- Volume 41, Issue 3, 1965
Volume 41, Issue 3, 1965
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THE SOCIETY FOR GENERAL MICROBIOLOGY
The Society for General Microbiology held its forty-fourth General Meeting at King’s College, Aberdeen, on Thursday, Friday and Saturday 16, 17 and 18 September 1965. The following communications were made:
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- Article
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The Antigenic Structure of Haemophilus and Corynebacterium Species from the Human Genital Tract Claimed to be Associated with or Derived from Mycoplasma Hominis
More LessSUMMARY:The antigenic structure of Haemophilus vaginalis (Gardner & Dukes, Edmunds, and Amies & Jones strains) was compared by means of gel-diffusion preciptin reactions with that of H. influenzae and Corynebacterium cervicis (Laughton). Haemophilus vaginalis (Amies & Jones) was closely related to H. influenzae, and formed a group with related species; H. vaginalis (Gardner & Dukes) and C. cervicis formed separate groups; but all three groups possessed common antigenic components.
These strains of bacteria are among those reported as being related to Mycoplasma hominis, and their antigenic relationships are thus of importance in this connexion.
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The Antigenic Structure of PPLO (Mycoplasma Hominis) and Related Bacteria
More LessSUMMARY:By gel-diffusion precipitin and antigen-absorption tests, 34 strains of PPLO (Mycoplasma hominis, types 1-4) were examined, and 15 antigenic components recognized. Antigens a, b, f and g were common to types 1, 2 and 4; c was specific to type 1; h was specific to type 2. Type 3 was antigenically unrelated to the remainder. Its two recognizable components were named j and k. Three further antigens in type 1 were recognized as 17, 39 and 40, previously defined in strains of Haemophilus and Coryne-bacterium associated with mycoplasma-like variants (Pease & Laughton, 1965); antigen 40 also occurred in type 2. Two diffusible antigens, α and β, were detected in strains of types 1 and 4; these and also g were found to be shared with the bacterial strains.
All genital strains of mycoplasma isolated in this laboratory belonged to type 1, all oral strains to type 4; one rat strain belonged to type 2.
Distribution of antigenic components in strains of mycoplasma and in different strains of bacteria, including those believed to be derived from mycoplasma (or vice versa), and also in others, notably Haemophilus influenzae, supports previous claims of relationship between Mycoplasma hominis types 1, 2 and 4, Corynebacterium and Haemophilus. The validity of Mycoplasma as a distinct group of micro-organisms is thus called into question.
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Salicylate Degradation Test for Differentiation of Mycobacterium Fortuitum from Other Mycobacteria
More LessSUMMARY:Most isolates of Mycobacterium fortuitum decomposed salicylate and stained black the Sauton agar medium containing salicylate (0.5 or 1 mg./ml.); and all isolates capable of decomposing salicylate were identified as M. fortuitum. Other species, including rapidly growing mycobacteria, did not decompose salicylate. Most but not all of the salicylate-decomposing isolates showed also PAS degradation and a positive 3-day arylsulphatase test. The salicylate-decomposing isolates utilized nitrite as sole nitrogen source and about one-half of them grew on a nitrite medium within 7 days. These reactions, salicylate degradation, PAS degradation, utilization of nitrite, and 3-day arylsulphatase activity, are shown to be useful for identifying M. fortuitum. The 3-day arylsulphatase test showed some exceptional cases; therefore, a positive reaction in this test was not sufficient to identify M. fortuitum. Positive reactions in the above four tests seemed to mean that an isolate is certainly M. fortuitum.
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Conversion of Salicylate to Catechol by Mycobacterium Fortuitum
More LessSUMMARY:It was reported in a previous paper that most strains of Mycobacterium fortuitum blackened a modified Sauton medium agar containing 0.1% (w/v) sodium salicylate. The mechanism of this blackening has been investigated. When a modified Sauton medium containing 0.1% salicylate was inoculated with any of three strains of M. fortuitum, the medium became black after incubation for four days at 37°. The brownish black formazan was isolated by paper chromatography and compared with formazans from the same medium containing 0.1% (w/v) catechol inoculated with the test organisms or without inoculation. These formazans showed similar RF values in three solvent systems and the same absorption spectra (maximum absorption at below 220 and 275 mμ). It has been shown that M. fortuitum is capable of converting salicylate to catechol and that the formazan in the medium is an oxidation product of catechol.
