摘要:

Of 289 fungi and actinomycetes tested, only 20 were found to produce high yields of proteolytic enzymes when grown in submerged culture. Strains ofGliocladium roseumandAlternaria tenuiswere found to be consistently proteolytic, and other good strains were also found in the generaChaetomium,Sordaria,Epicoccum,Rhizoctonia, andStreptomyces.

ISSN:1923-4287    

DOI:10.1139/cjr50c-034

出版商:NRC Research Press    

年代:1950

数据来源: NRC

摘要:

The main factors that influence the production of proteolytic enzymes by a few selected cultures have been studied. The time taken to reach the maximum yield of proteases is dependent upon the growth rate of each organism, and varies from two to five days. The fungi tested require the presence of an easily available carbohydrate source in addition to a protein substrate in order to produce high yields of proteolytic enzymes. TheStreptomycescultures will produce proteases in the absence of a carbohydrate source, but yields are generally low. The fungi studied will not produce significant amounts of proteases when grown on predominately inorganic nitrogen sources in contrast with theStreptomycescultures, one of which produced almost as high yields of proteolytic enzymes when grown with sodium nitrate as when grown with Klim. Of a number of protein sources Klim and malt sprouts provided the best media for protease production. The temperature of incubation and pH of the culture medium are also important factors affecting the yield of proteolytic enzymes.

ISSN:1923-4287    

DOI:10.1139/cjr50c-035

出版商:NRC Research Press    

年代:1950

数据来源: NRC

摘要:

Some of the general characteristics of the proteases liberated into the culture medium by molds and actinomycetes grown in submerged culture have been studied. Species ofAlternaria,Streptomyces,Mortierella, andGliocladiumwere used. The enzymes resemble trypsin in that they are most active at a pH slightly above 7 and are inhibited by a preparation of egg albumin. They are stable at low temperatures but suffer marked losses in activity when stored for 16 hr. above 40 °C. The most rapid hydrolysis of gelatin occurs at temperatures between 40 °C. and 50 °C. The enzymes from different organisms show definite differences with respect to their ability to attack different proteins, gelatin and casein being in general the most readily digested. The protease systems from different organisms also vary with respect to the extent to which they can digest gelatin; some enzymes are able to release about three times as many amino groups from gelatin as others. The limit of the hydrolysis is not dependent upon substrate concentration but is slightly affected by the concentration of enzyme. The enzymes were effective in liberating free amino acids from gelatin.

ISSN:1923-4287    

DOI:10.1139/cjr50c-036

出版商:NRC Research Press    

年代:1950

数据来源: NRC

摘要:

The optimum temperature for fermentation of seven strains of the Ford type ofBacillus subtilisis close to 45 °C. At these higher temperatures 10% glucose or equivalent hydrolyzed molasses ferments completely in six days while 10% fructose takes only three days. The rate of fermentation is similar under aerobic or anaerobic conditions but agitation or shallow layers of media increase this rate. The yields of 2,3-butanediol, acetoin, glycerol, and lactic acid are high under anaerobic conditions but in the presence of oxygen the yield of glycerol and lactic acid is decreased. The organism demonstrates strong oxidative tendencies and can give a large yield of acetoin. Other factors affecting the fermentation are also assessed.

ISSN:1923-4287    

DOI:10.1139/cjr50c-037

出版商:NRC Research Press    

年代:1950

数据来源: NRC

摘要:

Antibiotic XG has been studied for its possible application as a pea seed treatment in the control ofAscochytaleaf and pod spot. Fungistatic properties of Antibiotic XG againstAscochyta Pisiat various concentrations in relation to pH and temperaturein vitrowere studied. At antibiotic concentrations up to 1 p.p.m. no fungistatic effect was observed at pH values from 3.5 to 6.5, but, at concentrations above 1 p.p.m., complete inhibition of growth was found at all pH values tested. In the temperature range of 22 °C. to 30 °C. antibiotic concentrations of 1 p.p.m. had no effect on growth. Fungicidal activity to spores ofA.Pisihas also been tested. A spore suspension of 10,000 spores per ml. required an exposure of 12 hr. with an antibiotic concentration of 100 p.p.m. for complete lethal dosage. The soaking of diseased pea seed samples in Antibiotic XG at a concentration of 25 p.p.m. for a period of 18 hr. effectively controlsA.Pisiinfection as determined by laboratory test and does not seriously impair germination. This treatment is compatible with Spergon applied after the seed has been air-dried. Storage of treated seed for a period of three months did not affect the degree of control but reduced the germinative capacity in laboratory plate tests.

ISSN:1923-4287    

DOI:10.1139/cjr50c-038

出版商:NRC Research Press    

年代:1950

数据来源: NRC

摘要:

Elongation of the vegetative branch of the blueberry ceases early in June owing to the death of both the apical meristem and the distal portion of the axis. Coincident with this is the development of a flowering branch primordium in the axil of the penultimate leaf. During July, the apical meristem of the flowering branch becomes inactive. It is either laterally displaced or it elongates as a minute unbranched columnar structure. Coincident with this inactivation, the proximal flower primordia develop florets in which all flower parts may be recognized, but the distal flower primordia, that is those adjacent to the inactivated apical meristem, are retarded in their development. The retarded distal flower primordia are developed in acropetal succession but the proximal flower primordia do not exhibit acropetal succession. All the stages are illustrated by line diagrams.

