| 1. |
- Lindberg, A Michael, et al.
(author)
-
Genome of Coxsackievirus B3
- 1987
-
In: Virology. - : Elsevier BV. - 0042-6822 .- 1096-0341. ; 156:1, s. 50-63
-
Journal article (peer-reviewed)abstract
- The entire nucleotide sequence of the coxsackievirus B3 strain Nancy (CB3) genome has been determined from cDNA. The genome is 7396 nucleotides long, and encodes a 2185 amino acid long polyprotein. It exhibits the same gene organization as other enterovirus genomes. A detailed comparison was carried out between the proteins encoded by the CB3 and poliovirus type 1 strain Mahoney (PVI) genomes. The genes encoding the VPg polypeptide and the viral polymerase are the most conserved regions. The structural polypeptides VP1, VP2, and VP3 are less well conserved although proline and tryptophan residues frequently are found in identical positions. The VP1 protein of CB3 shows a particularly limited homology in those regions which have been found to induce neutralizing antibodies against PV1. The 5′ noncoding region of CB3 is closely related to that of PV1, with regard to both length and sequence organization, whereas the 3′ noncoding region of CB3 exhibits some unique features.
|
|
| 2. |
- Schnürer, Johan, 1957-, et al.
(author)
-
Effects of moisture on soil microorganisms and nematodes : A field experiment
- 1986
-
In: Microbial Ecology. - : Springer-Verlag New York. - 0095-3628 .- 1432-184X. ; 12:2, s. 217-230
-
Journal article (peer-reviewed)abstract
- The effects of soil moisture changes on bacteria, fungi, protozoa, and nematodes and changes in oxygen consumption were studied in a field experiment. In one plot the soil was drip-irrigated daily for 10 days, while an adjacent plot experienced one rainfall and was then allowed to dry out. Oxygen consumption was the parameter measured which responded most rapidly to changes in soil moisture content. Lengths of fluorescein diacetate-active hyphae paralleled oxygen consumption in both plots. Total hyphal length was not affected by one rainfall but increased from 700 mg-1 dry weight soil to more than 1,600 m in less than 10 days in the irrigated plot. In the rain plot, bacterial numbers doubled within 3 days and declined during the following period of drought. In the irrigated plot, numbers increased by 50% and then remained constant over the duration of the study. Only small changes in protozoan numbers were observed, with the exception of the last sampling date in the irrigated plot when large numbers of naked amoebae were recorded 2 days after a large natural rainfall. Nematode numbers, especially obligate root feeders, increased in both treatments. The increases were caused by decoiling rather than growth. The results indicate that fungal respiration was dominating, while bacteria, lacking a suitable source of energy, were less active, except for the first days.
|
|
| 3. |
|
|
| 4. |
|
|
| 5. |
- Andersson, Agneta, et al.
(author)
-
Release of aminoacids and inorganic nutrients by heterotrophic marine microflagellates
- 1985
-
In: Marine Ecology Progress Series. - 0171-8630 .- 1616-1599. ; 23, s. 99-106
-
Journal article (peer-reviewed)abstract
- Heterotrophic microflagellates isolated from the Baltic Sea and grown under laboratoryconditions were shown to release dissolved free amino acids (DFAA) when grazing bacteria. Flagellatesreleased 3H-amino acids when fed 3H-leucine-labelled bacteria, and concentrations of aminoacids increased in the experimental medium. Serine showed a strong positive correlation withflagellate feeding. Aspartic acid, glutamic acid and ornithine also increased more than other aminoacids. During consumption of bacteria, the flagellates released 13% of the ingested nitrogen asammonia, and 30 % of the ingested phosphorus as phosphate. In a field experiment off Scripps Pier, wemeasured bacterial production, flagellate abundance, and concentration of DFAA over a 28 h period.The concentration of DFAA showed a covariation with the flagellate numbers. Results from our fieldand laboratory experiments suggest that flagellates may be a source of DFAA in the sea.
|
|
| 6. |
|
|
| 7. |
|
|
| 8. |
- Fuhrman, J.A., et al.
(author)
-
Diel variations in bacterioplankton, phytoplankton, and related parameters in the Southern California Bight.
- 1985
-
In: Marine Ecology Progress Series. - 0171-8630 .- 1616-1599. ; 27, s. 9-20
-
Journal article (peer-reviewed)abstract
- The principal objectives of this study were (i) to determine the extent of coupling betweenphytoplankton and microheterotrophs on the shelf off Southern California. (ii) to compare differentmeasures of primary and bacterial secondary production, and (iii) to assess whether sampling timesshould be as strictly controlled for microheterotroph as for autotroph studies. Two diel cycles (May andOctober) were studied by sampling an isotherm as the ship followed paired submerged drogues. Wefound significant die1 changes of chlorophyll, 14C bicarbonate incorporation, bacterial abundance andthymidine incorporation, frequency of dividing bacterial cells (FDC), abundance of non-pigmentedflagellates, particulate organic carbon and nitrogen and their ratios, and dissolved oxygen. Theseparameters all had higher values dunng daylight hours than at night, showing close coupling betweenthe phytoplankton (light-forced) and the microheterotrophs. The ratio of in vivo to extractedchlorophyll a fluorescence, however, displayed a maximum at midnight and minimum at midday,suggesting an endogenous rhythm. Primary production measured by the 14C method was similar to netproduction inferred from in situ oxygen changes. Short-lived peaks in FDC values suggested partlysynchronized bacterial division.
|
|
| 9. |
- Fuhrman, J.A., et al.
