摘要:

Cellulolytic fungi were evaluated for their ability to use wheat bran and produce extracellular enzymes capable of solubilizing carbohydrate and protein fractions from wheat bran.Trichurus cylindricusgrew better than all other organisms tested and excreted an extracellular enzyme system which was distinguished by high C1and Cxcellulase and proteolytic activity. Evidence was also obtained for the existence of a partially extracellular lignolytic enzyme system. The extracellular enzyme system possessed high activity towards wheat bran and the dilute enzyme was able to bring about a 28% weight loss from the insoluble fraction of the wheat bran substrate in 24 h. The extracellular enzyme system fromTrichoderma virideandMyrothecium verrucariawere also studied but they were found to be inferior to those ofTrichurus cylindricusfor the solubilization of wheat bran. However, the crude enzyme preparation fromTrichurus cylindricushad a lower activity towards purified cellulose than the enzyme fromTrichoderma viride.

ISSN:0008-4166    

DOI:10.1139/m70-025

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

Radioactivity fromL-phenylalanine-carboxyl-14C was incorporated specifically into the carboxyl group of cinnamamide by cultures ofStreptomyces verticillatus.L-Phenylalanine ammonia-lyase (EC. 4.3.1.5) could be extracted from the mycelium. Cultures grown in defined medium produced little cinnamamide unless supplemented withL-phenylalanine; phenylalanine ammonia-lyase activity in the mycelium was directly related to the yield of cinnamamide.

ISSN:0008-4166    

DOI:10.1139/m70-026

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

Substitution of a chromosome pair (5B) from Apex (A), a variety of spring wheat (Triticum aestivum) relatively resistant to common root rot (primarilyCochliobolus sativus), for the corresponding chromosome of S-615 (S), a highly susceptible variety, changed the rhizosphere microflora qualitatively and quantitatively. Microbial analyses of the parental varieties, the substitution line (S-A5B), and non-rhizosphere soil included estimates of total microbial populations and physiological and nutritional groupings. In all characteristics a typical rhizosphere effect was evident, and significant differences were found between the different rhizospheres. In most characteristics the rhizosphere microflora of the substitution line was significantly different from either parent. The incidence of rhizosphere bacteria antagonistic toC.sativuswas the most notable exception. Twenty percent of the rhizosphere isolates from both Apex and the resistant substitution lineS-A5Bwere antagonistic toC.sativus. None of the isolates from the susceptible variety was antagonistic. The differences between the rhizospheres of the substitution line (S-A5B) and the recipient variety (S-615) are attributable to changes induced by disomic substitution of chromosome 5B.

ISSN:0008-4166    

DOI:10.1139/m70-027

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

The morphological parameters of the cylindrical gas vacuoles in the blue-green alga,Microcystis aeruginosa, were investigated by quantitative electron microscopy. The gas vacuoles are made up of a single layer of particles of 2.8 × 4.2 × 3 nm size. The particles are linearly arrayed in ribs that wind helically around the main axis of the organelle. The diameter of the cylinders is 71.1 ± 2.7 nm and their length is in the range of 360 ± 90 nm. The gas vacuoles can be flattened out under hydrostatic pressure.

ISSN:0008-4166    

DOI:10.1139/m70-028

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

Temperature-sensitive mutants of the RNA phage R17 were induced by treatment with 10−5 M5-fluorouracil. One of the temperature-sensitive mutants,ts24, was studied and the following facts were discovered: (1)ts24undergoes eclipse at the non-permissive temperature, 43 °C. (2) If the temperature is increased to non-permissive levels before 60 min of postinfection culture, phage multiplication ceases. (3) At 43 °C,ts24cannot synthesize progeny viral RNA. (4) Upon decreasing the temperature to permissive levels during the first 60 min of postinfection culture, RNA replication resumes almost instantaneously. It was concluded from these facts thatts24contains a temperature-sensitive mutation in the RNA replicating function.

