Three strains of red yeast Rhodosporidium kratochvilovae, Rhodotorula glutinis and Sporidiobolus salmonicolor were studied for their responses to the presence metal stress, oxidative stress and a combination of these stress factors. For all yeast strains, the production of β-carotene increased in stress conditions. The combination of H2 O2 and Zn2+ significantly activated the pathways for the production of torularhodin in the strain R. glutinis (from 250 to 470 μg g-1 DCW) as well as β-carotene (from 360 to 1100 μg g-1 DCW) and torulene (from 100 to 360 μg g-1 DCW) in Sp. salmonicolor. Strains of R. glutinis and Rh. kratochvilovae bound the majority of Zn(II) ions to the fibrillar part of the cell walls, whereas the strain Sp. salmonicolor bound them to both extracellular polymers and the fibrillar part of the cell walls. A decrease in the ability of yeasts to tolerate higher concentrations of Zn(II) in the presence of free radicals (hydrogen peroxide) was also found.
Fungi are commonly involved in dairy product spoilage and the use of bioprotective cultures can be a complementary approach to reduce food waste and economic losses. In this study, the antifungal activity of 89 Lactobacillus and 23 Pediococcus spp. isolates against three spoilage species, e.g., Yarrowia lipolytica, Rhodotorula mucilaginosa and Penicillium brevicompactum, was first evaluated in milk agar. None of the tested pediococci showed antifungal activity while 3, 23 and 43 lactobacilli isolates showed strong antifungal activity or total inhibition against Y. lipolytica, R. mucilaginosa and P. brevicompactum, respectively. Then, the three most promising strains, Lactobacillus paracasei SYR90, Lactobacillus plantarum OVI9 and Lactobacillus rhamnosus BIOIII28 at initial concentrations of 105and 107CFU/ml were tested as bioprotective cultures against the same fungal targets in a yogurt model during a 5-week storage period at 10 °C. While limited effects were observed at 105CFU/ml inoculum level, L. paracasei SYR90 and L. rhamnosus BIOIII28 at 107CFU/ml respectively retarded the growth of R. mucilaginosa and P. brevicompactum as compared to a control without selected cultures. In contrast, growth of Y. lipolytica was only slightly affected. In conclusion, these selected strains may be good candidates for bioprotection of fermented dairy products.
- MeSH
- antifungální látky farmakologie MeSH
- Lactobacillus fyziologie MeSH
- mléčné výrobky mikrobiologie MeSH
- Pediococcus fyziologie MeSH
- Penicillium růst a vývoj MeSH
- potravinářská mikrobiologie MeSH
- probiotika MeSH
- Rhodotorula růst a vývoj MeSH
- Yarrowia růst a vývoj MeSH
- Publikační typ
- časopisecké články MeSH
Pre-separation and pre-concentration of bacteria is an important step especially when they are uncultured and bacterial concentration in the matrix is low. This study describes a preparative method based on isoelectric focusing of colored microorganisms in a cellulose-based separation medium from a high conductivity matrix. The isoelectric points found for the examined cells were 1.8 for Micrococcus luteus, 3.5 for Dietzia sp., and 4.7 for Rhodotorula mucilaginosa using capillary isoelectric focusing. The final positions of the zones of colored microbial cells in the cellulose-bed are indicated by colored pI markers. Segments of the separation medium with cells were harvested by a spatula, simply purified using centrifugation and analyzed by capillary isoelectric focusing and matrix-assisted laser desorption/ionization time of flight mass spectrometry. The determined recovery ranged from 78% to 93%. The viability of the harvested cells was verified by their cultivation.