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Thymine Incorporation and Metabolism by Various Classes of Thymine-less Bacteria
More LessSUMMARY:Escherichia coli strain 15T- yielded 109 organisms from 1 μg. thymine and growth was continuous, not diphasic. Aminopterin-selected thymine-less bacteria, on the other hand, required 20-25 μg. thymine/ml. to sustain growth, although thymine incorporation was the same as for strain 15T-, approximately 10-9 μg./bacterium. In dearth of thymine the aminopterin-derived auxotrophs underwent thymine-less death (like strain 15T-), and in 5 μg. thymine/ml., after some initial growth, also underwent thymine-less death, although thymine uptake and DNA synthesis continued at a low rate. In 20 μg. thymine/ml. (and above) growth was diphasic. From these auxotrophs were derived, presumably the result of a second mutation, strains similar to strain 15T-. These differed from strain 15T-, however, as follows: they required 2 μg. thymine/ml. to initiate growth, they formed less thymidine phosphorylase, and they did not yield a particular class of revertant characteristic of strain 15T-. The aminopterin-derived auxotrophs were a thousand times more sensitive to inhibition by cytidine and uridine than were their double mutants or strain 15T-. This was the only trait discovered to correlate with their high thymine requirement. The high thymine requirement appeared not to be due to a permeability defect. Several classes of revertants were obtained from thymine-less bacteria. The majority regained thymidylate synthetase simultaneously with loss of ability to incorporate thymine efficiently. One class from strain 15T- was unique: it regained thymidylate synthetase without losing thymine in-corporation, and represented the one exception to the rule of mutual exclusion between these two traits. The aminopterin-derived auxotrophs were a distinctive, stable, and remarkably uniform class of thymine-less bacteria. They emphasized the uniqueness of strain 15T-, and illustrated the dual differentiation from a wild type possessed by their double mutants and also by strain 15T-.
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Deoxyribonucleic Acid Base Compositions among Thermophilic Actinomycetes: the Occurrence of two Strains with Low GC Content
More LessSUMMARY:Deoxyribonucleic acid (DNA) was extracted from two strains of Thermomonospora, two strains of Thermoactinopolyspora and one thermophilic strain of Streptosporangium. Base compositions were determined from ‘melting-temperatures’ (Tm) and, in two cases, from buoyant density. DNAs from both Thermoactinopolyspora strains and one Thermomonospora strain were of similar base composition to those previously reported for mesophilic actinomycetes. The other Thermomonospora strain and the Streptosporangium strain, both of which had higher temperature requirements and tolerance for growth, possessed DNA of lower GC content. These findings are discussed in relation to phylogeny, thermophily and the universality of the genetic code.
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Carotenoids in Mutants of Verticillium albo-atrum
More LessSUMMARY:An orange mutant (M 5) obtained from a wild-type isolate of Verticillium albo-atrum by u.v. irradiation was found to contain phytoene, β-carotene, γ-carotene, neo-lycopene A, lycopene, neurosporaxanthin and four unidentified pigments. It is suggested that this simultaneous production of several carotenoid pigments by a hitherto colourless fungus may be regarded as a de-repression leading to the synthesis of a specific precursor in the pathway of carotenoid synthesis. Ultraviolet irradiation of M 5 gave a number of secondary colour mutants that were again analysed: M 5.1, M 5.3 and M 5.4 contained the same pigments as the original M 5 but in widely differing amounts. M 5.2 was colourless like wild type and contained only phytoene. M 5.5 formed a hitherto undetected pigment, torulene, lacked neo-lycopene A and lycopene and produced very little neurosporaxanthin. M 5 and M 5.5 were further investigated over an extended growth period in order to elucidate the sequence of carotenoid formation. The results are discussed in relation to possible hypotheses of carotenoid biosynthesis.
