摘要:

Reichstein's compound S was successfully converted to prednisolone in a single-step fermentation using a mixed culture ofCurvularia lunataandMycobacterium smegmatis. Introducing additional medium at the time of bacterial inoculation and increasing theM.smegmatisinoculum to 8% were necessary for maximal dehydrogenation of cortisol to prednisolone (86%). However, beef extract, corn-steep solids, and malt extract were inhibitory to the dehydrogenase activity and stimulatory to hydroxylase. Of the vitamins tested, nicotinic acid and riboflavin at 0.2 and 1.13 mg/L, respectively, resulted in maximum transformation of Reichstein's compound S (100%) and optimized prednisolone yields (92%) in the mixed culture. The trace elements present in the medium were sufficient for maximal transformation, and there was no need for an exogenous supply. Addition of ATP, sodium acetate, and NAD inhibited the dehydrogenation reaction.Key words: biotransformation of Reichstein's compound S, mixed-culture transformations, transformation of steroids.

ISSN:0008-4166    

DOI:10.1139/m92-122

出版商:NRC Research Press    

年代:1992

数据来源: NRC

摘要:

The activity and regulation of α-aminoadipate reductase in threePenicillium chrysogenumstrains (Q176, D6/1014/A, and P2), producing different amounts of penicillin, were studied. The enzyme exhibited decreasing affinity for α-aminoadipate with increasing capacity of the respective strain to produce penicillin. The enzyme from all three strains was inhibited byL-lysine, and the enzyme from the lowest producer, Q176, was least sensitive. Between pH 7.5 and 6.5, inhibition of α-aminoadipate reductase byL-lysine was pH dependent, being more pronounced at lower pH. The highest producer strain, P2, displayed the lowest α-aminoadipate reductase activity at pH 7.0. In Q176, the addition of 0.5–1 mM of exogenous lysine stimulated penicillin formation, whereas the same concentration was ineffective or inhibitory with strains D6/1014/A and P2. The addition of higher (up to 5 mM) lysine concentrations inhibited penicillin production in all three strains. In mutants ofP.chrysogenumD6/1014/A, selected for resistance to 20 mM α-aminoadipate, highest penicillin production was observed in those strains whose α-aminoadipate reductase was most strongly inhibited byL-lysine. The results support the conclusion that thein vivoactivity of α-aminoadipate reductase from superior penicillin producer strains ofP.chrysogenumis more strongly inhibited by lysine, and that this is related to their ability to accumulate increased amounts of α-aminoadipate, and hence penicillin.Key words: α-aminoadipate, α-aminoadipate reductase, regulation of lysine biosynthesis, penicillin biosynthesis,Penicillium chrysogenum.

ISSN:0008-4166    

DOI:10.1139/m92-123

出版商:NRC Research Press    

年代:1992

数据来源: NRC

摘要:

Treatment of purified 3-hydroxydiether lipid fromMethanosarcina barkeriby standard conditions for head-group removal (2.5% methanolic HCl, 70 °C) resulted in conversion to six identifiable degradation products. The four most abundant products were identified by mass spectrometry and nuclear magnetic resonance as monophytanylglycerol, 3-methoxydiether, andcis–transisomers of a diether unsaturated between carbons 3 and 4. The latter lipid products may be mistaken for 2,3-di-O-phytanyl-sn-glycerol (standard diether) and 2-O-sesterterpanyl-3-O-phytanyl-sn-glycerol when separated by thin-layer chromatography.Key words: hydroxydiether lipids, degradation artifacts, methanolic HCl,Methanosarcina barkeri.

ISSN:0008-4166    

DOI:10.1139/m92-124

出版商:NRC Research Press    

年代:1992

数据来源: NRC

摘要:

Streptomyces antibioticusETHZ 7451 formed spores in cultures grown in a liquid medium from either a spore or a mycelium inoculum. The spores formed were similar to those formed on surface-grown cultures, except for reduced heat resistance. Both types of spores were sensitive to lysozyme, which is unusual forStreptomycesspores. Glucose and other carbon sources, which promoted different growth rates, did not affect sporulation efficiency. Nitrogen sources, such as casamino acids, that allowed high growth rates suppressed the sporulation. A remarkable repression was also observed in media with some nitrogen sources that promoted noticeably lower growth rates. In permissive media, with nitrogen sources that permitted relatively high growth rates, sporulation was conditioned to the consumption of ammonium in the medium, but not to that of other nitrogen sources, such as asparagine. Phosphate did not show a repressive effect on sporulation in the assayed conditions.Key words:Streptomyces antibioticus, sporulation.

