摘要:

Streptomyces venezuelaecontains intracellular α-glucosidases that are induced during growth on maltose, isomaltose, maltotriose, dextrin, starch, and other α-glucosides. Induction was prevented by rifampicin at 10 μg∙mL−1and inhibited by chloramphenicol or streptomycin, indicating thatde novosynthesis of messenger ribonucleic acid and protein was required. Glucose and other readily utilizable sugars did not repress induction of α-glucosidase activity whereas certain organic acids and amino acids effectively reduced enzyme synthesis. Extracts of mycelium grown in the presence of maltose as an inducer hydrolysed maltose and isomaltose rapidly. Sucrose and other α-glucosides were less suitable substrates whereas trehalose and starch were not hydrolysed. No activity was observed with β-glucosides, α-galactosides, or methyl α-mannosid

ISSN:0008-4166    

DOI:10.1139/m81-098

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

Of 33 pure strains of rumen bacteria from the Lethbridge laboratory collection, 5 degraded both 3-nitropropanol (NPOH) and 3-nitropropionic acid (NPA) under anaerobic conditions, and another 5 strains degraded only NPA. The nitroacid was metabolized at a faster rate than the nitroalcohol by both pure cultures of rumen bacteria and mixed rumen microorganisms.Nitrite was detected during incubation of NPOH and of NPA with resting cells but not with growing cultures of active strains of rumen bacteria. Nitrite was metabolized much faster than the nitrotoxins by both pure cultures of rumen bacteria and mixed rumen microorganisms. The results suggest that the nitro moiety of NPA or NPOH is metabolized to inorganic nitrite and nitrite is reduced to ammonia by rumen microorganisms, thereby resulting in its detoxification.

ISSN:0008-4166    

DOI:10.1139/m81-099

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

The new yeast speciesHanseniaspora nodinigriis described to accommodate members of the genusHanseniasporathat are unable to assimilate glucono-δ-lactone and isolated from stromatal tissue of black knots (Dibotryon morbosum) of chokecherry,Prunus viriginiana. The newly described taxon shows much resemblance, by other criteria, toH.vineaevan der Walt et Tscheuschner andH.osmophila(Niehaus) Phaff, Miller et Shifrine.

ISSN:0008-4166    

DOI:10.1139/m81-100

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

Electrophoresis patterns of cyanogen bromide (CNBr) peptides from the proteins of the cowpea (SBc), bean (SBb), Mexican (SBm), and Ghana (SBg) strains of southern bean mosaic virus showed a marked similarity between SBc and SBg and between SBb and SBm. A highly basic CNBr peptide from SBc, cCB-1, was isolated by Sephadex and ion-exchange chromatography. The size and amino acid composition of cCB-1 was similar but differed from that of the N-terminal CNBr peptide bCB-1 from SBb described previously.Antisera to cCB-1 or bCB-1 conjugated to tomato bushy stunt virus (TBSV) were used in gel diffusion tests with virus particles of the four SB strains. With the bCB-1–TBSV conjugate antiserum, SBb gave a reaction of identity with SBm and reactions of partial identity with SBc and SBg. With the cCB-1–TBSV conjugate antiserum, SBc gave a reaction of identity with SBg and reactions of partial identity with SBb and SBm. Cross absorption of bCB-1–TBSV conjugate antiserum with TBSV yielded an antiserum that reacted with SBb but not with TBSV. Cross absorption with bCB-1 yielded an antiserum that reacted with TBSV but not with SBb.Limited tryptic proteolysis of SBc in 0.01 Msodium phosphate buffer containing 0.01 Methylenediaminetetraacetic acid, pH 8.0, resulted in the formation of viruslike particles and smaller spherical particles. Sixteen peptides were isolated from these digests and the compositions of most of them were similar to but not identical to peptides isolated from limited tryptic proteolysis of SBb.

ISSN:0008-4166    

DOI:10.1139/m81-101

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

Macroconidia ofSporidesmium sclerotivorum, a mycoparasite ofSclerotiniaspp., were induced to germinte by aqueous and ethanolic extracts of sclerotia ofSclerotinia minor. Paper chromatography of sclerotial extracts indicated the presence of several amino acids and carbohydrates, chiefly glucose. Glucose was identified as the principal germination stimulant in ethanolic extracts. Glucose, fructose, mannose, cellobiose, sucrose, maltose, trehalose, soluble starch, and glycerol at 0.1% (w/v) stimulated macroconidia to germinate in 3–6 days at 25 °C. Crude sclerotial extracts, and glucose combined with inorganic and organic nitrogen sources, supported germination of greater numbers of macroconidia than glucose alone. Yeast extract, Casaminc acids, peptone, and several carbon substrates alone did not support germination. Macroconidia germinated well (> 30%) over the range of pH 3–7; maximum germination (> 80%) occurred at pH 5.0–5.5. Mycelial growth in a glucose – Casamino acids - mineral salts medium was also greatest in the range of pH 5.0–5.5, but growth fell off sharply below pH 4.5 and above pH 6.0. The fungus grew slowly on several complex agar media adjusted to pH 5.5.