(author)
-
Extraction from natural planktonic microorganisms of DNA suitable for molecular biological studies
- 1988
-
In: Applied and Environmental Microbiology. - 0099-2240 .- 1098-5336. ; 54:6, s. 1426-1429
-
Journal article (peer-reviewed)abstract
- We developed a simple technique for the high-yield extraction of purified DNA from mixed populations ofnatural planktonic marine microbes (primarily bacteria). This is a necessary step for several molecularbiological approaches to the study of microbial communities in nature. The microorganisms from near-shoremarine and brackish water samples, ranging in volume from 8 to 40 liters, were collected on 0.22-,um-pore-sizefluorocarbon-based filters, after prefiltration through glass fiber filters, to remove most of the eucaryotes. DNAwas extracted directly from the filters in 1% sodium dodecyl sulfate that was heated to 95 to 100°C for 1.5 to2 min. This procedure lysed essentially all the bacteria and did not significantly denature the DNA. The DNAwas purified by phenol extraction, and precautions were taken to minimize shearing. Agarose gel electrophoresisshowed that most of the final preparation had a large molecular size (>23 kilobase pairs). The DNA wassufficiently pure to allow complete digestion by the restriction endonuclease Sau3AI and ligation to vector DNA.In a sample in which the extracted DNA was quantified by binding to the dye Hoechst H33258, DNA wasquantitatively extracted, and 45% of the initially extracted DNA was recovered after purification. Final yieldswere a few micrograms of DNA per liter of seawater and were roughly 25 to 50% of the total bacterial DNAin the sample. Alternatives to the initial harvest by filtration method, including continuous-flow centrifugationand thin-channel or hollow-fiber concentration followed by centrifugation, were less efficient than filtration interms of both time and yield, largely because of the difficulty of centrifuging the very small bacteria typical ofmarine plankton. These methods were judged to be less appropriate for studies of natural populations as theyimpose a strong selection for the larger bacteria.
|
|
| 10. |
|
|
| 11. |
|
|
| 12. |
|
|
| 13. |
|
|
| 14. |
|
|
| 15. |
|
|
| 16. |
- Hagström, Åke, et al.
(author)
-
Microbial loop in an oligotrophic pelagic marine ecosystem: Possible roles of cyanobacteria and nanoflagellates in the organic fluxes
- 1988
-
In: Marine Ecology Progress Series. - 0171-8630 .- 1616-1599. ; 49, s. 171-178
-
Journal article (peer-reviewed)abstract
- In an attempt to quantify the organic fluxes within the microbial loop of oligotrophicMediterranean water, organic pools and production rates were monitored. The production of cyanobacteriaand its dynamics dominated the overall productivity in the system. The largest standing stock wasthat of the bacterioplankton and its growth consumed 8.3 pg C 1-' d-', hence about 60 % of the primaryproduction was required for bacterial growth. Using the MiniCap technique, we measured a predationon bacteria of 2 6 X 104 bacteria ml-' h-'. This was in good agreement with the bacterial production rateof 2.3 X 104 cells rnl-' h-' Thus, growth and predation were balanced for heterotrophic bacterioplankton.Almost all of this predation on bacteria was due to organisms passing a 12 vm Nuclepore filter. Thisraises the question of what mechanisms channel 60 % of primary production into bacteria. We thereforeoutlined a mass-balance model to illustrate routes that could explain this transfer. According to ourmodel the main flux route is cyanobacteria and concomitantly consumed heterotrophic bacteria carboninto bacterivores. A substantial fraction of the bacterivore and the microplankton carbon is released byexcretion and/or cell lysis, to be used by the heterotrophic bacterioplankton. About 86% of theautotrophic production is balanced by respiration due to heterotrophic bacteria and protozoa, leaving6 % of the primary production to higher trophic levels. This scenario should apply to ecosystems wherebacterial production rate is high and comparable to primary production, and the dominant primaryproducers are cyanobacteria. A significant fraction of the photosynthetically fixed carbon will bemineralized within a simple microbial loop, thus rendering it an energy sink in the foodweb.
|
|
| 17. |
|
|
| 18. |
|
|
| 19. |
- Horrigan, S.G., et al.
