- Volume 36, Issue 2, 1964

Summary: Bacteria able to decompose α-conidendrin were isolated from three of five soil samples by enrichment on this compound as sole source of carbon and energy. All the isolates obtained were small Gram-negative motile poorly flagellated rods, which were classified as members of the genus Agrobacterium. The ability of these bacteria to oxidize phenolic compounds was examined by manometric studies. From calculations of oxygen uptake, it was concluded that the oxidative rupture of the benzene ring of m- and p-hydroxybenzoic acid by these bacteria could not be explained entirely by the known metabolic paths which lead from these hydroxy-benzoic acids to protocatechuic acid or gentisic acid. It was indicated by simultaneous adaptation technique that neither monohydroxybenzoic acids nor monohydroxycinnamic acids were likely to be formed during the oxidative breakdown of α-conidendrin by these agrobacteria.

By the application of respirometric techniques, it was found that the a-conidendrin (I)-decomposing agrobacteria included strains which were adaptively or constitutively lignanolytic. The lignans isotaxiresinol (V), iso-olivil (VI), and olivil (VII) were rapidly oxidized by all the bacteria examined. The adaptive organisms showed a time-lag before oxidation of the lignans if they had been grown on a conidendrin-free medium. The lag required for oxygen uptake with a-conidendrin was shorter than that observed for the other lignans. Matairesinol (IV), which differs structurally from α-conidendrin through the lack of the ‘isolignan’ bond was not attacked by any of the agrobacteria examined. Olivil and iso-olivil were oxidized identically, giving results which indicate that the organisms bring about the isomerization olivil →iso-olivil. α-Conidendrol (II) was indicated by the simultaneous adaptation to be an intermediate in α- conidendrin decomposition. All the bacteria studied possess a constitutive ability to oxidize aromatic aldehydes (vanillin, iso vanillin, veratrum- aldehyde, syringaldehyde). By calculation from the total oxygen uptake, and by paper chromatography, it was found that these oxidations gave the corresponding acids. Simultaneously with oxidation to vanillic acid, a small amount of vanillin was reduced to vanillyl alcohol. Coniferyl alcohol was oxidized to ferulic acid.

SUMMARY: Fresh clinical isolates of Gram-positive and Gram-negative bacteria were tested for the production of β-lactamase and amidase. Techniques for identifying and studying the latter enzyme are described, in relation to its action upon penicillins and other substrates. Various commensal and pathogenic Gram-negative bacilli produce a ‘pen-amidase’ of relatively narrow specificity, though no species invariably produces it. A specific pen-amidase was not formed by the Gram-positive bacteria examined, though nonspecific amidases were present. Escherichia coli and paracolon bacilli produced pen-amidase more often than β-lactamase but the Klebsiella-aero- genes group did the reverse. Among other organisms, enzyme production was very variable but absence of either enzyme did not necessarily connote sensitivity of an organism to any penicillin. Administration of penicillin to a patient promotes colonization of the gut and oropharynx by β-lactamase- forming coliforms, but not of amidase-forming organisms. There is a strong association between resistance to the penicillins and formation of β-lact- amase by an organism; with pen-amidase, the association is less strong. Neither enzyme accounts completely for bacterial resistance to the penicillins, even within any one species of organism, but the lower resistance of coliforms to ampicillin may be related to the lesser susceptibility of this derivative to amidase.

SUMMARY: The carbonyl-β-lactam absorption band of penicillins and cephalosporins at 1760 cm.−1 is detectable when the antibiotics are mixed with enzymes or bacterial protein. This band can therefore be used for differentiating the two inactivating enzymes β-lactamase and amidase. Examined thus, methicil- lin, cloxacillin, amino-cephalosporanic acid (7-ACA) and thienylacetamido- 7-AC A were stable to staphylococcal β-lactamase but less stable to coliform β-lactamase. Only quinacillin among a range of therapeutic derivatives tested resisted both types of β-lactamase. The other inactivating enzyme, amidase, can exist independently of β-lactamase in coliform organisms. When methicillin and cloxacillin were treated with amidase, they lost their stability to β-lactamase.

