摘要:

The properties of methylglyoxal-metabolizing enzymes in prokaryotic and eukaryotic microorganisms were studied systematically and compared with those of mammalian enzymes. The enzymes constitute a glycolytic bypass and convert methylglyoxal into pyruvate via lactate. The first step in this conversion is catalyzed by glyoxalase I, methylglyoxal reductase, or methylglyoxal dehydrogenase. The regulation of the yeast glyoxalase system was analyzed. The system was closely related to the proliferative states of yeast cells, the activity of the system being high in dividing cells and low in nondividing ones. The gene for the glyoxalase I ofPseudomonas putidaand the genes responsible for the activity of glyoxalase I and methylglyoxal reductase inSaccharomyces cerevisiaewere cloned and their structural and phenotypic characters studied.Key words: 2-oxoaldehydes metabolism, regulation of glyoxalase system, cloning, glyoxalase I gene, methylglyoxal reductase gene, methylglyoxal metabolism.

ISSN:0008-4166    

DOI:10.1139/m89-065

出版商:NRC Research Press    

年代:1989

数据来源: NRC

摘要:

The arginine-independent,de novobiosynthetic pathway of pyrrolidines inDictyostelium discoideumis initiated by a class II carbamoyl-phosphate synthetase (EC 6.3.5.5) specific for pyrimidine biosynthesis which utilizedL-glutamine as its N donor and was partially inhibited by both UTP and CTP. The second step in thede novopathway was provided by an unregulated aspartate transcarbamoylase (EC 2.1.3.2) which primarily appeared as a multimeric enzyme of 105 kilodaltons. The next enzyme, dihydroorotase (EC 3.5.2.3), was approximately 90–100 kilodaltons. Although the early enzymatic activities of the pyrimidine pathway appeared to reside in independent protein complexes, various unstable molecular species were observed. These structural variants may represent proteolytic fragments of a multienzyme complex. In addition tode novosynthesis, the amoeba demonstrated the capacity for salvage utilization of uracil, uridine, and cytidine. Upon starvation on a solid substratum, axenically grown amoebas began a concerted developmental program accompanied by a restructuring of nucleotide metabolism. The absolute levels of the ribonucleotide pools droppedby 98% within 30 h; however, both the adenylate energy charge and the GTP/ATP ratios were maintained for 50 h after the initiation of development. The maintenance of these metabolic energy parameters required the tight cell–cell contact necessary for development, and the capacity for pyrimidine metabolism was maintained throughout developmental morphogenesis.Key words: aspartate transcarbamoylase, carbamoyl phosphate synthetase, development, pyrimidine biosynthesis.

ISSN:0008-4166    

DOI:10.1139/m89-066

出版商:NRC Research Press    

年代:1989

数据来源: NRC

摘要:

Pseudomonassp. strain B-300, which is able to utilize 2-chlorobenzoic acid, was isolated from a soil sample by enrichment culture. This strain was shown to grow on 2-chlorobenzoic acid and to completely degrade the substrate with concomitant chlorine ion release. Concentrations of 2-chlorobenzoic acid higher than 0.5% (w/v) were toxic to the cells. Our study also suggested that in the presence of glucose, 2-chlorobenzoic acid is converted to catechol or chlorocatechol; these are in turn transformed to muconic and chloromuconic acid, respectively, suggesting a repression by glucose of some of the degradation pathway enzymes. A similar scheme was already described for 3-chlorobenzoate degradation by pAC25 plasmid.Key words: 2-chlorobenzoate, biodegradation, catabolism, metabolism,Pseudomonas.

