摘要:

Details of the metabolism of α-terpineol byPseudomonas incognitaare presented. Degradation of α-terpineol by this organism resulted in the formation of a number of acidic and neutral metabolites. Among the acidic metabolites, β-isopropyl pimelic acid, 1-hydroxy-4-isopropenyl-cyclohexane-1-carboxylic acid, 8-hydroxycumic acid, oleuropeic acid, cumic acid, andp-isopropenyl benzoic acid have been identified. Neutral metabolites identified were limonene,p-cymene-8-ol, 2-hydroxycineole, and uroterpenol. Cell-free extracts prepared from α-terpineol adapted cells were shown to convert α-terpineol,p-cymene-8-ol, and limonene to oleuropeic acid, 8-hydroxycumic acid, and perillic acid, respectively, in the presence of NADH. The same cell-free extract contained NAD+-specific dehydrogenase(s) which converted oleuropyl alcohol,p-cymene-7,8-diol, and perillyl alcohol to their corresponding 7-carboxy acids. On the basis of various metabolites isolated from the culture medium, together with the supporting evidence obtained from enzymatic and growth studies, it appears thatP.incognitadegrades α-terpineol by at least three different routes. While one of the pathways seems to operate via oleuropeic acid, a second may be initiated through the aromatization of α-terpineol. The third pathway may involve the formation of limonene from α-terpineol and its further metabolism.

ISSN:0008-4166    

DOI:10.1139/m84-228

出版商:NRC Research Press    

年代:1984

数据来源: NRC

摘要:

The influence of 29 species of soil organisms (21 bacteria and 8 fungi) on nematode capture by 3 species of nematophagous fungi was investigated. Only the yeast,Saccharomyces cerevisiae, was found to bind to lectin-containing traps ofArthrobotrys conoidesandMonacrosporium rutgeriensisand prevent nematode capture. None of the organisms studied bound to the traps ofMonacrosporium eudermatum. The trap lectin ofArthrobotrys conoides, being specific for glucose – mannose, apparently binds to the mannan component of the yeast cell wall. At this time, it is not clear why the yeast binds to traps ofMonacrosporium rutgeriensissince the trap lectin is highly specific for 2-deoxyglucose, a saccharide that does not appear to occur in nature.

ISSN:0008-4166    

DOI:10.1139/m84-229

出版商:NRC Research Press    

年代:1984

数据来源: NRC

摘要:

Streptomyces hygroscopicusvar.geldanuscontrolled rhizoctonia root rot of pea in previously sterilized soil if incubated for 2 or more days prior to infesting soil withRhizoctonia solaniand planting.Streptomyces hygroscopicusalso reduced saprophytic growth and the population ofR.solaniin soil. Growth ofR.solaniwas inhibited by geldanamycin, an antibiotic produced byS.hygroscopicus, on nutrient media. Methanol extracts of soils in which the antagonist was incubated for 2 or more days inhibited growth ofR.solani. Geldanamycin concentration was 88 μg per gram of soil after 7 days of incubation. Bioautography of soil extracts indicated that the inhibitory compounds were geldanamycin and two other compounds, also found in the geldanamycin standard. The period of incubation necessary for antibiotic production and disease control was similar, with no disease control occurring where no antibiotic was detected. Amending soil with geldanamycin, in amounts equivalent to that produced after 2 or 7 days of incubation, controlled disease and reduced saprophytic growth of the pathogen. Lesser amounts of the antibiotic did neither. No evidence for antagonism owing to competition (nitrogen, carbon) or parasitism was found.Streptomyces hygroscopicusand geldanamycin also affected plant growth.

ISSN:0008-4166    

DOI:10.1139/m84-230

出版商:NRC Research Press    

年代:1984

数据来源: NRC

摘要:

Chlorate-resistant mutants with none of the usual pleiotropic effects such as defective nitrate reductase activity were isolated fromEscherichia coliK-12. These chlorate-resistant mutants (designatedchlHW) did not yield strains with a high level of nitrofurantoin resistance following selection with nitrofurantoin. The chlorate-resistance mutation reduced the nitrofurantoin resistance of high-level mutants to an intermediate level. Further mutation to resistance to streptomycin and other aminoglycoside antibiotics suppressed the effect ofchlHWon the level of nitrofurantoin resistance. Other chlorate-resistance genes examined did not have the same effect on nitrofurantoin resistance aschlHW. The gene was cotransducible (P1) with intermediate-level nitrofurantoin resistance andproC. It is suggested that thechlHWmutation may enhance the accumulation of nitrofurantoin inside the cell since it is known that a multiple aminoglycoside-resistance mutation with pleiotropic effects on the cell membrane can also confer high-level resistance to nitrofurantoin.

ISSN:0008-4166    

DOI:10.1139/m84-231

出版商:NRC Research Press    

年代:1984

数据来源: NRC

摘要:

Group BNeisseria meningitidis(SD1C) was grown on defined medium supplemented with each of a variety of sulphur compounds as the sole source of sulphur. The organism grew on sulphate, sulphite, bisulphite, thiosulphate, dithionite, hydrosulphide, thiocyanate,L-cysteine,L-cystine, reduced glutathione, methionine, mercaptosuccinate, and lanthionine, but not on dithionate unless previously sulphur starved. Good growth was seen on concentrations of sulphate or thiosulphate as low as 10 μM. When pregrown on and subsequently starved for sulphate, the meningococcus showed enhanced transport capacity for this ion. Optimal conditions for assessing sulphur transport by active sulphur-limited cells were determined. The maximal sulphate uptake velocity was 9.3 nmol sulphate∙mg protein−1∙min−1, and the apparentKmwas 1.4 μM, far below human nasopharyngeal or serum sulphate lev

