摘要:

Trichoderma harzianumexcreted β-1, 3-glucanase and chitinase into the medium when grown on laminarin and chitin, respectively, or on cell walls of the pathogenSclerotium rolfsii, as sole carbon source.Trichoderma harzianumalso showed high activity of both enzymes when grown on homogenizedS.rolfsiisclerotia. Glucanase activity increased by 67% when the fungus was grown on a mixture of laminarin and glucose (3:1, v/v). Similarly, high lytic activity was detected in wheat bran culture of the fungus and in soil inoculated with this culture. Protease and lipase activity were detected in the medium when the antagonist attacked mycelium ofS.rolfsii.Isolates ofT.harzianumwere found to differ in the levels of hydrolytic enzymes produced when mycelium ofS.rolfsii,Rhizoctonia solani, andPythium aphanidermatumin soil was attacked. This phenomenon was correlated with the ability of each of theTrichodermaisolates to control the respective soilborne pathogens.

ISSN:0008-4166    

DOI:10.1139/m82-110

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

Active immunization of mice with whole cell vaccine or cell surface polysaccharide from either the Smith diffuse strain ofStaphylococcus aureusor SS-615 (type Iaof group B streptococci) protected against challenge by either the homologous or heterologous strains. In the peritoneal cavity of mice immunized with either of these organisms rapid phagocytosis and reduction of the viable cells was observed at 6 h after the challenge. Cell surface polysaccharides extracted from strains Smith diffuse and SS-615, both prepared by the same procedure as that of the Smith surface antigen, were capable of absorbing the protective antibody in rabbit hyperimmune sera prepared with homologous or heterologous strains.

ISSN:0008-4166    

DOI:10.1139/m82-111

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

Bacillus circulansWL-12 secretes two endo-β-D-xylanases (A and B, respectively) (EC 3.2.1.8.) and one β-D-xylosidase (EC 3.2.1.37) when cultured in liquid media with xylan as the sole carbon source. Xylanases A and B have been partially characterized with respect to their main physicochemical parameters and β-D-xylosidase to a lesser extent on account of its low stability. Both endo-β-D-xylanase A and β-D-xylosidase were adsorbed on DEAE-Biogel A, had similar molecular weights (approximately 85 000), and had optimum pH values of 5.5–7, but exhibited different isoelectric points (4.5 for β-D-xylanase A and 4.7 for β-D-xylosidase) and different mobilities in polyacrylamide gel electrophoresis. The apparent Michaelis constant for β-D-xylanase A was 8 mg∙mL−1and the hydrolysis products produced were xylose, xylobiose, xylotriose, and xylotetraose.The second endo-β-D-xylanase (β-D-xylanase B) bound to CM-Biogel A and exhibited a molecular weight of approximately 15 000 and an optimum pH value in the range of 5.5–7. The isoelectric point was 9.1 and the apparent Michaelis constant was 4 mg∙mL−1. The hydrolysis products produced by this enzyme were xylobiose, xylotriose, and xylotetraose, but never xylose. In polyacrylamide gel electrophoresis at pH 8 the enzyme moved towards the negative electr

ISSN:0008-4166    

DOI:10.1139/m82-112

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

Dormant spores ofDictyostelium discoideumare contained in a viscous matrix of extracellular material at the top of sorocarps. Analysis of crude extracts of the sorus demonstrates that there is a higher specific activity of β-glucosidase in the matrix than in the dormant spores. Polyacrylamide gel electrophoresis of the matrix material reveals the presence of β-glucosidase 2 with trace amounts of β-glucosidase 1. In the dormant spores only β-glucosidase 2 is detected. Upon heat activation of the spores, β-glucosidase 2 activity decreases to approximately 25% of the activity found in the preheated spores. The enzyme appears to have a surface location in dormant spores, since trypsin treatment will destroy all of the β-glucosidase 2 activity. The normal germination of dormant spores after trypsin treatment suggests that β-glucosidase 2 activity is not required for activation, swelling, or emergence processes.During the emergence of myxamoebae, β-glucosidase 2 is replaced by a newly synthesized enzyme, β-glucosidase 1. The formation of this new enzyme requires both RNA and protein syntheses. The complete germination of a β-glucosidase 1 minus mutant, however, casts doubt on the necessity for β-glucosidase1 activity during emergence. This is further supported by the normal germination of strain SG1 which contains four- to five-fold higher β-glucosidase activity than that found in wild-type amoebae at the end of the germination period. In addition, strain SG1 may be activated with a number of techniques which results in a separation of the time of β-glucosidase synthesis from the time of myxamoebae emergence. Furthermore, spores (which have been blocked from emerging by cycloheximide treatment) will slowly release spheroplasts when treated with only pronase andD.discoideumcellulase. However, addition ofD.discoideumβ-glucosidase 1 to the cellulose–pronase-treated spores does accelerate the rate of spheroplast formation. Thus, β-glucosidase 1 activity may only play a minor and dispensable role inD.discoideumspore germination.

