摘要:

Cultures ofPenicillium oxalicumgrowing on a denned medium supplemented with yeast extract reached the onset of autolysis after 3 days at 25 °C. Thenceforth, autolysis was progressive and eventual reductions in dry weight of 96% were recorded by day 47. The pH of the medium fluctuated between 4.0 during the exponential phase of growth and 9.0 during autolysis. Electron microscopy of autolyzing cultures revealed a progressive loss of cytoplasmic ultrastructure. Digestion of the cell walls, with a rapid hydrolysis of the three external layers and a low hydrolysis of the two inner layers, was accompanied by deep pitting and by loss of the distinct five-layered structure. A lytic enzyme complex was obtained from the filtrates of extensively autolyzed cultures. It was rich in (1 → 3)-β-glucanase and other enzymes active against a range of fungal cell wall and storage polysaccharides. This enzyme complex degraded extensively isolated cell walls ofP.oxalicumand three other Ascomycetes but had less effect on walls isolated fromMucor mucedoorSchizophyllum commune. In the case ofP.oxalicum, cell walls harvested from young cultures were more readily digested than were the walls from older cultures.

ISSN:0008-4166    

DOI:10.1139/m82-192

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

The ability of primary alkylsulfate esters and alkanesulfonates to induce alkylsulfatase formation inPseudomonas aeruginosawas compared on the basis of maximum enzyme levels, induction rate, and levels of induction as a function of inducer concentration. ApparentKinducervalues for these effectors were calculated from linear relationships between reciprocals of induction rate and inducer concentration. Maximum enzyme levels estimated from linear progress relationships for each effector indicated that little major distinction could be made between effectors. Excepting carbon chain lengths of C8which induced about the same level of enzyme, sulfate esters were generally better inducers than sulfonates with little or no apparent induction occurring with effectors of chain length ≤ C6. These observations also held true when rates were compared, except that the rate for the C8ester was approximately ninefold greater than that for the analogous sulfonate. ApparentKinducerconstants decreased with increasing alkyl chain length for the esters (C6–C12) and the sulfonates (C8–C14). Values for the esters were approximately sixfold greater than those for sulfonates of equivalent chain length. Plots of log apparentKinducervalues against carbon chain length for each series of esters and sulfonates yielded straight-line relationships characteristic of an homologous series in each instance.

ISSN:0008-4166    

DOI:10.1139/m82-193

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

An external layer suggesting a capsule was demonstrated by electron microscopy on three strains ofBrucellabelonging to different species. This structure was disclosed only after the action of antibodies and was not present on all the bacteria examined; labelling with conjugated specific antibodies showed that it incorporates and transports antigens belonging probably to the outer membrane. Staining by ruthenium red showed that it contains acidic mucopolysaccharides.

ISSN:0008-4166    

DOI:10.1139/m82-194

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

During growth in a defined medium containing protoheme,Bacteroides fragilisstrain 2044 andBacteroides"ℓ" 7CM formed protoheme-containingb-type cytochromes. The major reduced versus oxidized spectral peaks found for strain 2044 were at 562 and 428 nm whereas the peaks observed for strain 7CM were at 559 and 427 nm. When protoheme was replaced by deuteroporphyrin, mesoporphyrin, or their manganese or magnesium chelates, both organisms formed deuteroheme- or mesoheme-containing cytochromes with difference spectral peaks at 546 to 547 nm and 411 to 413 nm. Pyridine hemochromogen spectra of cells grown in the presence of tetrapyrroles containing the deuteroporphyrin or mesoporphyrin moiety confirmed the presence of deuteroheme or mesoheme in the cells. Although capable of delayed and relatively scant growth in media devoid of added tetrapyrroles or in media containing the vanadium chelates of mesoporphyrin or deuteroporphrin, neither organism formed cytochromes under these growth conditions. The functional nature of the cytochromes containing deuteroheme or mesoheme was confirmed by their reduction by cells in the presence of 56 mMglucose and carbon dioxide compared with cells exposed to air. The use of tetrapyrroles by strains 2044 and 7CM is similar to that previously found forBacteroides ruminicolassp.ruminicola. Versatility in tetrapyrrole utilization for cytochrome synthesis appears to be a common characteristic of heme-requiring gastrointestinalBacteroidesspecie

ISSN:0008-4166    

DOI:10.1139/m82-195

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

Several highly cellulolytic fungi were initially screened for their cellulase and β-glucosidase activities. Culture filtrates fromTrichodermaE58 demonstrated the highest β-glucosidase activity, giving a value of 1.0 IU/mg protein. A variety of different cellulose and pretreated wood substrates were hydrolysed by various cellulase preparations. The importance of the pretreatment conditions and ensuing chemical extractions of the cellulosic substrates was demonstrated by the range of sugar and ethanol values obtained after saccharification and fermentation of the liberated sugars. The rate of hydrolysis of the cellulosic substrate byTrichodermaE58 culture filtrates, concentrated culture filtrates, and whole cell cultures was compared. An ethanol value of 2.2% (w/v) could be obtained after hydrolysis of 5% Solka floe by concentrated culture filtrates ofTrichodermaE58 and fermentation of the liberated sugars byZymomonas mobilisorSaccharomyces cerevisiae.