(author)
-
Inorganic nitrogen utilization by assemblages of marine bacteria in seawater culture
- 1988
-
In: Marine Ecology Progress Series. - 0171-8630 .- 1616-1599. ; 50, s. 147-150
-
Journal article (peer-reviewed)abstract
- Stimulation of heterotrophic bacterial growth by inorganic nitrogen (nitrate and ammonium) was observed in natural assemblages of marine bacteria growth in continuous culture with unsupplemented sea water as primary medium. In the presence of nitrogenous supplements, bacterial numbers increased approximately 3-fold. These results indicate that re-evaluation of the role of heterotrophic bacterioplankton in the pelagic nitrogen cycle may be necessary.
|
|
| 20. |
- Hultmark, Dan, 1949-
(author)
-
Insect immunity : Inducible antibacterial proteins from Hyalophora cecropia
- 1982
-
Doctoral thesis (other academic/artistic)abstract
- A powerful bactericidal activity can be induced in the hemolymph of many insects as a response to an injection of bacteria. The nature of the effector molecules of this immune response was investigated, using pupae of the Cecropia moth, Hyalophora cecropia. Three major types of antibacterial proteins were found: the cecropins, the P5 proteins, and lysozyme. They appear in the hemolymph as a result of de novo synthesis.Six different cecropins were purified and characterized. The full amino acid sequences of the three major cecropins A, B and D were determined, as well as partial sequences of the three minor cecropins C, E and F. The cecropins are all very small (Mr = 4,000) and basic (pI > 9.5) proteins, and they show extensive homology in their sequences. The three major cecropins are products of different genes. Their C-terminals are blocked by uncharged groups, which can be removed by mild acid hydrolysis. The minor cecropins are closely related to the major forms, and may be unblocked precursors or, in one case (cecropin F), a minor allelic form. The cecropins were shown to be lytic, and to be efficient against several Gram positive and Gram negative bacterial strains, but not against mammalian cells.The P5 proteins are bactericidal proteins, larger than the cecropins (Mr = 20,000 - 23,000). Six forms, differing in isoelectric point, were isolated. They form two closely related groups, the basic (P5 A-D) and the acidic forms (P5 E-F). Within each group, the different forms have almost identical amino acid compositions.The Cecropia lysozyme is similar to lysozymes isolated from other insects, as well as to that from hen egg white. It is lytic to a restricted number of Gram positive bacteria.The presence of cecropins and other antibacterial factors was demon-strated also in other lepidopterans, notably Galleria mellonella, and may explain earlier observations of antibacterial factors in the latter species.
|
|
| 21. |
- Lacoursière, Jean O., 1958-, et al.
(author)
-
Laboratory study of the influence of water temperature and pH on Bacillus thuringiensis var. israelensis efficacy against black fly larvae (Diptera: Simuliidae)
- 1988
-
In: Journal of the American Mosquito Control Association. - 8756-971X .- 1943-6270. ; 4:1, s. 64-72
-
Journal article (peer-reviewed)abstract
- An experimental formulation of Bacillus thuringiensis var. israelensis was used in the laboratory to assess the influence of water temperature and pH on the relationship between concentration, duration of exposure, and mortality of the northern black fly species Simulium decorum and Prosimulium mixtum/fuscum group. Mortality increases in both species with increases in duration of exposure, concentration, temperature and pH. Onset of death is shortened by increase in concentration and temperature. As temperature rises, the concentration of B. t. i required to induce mortality decreases; the sharpest decline occurring between 12 and 18 degree C for S. decorum , and between 4 and 8 degree C for P. mixtum/fuscum larvae. Lower pH induces a loss of efficacy of the B. t. i. formulation on S. decorum larvae at 4 and 12 degree C.
|
|
| 22. |
|
|
| 23. |
- Norquist, A., et al.
(author)
-
Protection against vibriosis and furunculosis by the use of attenuated strains of Vibrio anguillarum.
- 1989
-
In: Applied and Environmental Microbiology. - 0099-2240 .- 1098-5336. ; 55:6, s. 1400-1405
-
Journal article (peer-reviewed)abstract
- The fish pathogen Vibrio anguillarum causes a lethal infectionin rainbow trout (Salmo gairdneri). Three different avirulentmutants, constructed by transposon insertion mutagenesis (VAN20and VAN70) or as antibiotic-resistant mutants (VAN1000), wereisolated by screening 200 individual isolated mutants for avirulence.When used as live vaccines, all three avirulent mutants wereable to induce protective immunity against the homologous aswell as a heterologous strain of V. anguillarum. When VAN1000was used, protective immunity could be recorded 1 week afterbath vaccination with 10(7) bacteria per ml of water for 30min. A single-dose immunization was effective for at least 12weeks. Western immunoblotting showed that strains of V. anguillarumhave antigenic determinants in common with Aeromonas strains.Therefore, we tested and confirmed that VAN1000 also was ableto induce protective immunity against challenge with Aeromonassalmonicida.
|
|
| 24. |
- Ohlson, Sten, et al.
(author)
-
Steroid Hydroxylation Using Immobilized Spores of Curvularia lunata Germinated in situ
- 1980
-
In: European Journal of Applied Microbiology and Biotechnology. - 0171-1741. ; 10, s. 1-9
-
Journal article (peer-reviewed)abstract
- Spores of Curvularia lunata were immobilized in polyacrylamide granules and in calcium alginate beads (2–3 mm in diam.). Germination of the spores, initiated by the addition of nutrients, resulted in an even distribution of mycelium throughout the beads after 48 h. Such beads were used for the conversion of cortexolone to cortisol by steroid-11-hydroxylation. In order to improve the steroid transforming ability several parameters were studied. It was found that preparations based on calcium alginate gave the best results. The possible merits of immobilizing spores rather than vegetative cells, followed by in situ germination are discussed also for other microorganisms and immobilization processes.
|
|
| 25. |
- Rehnstam, Ann-Sofi, 1959-, et al.
