Anaerobic degradation of pimelate by newly isolated denitrifying bacteria.

A C7 dicarboxylic (pimelic) acid derivative is postulated as an intermediate in anaerobic degradation of benzoate. Four strains of Gram-negative, nitrate-reducing bacteria capable of growth with both pimelate and benzoate as sole carbon and energy source were isolated. The metabolism of strain LP-1, which was enriched from activated sludge with pimelate as substrate, was studied in detail. This strain grew only with oxygen or with oxidized nitrogen compounds as electron acceptor. In the presence of nitrate, a wide range of substrates excluding C1 compounds was degraded. The new isolate was catalase- and oxidase-positive, and had one single polar flagellum. Strain LP-1 was tentatively classified within the family Pseudomonadaceae. The catabolism of pimelate and benzoate was studied in cell-free extracts of strain LP-1. Both acids were activated with coenzyme A in a Mg(2E)- and ATP-dependent reaction. The corresponding acyl-CoA synthetases were specifically induced by the respective growth substrate. Pimelate was also activated by CoA transfer from succinyl-CoA. Pimelyl-CoA was oxidized by cell-free extracts in the presence of potassium ferricyanide. Degradation to glutaryl-CoA and acetyl-CoA proceeded by a sequence of beta-oxidation-like reactions. Glutaryl-CoA dehydrogenase and glutaconyl-CoA decarboxylase activities were expressed in cells grown with pimelate or benzoate, indicating the specific involvement of these enzyme activities in anaerobic degradation of these two acids. Enzyme activities responsible for further degradation of the resulting crotonyl-CoA to acetyl-CoA via classical beta-oxidation were also detected.

Tubular spinae are long-distance connectors between bacteria.

The marine pseudomonad D71 (NCMB 2018) ['Spinomonas maritima'] can be induced to produce long tubular surface appendages (spinae) in a growth medium of low osmolarity. In general, spina-carrying cells show these appendages with open distal ends. We examined cultured cells by scanning and transmission electron microscopy, using both critical-point drying and thin sectioning after embedding with agarose protection. By scanning electron microscopy, spinae were observed that connected cells over distances of several micrometers. Ultrathin sections often revealed an additional layer outside the outer membrane, resembling an S-layer. The inner and outer cell membranes were often joined at spina-insertion areas. Furthermore, evidence was found in ultrathin sections for uninterrupted tubes connecting two cells over a distance of up to 7 microns. We propose, therefore, that spinae form the framework for wide open cell clusters; we hypothesize that these spinae might also permit an exchange of cell-to-cell signals.

Effect of d-mannose on fimbriae of bacterial isolates from chicken carcasses.

Pseudomonad-like microbial isolates were obtained from commercially processed broiler chicken carcasses for use in experiments to determine if d-mannose would interfere with their ability to form pellicles and rims and prevent agglutination of blood and yeast cells. Inhibition of agglutination, rim formation, and pellicle formation would provide evidence that d-mannose acts on the fimbriae to prevent attachment of microorganisms to surfaces. Presence of 4% d-mannose in the growth medium interfered with the formation and stability of the pellicle in some isolates. The pellicles affected by d-mannose did not cover the entire surface and were easily dispersed. Addition of d-mannose did not prevent the formation of rims to the same extent it prevented pellicle formation, and it was concluded that d-mannose did not completely prevent growth of fimbriae. The addition of d-mannose prevented the agglutination of 1% sheep blood, 1% horse blood, and yeast cells by interfering with the formation of fimbriae or the mechanism of attachment by fimbriae. These experiments provided evidence that d-mannose can be used to prevent attachment of isolates normally found on chicken carcasses to specific cell surfaces by occupying mannose-sensitive receptor sites on the cell.

Three-dimensional reconstruction of the flagellar filament of Caulobacter crescentus. A flagellin lacking the outer domain and its amino acid sequence lacking an internal segment.

We obtained a three-dimensional reconstruction of the flagellar filament of Caulobacter crescentus CB15 from electron micrographs of negatively stained preparations. The C. crescentus filament appears, both in negative stain and in the frozen-hydrated state, significantly smoother and narrower than other filaments. Its helical symmetry, and unit cell size, however, are similar to that of other filaments. Although the molecular weight of the C. crescentus flagellin is about half that of other plain flagellins, there is only one monomer per unit cell as indicated by diffraction studies and by linear mass density measurements with the scanning transmission electron microscope. Alignment of the primary amino acid sequences of Salmonella typhimurium (serotype i) and C. crescentus (29,000 Mr) flagellins shows that whereas there is homology at the amino and carboxyterminal ends of the two sequences, the central segment of the S. typhimurium sequence has no homology to that of C. crescentus. A correlated comparison between the three-dimensional reconstructions of the two filaments and primary amino acid sequences of the two flagellins suggests that: (1) the C. crescentus subunit is missing the outer molecular domain but is, otherwise, similar to that of S. typhimurium; (2) the outer molecular domain in S. typhimurium corresponds, therefore, to a central stretch of the primary amino acid sequence; and (3) the outer molecular domain, missing in C. crescentus, is not obligatory for flagellar motility.

[The occurrence and properties of Selenomonas ruminantium bacteria in calves during the time of milk feedings]. / Výskyt a vlastnosti baktérií Selenomonas ruminantium u teliat v období mliecnej výzivy.

