ALBERT

Notes: Abstract The list of carboxydotrophic bacteria is constantly growing and we have found that burning charcoal piles harbor an especially rich CO-oxidizing microflora. The newly isolated Streptomyces thermoautotrophicus UBT1 is particularly interesting as it is thermophilic, capable of chemolithoautotrophic growth with CO or H2 plus CO2 and incapable of using organic substrates. Molybdenum is essential for CO-autotrophic growth.Some species of carboxydotrophic bacteria can denitrify under heterotrophic conditions yielding N2 (e.g. Pseudomonas carboxydoflava) or N2O (e.g. Pseudomonas carboxydohydrogena); others perform nitrate respiration (e.g. Azomonas B1). P. carboxydohydrogena could grow at the expense of H2 plus CO2 using nitrate as electron acceptor.In intact cells of Pseudomonas carboxydovorans, CO dehydrogenase has the ability of dissociating from and rebinding to the cytoplasmic membrane. That process can be simulated in vitro by removing CO dehydrogenase from cytoplasmic membranes and rebinding it to depleted membranes. Reconstitution of the enzyme onto depleted membranes requiring di- or trivalent cations, was specific for membranes from CO-grown bacteria and led to reactivation of respiratory activities with CO.A complex consisting of 1 molecule of CO dehydrogenase and 2 molecules of cytochrome b561 could be isolated from cytoplasmic membranes of P. carboxydovorans solubilized with dodecyl β-d-maltoside. Within the complex as well as in assays containing purified CO dehydrogenase and cytochrome b561 the latter could serve as an electron acceptor. CO dehydrogenase had hydrogenase activity, and its KM of only 5 mM H2 suggested a role in the formation of H2. P. carboxydovorans OM5 contains the 128-kilo-base pairs (kb) plasmid pHCG3 which is essential for CO- and H2-lithoautotrophic growth. Evidence for the existence of pHCG3-coded structural genes of CO dehydrogenase was obtained from dot blot hybridizations employing synthetic oligodeoxynucleotides as heterologous probes for the detection of the S- and M-subunit genes. Employing appropriate probe genes encoding membrane-bound hydrogenase, ribulose biphosphate carboxylase and phosphoribulokinase were also identified on plasmid pHCG3.

Notes: Abstract The bioenergetic properties of the thermoacidophilic archaebacterium Sulfolobus acidocaldarius are reviewed and discussed under the aspect whether this archaebacterium conserved energy by oxidative phosphorylation and how the involved catalysts are related to those from eubacteria and eukaryotes. The thermodynamic parameters contributing to the proton-motive force and the efficiency of proton pumping are presented. The major components of the electron transport system are identified and a novel type of heme-aa3 containing terminal oxidase is described, oxidizing reduced caldariella quinone. The properties of an F1-analogous ATPase and of a DCCD-binding proteolipid from the plasmamembrane of Sulfolobus are discussed as likely components of an F0F1-analogous ATP-synthase. The structural and functional properties of this and other archaebacterial ATPases are compared to each other and with respect to evolutionary relations.

Notes: Abstract The transcripts of the rubredoxin gene from C. pasteurianum have been shown to have a size of approx. 230 bases by Northern blotting techniques. The transcription start has been located within 41 bases upstream of the initiator codon. The data demonstrate that the rubredoxin gene is monocistronic. Two of the three open reading frames occurring upstream of the rubredoxin gene are adjacent and appear to encode a thioredoxin (or glutaredoxin) reductase and a thioredoxin (or glutaredoxin).

Notes: Abstract The biosynthesis of the hydantoin-hydrolysing enzymes hydantoinase and N-carbamyl amino acid amidohydrolase from Agrobacterium sp. IP I-671, a Gram-negative bacterium used as a biocatalyst for the production of enantiomerically pure (R) amino acids, was found to be highly inducible by the addition to the cultivation medium of different non-metabolizable thiolated hydantoins or pyrimidines. Among these inducers the hexacyclic pyrimidine thioderivatives were more potent than all the pentacyclic thiohydantoin compounds. Addition of 2,4-thiouracil to the cultures, at a rate of 0.1 g (g cell dry mass)−1, led to no appreciable growth inhibition and yielded a biocatalyst exhibiting a 40-fold higher hydantoinase and a 15-fold higher N-carbamyl amino acid amidohydrolase activity than the corresponding inducer-free cultures.

Notes: Abstract The horizontal flow of genetic material between microbes utilizes three principal routes: conjugation, transduction and transformation. While the significance in nature of the first two pathways is generally accepted, the in vivo role of transformation remains uncertain, despite the early observations by Griffith in 1928 on the transformation of streptococci from an avirulent to a virulent state [1]. Recently, circumstantial evidence was collected suggesting a role for transformation-mediated horizontal exchange in the modulation of virulence determinants of pathogenic Neisseriae and the variation of surface structures. In order to further assess the significance of transformation-mediated exchange we performed simple co-cultivation experiments of different Neisseria strains. We observed an efficient intra- and interspecies transfer of essential virulence determinants; the process was sensitive to the presence of DNaseI in the culture and was blocked in transformation-deficient recipients.

Notes: Abstract Respiratory nitrate reductase from the denitrifying bacterium Pseudomonas stutzeri is an iron-sulfur enzyme containing the molybdenum cofactor. Hydrolysis of native nitrate reductase with aqueous sulfuric acid revealed 0.92 mol of 5′-GMP per mol of enzyme. The pterin present in the molybdenum cofactor was liberated from the protein and reacted with iodoacetamide. The resulting di(carboxamidomethyl) (cam) derivative was purified on a C18-cartridge and analyzed for its structural elements. Treatment of the cam derivative with nucleotide pyrophosphatase and subsequent HPLC analysis revealed the formation of di(cam)molybdopterin and 5′-GMP at a 1:1 molar ratio and with a yield of 79% with respect to the molybdenum content of the enzyme. Treatment of the cam derivative with nucleotide pyrophosphatase and alkaline phosphatase led to the liberation of 0.51 mol dephosphodi(cam)molybdopterin and of 0.59 mol guanosine per mol of enzyme, which is equal to a molar ratio of 1:2.2. The results indicate, that the organic moiety of the molybdenum cofactor of nitrate reductase from P. stutzeri is molybdopterin guanine dinucleotide of which one mol is contained per mol of nitrate reductase.