(author)
-
Identification of Vibrio anguillarum in fish by using partial 16S rRNA sequences and a specific 16S rRNA oligonucleotide probe
- 1989
-
In: Applied and Environmental Microbiology. - 0099-2240 .- 1098-5336. ; 55:8, s. 1907-1910
-
Journal article (peer-reviewed)abstract
- 16S rRNA from seven different Vibrio anguillarum strains was partially sequenced and compared. From this sequence information we could design a 25-base-long oligonucleotide and use it as a specific probe for identification of V. anguillarum. This was determined by RNA-DNA colony hybridization and slot-blot hybridization. Strong, specific hybridization to the probe was observed for all V. anguillarum strains tested. Furthermore, no cross-hybridization could be seen against five other bacterial species. The detection limit was 5 x 10(3) bacteria per ml. It was even possible to detect V. anguillarum, by slot-blot hybridization, directly in a homogenized kidney from a fish that had died of vibriosis. The partial sequence information revealed small but significant differences between strains of the same species. These sequence differences are sufficiently significant to allow serotyping on the RNA level. Comparing strains of different serotypes revealed a 10-base and an 11-base difference in V. anguillarum serotypes O8 and O9, respectively, in a 122-base partial sequence.
|
|
| 26. |
- Rehnstam, A.-S., et al.
(author)
-
Identification of Vibrio anguillarum in fish using partial 16S rRNA sequences and a specific 16S rRNA oligonucleotide probe.
- 1989
-
In: Applied and Environmental Microbiology. - 0099-2240 .- 1098-5336. ; 55:8, s. 1907-1910
-
Journal article (peer-reviewed)abstract
- 16S rRNA from seven different Vibrio anguillarum strains waspartially sequenced and compared. From this sequence informationwe could design a 25-base-long oligonucleotide and use it asa specific probe for identification of V. anguillarum. Thiswas determined by RNA-DNA colony hybridization and slot-blothybridization. Strong, specific hybridization to the probe wasobserved for all V. anguillarum strains tested. Furthermore,no cross-hybridization could be seen against five other bacterialspecies. The detection limit was 5 x 10(3) bacteria per ml.It was even possible to detect V. anguillarum, by slot-blothybridization, directly in a homogenized kidney from a fishthat had died of vibriosis. The partial sequence informationrevealed small but significant differences between strains ofthe same species. These sequence differences are sufficientlysignificant to allow serotyping on the RNA level. Comparingstrains of different serotypes revealed a 10-base and an 11-basedifference in V. anguillarum serotypes O8 and O9, respectively,in a 122-base partial sequence.
|
|
| 27. |
|
|
| 28. |
- Schnürer, Johan, 1957-, et al.
(author)
-
Fluorescein diacetate hydrolysis as a measure of total microbial activity in soil and litter
- 1982
-
In: Applied and Environmental Microbiology. - Washington : American Society for Microbiology. - 0099-2240 .- 1098-5336. ; 43:6, s. 1256-1261
-
Journal article (peer-reviewed)abstract
- Spectrophotometric determination of the hydrolysis of fluorescein diacetate (FDA) was shown to be a simple, sensitive, and rapid method for determining microbial activity in soil and litter. FDA hydrolysis was studied in soil and straw incubated for up to 3h. Hydrolysis was found to increase linearly with soil addition. FDA hydrolysis by pure cultures of Fusarium culmorum increased linearly with mycelium addition both in shake cultures and after inoculation into sterile soil. FDA hydrolys is by Pseudomonas denitrificans increased linearly with biomass addition. The FDA hydrolytic activities in soil samples from different layers of an agricultural soil were correlated with respiration. Acetone was found to be suitable for terminating the reaction.
|
|
| 29. |
|
|
| 30. |
- Wikner, Johan, 1961-, et al.
(author)
-
Evidence for a tightly coupled nanoplanktonic predator-prey link regulating the bacterivores in the marine-environment
- 1988
-
In: Marine Ecology Progress Series. - Oldenburg : Inter-Research. - 0171-8630 .- 1616-1599. ; 50:1-2, s. 137-145
-
Journal article (peer-reviewed)abstract
- A coupled predator-prey chain, starting with bactenvores, was invest~gated using the mlnicell recapture technique (MiniCap) Water samples were subjected to slze fract~onation wth decreasing filter pore sue in order to obtain a successive truncation of the microbial food chaln Our results showed that the malor bacterivores were flagellates in the size range of 1 to 3 pm The truncation of the food chain caused increased or decreased predation on the bactena, d e p e n d~n go n whether the bacterivores 'ivere released from or subjected to increased predat~on pressure We present a model describing trophic interactions between organisms less than 12 pm In size This model suggests 4 trophic levels to form a regulatory chain exer t~nga tight control on major bacterivores.
|
|
| 31. |
|
|
| 32. |
|
|
| 33. |
- Öquist, G., et al.