ISSN:0008-4166    

DOI:10.1139/m70-029

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

When14C-labeled chloramphenicol was added to chloramphenicol-producing cultures ofStreptomycesstrain 13s, radioactivep-nitrophenylserinol, N-acetyl-p-nitrophenylserinol,p-nitrobenzyl alcohol, andp-nitrobenzoic acid were formed. The rate of catabolism varied with culture conditions. It was fastest during rapid growth on a medium supporting low chloramphenicol production. Periodic analysis of cultures indicated thatp-nitrophenylserinol accumulated only transitorily and was rapidly N-acetylated. In support of this conclusion14C-labeledp-nitrophenylserinol was rapidly and completely metabolized, giving mainly the N-acetyl derivative.p-Nitrobenzyl alcohol andp-nitrobenzoic acid were formed in only small amounts during catabolism of chloramphenicol orp-nitrophenylserinol. Chloramphenicol inhibited growth ofStreptomycesstrain 13sby increasing the lag phase. It also appeared to inhibit antibiotic synthesis. However, cultures supplemented withD-glucose-U-I4C produced radioactive chloramphenicol even when exposed to high concentrations of the antibiotic, and the titer at any time thus represents the product of both catabolic and biosynthetic reactions.

ISSN:0008-4166    

DOI:10.1139/m70-030

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

Enzymes of the Embden–Meyerhof–Parnas, tricarboxylic acid, glyoxylate, and pentose phosphate pathways were detected inVenturia inaequalis(Cke.) Wint. grown in potato dextrose broth.

ISSN:0008-4166    

DOI:10.1139/m70-031

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

When cell walls ofSchizosaccharomyces pombewere removed, the protoplast contained most of the ribonuclease but only about 50% of the aminopeptidase activity. In cell homogenates approximately 75% of the total peptidase activity was in the soluble fraction; the membrane fraction retained an average of 25% while the ribosomes had less than 1% of the total activity. The RNase activity was highest in stationary phase, aminopeptidase at mid log phase. Properties of the soluble aminopeptidase were similar in many respects to those of the enzyme fromEscherichia coli. In contrast, 90% of the ribonuclease activity was attached to the membrane fraction and up to 10% was found on the ribosomes. The ribosome-bound ribonuclease required incubation in 4 M urea for activation; however, the purified ribonuclease had properties similar to the ribonuclease I ofE.coli.

ISSN:0008-4166    

DOI:10.1139/m70-032

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

Fischerella muscicola(Thuret) Gom. was isolated in axenic culture, from the roof of a building. Effects of the incorporation of manganous chloride, caffeine, lanthanum acetate, maleic hydrazide, coumarin, thioglycollic acid, colchicine, and uranyl nitrate in the culture medium on the alga was investigated. The sublethal and lethal concentrations of chemicals were manganous chloride 5.0 mMand 7.5 mM; caffeine 5.0 mMand 10.0 mM; lanthanum acetate 0.7 mMand 1.5 mM; maleic hydrazide 2.0 mMand 4.0 mM; coumarin 1.4 mM; thioglycollic acid 1.0 mM; colchicine 10.0 mM; and uranyl nitrate 0.5 mMand 1.0 mM. The sublethal concentrations thus determined were higher than those found in bacteria.Among the effects, the killing of a few cells, lag in division of cells, cell enlargement or elongation, and formation of irregular clusters of cells were temporary in nature. On the other hand, the changes in pigment composition, vacuolization, production of gas vacuoles, increase in frequency of heterocysts, suppression of akinete formation, and formation of uniseriate prostrate branches were permanent.

ISSN:0008-4166    

DOI:10.1139/m70-033

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

Thirteen strains of five group A streptococcal serotypes were efficiently transduced to streptomycin resistance by ultraviolet-irradiated virulent bacteriophages.

ISSN:0008-4166    

DOI:10.1139/m70-034

出版商:NRC Research Press    

年代:1970

数据来源: NRC