ISSN:0008-4166    

DOI:10.1139/m89-067

出版商:NRC Research Press    

年代:1989

数据来源: NRC

摘要:

A detailed biochemical analysis has shown that during larval development on artificial medium, the amounts of K+, Na+, and Ca2+in the hemolymph of healthyChoristoneura fumiferanavaried from 85 to 110 mg/100 mL, 29 to 33 mg/100 mL, and 4.8 to 7.3 mg/100 mL, respectively. Similar results were obtained withMalacosoma disstria. Intoxication byBacillus thuringiensis"H3a,3b" (B.t.) considerably modified the amounts of the cations. Thus, after 4 h, the quantity of K+inM.disstriaincreased from 99 to 229 mg/100 mL and Na+from 26.5 to 50.3 mg/100 mL while that of Ca2+decreased from 5.8 to 1.2 mg/100 mL. Similar results were observed withC.fumiferana, but these variations occurred after 2 to 4 days ofB.t. intoxication. The variations detected during the bacillosis, with respect to the cationic composition of the insect hemolymph, are rapidly detectable, well before light microscope observation can confirm the presence of this intoxication. Aspartate aminotransferase, alanine aminotransferase, α-hydroxybutyrate dehydrogenase, and isocitrate dehydrogenase activity fluctuated very slightly in the hemolymph of either healthy or bacillosed larvae of the two insects under study. These results suggest that it is possible to diagnose biochemically the presence of aB.t. intoxication in lepidopteran forest pests following treatments by this biological insecticide for their control.Key words: lepidoptera,Bacillus thuringiensis, intoxication, biochemical diagnosis, cations.

ISSN:0008-4166    

DOI:10.1139/m89-068

出版商:NRC Research Press    

年代:1989

数据来源: NRC

摘要:

Obligate moderately thermophilic bacilli and obligate moderately thermoacidophilic bacilli contained spermine as the major polyamine in addition to putrescine and spermidine. The identity of spermine was confirmed by thin-layer chromatography and high-performance liquid chromatography before and after treatment with putrescine oxidase. Using these methods, thermospermine and spermine can be separated; thermospermine was not present in these organisms. On the other hand, various facultative thermophiles and mesophilic strains of the genusBacillus, including alkalophiles and halophiles, lack spermine and other tetraamines. No spermine was detected in several strains of mesophilic or facultative slightly thermophilic lactic acid bacteria,LactobacillusandStreptococcus.Key words: polyamine, spermine,Bacillus,Lactobacillus,Streptococcus.

ISSN:0008-4166    

DOI:10.1139/m89-069

出版商:NRC Research Press    

年代:1989

数据来源: NRC

摘要:

Increases in root and shoot fresh weight were observed when the nutrient solutions used for growth of tomato, cucumber, lettuce, and potato plants were bacterized with plant growth promotingPseudomonasstrains. It is hypothesized that plant growth promotion is due to the suppression of a deleterious rhizosphere microflora, especially deleterious endorhizosphere bacteria. The composition of the microbial community in artificial substrates, such as nutrient films and rockwool, is thought to be less complex than in soil. Therefore, development of a microflora deleterious for plant growth has to be anticipated. Microbial development in hydrocultures was simulated by preinoculating plant nutrient solutions with rhizosphere suspensions from plants that had been grown for different lengths of time in hydroponic cultures. After 16 days the plants in preinoculated nutrient solutions showed a growth reduction that correlated with the extent of root colonization by fluorescent pseudomonads in the endorhizosphere. Bacterization with plant growth promotingPseudomonassp. strain WCS417r counteracted this plant growth reduction. This increase in plant growth was accompanied by a dense colonization of the endorhizosphere by WCS417r and by a consequent displacement of indigenous endorhizosphere-inhabiting pseudomonads.Key words:Pseudomonas, endorhizosphere, hydroponics, plant growth, colonization.

ISSN:0008-4166    

DOI:10.1139/m89-070

出版商:NRC Research Press    

年代:1989

数据来源: NRC

摘要:

Bacteria resemblingRhizobium leguminosarum, but lacking symbiotic information, were isolated from soil of two different geographical origins. One of these bacteria belongs to a previously describedRhizobium leguminosarumbv.phaseolisomatic serogroup, is fully complemented for nodulation and nitrogen fixation by anR.leguminosarumbv.phaseolisymbiotic plasmid, and is able to compete for bean nodulation with indigenousR.leguminosarumbv.phaseolistrains. This is the first report giving evidence for persistence in soil ofRhizobiumlacking symbiotic information.Key words:Rhizobiumecology, symbiotic plasmid, nodulation, plasmid transfer.

