In almost all photosynthetic organisms the photosynthetic pigments chlorophyll and bacteriochlorophyll (BChl) are Mg2+ containing complexes, but Mg2+ may be exchanged against other metal ions when these are present in toxic concentrations, leading to inactivation of photosynthesis. In this report we studied mechanisms of copper toxicity to the photosynthetic apparatus of Acidiphilium rubrum, an acidophilic purple bacterium that uses Zn2+ instead of Mg2+ as the central metal in the BChl molecules ([Zn]-BChl) of its reaction centres (RCs) and light harvesting proteins (LH1). We used a combination of in vivo measurements of photosynthetic activity (fast fluorescence and absorption kinetics) together with analysis of metal binding to pigments and pigment-protein complexes by HPLC-ICP-sfMS to monitor the effect of Cu2+ on photosynthesis of A. rubrum. Further, we found that its cytoplasmic pH is neutral. We compared these results with those obtained from Rhodospirillum rubrum, a purple bacterium for which we previously reported that the central Mg2+ of BChl can be replaced in vivo in the RCs by Cu2+ under environmentally realistic Cu2+ concentrations, leading to a strong inhibition of photosynthesis. Thus, we observed that A. rubrum is much more resistant to copper toxicity than R. rubrum. Only slight changes of photosynthetic parameters were observed in A. rubrum at copper concentrations that were severely inhibitory in R. rubrum and in A. rubrum no copper complexes of BChl were found. Altogether, the data suggest that [Zn]-BChl protects the photosynthetic apparatus of A. rubrum from detrimental insertion of Cu2+ (trans-metallation) into BChl molecules of its RCs.
- MeSH
- Acidiphilium chemie MeSH
- bakteriochlorofyl A chemie MeSH
- fotosyntéza MeSH
- hmotnostní spektrometrie MeSH
- hořčík chemie MeSH
- koncentrace vodíkových iontů MeSH
- měď chemie toxicita MeSH
- Rhodospirillum rubrum chemie MeSH
- světlosběrné proteinové komplexy chemie MeSH
- vysokoúčinná kapalinová chromatografie MeSH
- vztahy mezi strukturou a aktivitou MeSH
- zinek chemie MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
In this report, Gluconobacter strains were screened for coenzyme Q10 (CoQ10) production. A thermotolerant strain, Gluconobacter japonicus FM10, was eventually employed for CoQ10 production optimization. To do so, a two-step optimization strategy was used. The first step focused on biomass increase and the second step focused on increase in CoQ10 production. Factors including temperature, pH, carbon, and nitrogen sources were optimized at the first step, and temperature, pH, and aeration were optimized at the second step. The batch culture fermentation was used with the optimized factors of the first phase (30 °C, pH 6.5, D-sorbitol, and yeast extract-peptone as the carbon and nitrogen sources). After 18 h, the temperature, pH, and aeration were shifted to the optimized values of the second step (36 °C, pH 7, and no aeration). By this strategy, the dry cell mass (17.1 g/L) and CoQ10 (23.2 mg/L) were obtained after 20 h, which the latter was 2.3 times higher than that of the first step of optimization. Among the conditions tested, carbon source was the most important factor on the cell growth at the first step while no aeration was the key factor for CoQ10 production in the second step of optimization.
- MeSH
- dusík metabolismus MeSH
- fermentace MeSH
- Gluconobacter chemie genetika růst a vývoj metabolismus MeSH
- koncentrace vodíkových iontů MeSH
- kultivační média metabolismus MeSH
- ubichinon analogy a deriváty biosyntéza MeSH
- uhlík metabolismus MeSH
- vysoká teplota MeSH
- Publikační typ
- časopisecké články MeSH
Bacterial cellulose (BC) produced by Komagataeibacter sucrofermentans was magnetically modified using perchloric acid stabilized magnetic fluid. Magnetic bacterial cellulose (MBC) was used as a carrier for the immobilization of affinity ligands, enzymes and cells. MBC with immobilized reactive copper phthalocyanine dye was an efficient adsorbent for crystal violet removal; the maximum adsorption capacity was 388mg/g. Kinetic and thermodynamic parameters were also determined. Model biocatalysts, namely bovine pancreas trypsin and Saccharomyces cerevisiae cells were immobilized on MBC using several strategies including adsorption with subsequent cross-linking with glutaraldehyde and covalent binding on previously activated MBC using sodium periodate or 1,4-butanediol diglycidyl ether. Immobilized yeast cells retained approximately 90% of their initial activity after 6 repeated cycles of sucrose solution hydrolysis. Trypsin covalently bound after MBC periodate activation was very stable during operational stability testing; it could be repeatedly used for ten cycles of low molecular weight substrate hydrolysis without loss of its initial activity.
