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Biomedical subjects

E Juni

Publications and source records attributed to E Juni.

29 records · Page 2Linked to original sources
PubMed1974

Simple genetic transformation assay for rapid diagnosis of Moraxella osloensis.

A genetic transformation assay for unequivocal identification of strains of Moraxella osloensis is described. In this assay a stable tryptophan auxotroph is transformed to prototrophy by deoxyribonucleic acid (DNA) samples from other strains of M. osloensis but not by DNA samples from unrelated bacteria. The test is simple to perform and definitive results can be obtained in less than 24 h. The procedure, which is suitable for routine diagnosis in a clinical laboratory, involves a rapid method for preparation of crude transforming DNA from small quantities of bacterial cells and permits simultaneous examination of large numbers of isolated cultures. The assay was shown to correctly identify 27 strains previously classified as M. osloensis. Forty-five other gram-negative, oxidase-positive, nonmotile coccobacilli, which might be confused with M. osloensis unless subject to more extensive testing, were shown to be unrelated genetically to M. osloensis. The transformation assay clearly distinguishes M. osloensis from Acinetobacter. Although most strains of M. osloensis are nonfastidious, being able to grow in a mineral medium supplemented with a single organic carbon source, one of the strains tested was only able to grow on fairly complex media and could not be transformed to grow on simple media. Inability to alkalize Simmons citrate agar was shown not to be characteristic of all strains of M. osloensis.

Acinetobacter↗
PubMed1974

Isolation and characterization of a generalized transducing bacteriophage for Acinetobacter.

A series of bacteriophages which grow in various strains of Acinetobacter have been isolated. One of these, phage P78, which forms turbid plaques on Acinetobacter strain 78 is specific for this particular host and fails to attack 389 other independently isolated strains of Acinetobacter. Phage P78 appears to be a temperate phage which lysogenizes its host. Various agents such as N-methyl-N'-nitro-N-nitrosoguanidine, diethyl sulfate, mitomycin C, and ultraviolet light are effective inducers of the lysogen. Phage lysates of wild-type cells are capable of transducing auxotrophs of strain 78 to prototrophy at frequencies ranging from 0.3 x 10(-7) to 34 x 10(-7) per plaque-forming unit adsorbed. To date, no linkage has been detected between any of the markers studied in two-factor crosses. Donor phage grown in one particular mutant, strain 78 (arg-1), has been shown to give rise to significantly higher transduction frequencies than when phage is grown on wild-type or other auxotrophic strains. Phage P78 is rapidly adsorbed to its bacterial host and has a latent period of 25 min, and infection results in a burst size of approximately 50. Some of the physical properties of phage P78 and its DNA are described.

Adsorption↗
PubMed1972

Interspecies transformation of Acinetobacter: genetic evidence for a ubiquitous genus.

The availability of a strain of Acinetobacter competent for transformation has made it possible to demonstrate the genetic relatedness of a large variety of gram-negative, oxidase-negative, nonmotile, and aerobic coccobacilli originally classified into eleven different genera. Deoxyribonucleic acid (DNA) species from 265 such strains are capable of transforming stable auxotrophs of the competent Acinetobacter to prototrophy. The compositions of these DNA species vary from 40 to 46.8% guanine plus cytosine. Strains with widely differing phenotypic properties are also included in this collection of acinetobacters. DNA species from all oxidase-positive strains of Moraxella and from a variety of common bacteria are unable to transform the competent Acinetobacter. Although acinetobacters are usually considered to be unable to reduce nitrate to nitrite, six strains known to carry out this reduction have been shown to be authentic acinetobacters since their DNA species readily transform the competent Acinetobacter auxotrophs to prototrophy. In contrast to previous findings that acinetobacters rarely grow with glucose as a sole carbon source, the results of the present study show that 17 of the 265 strains grow readily in a glucosemineral medium, and 48 other strains can mutate spontaneously to grow in such a medium. A second competent strain of Acinetobacter, originally unable to use glucose, d-xylose, or d-ribose as carbon sources, has been transformed for ability to dissimilate these compounds using DNA species from strains that normally grow on these sugars. Although most of the 265 Acinetobacter strains studied were originally grown on complex media when isolated from human sources, only nine of these strains require growth factors in order to grow in a mineral medium containing a single carbon and energy source. A simple transformation assay has been devised for rapid examination of large numbers of strains to determine whether or not they are acinetobacters. This assay, which is suitable for routine diagnostic work, includes a procedure for preparation of crude transforming DNA from a small quantity of bacterial paste. Samples of DNA prepared from Acinetobacter cultures that had died on slants and plates were still able to effect transformation of the competent auxotrophs to prototrophy.