ISSN:0008-4166    

DOI:10.1139/m82-196

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

The intracytoplasmic accumulation of polysaccharides has been demonstrated in four species ofStreptomyces. After extraction and purification, the structural properties of these polysaccharides were investigated by chemical, spectrophotometric, and enzymatic methods. The results clearly indicated that the streptomycete polysaccharides have a degree of branching and a macromolecular structure similar to that of the glycogens isolated from other bacteria and animal sources.

ISSN:0008-4166    

DOI:10.1139/m82-197

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

A strain ofPseudomonas putidagrew rapidly on cyclohexanecarboxylic acid as a sole source of carbon. A CoA-mediated β-oxidation pathway was induced for the metabolism of the compound. The organism could not utilize 3-cyclohexenecarboxylic acid as a sole source of carbon for growth, but cells grown on gluconate in the presence of 3-cyclohexenecarboxylic acid were induced to metabolize cyclohexanecarboxylic acid, benzoic acid, and catechol. Evidence is presented that 3-cyclohexenecarboxylic acid was slowly metabolized by a β-oxidation pathway and by a pathway involving benzoic acid as an intermediate. For this strain ofPseudomonas putida, 3-cyclohexenecarboxylic acid acts as an oxidizable, nongrowth substrate and induces the metabolism of cyclohexanecarboxylic acid and benzoic acid.

ISSN:0008-4166    

DOI:10.1139/m82-198

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

In the course of the symbiotic development of free-living rhizobia to mature bacteroids in alfalfa nodules, mRNA transcripts of the nitrogenase structural genes are first detected when the rhizobia are inside the infection threads. These transcripts are most abundant in the mature bacteroids of young (6 to 8 weeks) root nodules and are present in a much lower level in bacteroids from senescent root nodules (13 weeks). Translation of these and related rhizobial genes essential for the symbiotic association apparently occurs very early in the symbiosis because the protein pattern of the "infection thread rhizobia" is very similar to that of the mature bacteroids and is different from that of the cultured vegetative rhizobia. Although bacteroids have a higher DNA content than the vegetative bacteria and are very different in the nucleoid organization, no specific amplification or rearrangement of the nitrogenase genes is detected in bacteroids.

ISSN:0008-4166    

DOI:10.1139/m82-199

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

Efforts have been made to develop a simple chemically defined resuspended mycelial system which may be used for carrying out fundamental studies regarding the mechanism of kojic acid biosynthesis. As a first step, it was found that mycelia grown in yeast extract sucrose (YES) medium and resuspended in YES medium or in 0.2 Mphosphate buffer, pH 6.5, supplemented with 20% glucose or sucrose produced kojic acid almost to the same extent as in the case of growth medium. No kojic acid was formed if buffers or media used for resuspension lacked carbohydrate. Intact mycelia preincubated in buffer alone for 7 days and 3-week-old mycelia could still form kojic acid in large amounts if resuspended in buffer containing glucose. The amount of kojic acid produced by the intact mycelia was found to be more than that produced by the disrupted mycelia. In contrast with static resuspension studies, whenAspergillus flavusmycelia were resuspended in flasks placed on a rotary shaker, much smaller amounts of kojic acid were synthesized.

ISSN:0008-4166    

DOI:10.1139/m82-200

出版商:NRC Research Press    

年代:1982

数据来源: NRC

摘要:

The ontogeny and ultrastructure of sclerotia of the fungusBotrytis cinereaPers. ex Nocca & Balbis were studied by light, scanning, and transmission electron microscopy. Exudation droplets of various sizes and colour accumulated on sclerotial surfaces during development and eventually disappeared. A surface hyphal weft was present over sclerotia at maturity, forming a dense covering which often obscured the underlying rind. The rind consisted of highly vacuolated cells with thick, pigmented walls that remained intact even in old sclerotia. The cortex was poorly defined and usually consisted of only one layer of cells. The prosenchymatous medulla constituted the main volume of mature sclerotia. The ultrastructure of young sclerotial hyphae was similar to that of actively growing vegetative hyphae. Hyphae of mature sclerotia contained fewer nuclei and profiles of mitochondria and endoplasmic reticulum than young sclerotial hyphae. Electron-dense structures, tentatively identified as protein and polyphosphate bodies, were observed in hyphae of the cortex and medulla. Sclerotia ofB.cinereawere structurally similar to those ofSclerotiniaspp.

ISSN:0008-4166    

DOI:10.1139/m82-201

出版商:NRC Research Press    

年代:1982

数据来源: NRC