ISSN:0008-4166    

DOI:10.1139/m89-071

出版商:NRC Research Press    

年代:1989

数据来源: NRC

摘要:

The effect of temperature on the ability of five species ofTrichodermato decompose cellulose was evaluated in three types of sterilized soils. The loss in tensile strength of cotton strips was used as an index of cellulose decomposition. The influence of levels of nitrogen on cotton degradation was also evaluated using silica sand as a substitute for soil. A greater loss in cotton tensile strength was obtained withT.virensandT.viridethan withT.hamatum,T.polysporum, orT.koningii. All species responded similarly to nitrogen levels and temperature, with decreased activity at low nitrogen and low temperature. The soil also had a large influence on the rate of decomposition of the strips. The soil from a maple forest gave rise to greater losses in tensile strength than did soil from a white pine or Norway spruce plantation. These results emphasize the importance of the soil chemistry in determining fungal activities in the field, and the difficulties of extrapolating results of cellulose utilization studies in the laboratory to the field.Key words:Trichoderma, cellulolysis, soil, nitrogen, temperature.

ISSN:0008-4166    

DOI:10.1139/m89-072

出版商:NRC Research Press    

年代:1989

数据来源: NRC

摘要:

The long-term survival of three human enterovirus serotypes, Coxsackievirus B3, echovirus 7, and poliovirus 1 was examined in samples of surface freshwater collected from five sites of physically different character. These were an artificial lake created by damming a creek, a small groundwater outlet pond, both a large- and a medium-sized river, and a small suburban creek. Survival was studied at temperatures of −20, 1, and 22 °C. The average amount of viral inactivation was 6.50–7.0 log10units over 8 weeks at 22 °C, 4–5 log10units over 12 weeks at 1 °C, and 0.4–0.8 log10units over 12 weeks at −20 °C. The effect of incubation temperature upon viral inactivation rate was statistically significant (p < 0.00001). As determined by pairing tests, survival was also significantly related to both viral serotype and water source at each of the three incubation temperatures (p ≤ 0.05). Efforts were made to determine whether the rate of viral inactivation observed at the different incubation temperatures was related to characteristics inherent to the water that was collected from the different locations. The characteristics examined included physical and chemical parameters, indigenous bacterial counts, and the amount of bacterial growth that the waters would support (measured as the maximum number of generations which seeded bacteria could undergo after being placed into either pasteurized or sterile-filtered water samples). Analysis of viral inactivation rate versus these characteristics revealed three apparent effectors of viral persistence. These were (i) hardness and conductivity, both of which strongly correlated with one another; (ii) turbidity and suspended solids content, both of which strongly correlated with one another; and (iii) the number of generations of bacterial growth that a sample was capable of supporting, which also correlated with hardness and conductivity.Key words: virus, survival, inactivation rate, water.

ISSN:0008-4166    

DOI:10.1139/m89-073

出版商:NRC Research Press    

年代:1989

数据来源: NRC

摘要:

The proton motive force mediated the transport of seleniteinClostridium pasteurianumcells by proton symport. The proton conductor, carbonyl cyanidem-chlorophenylhydrazone, inhibiteduptake whileN,N′-dicyclohexylcarbodiimide preventeduptake by presumably inhibiting the unidirectional ATPase. Acid pulse studies and antibiotic experiments with valinomycin suggest that the transmembrane ΔpH component of the proton motive force mediated the transport ofinto the cells. Theporter system inC.pasteurianumwas found to be dependent upon energy source, temperature, and medium pH.Key words: proton motive force, anion transport, selenite,Clostridium pasteurianum.

ISSN:0008-4166    

DOI:10.1139/m89-074

出版商:NRC Research Press    

年代:1989

数据来源: NRC