ISSN:0008-4166    

DOI:10.1139/m84-232

出版商:NRC Research Press    

年代:1984

数据来源: NRC

摘要:

Metabolism of side chain and ring14C-labelled carbaryl and carbofuran in a mineral salts medium by soil-enrichment cultures and aBacillussp. was studied. A change in the substrate of the medium from carbaryl to carbofuran led to a marked shift in the dominant bacterium fromBacillussp. toArthrobactersp. although carbaryl-enrichment culture was the primary inoculum in both media. Hydrolysis was the major route of microbial degradation of both carbamate insecticides. During carbaryl degradation by enrichment cultures andBacillussp., 1-naphthol and 1,4-naphthoquinone accumulated in the medium. Of the three metabolites formed from carbofuran, 3-hydroxycarbofuran and 3-ketocarbofuran were further metabolized rapidly, while carbofuran phenol was resistant to further degradation. Evolution of14CO2and other gaseous14C-labelled products from both side chain and ring labels was negligible. This and slow degradation of the hydrolysis products led to significant accumulation of14C in the medium even after prolonged incubation.

ISSN:0008-4166    

DOI:10.1139/m84-233

出版商:NRC Research Press    

年代:1984

数据来源: NRC

摘要:

The effect of hydrogen peroxide onTreponema pallidumwas investigated. Thein vitroloss of virulence (as measured by rabbit inoculation) ofT.pallidumwas accelerated by as low as 100 μMhydrogen peroxide in the complex maintenance medium used. Higher doses led to rapidly accelerated death with 500 μMhydrogen peroxide causing sterilization of the medium within 3 to 4 h. Since hydrogen peroxide is known to cause single-stranded breaks in DNA, the effect of hydrogen peroxide on the treponemal genome was examined. Extensive breakage was caused by 100 μMhydrogen peroxide as determined on alkaline sucrose gradients. A limit was reached at 250 μMand above. Single-stranded breaks could be demonstrated as early as 5 – 10 min after exposure to hydrogen peroxide when the treponemes were exposed to 250 μMhydrogen peroxide; accelerated death was evident by 2 h past exposure demonstrating that DNA breakage was preceding death. Treponemal death caused by penicillin did not result in DNA breakage. The repair-proficient bacteriumEscherichia coliK-12 was compared withT.pallidum. It required 10 – 100 times more hydrogen peroxide to cause various levels of breakage.Escherichia coliK-12 rapidly repaired DNA breakage once hydrogen peroxide was removed by addition of catalase.Treponema pallidum, in comparison, showed little or no repairin vitro. Addition of catalase or dithiothreitol to the medium protected against all but a low level of breakage; this may reflect on the ability of catalase and reducing agents to protectT.pallidumagainst oxygen toxicityin vitro.

ISSN:0008-4166    

DOI:10.1139/m84-234

出版商:NRC Research Press    

年代:1984

数据来源: NRC

摘要:

A rod-shaped Gram-positive methanogenic bacterium was isolated from marshy soil. It uses H2– CO2as sole energy and carbon source. Optimal growth occurs around 40 °C. The cell wall contains pseudomurein. The G + C content of the DNA is about 32 mol%. The DNA – DNA homology values of the isolate withMethanobacterium bryantiistrains M.o.H. and M.o.H.-G. are 53 and 7%, respectively. The isolate is considered to be a new species within the genusMethanobacteriumand it was namedMethanobacterium uliginosum.

ISSN:0008-4166    

DOI:10.1139/m84-235

出版商:NRC Research Press    

年代:1984

数据来源: NRC

摘要:

The modes of hyphal interaction between a mycoparasite,Pythium nunn, and several soil fungi were studied by both phase-contrast and scanning-electron microscopy. In the zone of interaction,Pyth.nunnmassively coiled around and subsequently lysed hyphae ofPyth.ultimumandPyth.vexans. In contrast,Pyth.nunnpenetrated and eventually parasitized hyphae ofRhizoctonia solani,Pyth.aphanidermatum,Phytophthora parasitica, andPhyto.cinnamomiby forming appressoriumlike structures. However,Pyth.nunnwas not mycoparasitic againstFusarium oxysporumf.sp.cucumerinumorTrichoderma koningniiand was destroyed byT.harzianumandT.viride. These observations demonstrated thatPyth.nunnwas a necrotrophic mycoparasite, with a limited host range and differential modes of action among suscepts.

ISSN:0008-4166    

DOI:10.1139/m84-236

出版商:NRC Research Press    

年代:1984

数据来源: NRC

摘要:

Verticillium dahliae, a vascular parasite of sunflower, was grown in a medium supplemented with sunflower cell walls as a sole nitrogen source. The culture filtrate contained three proteinases. The largest amounts were associated with the proteinase PIII fraction, while proteinases PI and PII fractions were in very small quantities. The properties of the purified proteinases were similar and it seemed likely that PI and PII fractions resulted from autolysis of the PIII fraction. The PIII proteinase showed a molecular weight of 12 750 and optimal action at pH in the 7.5–9.5 range. Activity was that of an endopeptidase which hydrolyzed casein, haemoglobin, gelatin, andN-benzoyl-DL-arginine-p-nitroanilide and was much less active onN-tosyl-L-arginine methyl ester and did not hydrolyzeN-benzoyl-L-tyrosine ethyl ester. Ethylenediaminetetraacetate and calcium had no effect on the PIII proteinase which was inhibited by HgCl2, phenyl-methyl-sulfonyl fluoride,N-p-tosyl-L-lysine-chloromethyl ketone andL-1-tosyl-amide-2-phenyl-ethyl-chloromethyl ketone. This indicated that the active site in the PIII proteinase probably contained free sulfhydryl groups.

ISSN:0008-4166    

DOI:10.1139/m84-237

出版商:NRC Research Press    

年代:1984

数据来源: NRC