The occurrence, morphological properties, urease and alpha-amylase activities of Selenomonas ruminantium were investigated in calves in the period of milk nutrition. The average number of the organisms was found to range between 10(7) and 10(8) per 1 millilitre of rumen contents. The alpha-amylase activity of the Selenomonas strains ranged from 0.1 to 8.8 ncat.ml-1 whereas their urease activity ranged from 6.3 to 261 ncat.ml-1 of nutrient medium. The presence of morphologically typical Selenomonas ruminantium and spontaneous formation of spheroplasts were found by electron microscopic examination.

Isolation and genetic analysis of Caulobacter mutants defective in cell shape and membrane lipid synthesis.

In this paper we report the isolation, characterization and genetic analysis of several C. crescentus mutants altered in membrane lipid synthesis. One of these, a fatty acid bradytroph, AE6002, was shown to be due to a mutation in the fatA gene. In addition to the presence of the fatA506 mutation, this strain was found to contain two other mutations, one of which caused the production of a water-soluble brown-orange pigment (pigA) and another which caused formation of helical cells (hclA). Expression of the latter two phenotypes required complex media and both were repressed by glucose. However, the lesions were mapped to loci that are separated by a substantial distance. The hclA and the fatA genes mapped close together, possibly implying that comutation had occurred in AE6002. Data are presented that allow the unambiguous identification of a second Fat gene (fatB) in C. crescentus. The map position of another mutation in membrane lipid biogenesis, the glycerol-3-PO4 auxotroph gpsA505, was also determined. During this study the flaZ gene was fine-mapped and the positions of proC and rif changed from the previously reported location.

Effect of intracytoplasmic membrane development on oxidation of sorbitol and other polyols by Gluconobacter oxydans.

By using membrane-bound dehydrogenases, Gluconobacter oxydans characteristically accomplishes single-step oxidation of many polyols and quantitative release of the oxidation product into the medium. These cells typically differentiate by forming intracytoplasmic membranes (ICM) after exponential growth on glycerol. Earlier experiments demonstrated that glycerol-grown cells containing ICM oxidized glycerol more rapidly than cells which were harvested during exponential growth and lacked ICM (Claus et al., J. Bacteriol. 123:1169-1183). This report demonstrates that ICM are also formed after growth on sorbitol. Sorbitol-grown, ICM-containing maximum stationary-phase (MSP) cells showed from 50 to 300% greater oxidation (respiration) rates on mannitol, glycerol, glucose, meso-erythritol, and meso-inositol than did exponential-phase (EXP) cells which lacked ICM. Both EXP and MSP cells exhibited maximum sorbitol oxidation at pH 5.0, 38 degrees C, and 5% (wt/vol) sorbitol. When assayed under these optimum conditions, ICM-containing MSP cells demonstrated a 72% increase in respiration on sorbitol compared with that of EXP cells lacking ICM (oxygen quotients of 3,100 and 1,800, respectively). Gas chromatographic studies showed that sorbose was the only detectable product released from cells during oxygen quotient analysis. The specific activity of particulate-bound sorbitol dehydrogenase from ICM-containing MSP cells was twice that obtained from particulate fractions prepared from EXP cells lacking ICM. These results show that neither ICM formation after exponential growth nor increased respiration of other polyols is dependent upon the polyol used to grow cells. Our results suggest that increased respiratory activity of MSP cells is caused both by ICM formation and by increased synthesis (or activity) of the polyol dehydrogenases found in these membranes.

[Species of the genus Beijerinckia Derx isolated from a soil of Corrientes (Argentina)]. / Especies del género Beijerinckia Derx aisladas en un suelo de Corrientes (República Argentina).

Four species of bacteria were isolated from one soil of Corrientes (Argentina). They were first classified as Beijerinckia genus based on their cultural, morphological and physiological characteristics. The basic criteria were: growth media without combined nitrogen and fixation of high amounts of gaseous nitrogen (as determined by the acetylene-ethylene assay). Further studies permitted the classification of these microorganisms in the following species: Beijerinckia indica, Beijerinckia fluminensis, Beijerinkia mobilis and Beijerinckia derxii.

Microbiological examination of some Sudanese soils.

The composition of the microflora in different layers of four representative oil profiles of Sudan were studied. Counts of all types of microorganisms decreased significantly with depth in soil. Azotobacter, in particular, occurred in high densities; representative strains were isolated and studied for their different characteristics. Beijerinckia was detected as well, and a new method for the estimation of their numbers in pure cultures, based on the overlay agar technique, is described.

Intracytoplasmic membrane formation and increased oxidation of glycerol growth of Gluconobacter oxydans.

Gluconobacter oxydans is well known for the limited oxidation of compounds and rapid excretion of industrially important oxidation products. The dehydrogenases responsible for these oxidations are reportedly bound to the cell's plasma membrane. This report demonstrates that fully viable G. oxydans differentiates at the end of exponential growth by forming dense regions at the end of each cell observed with the light microscope. When these cells were thin sectioned, their polar regions contained accumulations of intracytoplasmic membranes and ribosomes not found in undifferentiated exponentially growing cells. Both freeze-fracture-etched whole cells and thin sections through broken-cell envelopes of differentiated cells demonstrate that intracytoplasmic membranes occur as a polar accumulation of vesicles that are attached to the plasma membrane. When cells were tested for the activity of the plasma membrane-associated glycerol dehydrogenase, those containing intracytoplasmic membranes were 100% more active than cells lacking these membranes. These results suggest that intracytoplasmic membranes are formed by continued plasma membrane synthesis at the end of active cell division.