摘要:

Mycodextranase is an α-glucanase which splits only the α-1,4 linkages in a substrate having alternating α-1,3 and α-1,4 links. It ïs a fungal enzyme of rather infrequent occurrence, adaptive in nature, and in its properties strongly resembling other fungal glucanases. The products of its action on mycodextran are a tetramer and nigerose. The hypothesis is advanced that this glucanase, and others, contain a site which binds a dimeric portion of the polymer; in mycodextranase, the bound dimer is nigerose, the α-1,3-disaccharide.

ISSN:0008-4166    

DOI:10.1139/m64-017

出版商:NRC Research Press    

年代:1964

数据来源: NRC

摘要:

not available

ISSN:0008-4166    

DOI:10.1139/m64-018

出版商:NRC Research Press    

年代:1964

数据来源: NRC

摘要:

Sonic extracts ofB.pertussiswere fractionated by chromatography employing DEAE-cellulose. Mouse protective antigen (MPA) was absorbed to the column and was found to be eluted over a range of salt concentrations from 0.05 to 0.35 MNaCl in dilute phosphate buffer, pH 7.2. The MPA was freed from nucleic acid impurities since these remained fixed to the column and could only be eluted with salt concentrations of 0.5 to 2.0 molarity. Some impurities of protein nature passed directly through the column. The measurable precipitating antigens associated with the crude extract were fractionated into two groups by the DEAE-cellulose. Dilute buffer elutions removed material that developed several cathodic bands by immunoelectrophoresis. More concentrated salt buffers eluted materials that exhibited one anodic band by immunoelectrophoresis against the wholeB.pertussisantiserum. The measurement of significant potencies of MPA in the absence of either cathodic or anodic precipitinogens suggests that the latter represent impurities which may or may not have a relation to other known biological activities associated withB.pertussis(e.g., toxin).Certain discrepancies between mouse protective antigen and histamine-sensitizing factor based on the lack of proportionality of the activities from fraction to fraction suggest that their chemical natures are dissimilar.

ISSN:0008-4166    

DOI:10.1139/m64-019

出版商:NRC Research Press    

年代:1964

数据来源: NRC

摘要:

Combined manometric and radioactive techniques were used to determine oxygen uptake and C14O2evolution during the oxidation of C14-acetate in soil. It was found that a large percentage of C14O2is remained in the soil causing anomalous respiratory quotients during the first hours of respiration. Acidification of the soil to pH 5.0 released this residual C14O2with the result that the total C14O2collected after the acid treatment compared favorably with the corresponding oxygen uptake. Recovery of C14O2during the 6 hour exposure of soil to C14-acetate indicated that only 30% of the substrate was completely oxidized. The remainder of the acetate is assimilated into microbial tissue to be deposited eventually in the soil organic fraction.

ISSN:0008-4166    

DOI:10.1139/m64-020

出版商:NRC Research Press    

年代:1964

数据来源: NRC

摘要:

Studies were conducted to examine further the circumstances prevailing during the phase of rapid decline in the respiration rate of soil after the addition of a soluble carbon substrate, and to investigate the potential metabolic activity of the microbial population at different stages in its sequential development. When the supply of required inorganic nutrients was adequate, the rapid decline in the rate of respiration following attainment of the respiratory peak resulted primarily from depletion of available carbon substrates, even though by this time only 30 to 50% of the carbon in the substrate (glucose) added had been recovered as CO2. Supplementary additions of the same substrate, regardless of the concentration and time of addition, however, did not elicit secondary peaks comparable in height to the primary peaks, nor was the recovery as CO2from the supplements as high as from the initial substrate addition. This attenuation of the metabolic activity was attributed to limiting factors introduced by the initial growth of a large and active microbial population which restricted the development of sequential populations. The nature of these limiting factors and their implication in maintaining the ecological balance of microorganisms in soil are discussed.

