Evaluation of the prebiotic potential of arabinoxylans extracted from wheat distillers’ dried grains with solubles (DDGS) and in-process samples

Applied Microbiology and Biotechnology - Distillers’ dried grains with solubles (DDGS) is a low-value agro-industrial by-product, rich in arabinoxylans (AX), which is produced by commercial...     

Cytokinin-like effects of caffeine in bioassays

Cytokinin-like effects of pure caffeine were tested in bioassays specific for this hormonal activity [radish cotyledon growth and chlorophyll (Chl) biosynthesis in cucumber cotyledon and tobacco cell suspension] and in cell elongation bioassays [elongation of segments from soybean internode and internode elongation in dwarf cultivars of guandu (Cajanus cajan) and mucuna (Mucuna deeringiana)]. 6-Benzyl-aminopurine and kinetin (KIN) were used for comparison with caffeine. Although weaker than those given by cytokinins, positive responses were observed in all specific bioassays and in elongation of soybean internodes. A remarkable synergistic effect between caffeine and KIN was observed for the synthesis of Chl in the tobacco cell suspension bioassay, in which different concentrations of the alkaloid were combined with a single concentration of KIN. The hormone-like effect of caffeine might be related to the resemblance between caffeine and adenine derivatives. This revised version was published online in August 2006 with corrections to the Cover Date.     

Successful Posaconazole Therapy of Disseminated Alternariosis due to <Emphasis Type="Italic">Alternaria infectoria</Emphasis> in a Heart Transplant Recipient

We report a case of phaeohyphomycosis caused by Alternaria infectoria in a 61-year-old heart transplant recipient with multiple skin lesions and pulmonary infiltrates. The infection spread via the haematogenous route from the primary cutaneous lesions into the lungs. The diagnosis was based on the histopathological examination, direct microscopy, skin lesion cultures and detection of Alternaria DNA in the bronchoalveolar lavage fluid using molecular methods. The treatment consisted of a combination of surgical excision and systemic antifungal therapy. Voriconazole was the first agent used but had a weak effect. Posaconazole was subsequently used to achieve a successful response. The isolate was identified as A. infectoria by sequencing of the rDNA ITS region and the partial β-tubulin gene.     

Antenna ring around trimeric Photosystem I in chlorophyll b containing cyanobacterium Prochlorothrix hollandica

Prochlorothrix hollandica is one of the three known species of an unusual clade of cyanobacteria (formerly called “prochlorophytes”) that contain chlorophyll a and b molecules bound to intrinsic light-harvesting antenna proteins. Here, we report the structural characterization of supramolecular complex consisting of Photosystem I (PSI) associated with the chlorophyll a/b-binding Pcb proteins. Electron microscopy and single particle image analysis of negatively stained preparations revealed that the Pcb-PSI supercomplex consists of a central trimeric PSI surrounded by a ring of 18 Pcb subunits. We conclude that the formation of the Pcb ring around trimeric PSI represents a mechanism for increasing the light-harvesting efficiency in chlorophyll b-containing cyanobacteria.     

Tobacco cells transformed with the fission yeast Spcdc25 mitotic inducer display growth and morphological characteristics as well as starch and sugar status evocable by cytokinin application.

In plants, the G2/M control of cell cycle remains an elusive issue as doubts persist about activatory dephosphorylation--in other eukaryotes provided by CDC25 phosphatase and serving as a final all-or-nothing mitosis regulator. We report on the effects of tobacco (Nicotiana tabacum L., cv. Samsun) transformation with fission yeast (Schizosaccharomyces pombe) cdc25 (Spcdc25) on cell characteristics. Transformed cell suspension cultures showed higher dry mass accumulation during the exponential phase and clustered more circular cell phenotypes compared to chains of elongated WT cells. Similar cell parameters, as in the transformants, can be induced in WT by cytokinins. Spcdc25 cells, after cytokinin treatment, showed giant cell clusters and growth inhibition. In addition, Spcdc25 expression led to altered carbohydrate status: increased starch and soluble sugars with higher sucrose:hexoses ratio, inducible in WT by cytokinin treatment. Taken together, the Spcdc25 transformation had a cytokinin-like effect on studied characteristics. However, endogenous cytokinin determination revealed markedly lower cytokinin levels in Spcdc25 transformants. This indicates that the cells sense Spcdc25 expression as an increased cytokinin availability, manifested by changed cell morphology, and in consequence decrease endogenous cytokinin levels. Clearly, the results on cell growth and morphology are consistent with the model of G2/M control including cytokinin-regulated activatory dephosphorylation. Nevertheless, no clear link is obvious between Spcdc25 transformation and carbohydrate status and thus the observed cytokinin-like effect on carbohydrate levels poses a problem. Hence, we propose that Spcdc25-induced higher CDK(s) activity at G2/M generates a signal-modifying carbohydrate metabolism to meet high energy and C demands of forthcoming cell division.     

Biofiltration of paint solvent mixtures in two reactor types: overloading by hydrophobic components

Steady-state performance characteristics of a trickle bed reactor (TBR) and a biofilter (BF) in loading experiments with increasing toluene/xylenes inlet concentrations while maintaining a constant loading rate of hydrophilic components (methyl ethyl and methyl isobutyl ketones, acetone, and n-butyl acetate) of 4 g m⁻³ h⁻¹ were evaluated and compared, along with the systems’ dynamic responses. At the same combined substrate loading of 55 g m⁻³ h⁻¹ for both reactors, the TBR achieved more than 1.5 times higher overall removal efficiency (RE_W) than the BF. Increasing the loading rate of aromatics resulted in a gradual decrease of their REs. The degradation rates of acetone and n-butyl acetate were also inhibited at higher loads of aromatics, thus revealing a competition in cell catabolism. A step-drop in loading of aromatics resulted in an immediate increase of RE_W with variations in the TBR, while the new steady-state value in the BF took 6–7 h to achieve. The TBR consistently showed a greater performance than BF in removing toluene and xylenes. Increasing the loading rate of aromatics resulted in a gradual decrease of their REs. The degradation rates of acetone and n-butyl acetate were also lower at higher OL_AROM, revealing a competition in the cell catabolism. The results obtained are consistent with the proposed hypothesis of greater toxic effects under low water content, i.e., in the biofilter, caused by aromatic hydrocarbons in the presence of polar ketones and esters, which may improve the hydrocarbon partitioning into the aqueous phase.