ISSN:0008-4166    

DOI:10.1139/m92-125

出版商:NRC Research Press    

年代:1992

数据来源: NRC

摘要:

We have previously reported that the lethal toxicity of 5-fluorouracil (5-FU) in specific-pathogen-free mice is due to an indigenous infection withEscherichia coli(K. Nomoto, T. Yokokura, Y. Yoshikai,et al. Can. J. Microbiol. 37: 244–247, 1991). In the present study, we demonstrate that nonspecific immunostimulation augments host resistance against the lethal toxicity of 5-FU in tumor-bearing mice. Intravenous administration of a preparation of heat-killedLactobacillus casei(LC 9018), a nonspecific immunostimulant, at a dose of 20 mg/kg to BALB/c mice augmented their resistance against the lethal toxicity of 5-FU if the preparation was injected into the mice 10–40 days before administration of 5-FU. Injection of LC 9018 into BALB/c mice bearing Meth A fibrosarcoma also enhanced their resistance against the lethality of 5-FU. Systemic infection withE.coliwas induced in all of the 5-FU-treated tumor-bearing mice 10 days or more after administration of the drug at a lethal dose of 500 mg/kg, and it was accompanied by an overgrowth of the bacteria in the intestine. Treatment of tumor-bearing mice with LC 9018 resulted in decreased rates of occurrence of systemic infection withE.coliand inhibition of overgrowth of the bacteria in the intestine after administration of 5-FU. A single administration of either LC 9018 or 5-FU significantly inhibited the growth of Meth A cells in vivo, and a combined antitumor effect was shown in the mice treated with both 5-FU and LC 9018.Key words: tumor-bearing mice, fluorouracil, nonspecific immunostimulation, indigenous infection,Escherichia coli.

ISSN:0008-4166    

DOI:10.1139/m92-126

出版商:NRC Research Press    

年代:1992

数据来源: NRC

摘要:

A technique was developed for preparation ofFrankiasymbiotic vesicles, free of hyphae. The symbiotic vesicles were isolated by isopycnic centrifugation of disruptedFrankiavesicle clusters prepared from root nodules ofAlnus incana(L.) Moench. Activities in symbiotic vesicles were compared with activities in intact symbiotic vesicle clusters on a total protein basis. Respiratory capacity was tested with 6-phosphogluconate, malate + glutamate, and NADH as added substrates. With all three substrates, specific respiration was doubled after symbiotic vesicle isolation. Nitrogenase was used as a symbiotic vesicle specific marker and its specific activity increased similarly to respiration. Activities of four respiratory enzymes were assayed on crude cell-free extracts obtained after sonication of symbiotic vesicle preparations. According to the increased specific rates after symbiotic vesicle isolation, NAD+:6-phosphogluconate dehydrogenase (EC 1.1.1.44) and glucose-6-phosphate dehydrogenase (EC 1.1.1.49) were mainly localized in symbiotic vesicles. NAD+:malate dehydrogenase (EC 1.1.1.37) and glutamate-oxaloacetate transaminase (EC 2.6.1.1) were also present in symbiotic vesicles, but their specific activities were not increased compared with the symbiotic vesicle clusters. The magnitude of increased activities suggested that the symbiotic vesicle is a major site for hexose respiration in symbioticFrankia. An apparentKmfor O2between 20 and 30 μM indicated that symbiotic vesicles in symbiotic vesicle clusters have a restricted oxygen diffusion rate.Key words:Frankia, symbiotic vesicles, respiration, nitrogenase, oxygen diffusion.

ISSN:0008-4166    

DOI:10.1139/m92-127

出版商:NRC Research Press    

年代:1992

数据来源: NRC

摘要:

Interactions between copper ions and exopolymer from the marine film-forming bacteriumAlteromonas atlanticawere evaluated by a two-phase model that treats the polymer as if it exists in a phase separate from the bulk solution. The model takes into account electrostatic interactions and molecular volume changes within the polymer phase to determine the copper activity in the domain where copper interacts with the ligands on the polymer molecule(s). The volume of the polymer phase varied with pH, ionic strength, and copper ion concentration. Exopolymer recovered from chemostat cultures grown at different dilution rates exhibited unique interligand distances, number of ionizable ligands, and molecular volumes. The variations in physical properties, in part, reflected differences in polymer chemistry. The exopolymer contained a lower density of ionizable groups and a smaller molecular volume per number of ionizable groups than alginic acid. The numerical procedure yielded a stability constant of 1 × 105 L/mol for a type I complex between copper ion and exopolymer produced at a dilution rate of 0.02 h−1that was valid over a range of hydrogen ion concentrations and ionic strengths. The approach provided useful insight on how environmental variables affect the physicochemical properties of microbial exopolymers.Key words: exopolysaccharide, metal ions, chemostat culture.