Growth of Escherichia coli was partially inhibited by 1·2 × 10−4 m-ethidium bromide, a phenanthridinium trypanocide. In the presence of manganese the drug’s effect was decreased. During growth in the presence of ethidium, RNA and protein contents were relatively unaffected when comparison was made between experimental and control cultures at similar turbidities; DNA content, on the other hand, was considerably decreased. A differential effect of ethidium on the formation of polynucleotide pyrimidines from labelled uracil and orotic acid was observed. Oxygen uptake continued almost unchanged during growth whether in the presence or absence of drug.

Bacillus cereus was extremely sensitive to the growth-inhibitory action of ethidium (10−5 m) and morphological changes were observed. Manganese protected the organisms from the drug’s actions. RNA and DNA biosynthesis were both suppressed during inhibition of growth to a greater extent than was total protein formation, whereas diaminopimelic acid incorporation into cell wall and oxygen uptake continued almost unaffected. Some evidence was obtained that the pattern of protein synthesis was disturbed.

It was concluded that the drug’s actions were species dependent, and that the effect on Escherichia coli resembled that described for a flagellate, while that on Bacillus cereus did not. Evidence for compartmentation of nucleic acid synthesis, as obtained with the drug in tumour cells, was not shown for either micro-organism.

SUMMARY: A deoxyribonuclease-treated deoxyribonucleic acid (DNase and DNA), further supplemented with all eight of the naturally occurring deoxynucleo- sides and deoxynucleotides enhanced the rate and extent of multiplication of several virulent strains of group A ^-haemolytic streptococci (Streptococcus pyogenes) without affecting the multiplication of related avirulent strains. Ribonucleic acid (RNA) degradation products or yeast extract did not exert such selective effects. An enhancement of DNA synthesis occurred in suspensions of virulent strains augmented with the DNA degradation products, whereas avirulent strains did not respond. In addition, DNA synthesis was enhanced selectively in comparison to RNA and protein syntheses. The rate at which mice succumbed to infection by streptococci was enhanced considerably by the DNA degradation products, but the LD 50 remained unchanged.

SUMMARY: Mn2+ depressed the rate and extent of multiplication of several virulent strains of group A beta-haemolytic streptococci {Streptococcus pyogenes), and caused a 6–12 hr increase in the lag phases of related avirulent strains. Several other cations did not exert such differential inhibitory effects. Ca2+ overcame the inhibitory effects of Mn2+ in both kinds of organism. In suspensions of virulent strains, Mn2+ depressed both nucleic acid and protein syntheses below the control values, but only nucleic acid synthesis was depressed in avirulent-organism suspensions; protein synthesis was largely unaffected. The oxidation of glucose was depressed below control values by Mn2+ to a much greater extent in virulent strains than in avirulent strains.

SUMMARY: Wet and dry Gram staining procedures have different characteristics in respect to their rates of decolorization. It has been proposed that this difference is due to a Gram-positive substrate which dissociates (becomes Gram-negative) in the presence of water. However, the differences between wet and dry Gram procedures can also be explained on the hypothesis that water influences the rate of solvent permeation through cell envelopes. Since no direct proof exists for the reality of the proposed Gram-positive substrate, and since evidence is presented here which cannot be explained by such a hypothesis, it is felt that the solvent permeation concept should be considered seriously as an explanation for the decolorization differences observed between wet and dry Gram procedures.

The interphase nucleus of Gonyaulax tamarensis is U-shaped with a lens-shaped central body lying between the arms of the U. At the beginning of division the chromosomes become arranged around the central body and can be seen to be split into pairs of chromatids which are held together by relational coiling. The pairs lie across the plane of the equator. The beginning of anaphase is obscure but as the chromatids separate into the daughter nuclei they exhibit a variety of arrangements which seem to exclude the possibility of localized centromere and normal spindle. The central body divides into two at this stage. During telophase the ball of chromosomes breaks open and the chromosomes lose some condensation as they twist together and the U-shaped interphase nucleus is re-established. In some of these features Gonyaulax differs from other dinoflagellates which have been studied as well as exhibiting a vastly different nuclear division to that found in higher organisms. The central body behaves like the endosome of the Euglenophyta but also has similarities with the central spindle reported from certain flagellates and diatoms.