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Temperate Phages Influencing Lipase Production by Staphylococcus Aureus
More LessSUMMARY:Phages capable of changing the production of the ‘Tween’-splitting enzyme by lysogenic conversion of Staphylococcus aureus strains were isolated from lysogenic strains within the phage type 52/52A/80/81 complex.
Phages isolated from TW- strains were able to block the production of the ‘Tween’-splitting enzyme when they lysogenized TW+ strains. When the TW+ receptor strains were originally lysogenic, double lysogenization occurred. This change in the ‘Tween’ reaction was shown to be an example of lysogenic conversion. Phages isolated from TW+ strains were found able, in some instances, to change TW- strains to TW+ strains on lysogenization. This change in reaction was found to be due to loss of the converting phage carried by the recipient strains by prophage substitution. Where prophage substitution did not occur and the strains became doubly lysogenic, the strains remained TW-.
In these experiments a change of the typing pattern was found after lysogenization. The phage type of the lysogenized strain became similar to that of the donor strain. Non-typable strains were found, doubly lysogenic for phages which between them blocked all the reactions to the typing phages employed. The significance of these findings is discussed, especially the use of lysogenized strains in experiments designed to investigate the role of ‘Tween’ negavity as a virulence factor.
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The Taxonomy of certain Thiobacilli
More LessSUMMARY:Numerical analysis has been applied to the taxonomy of certain Thiobacilli; 54 strains were examined, including both authentic cultures and new isolates, using 48 tests. The groups found corresponded to Thiobacillus trautweinii, T. novellus, T. thioparus and T. neapolitanus, and these were very well differentiated with no intermediate organisms. A check of the numerical method indicated that the results were independent of the tests used. A comparison of authentic strains from different laboratories showed their characteristics to be very stable, and any changes were within the error of the test method.
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Efflux of Macromolecules from Washed Dictyostelium Discoideum
More LessSUMMARY:Dilution of washed Dictyostelium discoideum amoebae in distilled water leads to an essentially immediate and specific efflux of RNA and protein into the extracellular environment. A substance's ability to prevent leakage correlates with its ability to stimulate the rate of morphogenesis.
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The Cell Walls of Streptococci
More LessSUMMARY:The cell-wall compositions of 197 strains of streptococci were determined by paper chromatography. The residues formed 26 patterns, but 117 strains had one or other of only 3 patterns. The results suggest possibilities for future investigations of some poorly defined taxa.
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Self-heating of Hay and Grain in Dewar Flasks and the Development of Farmer's Lung Antigens
More LessSUMMARY:In moist hay allowed to self-heat aerobically in Dewar flasks, the pattern of temperature change with time was affected considerably by the type of hay and duration of storage, but there was a relationship between water content and maximum temperature reached. Below 29% water content there was little heating or antigen production; in the critical range of 29-34% water content, different lots of hay self-heated to different temperatures between 33 and 55° and varied widely in their content of farmer's lung hay antigen complex (FLH), the wetter hays usually producing the more antigen; all samples with 40% water heated to c. 65° and produced FLH antigen, associated with the presence of Thermopolyspora polyspora. Progressively less antigen, especially in the lower regions of the flasks, was produced as water content increased from 47 to 68%. Moist barley and oat grain also self-heated and produced FLH antigen, usually only in the middle of the grain mass, where T. polyspora was most abundant; the drier upper layers and the lower regions where excess water accumulated were free from the antigen.
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Carotenoids and Cholesterol in Membranes of Mycoplasma Laidlawii
More LessSUMMARY:Carotenoids synthesized by Mycoplasma laidlawii and cholesterol incorporated from the growth medium were confined to the cell membrane. Increased carotenogenesis induced by addition of sodium acetate to the growth medium, or inhibition of carotenogenesis by thallium acetate or diphenylamine did not affect the incorporation of cholesterol into membrane lipids. Growth of the organisms in media with various amounts of cholesterol modified the cholesterol content of the membranes with no significant effect on carotenoid formation. These results indicate that carotenoids do not interfere with the incorporation of cholesterol into M. laidlawii membranes.
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- Society For General Microbiology: Proceedings
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- Book Received
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