Aerobiosis↗
PubMed1969

Immunochemistry of the capsular polysaccharide of an acinetobacter.

The capsular polysaccharide of a strain, BD4, of Acinetobacter calco-aceticus (A.c-a), composed of L-rhamnose and D-glucose, 4:1, precipitates all streptococcal group B antisera tested, as well as streptococcal group G antisera and antipneumococcal (Pn) type XXIII serum. Nonreducing end groups of L-rhamnose, known to be major determinants of the antigens giving rise to these antisera, are thus identified in A.c-a, which also precipitates anti-Pn VI sera. Both the rhamnose and glucose in the capsular polysaccharide (S) of Pn VI are linked 1,3-, as is the rhamnose in Pn S II, which also precipitates anti-Pn VI because of this linkage. A.c-a and S II precipitate the same fraction of anti-Pn VI, identifying a second portion of the rhamnose of A.c-a as 1,3-linked. This is confirmed by the stability of a portion of the rhamnose on oxidation of A.c-a with periodate, and 1,3-linked glucose or a periodate-stable branch point is also indicated in the same way. Two features of the fine structure of A.c-a have thus been established and a third indicated.

Bacteria↗
PubMed1969

Transformation of Acinetobacter calco-aceticus (Bacterium anitratum).

A highly efficient transformation system has been demonstrated in a strain of Acinetobacter calco-aceticus (Bacterium anitratrum). During mixed growth of various stable, unencapsulated, mutant strains, deoxyribonucleic acid (DNA) is liberated and fully encapuslated transformants can be isolated. Purified DNA preparations have been used to transform suitable recipient mutant strains for ability to synthesize capsules, ability to dispense with a growth factor requirement, and resistance to streptomycin. When the wild-type strain is deprived of its capsule, either by mechanical stripping or by mutation, the unencapsulated cells tend to form large clumped masses. A nonclumping mutant of an unencapsulated strain has been isolated. When ability to synthesize capsules is transformed into this nonclumping strain, the resultant cells no longer form chains, unlike the wild-type encapsulated strain. It appears likely that the occurrence of transformation during growth of mixed cultures, with glucose or gluconate as the carbon source, may be the result of osmotic rupture resulting from the inability of unencapsulated strains to oxidize triose phosphates as fast as they are formed. The finding of transformation in Acinetobacter may provide an additional useful organism for the study of this mode of genetic transfer since this strain grows well in a simple mineral medium containing a single oxidizable source of carbon. Furthermore, no special supplementary factors seem to be required for transformation to take place.

Alcaligenes↗
PubMed1964

PATHWAYS FOR BIOSYNTHESIS OF A BACTERIAL CAPSULAR POLYSACCHARIDE. IV. CAPSULE RESYNTHESIS BY DECAPSULATED RESTING-CELL SUSPENSIONS.

Juni, Elliot (Emory University, Atlanta, Ga.), and Gloria A. Heym. Pathways for biosynthesis of a bacterial capsular polysaccharide. IV. Capsule resynthesis by decapsulated resting-cell suspensions. J. Bacteriol. 87:461-467. 1964.-Methods were devised for stripping capsules from encapsulated bacteria. By use of stripped resting-cell suspensions of a gram-negative capsule-forming coccus, it was shown that polysaccharide capsule resynthesis depends upon the presence of air and an oxidizable substrate. Capsule resynthesis proceeds linearly with time. For a given quantity of stripped cells, the net amount of polysaccharide capsule synthesized is a linear function of the amount of substrate oxidized. The only factor that appears to limit the extent of capsule synthesis by resting cells is the amount of substrate utilized. A series of photomicrographs of wet mounts made in India ink show the appearance of stripped cells and resynthesized capsules formed during oxidation of pyruvate and glucose by stripped resting-cell suspensions.

Acetates↗