Summary: The two chrysomonads, Coccolithus huxleyi and a Hymenomonas sp., contained chlorophylls a and c, carotene and fucoxanthin, and a number of minor xanthophylls. Coccolithus huxleyi was rich in chlorophyll c and had a chlorophyll a:c ratio of 1·5:10; in Hymenomonas the ratio was 5:1. Incubation of broken-cell preparations at high light intensities resulted in the decomposition of chlorophyll a, whereas chlorophyll c was stable under these conditions. This photochemical bleaching of chlorophyll a shifted the spectrum from 678 to 674 mµ with a difference spectrum showing a maximum at 680 mµ Maximum photosynthetic rates of 150-200 µmoles CO2/mg. chlorophyll a + c/hr were reached in 10-day cultures. Maximum populations of 106 organisms/ml. for Hymenomonas and 107 for C. huxleyi were reached in about 14 days. Hymenomonas grew best at light intensities of 800 ft.c. or higher, whereas growth of C. huxleyi was independent of light intensity above 60 ft.c. Maximum photosynthetic rates were obtained at a light intensity of 3500 ft.c.

SUMMARY: A low-sporing isolate of Pithomyces chartarum was grown in submerged liquid culture in defined medium, and a hyphal wall fraction isolated by mechanical disruption. It contains about 20% protein, 40% bound hexoses, 10 % bound glucosamine, 10 % lipid and 5 % ash.

SUMMARY: Cytological changes in Candida albicans, associated with exposure to the antimicrobial agent thiobenzoate, were investigated with the electron microscope. After incubation of proliferating cells for 2–3 hr with the inhibitor, the nucleus displayed a lessened electron density. Following this, gaps appeared in the nuclear membrane and canaliculi emanated toward the periphery of the cell. Complete loss of cytoplasmic organization appeared to be the terminal event. These changes were shown to differ from those incurred during autolysis, induced either by substrate deprivation by washing, or by a combination of substrate deprivation and accumulation of metabolic products in an ageing culture.

Partially purified preparations of the Kofi Pare isolate of cocoa swollen-shoot virus (CSSV) were usually inactivated after 10 min. at 50°, but not after 10 min. at 45°. Infectivity of freshly made preparations was greatly lessened by diluting 1/10, and lost at 1/100. The infectivity of preparations increased after storage for 24 hr; after 96 hr infectivity was retained at 0–4° but soon lost at 25°. The virus survived freezing in vitro and, with some loss of infectivity, freezing in leaves and storage in leaves dried over aluminium oxide. Infective material was precipitated from dilute extracts by half saturation with ammonium sulphate at 25°; it appeared to be equally stable over the range pH 6 to pH 8. Preparations of the sympto-matologically distinct Kofi Pare, Mampong, Dawa, Nsaba and Bosomuoso isolates all contained similar rod-shaped particles of size about 121 × 28 mμ.

Summary: Analysis of the genetic behaviour of the colicinogenic factor E1 (colEj) in crosses involving Hfr or F+ and F− strains of Escherichia coli k12 shows: (1) this factor is transferred with very high frequency from different donor bacteria; (2) its transfer begins to take place early whatever the type of donor cell; (3) it is not linked with chromosomal markers; (4) it multiplies autonomously in the zygote at such a rate that its passage to all descendent cells is assured; (5) the non-colicinogenic character of the donor parent does not appear among recombinant or recipient cells; (6) no lethal zygosis occurs related to the transfer of a presumptive colE 1 − locus.

All these facts suggest that colE 1 exists in an extra-chromosomal state in Hfr, F+ and F− bacteria.

No transfer of colE 1 from F− to F− or Hfr bacteria was observed.

SUMMARY: Nuclease activity was observed in several saprophytic and parasitic Mycoplasma organisms; the nucleases of Mycoplasma laidlawii were studied in detail. Nuclease activity of this organism was highest at the early logarithmic phase of growth, and was found mainly in the soluble fraction of the organisms. Anion-exchange chromatography of the proteins of the soluble fraction separated ribonuclease from deoxyribonuclease activity. Each enzyme had an alkaline pH optimum, required magnesium ions for activity, and degraded native and heat-denatured nucleic acids. M. laidlawii RNase degraded RNA-core. RNA inhibited the degradation of DNA by M. laidlawii deoxyribonuclease. The implications of these findings with respect to the effects of RNA and DNA on growth of M. laidlawii are discussed.