ISSN:1923-4287    

DOI:10.1139/cjr50c-039

出版商:NRC Research Press    

年代:1950

数据来源: NRC

摘要:

Investigations into the biology ofSeptoria lycopersiciSpeg., a leaf-spotting fungus parasite of the tomato, reveal that this fungus species is composed of at least two physiologic races which show both qualitative and quantitative differences in their pathogenicity. Other factors, such as humidity, temperature, light, and host nutrition, which influence host–parasite interaction, have been shown to cause further variability in the symptomatological picture. Studies of spore germination and the prepenetration phase of host–parasite relationships suggest an interaction before actual penetration which, in some cases, is sufficient to condition the germination of the spores themselves. A minimum period of 48 hr. at saturation is required to promote germination and stomatal penetration, but this experience at high humidity need not be continuous. The fungus inhabits an intercellular locus, but is very intimately associated with the cells of the tissues parasitized. There is no evidence of action in advance; rather a certain measure of host–parasite equilibrium is maintained, and the pathogen is enabled to complete its life cycle and reinitiate infection. Although this evidence suggests a rather high degree of specialization of parasitism, the nature of the host–parasite association is yet considerably removed from that of an obligate relationship. It is pointed out that whileS.lycopersicimight be considered, in the sense of de Bary, either as a facultative saprophyte or an obligate parasite, its peculiar behavior makes it exceedingly difficult, if not impossible, to place it into any one category which might describe its biological activity.

ISSN:1923-4287    

DOI:10.1139/cjr50c-040

出版商:NRC Research Press    

年代:1950

数据来源: NRC

摘要:

Carbonic anhydrase was found in leaf extracts prepared from 19 of 22 land and aquatic plant species examined. The most active preparations were obtained fromSpinacia oleraceaL.,Tetragonia expansaThunb.,Tropaeolum majusL., andSambucus canadensisL. Carbonic anhydrase is located in the leaf cytoplasm. Previously conflicting observations concerning its intracellular localization have been reconciled experimentally. Plant carbonic anhydrase is strongly inhibited byM/1000 azide,M/1000 cyanide, andM/2000 sulphanilamide and is weakly inhibited by 2,4-dichlorophenoxyacetic acid, diethyldithiocarbamate, ando-phenanthroline. The white zones of variegatedTradescantialeaves contain 50% less carbonic anhydrase than their green counterparts. Albino barley leaves contain 75% less carbonic anhydrase than normal barley leaves of the same size and age. The carbonic anhydrase content of green leaves kept in darkness for four and five days was lowered by 30–50%. Very young leaves contain less enzyme than mature leaves. These results are discussed in relation to the possible role of carbonic anhydrase in photosynthesis.

ISSN:1923-4287    

DOI:10.1139/cjr50c-041

出版商:NRC Research Press    

年代:1950

数据来源: NRC

摘要:

Of 660 cultures of actinomycetes isolated on a nonselective basis from soils from five locations in Northern Canada, 404 strains, or 61.2%, showed antagonism against at least one of eight test organisms consisting of five bacteria and three plant pathogenic fungi. The degree of activity ranged from slight to strong, with the number of test organisms inhibited by any single culture varying from one to six. In all, 49 different antibiotic spectra were observed. Activity against one or more of the pathogenic fungi was shown by 138 cultures, 20.9% of the isolates. The percentage of active cultures was greater, and the degree of inhibition much more marked, againstHelminthosporium sativumthan againstFusarium culmorumorFusarium lini. The percentage of active isolates varied with the location and with the depth of the soil. It is suggested that the high proportion of actinomycetes with antagonistic properties occurring in northern soils may be related to the lower degree of plant development in such regions.

ISSN:1923-4287    

DOI:10.1139/cjr50c-042

出版商:NRC Research Press    

年代:1950

数据来源: NRC

摘要:

Turnip plants, heavily infested with the cabbage aphid,Brevicoryne brassicae(L.), and the green peach aphid,Myzus persicae(Sulz.), were inoculated with a virulent strain ofXanthomonas campestris(Pammel), the causal organism of black rot disease of turnips, and placed in special cages together with healthy turnip plants. Some aphids of both species were allowed to migrate naturally, and others were transferred mechanically from the diseased to the healthy plants, but no symptoms of black rot ever appeared in any of the latter plants.X.campestriswas isolated from only 15% of theB.brassicaeand from less than 1% of theM.persicaetaken from the diseased plants. Aphids of both species were artificially contaminated externally withX.campestrisby exposures to Petri plate and broth cultures of the pathogen. Internal contamination of other aphids of both species was accomplished by feeding them 0.2% aqueous dextrose solutions containingX.campestris. The pathogen was isolated from individuals m both groups of aphids thus contaminated, but none of the aphids in either group was able to infect caged, healthy turnip plants with black rot.

ISSN:1923-4287    

DOI:10.1139/cjr50c-043

出版商:NRC Research Press    

年代:1950

数据来源: NRC