(author)
-
Chlorophyll a fluorescence an alternative method for estimating primary production
- 1982
-
In: Marine Biology. - 1230-7688. ; 68:1, s. 71-75
-
Journal article (peer-reviewed)abstract
- The in vivo chlorophyll a fluorescence index (F+DcM u-F-DcMu/F+DcMU) of natural waters was compared to the 14C-determined primary production, and the fluorescence intensity in the presence of 3-(3,4-dichlorophenyl)-l,l-dimethylurea (F + DCM~) was studied as a function of extracted and spectrophotometrically determined chlorophyll concentrations. Samples were taken every second week from May through October, 1979, at the station "Systrarna" situated in a coastal area of the Bottnian Sea. In addition, samples from the Archipelago Sea of the Baltic were collected on board the Finnish research vessel R/S "Aranda" during the September cruise 1979. The correlations between the fluorescence index and the 14C-determined primary production and between F+DcMu and total chlorophyll concentration were good when samples taken over short time intervals were compared. The shortcomings of both the fluorescence and the 14C methods are discussed. It is concluded that the fluorescence method is useful if it is desirable to follow with high time resolution any changes in the potential for photosynthesis (or pirmary production) in a water mass over relatively short time periods; e.g. during an algal bloom. The fluorescence method can furthermore be technically developed for automatic monitoring with a high time resolution. Efforts are being made in our laboratory to develop the method further to give information about the in situ rates of photosynthesis rather than the potential for photosynthesis in a phytoplankton population.
|
|
| 34. |
- Wold, Agnes E, 1955, et al.
(author)
-
Difference between bacterial and food antigens in mucosal immunogenicity.
- 1989
-
In: Infection and immunity. - 0019-9567. ; 57:9, s. 2666-73
-
Journal article (peer-reviewed)abstract
- The mucosa-associated lymphoid tissue may deviate from its systemic counterpart in being able to discriminate between microbial and nonmicrobial antigens. To study this, the systemic and mucosal antibody responses to bacterial and food antigens were followed in parallel in female rats during two pregnancies and lactation periods. Germfree rats were monocolonized with an Escherichia coli O6K13H1 strain, and their diet was switched to pellets containing large amounts of ovalbumin and beta-lactoglobulin. Antibodies against O6 lipopolysaccharide already appeared in serum and bile 1 week after colonization, and those against type 1 fimbriae appeared a few weeks later. Serum immunoglobulin G antibodies against the E. coli enzyme beta-galactosidase were found in moderate titers in all rats after 16 weeks of exposure. In contrast, few rats had detectable antibody levels against the dietary proteins ovalbumin and beta-lactoglobulin in serum or bile even after 16 weeks of exposure. In the milk, antibodies against E. coli beta-galactosidase and type 1 fimbriae reached the highest titers, while moderate titers were found against the food antigens and against O6 lipopolysaccharide. The difference in immune reactivity against bacterial versus dietary antigens was not likely due to insufficient amounts of the latter reaching lymphoid tissue, since (i) uptake studies indicated that ovalbumin was more efficiently taken up than endotoxin and (ii) the same difference in antigenicity between ovalbumin and E. coli was seen after immunization directly into Peyer's patches. We therefore suggest that a prerequisite for a strong mucosal antibody response is that the antigen be encountered by the gut-associated lymphoid tissue within microorganisms capable of stimulating antigen presentation.
|
|
| 35. |
- Aevarsson, A, et al.
(author)
-
Ligands to the 2Fe iron-sulfur center in succinate dehydrogenase
- 1988
-
In: FEBS Letters. - : Wiley. - 1873-3468 .- 0014-5793. ; 232:2, s. 298-302
-
Journal article (peer-reviewed)abstract
- Membrane-bound succinate oxidoreductases are flavoenzymes containing one each of a 2Fe, a 3Fe and a 4Fe iron-sulfur center. Amino acid sequence homologies indicate that all three centers are located in the Ip (B) subunit. From polypeptide and gene analysis of Bacillus subtillis succinate dehydrogenase-defective mutants combined with earlier EPR spectroscopic data, we show that four conserved cysteine residues in the first half of Ip are the ligands to the [2Fe-2S] center. These four residues have previously been predicted to be the ligands. Our results also suggest that the N-terminal part of B. subtilis Ip constitutes a domain which can incorporate separately the 2Fe center and interact with Fp, the flavin-containing subunit of the dehydrogenase.
|
|
| 36. |
- Carlsson, Peter, et al.