ISSN:0008-4166    

DOI:10.1139/m64-021

出版商:NRC Research Press    

年代:1964

数据来源: NRC

摘要:

Zoospores ofPythium aphanidermatumin distilled water suspension responded to intact pea roots by massing in large numbers at the sites of elongation behind the root tips. They showed preferential attraction to wounds made by puncturing the epidermis, and to the stele exposed at the cut ends of roots. Massing of zoospores was followed, almost immediately, by encystment and early germination, the germ tubes being directed towards the source of stimulation. The phenomenon was non-specific over a wide range of plants examined. Root exudate and extract, diffusing from the ends of capillary tubes containing these materials in agar, caused identical zoospore responses. Analysis of zoospore movement under stimulation revealed a sequence of responses—initial disruption of the typical course of movement, attraction, trapping, and early cessation of movement by encystment. Attraction was equated with chemotaxis, whilst trapping showed features of kineses.

ISSN:0008-4166    

DOI:10.1139/m64-022

出版商:NRC Research Press    

年代:1964

数据来源: NRC

摘要:

A comparison was made of the minimal inhibitory concentrations (MIC) of penicillin G, methicillin, oxacillin, and cephalosporin C for 16 non-penicillinase-producing strains ofStaphylococcus aureusfrom cows with mastitis and on 22 penicillinase-producing strains (20 from cows with mastitis and 2 from humans), All strains were sensitive to methicillin, oxacillin, and cephalosporin C. The addition of whole or skim milk did not affect the tests. Strains with induced resistance to one of the three latter antibiotics developed resistance to the other two. By increasing the inocula of organisms in the test, the MIC was increased to the greatest extent with penicillin, to some extent with oxacillin, and negligibly with the other two antibiotics.

ISSN:0008-4166    

DOI:10.1139/m64-023

出版商:NRC Research Press    

年代:1964

数据来源: NRC

摘要:

Several aspects of processing human amnion for tissue culture were studied, with particular emphasis on cell separation and infection control. EDTA proved a desirable substitute for trypsin as a wash and predigestion agent. Cultures for bacteria and fungi showed most amnions to be infected with bacteria or yeast or both. Chloramphenicol, benzyl penicillin, or Ilosone were the most effective antibiotics against bacteria and Mycostatin the most effective antibiotic against yeast.

ISSN:0008-4166    

DOI:10.1139/m64-024

出版商:NRC Research Press    

年代:1964

数据来源: NRC

摘要:

A strain ofPseudomanasisolated from soil with cinnamic acid as a sole carbon source was found to be simultaneously adapted to the utilization of cinnamic acid and phenylpropionic acid. During growth on either of these compounds,o-hydroxyphenylpropionic acid and 2,3-dihydroxyphenylpropionic acid were produced in the culture medium. The organism, when grown on either cinnamic acid or phenylpropionic acid, was adapted to the utilization ofm-hydroxyphenylpropionic acid and 2,3-dihydroxyphenylpropionic acid, but not to the utilization ofo-hydroxyphenylpropionic acid. According to the principle of sequential induction introduced by Stanier, the initial steps in the metabolism of cinnamic acid appear to involve the intermediates phenylpropionic acid,m-hydroxyphenylpropionic acid, and 2,3-dihydroxyphenylpropionic acid.

ISSN:0008-4166    

DOI:10.1139/m64-025

出版商:NRC Research Press    

年代:1964

数据来源: NRC

摘要:

The fatty acid compositions of the mycelia of a parasitic species ofPythiumand of various hosts are reported. ThePythiumspp. contained high concentrations of myristic acid and low concentrations of linoleic and linolenic acids in comparison with concentrations in other fungi tested. Appreciable amounts of unsaturated C20acids, uncommon in fungi, were found in the Phycomycetes tested. Vegetable oils and other fats of widely varying fatty acid compositions were all effective in stimulating sexual reproduction of thePythiumsp. It was concluded that substance(s) other than fatty acids present in the vegetable oils were responsible for the stimulation observed. The most active fraction in sunflower seed oil was isolated and identified as a phytosterol, probably β-sitosterol. The results of testing for stimulatory activity a series of structurally related compounds indicated that the sexual reproduction of thePythiumsp. studied required the presence of a substance such as β-sitosterol or cholesterol or one with similar structure and which similarly satisfied certain specific structural requirements regarding length of the C17side chain, stereochemistry, and position of the oxygenated function. β-Sitosterol and cholesterol were effective at 0.2 γ/ml in potato dextrose agar.

ISSN:0008-4166    

DOI:10.1139/m64-026

出版商:NRC Research Press    

年代:1964

数据来源: NRC