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  • 1
    ISSN: 1432-072X
    Keywords: Key words Chromatium vinosum ; Phototrophic ; sulfur bacteria ; Sulfur globules ; Extracytoplasmic ; localization ; Sulfide oxidation ; Sulfur deposition ; Thiocapsa roseoperscina ; Interposon mutagenesis ; phoA fusion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Purple sulfur bacteria store sulfur as intracellular globules enclosed by a protein envelope. We cloned the genes sgpA, sgpB, and sgpC, which encode the three different proteins that constitute the sulfur globule envelope of Chromatium vinosum D (DSMZ 180T). Southern hybridization analyses and nucleotide sequencing showed that these three genes are not clustered in the same operon. All three genes are preceded by sequences resembling σ70-dependent promoters, and hairpin structures typical for rho-independent terminators are found immediately downstream of the translational stop codons of sgpA, sgpB, and sgpC. Insertional inactivation of sgpA in Chr. vinosum showed that the presence of only one of the homologous proteins SgpA and SgpB suffices for formation of intact sulfur globules. All three sgp genes encode translation products which – when compared to the isolated proteins – carry amino-terminal extensions. These extensions meet all requirements for typical signal peptides indicating an extracytoplasmic localization of the sulfur globule proteins. A fusion of the phoA gene to the sequence encoding the proposed signal peptide of sgpA led to high specific alkaline phosphatase activities in Escherichia coli, further supporting the envisaged targeting process. Together with electron microscopic evidence these results provide strong indication for an extracytoplasmic localization of the sulfur globules in Chr. vinosum and probably in other Chromatiaceae. Extracytoplasmic formation of stored sulfur could contribute to the transmembranous Δp that drives ATP synthesis and reverse electron flow in Chr. vinosum.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 164 (1995), S. 217-222 
    ISSN: 1432-072X
    Keywords: Key wordsChromatium vinosum ; Purple sulfur ; bacteria ; Conjugation ; Broad-host-range vectors ; Antibiotic sensitivity ; IncP plasmids ; IncQ plasmids ; Rhodospirillum rubrum ; Escherichia coli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Establishment of a system for manipulative genetics in phototrophic sulfur bacteria of the family Chromatiaceae has mainly been hampered by the lack of reliable methods for growth of these organisms on agar surfaces, techniques for streaking, growth on selective media, screening for antibiotic resistance markers, and most importantly by the lack of a system for DNA transfer. We, therefore, developed minimal and complex agar media for Chromatium vinosum strain D (DSM 180T), a representative of the purple sulfur bacteria. Sensitivity of C. vinosum towards a broad range of antibiotics was tested in liquid cultures and solidified media, allowing us to select appropriate antibiotic resistance markers. Furthermore, a system for conjugative transfer of IncP-mobilizable plasmids from Escherichia coli to C. vinosum was established. Broad-host-range IncQ vectors were mobilized to C. vinosum with the aid of plasmid RP4 either present extrachromosomally or integrated in the chromosome of E. coli S17-1. Conjugation efficiencies of up to 1 were observed. Agarose gel electrophoretic analysis showed that transconjugants contained the transferred plasmids in addition to the two detectable plasmids of wild-type C. vinosum. All genetic markers tested (kanamycin, gentamicin, ampicillin, amikacin, tetracycline) were expressed in C. vinosum. Furthermore, high-frequency transfer of plasmid RP4 from C. vinosum to E. coli and to Rhodospirillum rubrum K100 was demonstrated.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-072X
    Keywords: Key wordsChromatium vinosum ; Flavocytochrome c ; Sulfide:quinone oxidoreductase ; Sulfide oxidation ; Phototrophic sulfur bacteria ; Interposon mutagenesis ; phoA fusion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Sulfide oxidation in the phototrophic purple sulfur bacterium Chromatium vinosum D (DSMZ 180T) was studied by insertional inactivation of the fccAB genes, which encode flavocytochrome c, a protein that exhibits sulfide dehydrogenase activity in vitro. Flavocytochrome c is located in the periplasmic space as shown by a PhoA fusion to the signal peptide of the hemoprotein subunit. The genotype of the flavocytochrome-c-deficient Chr. vinosum strain FD1 was verified by Southern hybridization and PCR, and the absence of flavocytochrome c in the mutant was proven at the protein level. The oxidation of thiosulfate and intracellular sulfur by the flavocytochrome-c-deficient mutant was comparable to that of the wild-type. Disruption of the fccAB genes did not have any significant effect on the sulfide-oxidizing ability of the cells, showing that flavocytochrome c is not essential for oxidation of sulfide to intracellular sulfur and indicating the presence of a distinct sulfide-oxidizing system. In accordance with these results, Chr. vinosum extracts catalyzed electron transfer from sulfide to externally added duroquinone, indicating the presence of the enzyme sulfide:quinone oxidoreductase (EC 1.8.5.-). Further investigations showed that the sulfide:quinone oxidoreductase activity was sensitive to heat and to quinone analogue inhibitors. The enzyme is strictly membrane-bound and is constitutively expressed. The presence of sulfide:quinone oxidoreductase points to a connection of sulfide oxidation to the membrane electron transport system at the level of the quinone pool in Chr. vinosum.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 45 (1980), S. 0 
    ISSN: 1750-3841
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Two heat processes were used to simulate preparation of beef loaf as would occur in hospital cook/chill foodservice systems. Thiamin content of beef loaf was evaluated before initial cooking; after initial cooking to 63-66°C and 24 hr chilled storage at 6°C; and after 0, 20, 50, 80 or 110 set of microwave-heating (2450 MHz; 1408W output). Values for thiamin, determined using a fluorometric method, were adjusted to account for weight losses after two heat processes and storage of the beef loaf. A decrease in thiamin content (mean 0.9 μg thiamin/g of beef loaf uncooked) was not related to time or end-temperature of microwave-heating. Microwave-heating accounted for l/3 of the 30% total thiamin loss.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Biochemical and Biophysical Research Communications 46 (1972), S. 885-891 
    ISSN: 0006-291X
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Superlattices and Microstructures 15 (1994), S. 441 
    ISSN: 0749-6036
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Biochemical and Biophysical Research Communications 46 (1972), S. 885-891 
    ISSN: 0006-291X
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Archives of Biochemistry and Biophysics 93 (1961), S. 491-495 
    ISSN: 0003-9861
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Archives of Biochemistry and Biophysics 93 (1961), S. 491-495 
    ISSN: 0003-9861
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Energy Economics 3 (1981), S. 30-35 
    ISSN: 0140-9883
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Economics
    Type of Medium: Electronic Resource
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