(author)
-
Bacillus subtilis citM, the structural gene for dihydrolipoamide transsuccinylase: cloning and expression in Escherichia coli
- 1987
-
In: Gene. - : Elsevier BV. - 1879-0038 .- 0378-1119. ; 61:2, s. 217-224
-
Journal article (peer-reviewed)abstract
- The 2-oxoglutarate dehydrogenase multienzyme complex is composed of three different subenzymes: 2-oxoglutarate dehydrogenase (E1o), dihydrolipoamide transsuccinylase (E2o), and dihydrolipoamide dehydrogenase (E3). Bacillus subtilis E1o and E2o are encoded by the citK and citM genes, respectively. A 3.4-kb BamHI DNA fragment containing citK and citM markers was isolated from a library of B. subtilis DNA in Escherichia coli. Functional E2o was expressed from the cloned DNA both in B. subtilis and E. coli. E2o had an apparent Mr of 60000 when expressed in E. coli. The B. subtilis E2o component complemented an E. coli E2o-defective mutant in vivo and in vitro. It is concluded that functional B. subtilis E2o can be produced in E. coli and can interact with E. coli and E1o and E3 to form an active chimeric enzyme complex.
|
|
| 37. |
- Carlsson, P., et al.
(author)
-
Genetic Characterization of Bacillus subtilis odhA and odhB, encoding 2-oxoglutarate dehydrogenase and dihydrolipoamide transsuccinylase, respectively
- 1989
-
In: Journal of Bacteriology. - : American Society for Microbiology. - 0021-9193 .- 1098-5530. ; 171:7, s. 3667-3672
-
Journal article (peer-reviewed)abstract
- The 2-oxoglutarate dehydrogenase complex consists of three different subenzymes, the E1o (2-oxoglutarate dehydrogenase) component, the E2o (dihydrolipoyl transsuccinylase) component, and the E3 (dihydrolipoamide dehydrogenase) component. In Bacillus subtilis, the E1o and E2o subenzymes are encoded by odhA and odhB, respectively. A plasmid with a 6.8-kilobase-pair DNA fragment containing odhA and odhB was isolated. Functional E1o and E2o are expressed from this plasmid in Escherichia coli. Antisera generated against B. subtilis E1o and E2o expressed in E. coli reacted with antigens of the same size from B. subtilis. The nucleotide sequence of odhB and the terminal part of odhA was determined. The deduced primary sequence of B. subtilis E2o shows striking similarity to the corresponding E. coli protein, which made it possible to identify the lipoyl-binding lysine residue as well as catalytic histidine and aspartic acid residues. An mRNA of 4.5 kilobases hybridizing to both odhA and odhB probes was detected, indicating that odhA and odhB form an operon.
|
|
| 38. |
- Carlsson, Peter, et al.
(author)
-
In vitro complementation of Bacillus subtilis and Escherichia coli 2-oxoglutarate dehydrogenase complex mutants and genetic mapping of B. subtilis citK and citM mutations
- 1986
-
In: FEMS Microbiology Letters. - : Oxford University Press (OUP). - 1574-6968 .- 0378-1097. ; 37:3, s. 373-378
-
Journal article (peer-reviewed)abstract
- AbstractThe 2-oxoglutarate dehydrogenase complex of the tricarboxylic acid cycle (TCA) consists of multiple copies of 3 different subenzymes; E1, E2 and E3. The E3 subenzyme is also a component of the pyruvate dehydrogenase complex. Bacillus subtilis 2-oxoglutarate dehydrogenase mutants were studied. The mutants defective in E1, E2 and E3 subenzyme activity, respectively, could be separated into 3 groups by biochemical complementation analyses. The groups correspond to the citK, citM and citL genes. A B. subtilis subenzyme defect, probably E1, could be complemented with the corresponding Escherichia coli wild-type subenzyme and vice versa. Mutations in citK and citM are closely linked. The gene order kauA--- ---citK-citM was determined from 3-factor transformation crosses. It is concluded that the gene organization and the subenzyme structure of the 2-oxoglutarate dehydrogenase complex are similar in B. subtilis and E. coli.
|
|
| 39. |
- Fridén, H, et al.
(author)
-
Cytochrome b558 of Bacillus subtilis
- 1988
-
In: Cytochrome Systems : Molecular Biology and Bioenergetics - Molecular Biology and Bioenergetics. - 9781461290780 - 9781461319412 ; , s. 641-647
-
Book chapter (peer-reviewed)abstract
- The membranebound tricarboxylic acid cycle enzyme succinate dehydrogenase (SDH) is associated with a b-type cytochrome in many organisms. 1,2 The cytochrome b is often found in stoichiometric amounts in isolated succinate-ubiquinone oxidoreductase (complex II) from bovine heart,3Neurospora crassa,4Ascaris suum5 and plant6 mitochondria as well as in SDH complexes isolated from both Gram-negative and Gram-positive8,9 bacteria whereas yeast (Saccharomyces cerevisiae) apparently lacks this type of cytochrome.10
|
|
| 40. |
- Fridén, H, et al.
