摘要:

Two rhizobiophages, RS1 and RS2, were isolated in Senegal from a soil sample and dry stem nodules ofSesbania rostrata, a tropical legume that is infected by two categories ofRhizobiumstrains: "stem strains," which nodulate both roots and stems (type strain, ORS571), and "root strains," which induce effective nodules only on roots. Both phages were found to have a host range restricted to ORS571; all root strains were found to be resistant. By electron microscopy, phage RS1 showed an hexagonal head 63 nm wide and a tail 87 nm long; phage RS2 revealed an hexagonal head 60 nm wide. Characterization of phage growth cycle by one-step growth experiments showed that the latent period was ca. 75 min for RS1 and ca. 4 h for RS2, that the rise period lasted ca. 2 h for both RS1 and RS2, and that the average burst size was ca. 100 for RS1 and 130 for RS2. Temperature denaturation occurred at 60–65 °C (RS1) and 45–50 °C (RS2). Serum neutralization tests revealed that the phages were not serologically related. In contrast to RS1, RS2 appeared to be temperate, since stable lysogens were isolated.

ISSN:0008-4166    

DOI:10.1139/m84-079

出版商:NRC Research Press    

年代:1984

数据来源: NRC

摘要:

The pathway of glucose metabolism byTreponema bryantii, an obligately anaerobic spirochete isolated from bovine rumen contents, was studied. Washed cell suspensions of the spirochete consumed glucose and CO2and produced equimolar amounts of acetate, formate, and succinate. Carbon dioxide was essential for glucose metabolism. Determination of radioactivity in products formed from14C-labelled glucose and NaH14CO3and assays of enzyme activities in cell-free extracts were used to determine the pathway of glucose metabolism.Treponema bryantiicatabolized glucose to pyruvate via the Embden–Meyerhof–Parnas pathway. The spirochete used a coliform pyruvate–formate lyase to degrade pyruvate and produce formate and acetate. Succinate was formed by a pathway which involved the condensation of CO2with pyruvate (or phospho(enol)pyruvate) formed from the breakdown of glucose.

ISSN:0008-4166    

DOI:10.1139/m84-080

出版商:NRC Research Press    

年代:1984

数据来源: NRC

摘要:

Pyruvate carboxylase (EC 6.4.1.1) fromThiobacillus novellus(ATCC 8093) was highly purified and found to have a pH optimum of 7.6, a temperature optimum of 25–35 °C, and a requirement for a monovalent and a divalent cation, as well as a CoA derivative, for maximum activity. These were best served by K+, Mg2+, and acetyl-CoA.Kmvalues for pyruvate, ATP, HCO3−and Mg2+were 0.25, 0.04, 0.27, and 0.44 mM, respectively. Initial velocity plots of increasing acetyl-CoA concentrations gave a sigmoidal curve withKaof 4.2 μM, and Hill coefficients of 2.2. Plots of fixed acetyl-CoA concentrations against varying concentrations of pyruvate, ATP, or CO2all gave rectangular hyperbolae. Apart from end products, only hydroxypyruvic acid was found to be inhibitory. The enzyme was very sensitive to mercurials. This enzyme is not believed to serve an anaplerotic function, because of the simultaneous presence of the highly regulated phosphoenolpyruvate carboxylase in the organism. Instead, it may function either to supply oxaloacetate to the citrate cycle or as part of the system that provides reduced NADP+.

ISSN:0008-4166    

DOI:10.1139/m84-081

出版商:NRC Research Press    

年代:1984

数据来源: NRC

摘要:

Fusion experiments, involving protoplasts of selected hybridizing and nonhybridizingKluyveromycesstrains, are reported. The results obtained indicate that prototrophic fusion products were recovered from all 54 crosses involving the protoplasts of hybridizing strains. These products showed varying degrees of stability. Although two different methods of protoplast preparation and protoplast fusion were employed, only 7 out of 32 fusion experiments involving nonhybridizing strains yielded prototrophic fusion products. All these fusion products proved to be unstable after a single passage through a complete medium. reverting directly to the parental strains.

ISSN:0008-4166    

DOI:10.1139/m84-082

出版商:NRC Research Press    

年代:1984

数据来源: NRC

摘要:

Cell walls ofBacillus anthraciswere found to be resistant to lysozyme, and partially resistant to mutanolysin, a muramidase fromStreptomyces globisporus. Following treatment with acetic anhydride, it was observed that the walls were highly susceptible to hydrolysis by lysozyme or mutanolysin. Analyses of cell walls, prior to and following derivatization with fluorodinitrobenzene, revealed that approximately 88% of the glucosamine residues and 34% of the muramic acid residues of the peptidoglycan contained unsubstituted amino groups, thereby providing an explanation for the resistance of the walls to lysozyme. The walls ofB.anthraciswere approximately 19% cross-linked, based on the findings that 81% of the diaminopimelic acid residues could be modified by fluorodinitrobenzene. Walls ofB.thuringiensis4040 andB.cereusATCC 19637 also contained high percentages of unsubstituted amino sugars, and unless acetylated, were also relatively resistant to lysozyme and mutanolysin. WhenB.anthracis,B.cereus, orB.thuringiensiswere grown in the presence of 100 μg/mL lysozyme, there was a decrease in the average number of cells per chain, but there was no decrease in growth rates, suggesting that the enzyme was acting at septa. It is unlikely that lysozyme and autolysins act synergistically inBacillus, because azide anion, which activates autolysins, did not enhance the lytic action of lysozyme inB.anthracis,B.cereus, orB.thuringiensis.