ISSN:0008-4166    

DOI:10.1139/m92-128

出版商:NRC Research Press    

年代:1992

数据来源: NRC

摘要:

Cocultures of differentAzospirillumspecies withBacillus polymyxaorBacillus subtilisallow the efficient utilization of pectin as carbon and energy sources for nitrogen fixation. The nitrogenase activity obtained with cocultures was as high as 30–80 nmol C2H4h−1mL−1, a much higher value than that obtained with pure cultures of eitherAzospirillum(up to 13 nmol C2H4h−1mL−1) orB.polymyxa(up to 2 nmol C2H4h−1mL−1) alone. To establish to what extent each partner contributed to nitrogenase activity, acetylene reduction was assayed as a function of time and it was also measured onAzospirillumcultivated in the cultures filtrates of theBacillus. The results suggested that the nitrogenase activity was mostly produced byAzospirillum. The nitrogenase activity occurred at the expense of the degradation and fermentation products of the pectin. The new pectinolytic species,Azospirillum irakense, utilized both degradation and fermentation products of pectin, whereas the nonpectinolytic strains (Azospirillum brasilense,Azospirillum lipoferum,Azospirillum amazonense) utilized only the fermentation products of pectin, including acetic and succinic acids. These cocultures can be considered as metabolic associations, where theBacillusproduces degradation and fermentation products of pectin, which can be used byAzospirillumspecies.Key words: cocultures, nitrogen fixation, pectin degradation,Azospirillum,Bacillus, metabolic association.

ISSN:0008-4166    

DOI:10.1139/m92-129

出版商:NRC Research Press    

年代:1992

数据来源: NRC

摘要:

ThirtyAzospirillumstrains were isolated from the rhizosphere of 13 maize (Zea maysL.) cultivars grown in 14 French soils, using a new specific method, which has been given the nameROSEA. Among these strains 26 wereAzospirillum lipoferumand 4 wereAzospirillum brasilense. Their characterization was achieved using biochemical tests and plasmid profiles. Biochemical patterns allowed clear differentiation between the two species. A large diversity in carbon source metabolism was found among theAzospirillumsp. strains regardless of their origin. TheA.brasilensewere much more closely related, and were found in only two of the rhizospheres studied. The 30 plasmid patterns were all different, and the plasmid-profiling technique can therefore be considered as strain specific. All theA.lipoferumharboured a 150-MDa plasmid, while all theA.brasilenseharboured a 90 to 100-MDa plasmid. This result reinforces the hypothesis of the presence of such plasmids as an additional criterion for differentiating these two species.Key words:Zea mays,Azospirillum,ROSEAmethod, biochemical tests, plasmid profiles.

ISSN:0008-4166    

DOI:10.1139/m92-130

出版商:NRC Research Press    

年代:1992

数据来源: NRC

摘要:

The conventional methods for the laboratory diagnosis of tuberculosis and other mycobacterial diseases are time consuming and beyond the scope of most of the small and medium-sized hospital facilities. Therefore, there has been considerable interest in the development of a serological method for the detection of antibodies against mycobacteria. We recently evaluated a commercially availableELISAtest (Anda Biologicals, Strasbourg, France) that measures antibody levels to A60 antigen, a membrane glycoprotein that is found in most mycobacteria. Of the 123 patients with positive pulmonary cultures forMycobacterium tuberculosis, 82% had detectable antibodies against the kit antigen. Of the 68 patients with extrapulmonary tuberculosis, 59% yielded positive results. Specimens from 2 of the 12 patients that grewMycobacterium avium–intracellularecomplex, and one each withMycobacterium fortuitumandMycobacterium chelonei, were considered significant on the basis of medical history and repeated isolation of the bacterium from clinical specimens, and these patients yielded positive serology. Of the healthy, normal PPD positive and PPD negative controls, 24% gave false positive results.Key words: Anda A60-tbELISA, serodiagnosis of mycobacteria, mycobacterium.

ISSN:0008-4166    

DOI:10.1139/m92-131

出版商:NRC Research Press    

年代:1992

数据来源: NRC