ISSN:0008-4166    

DOI:10.1139/m81-102

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

The major fatty acids (> 10%) ofEntomophthora egressawere C16:0and C18:1. Minor fatty acids, which varied with the stage of fungal development, included C11:0, C12:0, C13:0, C14:0, C15:0, C16:1, C17:0, C18:0, C18:2, C18:3, C20:1, C20:2, C20:3, C20:4, C20:5, and two unidentified unsaturated fatty acids. Differences were observed between the total fatty acid levels of C12:0, C14:0, C17:0, C18:0, and C20:5and the degree of unsaturation of the fatty acids of 37-h protoplasts grown in modified Grace's medium and a simplified growth medium (SGM). The levels of C12:0, C14:0, C18:1, C20:4, and C20:5decreased and the levels of C18:0and C20:2increased with the formation of spherical hyphal body (shb) initials. With the production of mature shb increased levels of C12:0, C14:0, C15:0, C18:1, C20:4, and C20:5were detected. During the germination of the shb the levels of C14:0, C16:1, C18:1, and C20:4increased, whereas C15:0and C20:5levels declined. The fatty acid levels, except for Cl2:0, C13:0, and C20:2, remained constant during the mycelial stage. The degree of fatty acid unsaturation decreased during early stages of development (protoplasts through shb initials). In SGM the degree of fatty acid unsaturation was lowest during the shb initial stage and highest during the shb stage. The total lipid level increased during shb maturation and declined during shb germination.

ISSN:0008-4166    

DOI:10.1139/m81-103

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

Samples of subgingival plaque from patients with periodontal disease and control subjects were stained with the Fluoretec fluorescent test kits (Pfizer Inc., New York) developed for the rapid detection of members of theBacteroides fragilisandB.melanino genicusgroups of anaerobes. The same fluorescent fields were also examined by dark-field microscopy for the total count of bacteria.Bacteroides fragilisandB.melaninogenicuswere found in plaque samples of healthy subjects and periodontally diseased patients with no significant difference in percent of total flora. Oral spirochetes also fluoresced with the antisera used. Samples from healthy sites showed virtually no spirochetes; spirochetes were present in diseased sites. Tests with other antisera also showed that fluorescein-labelled antibodies can be absorbed nonspecifically to the surface of spirochetes. Such a phenomenon can be used to monitor an individual's periodontal disease state.

ISSN:0008-4166    

DOI:10.1139/m81-104

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

Growth ofEscherichia coliwas faster in liquid cultures than on the same medium solidified with agar. Colony profiles indicated a common basic structure with a size variation due to nutritional conditions. Radial growth rates were linear and height also increased approximately linearly, especially in the early part of the growth period. The ratio of rate of height increase to diameter increase depended on nutrition. Conditions favouring rapid growth led to faster radial growth relative to height increase. A rise in incubation temperature led to increases in height and in diameter; however, diameter increased relatively more than height. These results are discussed in terms of the structure of the colony.

ISSN:0008-4166    

DOI:10.1139/m81-105

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

Three of five isolates ofSporidesmium sclerotivorum, a mycoparasite ofSclerotiniaspp., grew well on an agar medium containing mineral salts, glucose, thiamine, and glutamine or Casamino acids as the nitrogen source. The nitrogen requirement for two of the isolates was satisfied by NH4Cl, Casamino acids, or glutamine. Glutamine was the best single nitrogen source. Only one isolate, CS-1, was used in further nutritional studies. The optimum concentration of glutamine for growth was 5 g/L. Glucose, mannose, mannitol, and cellobiose were excellent carbon sources. A glucose concentration of 20 g/L was optimum. Mannitol supported greater growth than glucose with Casamino acids as the nitrogen source but glucose was the superior carbon source with glutamine as the nitrogen source. Greatest growth was achieved with a combination of these carbon and nitrogen sources.Sporidesmium sclerotivorum, isolate CS-1, required thiamine for growth and sporulation. Biotin stimulated growth. The fungus developed maximally within the range of pH 5.0–5.5 and growth was greatly reduced at a pH below 4.0 or above 6.0. Control of acidity by the periodic addition of NaOH solution permitted substantially increased growth. The optimum temperature for growth was 22.5–25.0 °C but production of macroconidia was greatest at 15–20 °C.

ISSN:0008-4166    

DOI:10.1139/m81-106

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

APseudomonassp. isolated from crude oil reduced ferric ions (Fe(III)) to ferrous ions (Fe(II)). In the presence of nitrate (NO3−) after prolonged incubation, the amount of Fe(II) was lower than in its absence. However, during short incubation periods, the presence of NO3−significantly increased (99.5% confidence limit) the amount of Fe(II) produced. The decrease in Fe(II) on prolonged incubation was associated with increased production and accumulation of nitrite (NO2−). Under low NO3−levels, where the production of NO2−was limited, a decrease in NO2−concentration was accompanied by an increase in Fe(II) production to levels comparable with those obtained in the absence of NO3−. Preinduction of cells for nitrate reductase, which favoured rapid NO2−production, resulted in a more rapid decrease in Fe(II) production than in cells that were not preinduced. It is proposed that the inhibitory effect of NO3−on microbial reduction of Fe(III) is due to a secondary reaction, which involves the chemical oxidation of Fe(II) by NO2−.

ISSN:0008-4166    

DOI:10.1139/m81-107

出版商:NRC Research Press    

年代:1981

数据来源: NRC