- MeSH
- Acetobacteraceae chemie MeSH
- bakteriální polysacharidy chemie MeSH
- celulosa chemie MeSH
- enzymy imobilizované chemie MeSH
- genciánová violeť chemie MeSH
- imobilizované buňky cytologie MeSH
- indoly chemie MeSH
- magnetismus MeSH
- nosiče léků chemie MeSH
- organokovové sloučeniny chemie MeSH
- Saccharomyces cerevisiae cytologie MeSH
- skot MeSH
- trypsin chemie MeSH
- zvířata MeSH
- Check Tag
- skot MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
OBJECTIVES: To convert α-acetolactate into acetoin by an α-acetolactate decarboxylase (ALDC) to prevent its conversion into diacetyl that gives beer an unfavourable buttery flavour. RESULTS: We constructed a whole Saccharomyces cerevisiae cell catalyst with a truncated active ALDC from Acetobacter aceti ssp xylinum attached to the cell wall using the C-terminal anchoring domain of α-agglutinin. ALDC variants in which 43 and 69 N-terminal residues were absent performed equally well and had significantly decreased amounts of diacetyl during fermentation. With these cells, the highest concentrations of diacetyl observed during fermentation were 30 % less than those in wort fermented with control yeasts displaying only the anchoring domain and, unlike the control, virtually no diacetyl was present in wort after 7 days of fermentation. CONCLUSIONS: Since modification of yeasts with ALDC variants did not affect their fermentation performance, the display of α-acetolactate decarboxylase activity is an effective approach to decrease the formation of diacetyl during beer fermentation.
Stereospecific nucleation of mesoporous hybrid microspheres composed of CaCO3 and carrageenan was appended to one side of bacterial cellulose membrane synthesized in static cultures of Gluconacetobacter hansenii to develop an implantable drug delivery device. The synthesis of the hybrid microparticles proceeds by self-assembly mechanism in the presence of calcium and contains tailorable amounts of doxorubicin. However, in the absence of the particles, doxorubicin was distributed along the BC film, but without control release of drug. Infrared spectroscopy, confocal and scanning electron microscopies analyses demonstrate that the doxorubicin is entrapped inside the hybrid particles with approximately 80% drug loading compared to the 11% obtained for native bacterial cellulose. Doxorubicin content in the hybrid particles can be increased by a factor of 10 (from 258.6 to 2586.3 nmol ml−1), and also by the quantities of particles regulated by the CaCO3–carrageenan content and the physicochemical microenvironment. The hybrid BC system can be considered as smart device since the kinetic release of doxorubicin from the hybrid cellulose system rise from 1.50 to 2.75 μg/membrane/day when the pH decreases from 7.4 to 5.8 at 37 °C, a pathologic simulated environment. The hybrid microparticle system can be potentially used as an implantable drug delivery system for personalized oncological therapies.
- MeSH
- bakteriální polysacharidy biosyntéza farmakologie metabolismus MeSH
- biomedicínský výzkum metody trendy MeSH
- celulosa * biosyntéza farmakologie MeSH
- doxorubicin aplikace a dávkování farmakologie MeSH
- elektronová mikroskopie metody využití MeSH
- Gluconacetobacter růst a vývoj účinky léků MeSH
- individualizovaná medicína metody trendy využití MeSH
- karagenan * biosyntéza metabolismus MeSH
- konfokální mikroskopie metody využití MeSH
- lékové transportní systémy metody využití MeSH
- lidé MeSH
- nanokompozity chemie mikrobiologie využití MeSH
- protinádorové látky aplikace a dávkování terapeutické užití toxicita MeSH
- spektrofotometrie infračervená metody využití MeSH
- statistika jako téma metody MeSH
- techniky in vitro MeSH
- uhličitan vápenatý * chemická syntéza metabolismus MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- práce podpořená grantem MeSH
Biotransformation of glycerol to 1,3-dihydroxyacetone was carried out in an isothermal isochoric batch reactor with Gluconobacter oxydans immobilized in poly(vinyl alcohol) gel capsules. The reaction course was described with a three-step kinetic model. Two reaction schemes were proposed and compared with 8 kinetic experiments at 25 °C. The experimental dependences of glycerol and dihydroxyacetone concentrations on reaction time were simulated very well by the autocatalytic model. The effects of reaction temperature and initial concentrations of yeast extract and glycerol were studied. Temperature 25-30 °C, initial yeast extract concentration 2-4 g l-1 and initial glycerol concentration 20-50 g l-1 were found as optimal. The determined rate constants can be used to advantage for industrial production of dihydroxyacetone from glycerol.