ISSN:0008-4166    

DOI:10.1139/m82-113

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

The filamentous bacteriumFrankiasp. CpI1 of the Actinomycetales, responsible for symbiotic nitrogen fixation in the nodules of certain woody dicots, also fixes dinitrogen when grown independently of the host in a nitrogen-free synthetic nutrient medium under aerobic conditions. In structural studies ofFrankiagrown in culture it has been shown that the bacterial filaments form vesicles, enlarged terminal endings in which the enzyme nitrogenase is formed. Microscopic examination of cultures shows that the vesicles possess a specialized envelope consisting of a number of thin layers or laminae which in polarized light show birefringence and in freeze-etch electron microscopy are resolved as multiple (12–15) laminae approximately 35–40 Å (1 Å = 0.1 nm) in thickness. Comparisons are made between the structure of the vesicle envelope in culturedFrankiaand the strikingly similar innermost laminated layer in the dinitrogen-fixing heterocysts of the cyanobacteriumAnabaena. Comparable protective functions in limiting oxygen to the dinitrogen-fixing sites are suggested for these similar structures in two quite unrelated microorganisms.

ISSN:0008-4166    

DOI:10.1139/m82-114

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

Thirty strains ofPropionibacterium acneswere grown in basal salt medium containing lecithin as a lipid substrate and in other media. The cultures were assayed for production of lipase (measured as fatty acid esterase) and other exoenzymes. Lipase was assayed spectrophotometrically; other enzymes were assayed using the API ZYM system (Analytab Products Inc., Plainview, NY). Substrates for lipase were α- and β-naphthol esters of propionic, butyric, valeric, caprylic, lauric, myristic, and oleic acids. All strains showed fatty acid esterase activity. Using the API ZYM system 19 enzymes were detected, 8 of which were found frequently and had high activity in most strains. Acid and alkaline phosphatases, phosphoamidase, ester lipase, trypsin–chymotrypsin-like proteases, β-glucuronidase (80%),β-galactosidase (80%), andN-acetyl-β-glucosaminidase were found. Many enzymes ofP.acnesappear to be adaptive, dependent on the culture subtrate.

ISSN:0008-4166    

DOI:10.1139/m82-115

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

Protein and isoenzyme patterns of polyphenol (DOPA) oxidase, peroxidase, acetyl esterase, and acid and alkaline phosphatases from mycelial and extracellular extracts, as detected by polyacrylamide gel electrophoretic techniques, reflected marked variations among five differentially virulent isolates ofRhizoctonia solani, the causal organism of sheath blight disease of rice. Although no correlation could be obtained with the enzyme patterns and virulence of the isolates, two isolates with the lowest virulence showed mycelial and extracellular peroxidase bands and only the least virulent isolate gave mycelial alkaline phosphatase bands.

ISSN:0008-4166    

DOI:10.1139/m82-116

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

The sulphur requirement for growth ofAcetivibrio cellulolyticuswas determined using a mineral salts basal medium reduced with titanium(III) citrate and supplemented with 1% (w/v) cellobiose and 0.05% (w/v) yeast extract. Inorganic sulphide (Na2S∙9H2O) in the range of 0.7–1.0 mMwas found to support maximum growth whereas 8.0 mMsulphide caused complete inhibition. Of the other sulphur-containing compounds tested (cystine, sodium thioglycollate, methionine, glutathione, homocystine,S-methyl-L-cysteine, inorganic sulphate) cysteine-HCl at 10–15 mMconcentration was the only one which supported maximum growth that was at least 80% of that obtained in the optimum sulphide medium. A modified medium incorporating the optimum inorganic sulphide concentration supported maximum growth that was about twice that obtained in a conventional medium reduced with cysteine-Na2S. The possible reasons for the inhibition of growth in defined media containing Na2S as the sole reducing agent and the sulphur source are discusse

ISSN:0008-4166    

DOI:10.1139/m82-117

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

The roots of several dicotyledonous xerophytic plants exhibited nitrogenase activity.Azospirillum lipoferumwas isolated from the roots of these plants including several species ofOpuntiahaving crassulacean acid metabolism. These isolates showed high rates of acetylene reduction; maximum nitrogenase activity was observed with the isolate fromOpuntia vulgaris. Organic acids rather than sugars were preferred as carbon source for two selected isolates studied. However, no activity was detected with formic, oxalic, or lactic acid. Inorganic nitrogen sources caused significant reduction in nitrogenase activity, while organic sources such as amino acids and proteins either stimulated or did not significantly inhibit the activity. However, urea completely inhibited formation of nitrogenase activity. Growth measured as optical density was enhanced with all the nitrogen sources except potassium nitrite.

ISSN:0008-4166    

DOI:10.1139/m82-118

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

A method is described for the second-step concentration of viruses from large volumes of drinking and surface waters. Seeded viruses present in the first eluate, performed with 50 mMglycine buffer, pH 11.5, were adsorbed on a preformed magnesium hydroxide precipitate. After low-speed centrifugation they were desorbed and ajusted to pH 7 with McIlvaine citrate–phosphate buffer. In these experimental conditions 90% of the viruses present in the 300-mL first eluate were reconcentrated in a final volume of 40 mL. The recovery efficiency was independant of either virus concentration or water quality.

ISSN:0008-4166    

DOI:10.1139/m82-119

出版商:NRC Research Press    

年代:1982

数据来源: NRC