(author)
-
Genetic and biochemical characterization of Bacillus subtilis mutants defective in expression and function of cytochrome b-558
- 1987
-
In: European Journal of Biochemistry. - : Wiley. - 0014-2956 .- 1432-1033. ; 168, s. 695-701
-
Journal article (peer-reviewed)abstract
- Bacillus subtilis succinate dehydrogenase is bound to the cytoplasmic membrane by cytochrome b-558, a 23-kDa transmembrane protein which also functions as electron acceptor to the dehydrogenase. The structural gene for the apocytochrome, sdhC, has previously been cloned and sequenced. In this work the structure and translation of cytochrome b-558 was studied in different sdhC mutants. Mutant cytochrome was analyzed both in B. subtilis and after amplification in Escherichia coli. It is concluded that amino acid substitutions in the C-terminal half of the cytochrome can prevent the binding of succinate dehydrogenase without affecting membrane binding of the cytochrome protein or heme ligation. Mutagenesis of His-113 excludes this residue as an axial heme ligand. A base-pair exchange of G to A in the ribosome-binding sequence of sdhC was found to reduce cytochrome b-558 translation about tenfold in B. subtilis, whereas the mutation had no effect on translation in E. coli. Translation of the two succinate dehydrogenase genes from the sdhCAB polycistronic transcript does not seem to be coupled to translation of sdhC. Less than 10% of the wild-type amount of membrane-bound succinate dehydrogenase in B. subtilis still allows growth on non-fermentable substrate, but makes the dehydrogenase a limiting enzyme in the tricarboxylic acid cycle and leads to succinate accumulation.
|
|
| 41. |
- Hederstedt, Lars, et al.
(author)
-
Covalent binding of FAD to Bacillus subtilis succinate dehydrogenase
- 1987
-
In: Flavins and Flavoproteins : Proceedings of the Ninth International Symposium, Atlanta, Georgia, U. S. A. June 7-12, 1987 - Proceedings of the Ninth International Symposium, Atlanta, Georgia, U. S. A. June 7-12, 1987. - 3110109506 - 0899253067 ; , s. 729-736
-
Conference paper (peer-reviewed)
|
|
| 42. |
- Hederstedt, Lars, et al.
(author)
-
New properties of Bacillus subtilis succinate dehydrogenase altered at the active site
- 1989
-
In: Biochemical Journal. - : Portland Press Ltd.. - 0264-6021 .- 1470-8728. ; 260:2, s. 491-497
-
Journal article (peer-reviewed)abstract
- Mammalian and Escherichia coli succinate dehydrogenase (SDH) and E. coli fumarate reductase apparentlycontain an essential cysteine residue at the active site, as shown by substrate-protectable inactivation withthiol-specific reagents. Bacillus subtilis SDH was found to be resistant to this type of reagent and containsan alanine residue at the amino acid position equivalent to the only invariant cysteine in the flavoproteinsubunit of E. coli succinate oxidoreductases. Substitution of this alanine, at position 252 in the flavoprotein subunit of B. subtilis SDH, by cysteine resulted in an enzyme sensitive to thiol-specific reagents and protectable by substrate. Other biochemical properties of the redesigned SDH were similar to those of the wild-type enzyme. It is concluded that the invariant cysteine in the flavoprotein of E. coli succinate oxidoreductases corresponds to the active site thiol. However, this cysteine is most likely not essential for succinate oxidation and seemingly lacks an assignable specific function. An invariant arginine in juxtaposition to Ala-252 in the flavoprotein of B. subtilis SDH, and to the invariant cysteine in the E. coli homologous enzymes, is probably essential for substrate binding.
|
|
| 43. |
|
|
| 44. |
- Nilsson, Kjell, et al.
(author)
-
A General Method for the Immobilization of Cells with Preserved Viability
- 1983
-
In: Applied Microbiology and Biotechnology. ; 17, s. 319-326
-
Journal article (peer-reviewed)abstract
- Microbial, algal, plant and animal cells have been immobilized, with preserved viability, by entrapment in various matrices according to a new bead polymerization technique. The cell polymer/monomer mixture is kept suspended in a hydrophobic phase such as soy, paraffin, or silicon oil, tri-n-butylphosphate, or dibutyphtalate, which is compatible with the cells. The various monomers or polymers tested include agarose, agar, carrageenan, alginate, fibrin, and polyacrylamide. Furthermore, by adjustment of the stirring speed of the suspension, beads of desired diameter can easily be obtained. The entrapped cells are fully viable and biosynthetically active.
|
|
| 45. |
- Petricek, M, et al.
(author)
-
The structural gene for aspartokinase II in Bacillus subtilis is closely linked to the sdh operon
- 1989
-
In: FEMS Microbiology Letters. - 1574-6968. ; 61:1-2, s. 85-87
-
Journal article (peer-reviewed)abstract
- The aecA and aecB loci map at 250 and 290 degrees, respectively, on the Bacillus subtilis chromosomal genetic map. The aecB locus has been proposed as the structural gene for aspartokinase II. From DNA sequence analyses and comparisons to the sequence of the aspartokinase II gene, it can be concluded that the structural gene for aspartokinase II is located close to sdh at 250 degrees and cannot be aecB. A detailed map over 7 kbp in the 250 degree region is presented.
|
|
| 46. |
- Tham, Wilhelm, 1951-, et al.
