nearest-neighbor analysis yielded the highest prospective classification accuracy for gram-negative organisms, 90%. When those organisms displaying an atypical antibiotic resistance pattern were excluded from the data, the gram-negative classification accuracy improved to 95%. These results are inferior to currently accepted biochemical identification methods. Microorganisms with atypical antibiotic resistance patterns are likely to be misidentified and are common enough (17% of our isolates) to limit the feasibility of routine identification of microorganisms from their antibiotic sensitivities.
Vibrio parahaemolyticus: suspicion of presence based on aberrant biochemical and morphological features
Authors: Bottone E J , Robin T
Published: June 2021

Vibrio parahaemolyticus was isolated from a stool specimen of a patient who developed gastroenteritis after ingestion of crab meat. Recognition and identification of this halophilic microorganism was facilitated by the microscopic observation of a darting, vibrant motility in condensate derived from Kligler iron agar and the bizarre morphological aberrations noted in the condensate obtained from Christensen urea agar. Sodium chloride supplementation (1.1%) of biochemical test media revealed the halophilic nature and fermentative capability of the isolate and abolished the aberrent morphology observed in unsupplemented Christensen medium.
Simultaneous nosocomial outbreaks caused by multiply resistant Klebsiella pneumoniae types 2 and 30
Authors: Thiemke W A , Nathan D M
Published: June 2021

Two simultaneous Klebsiella pneumoniae outbreaks resistant to multiple antibiotics are reported. The closely related strains were distinguished by comparing the zone diameters obtained by disk diffusion susceptibility testing but not by interpretations of susceptible, resistant, or intermediate. Similar conclusions were made when minimal inhibitory concentrations were considered. The separation was subsequently confirmed by capsular serotyping into types 2 and 30. The data presented suggest that routine antimicrobial susceptibility patterns obtained from disk diffusion and/or minimal inhibitory concentrations may serve as an inexpensive and reliable typing system for epidemiological investigations.
The Delta Cooperative Model: a Dynamic and Innovative Team-Work Activity to Develop Research Skills in Microbiology
Authors: RIOS-VELAZQUEZ CARLOS , ROBLES-SUAREZ REYNALDO , GONZALEZ-NEGRON ALBERTO J. , BAEZ-SANTOS IVAN
Published: June 2021

The Delta Cooperative Model (DCM) is a dynamic and innovative teamwork design created to develop fundamentals in research skills. High school students in the DCM belong to the Upward Bound Science and Math (UBSM) program at the Inter American University, Ponce Campus. After workshops on using the scientific method, students were organized into groups of three students with similar research interests. Each student had to take on a role within the group as either a researcher, data analyst, or research editor. Initially, each research team developed hypothesis-driven ideas on their proposed project. In intrateam research meetings, they emphasized team-specific tasks. Next, interteam meetings were held to present ideas and receive critical input. Finally, oral and poster research presentations were conducted at the UBSM science fair. Several team research projects covered topics in medical, environmental, and general microbiology. The three major assessment areas for the workshop and DCM included: (i) student’s perception of the workshops’ effectiveness in developing skills, content, and values; (ii) research team self- and group participation evaluation, and (iii) oral and poster presentation during the science fair. More than 91% of the students considered the workshops effective in the presentation of scientific method fundamentals. The combination of the workshop and the DCM increased student’s knowledge by 55% from pre- to posttests. Two rubrics were designed to assess the oral presentation and poster set-up. The poster and oral presentation scores averaged 83% and 75% respectively. Finally, we present a team assessment instrument that allows the self- and group evaluation of each research team. While the DCM has educational plasticity and versatility, here we document how the this model has been successfully incorporated in training and engaging students in scientific research in microbiology.
Complete Genome Sequence of Rhodococcus qingshengii Strain VKM Ac-2784D, Isolated from Elytrigia repens Rhizosphere
Authors: Petrushin Ivan S. , Markova Yulia A. , Karepova Marina S. , Zaytseva Yulia V. , Belovezhets Lyudmila A.
Published: June 2021

Rhizosphere bacteria are considered to be promising destructors of oil and its components. Bacterial species of the genus
Rhodococcus
can degrade a variety of hydrocarbons and are widely used for the bioremediation of polluted environments. Here, we report the complete genome sequence of
Rhodococcus qingshengii
strain VKM Ac-2784D.
Supplemental Material: Vein topology, structures, and distribution during the prograde formation of an Archean gold stockwork
Authors: Turlin François , al. et
Published: June 2021

Structural features investigated on the Cheechoo tonalite/granodiorite including the topological measures carried out on the outcrop and on drill cores, along with the gold grades and facies variability, and the structural measures of foliation and veins from the main stripped area.