ISSN:0008-4166    

DOI:10.1139/m84-083

出版商:NRC Research Press    

年代:1984

数据来源: NRC

摘要:

Mutations in the DNA polymerase locus of phage, bacteria, and eukaryotic cells may change the mutation rates at other loci of the genome. We used resistance to phosphonoacetate to select mutants of herpes simplex virus with mutated DNA polymerase and then determined the reversion frequency of viral thymidine kinase mutation in mutants and recombinants. The results obtained indicate that mutations causing resistance to phosphonoacetate do not affect the mutation rate of the viral genes. This finding is consistent with the existence of two functional regions in the DNA polymerase molecule, one involving the pyrophosphate acceptor site and responsible for resistance to phosphonoacetate and another involved in the editing ability and recognition specificity of the enzyme.

ISSN:0008-4166    

DOI:10.1139/m84-084

出版商:NRC Research Press    

年代:1984

数据来源: NRC

摘要:

Seventy-four yeasts and 224 fungi were isolated from marine water and sediment samples taken from the Strait of Juan de Fuca and northern Puget Sound. When these isolates were grown in the presence of Prudhoe Bay crude oil, only three yeasts and 63 fungi were able to degrade some or all of then-alkanes. None degraded the isoprenoids, pristane and phytane. Forty-seven isolates were identified asPenicilliumspecies and of these, 39 attacked then-alkanes in the crude oil. Twelve organisms which degraden-alkanes were tested for their ability to mineralize [14C]naphthalene and [14C]phenanthrene which had been added to the crude oil. No14CO2was detected from any of the cultures containing these compounds. Capillary gas chromatographic analyses of the aromatic fractions from these 12 cultures showed no loss of hydrocarbons or sulfur hetero-cycles, indicating that they were unable to completely or partially oxidize any of the resolvable compounds in this fraction.

ISSN:0008-4166    

DOI:10.1139/m84-085

出版商:NRC Research Press    

年代:1984

数据来源: NRC

摘要:

The membrane-bound NADH oxidase ofParacoccus halodenitrificanswas inhibited by dicoumarol, 2-n-heptyl-4-hydroxyquinoline-N-oxide (HQNO), and exposure to ultraviolet light (at 366 nm). When the membranes were extracted withn-pentane, NADH oxidase activity was lost. Partial restoration was achieved by adding the ubiquinone fraction extracted from the membranes. Succinate oxidation was not inhibited by dicoumarol or HQNO, but was affected by ultraviolet irradiation orn-pentane extraction. However, the addition of the ubiquinone fraction to the membranes extracted withn-pentane did not restore enzyme activity. These observations suggested that NADH and succinate were not oxidized through a common ubiquinone pool.

ISSN:0008-4166    

DOI:10.1139/m84-086

出版商:NRC Research Press    

年代:1984

数据来源: NRC

摘要:

The surface microlayer of two small ponds in Wisconsin were studied from March 1979 through November 1979 using glass plate and screen microlayer sampling devices. The numbers of fungal colony-forming units (CFU) in the surface microlayer were determined and compared with numbers in subsurface waters; diel fluctuations were correlated with nutrients; and experiments were conducted to estimate the contribution of spores to surface microlayer populations. The data obtained indicates that the highest number of fungal CFU were located in the surface microlayers of the ponds studied. The numbers present, as well as their enrichment in the surface microlayer, underwent both seasonal and diel fluctuations. Most of the fungal CFU in the surface microlayer appeared to be spores arriving from both allochthonous and autochthonous sources. Qualitative investigations would be necessary to determine the relative importance of either source to the total numbers of fungi observed.

ISSN:0008-4166    

DOI:10.1139/m84-087

出版商:NRC Research Press    

年代:1984

数据来源: NRC

摘要:

The unique sequence DNA's of several wild and cultivated fungi includingAgaricus brunnescens(=Agaricus bisporus),Agaricus bitorquis,Amanita muscaria,Amanita phalloides,Pleurotus ostreatus,Lentinus edodes, andSchizophyllum communewere compared by DNA–DNA hybridization. In addition, the characterization of a number of fungal DNA's are reported for the first time. Unique sequence DNA fromAgaricus brunnescensandP.ostreatuswas labeled by nick translation and each was hybridized with an excess of unlabeled driver DNA. Unique sequence DNA from two different isolates ofAgaricus brunnescensshowed nearly complete homology with one another, while only 56% of the unique sequence DNA fromAgaricus bitorquishybridized with the sameAgaricus brunnescensDNA. Furthermore, very little sequence homology existed betweenAgaricus brunnescensDNA and the DNA's of the other mushrooms studied. Similarly, very little hybridization occurred betweenP.ostreatuslabeled DNA and the DNA's of the other species. The stability of the DNA duplexes was examined by thermal elution. TheTmofAgaricus brunnescens:Agaricus bitorquisduplexes was 7.7 °C lower thanAgaricus brunnescens:Agaricus brunnescensduplexes. This indicated a 7.7–11.6% mismatch between the unique DNA's of these two species.

ISSN:0008-4166    

DOI:10.1139/m84-088

出版商:NRC Research Press    

年代:1984

数据来源: NRC