(author)
-
A comparison of six media for isolating Staphylococcus aureus from foods
- 1987
-
In: Food microbiology (Print). - : Elsevier. - 0740-0020 .- 1095-9998. ; 4:2, s. 133-146
-
Journal article (peer-reviewed)abstract
- Six culture media were compared with blood agar regarding colony counts and colony diameters of 53 Staphylococcus aureus strains. There were no statistically significant differences between the media. The forced differentiation of the results via cluster analysis, however, gave some indications that differences existed. In terms of colony counts, LSM, BP Oxoid and BP Oxoid + pp gave results similar to those given by blood agar. Colony diameter seemed to be a doubtful measure of the media's suitability and none of the six media showed similar diameter values to those of blood agar. As regards the appearance of the S. aureus strains on the six media, BP BBL and LSM corresponded the most closely to the inventors descriptions. The selectivities of the media were tested by cultivating 102 food samples from various sources. The most favourable retardation against micro-organisms other than S. aureus was shown by BP BBL, KRANEP and LSM. In terms of all tests performed, BP BBL was the most satisfactory medium for isolating S. aureus. PCVJ was the poorest of all media used in this study.
|
|
| 47. |
- Tham, Wilhelm, 1951-
(author)
-
Histamine formation by enterococci isolated from home-made goat cheeses
- 1988
-
In: International Journal of Food Microbiology. - : Elsevier. - 0168-1605 .- 1879-3460. ; 7:2, s. 103-108
-
Journal article (peer-reviewed)abstract
- A survey was made of the histamine-producing capability of enterococci isolated from goat cheeses. The strains, 130 Streptococcus faecium and 106 S. faecalis, were grown in Trypticase Soy Broth Histidine medium (TSBH) at 35°C for 24 h and the histamine formed was determined by fluorometry. Forty-one (31.5%) of the S. faecium strains and 2 (1.9%) of the S. faecalis strains produced histamine. The largest amount detected was 4.0 μg histamine/ml TSBH. Compared with the amounts of histamine produced by some Gram-negative bacteria, the histamine production by enterococci seems to be low. Under the present conditions the enterococci seem to have no relevance from a histamine intoxication point of view.
|
|
| 48. |
- Birnbaum, Staffan, et al.
(author)
-
Covalent stabilization of alginate gel for the entrapment of living whole cells
- 1981
-
In: Biotechnology Letters. - 0951-208X. ; 3, s. 393-400
-
Journal article (peer-reviewed)abstract
- Three methods were developed for preparing alginate gels containing cells that are stable in phosphate containing media. In Method I preformed alginate beads containing entrapped cells were treated with polyethyl eneimine followed by glutaraldehyde. In Method II alginate sol was treated with a carbodiimide and N-hydroxysuccinimide (to form active esters), mixed with cells and extruded into calcium chloride solution. The beads were subsequently cross-linked with polyethyleneimine. In Method III alginate so] was treated with periodate (to form aldehyde groups), mixed with cells and extruded into calcium chloride solution. The beads were subsequently cross-linked with polyethyleneimine.Saccharomyces cerevisiae cells, immobilized in such stabilized gels, exhibited almost the same fermentation activity as the standard preparation. The viability of the immobilized cells was retained during the stabilization procedure as judged from their ability to multiply in the presence of nutrients.The preparations remained stable in phosphate buffer for at least ten days without substantial release of cells. The extent of cross-linking was controlled by varying the time and the concentration of reactants, thus giving preparations ranging from beads with a thin stabilized shell to beads homogeneously stabilized.
|
|
| 49. |
- Flygare, Susanne, et al.
(author)
-
Steroid transformation using magnetically immobilized Mycobacterium sp.
- 1987
-
In: Enzyme and Microbial Technology. - : Elsevier BV. - 0141-0229. ; 9:8, s. 494-499
-
Journal article (peer-reviewed)abstract
- Mycobacterium sp. (NRRL-B 3683) has been immobilized by adhesion of magnetic materials of submicron size to the bacterial surface. Preparations based on laboratory-prepared magnetic oxide that had been derivatized with hydrophobic octyltrichlorosilane showed the best properties. The magnetically immobilized bacteria were used for side-chain degradation of cholesterol into androsta-1,4-diene-3,17-dione. The magnetic bacteria behaved as free cells in the transformation media and no mass transfer limitations were observed. The magnetic bacteria could be used repeatedly without any cell loss, the cells being retrieved at the end of each transformation cycle by a magnet.
|
|
| 50. |
- Flygare, Susanne, et al.
(author)
-
Steroid transformation in aqueous two-phase systems: side-chain degradation of cholesterol by Mycobacterium sp.
- 1989
-
In: Enzyme and Microbial Technology. - : Elsevier BV. - 0141-0229. ; 11:11, s. 752-759
-
Journal article (peer-reviewed)abstract
- We report on the use of aqueous two-phase systems for the side-chain degradation of cholesterol into androst-4-ene-3,17-dione (AD) and androsta-1,4-diene-3,17-dione (ADD) by Mycobacterium sp. A problem encountered at the start of this investigation, extensive aggregation of the cells, was solved by careful choice of the polymer and detergent composition of the phase system. The systems showing the best properties were composed of polyethylene glycol, dextran and Brij 35 or polyvinylpyrrolidone, dextran and Brij 35 (or Tween 40). The bacterium maintained in the upper polyethylene glycol-rich (or polyvinylpyrrolidone-rich) phase was found to have high activity. The substrated partitioned to the upper phase or the interface (if present as crystals), while the products had partition coefficients around 2.
|
|