Carotenoids are industrially significant pigments produced in many bacteria, fungi, and plants. Carotenoid biosynthesis in yeasts is involved in stress response mechanisms. Thus, controlled physiological and nutrition stress can be used for enhanced pigment production. Huge commercial demand for natural carotenoids has focused attention on developing of suitable biotechnological techniques including use of liquid waste substrates as carbon and/or nitrogen source. In this work several red yeast strains (Sporobolomyces roseus, Rhodotorula glutinis, Rhodotorula mucilaginosa) were enrolled into a comparative screening study. To increase the yield of these pigments at improved biomass production, several types of exogenous as well as nutrition stress were tested. Each strain was cultivated at optimal growth conditions and in medium with modified carbon and nitrogen sources. Synthetic media with addition of complex substrates (e.g. yeast extract) and vitamin mixtures as well as some waste materials (whey, potato extract) were used as nutrient sources. Peroxide and salt stress were applied too. The production of carotene enriched biomass was carried out in flasks as well as in laboratory fermentor. The best production of biomass was obtained in inorganic medium with yeast extract. In optimal conditions tested strains differ only slightly in biomass production. All strains were able to use most of waste substrates. Biomass and pigment production was more different according to substrate type. In laboratory fermentor better producers of enriched biomass were both Rhodotorula strains. The highest yields were obtained in R. glutinis CCY 20-2-26 cells cultivated on whey medium (cca 45 g per liter of biomass enriched by 46 mg/L of beta-carotene) and in R. mucilaginosa CCY 20-7-31 grown on potato medium and 5% salt (cca 30 g per liter of biomass enriched by 56 mg/L of beta-carotene). Such dried carotenoid-enriched red yeast biomass could be directly used in feed industry as nutrition supplement.
- MeSH
- biologické pigmenty metabolismus MeSH
- biomasa MeSH
- karotenoidy biosyntéza MeSH
- kultivační média MeSH
- kvasinky růst a vývoj metabolismus MeSH
- odpadní produkty MeSH
- průmyslová mikrobiologie přístrojové vybavení metody MeSH
- Rhodotorula metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
The fluorescent dye 3,3'-dipropylthiadicarbocyanine, diS-C(3)(3), is a suitable probe to monitor real changes of plasma membrane potential in yeast cells which are too small for direct membrane potential measurements with microelectrodes. A method presented in this paper makes it possible to convert changes of equilibrium diS-C(3)(3) fluorescence spectra, measured in yeast cell suspensions under certain defined conditions, into underlying membrane potential differences, scaled in the units of millivolts. Spectral analysis of synchronously scanned diS-C(3)(3) fluorescence allows to assess the amount of dye accumulated in cells without otherwise necessary sample taking and following separation of cells from the medium. Moreover, membrane potential changes can be quantified without demanding calibration protocols. The applicability of this approach was demonstrated on the depolarization of Rhodotorula glutinis yeast cells upon acidification of cell suspensions and/or by increasing extracellular K(+) concentration.
Simple and effective protocols of cell wall disruption were elaborated for tested fungal strains: Penicillium citrinum, Aspergillus fumigatus, Rhodotorula gracilis. Several techniques of cell wall disintegration were studied, including ultrasound disintegration, homogenization in bead mill, application of chemicals of various types, and osmotic shock. The release of proteins from fungal cells and the activity of a cytosolic enzyme, glucose-6-phosphate dehydrogenase, in the crude extracts were assayed to determine and compare the efficacy of each method. The presented studies allowed adjusting the particular method to a particular strain. The mechanical methods of disintegration appeared to be the most effective for the disintegration of yeast, R. gracilis, and filamentous fungi, A. fumigatus and P. citrinum. Ultrasonication and bead milling led to obtaining fungal cell-free extracts containing high concentrations of soluble proteins and active glucose-6-phosphate dehydrogenase systems.
- MeSH
- Aspergillus fumigatus účinky léků enzymologie MeSH
- buněčná stěna účinky léků MeSH
- buněčné extrakty chemie MeSH
- detergenty farmakologie MeSH
- fungální proteiny analýza metabolismus MeSH
- glukosa-6-fosfátdehydrogenasa analýza metabolismus MeSH
- osmotický tlak MeSH
- Penicillium účinky léků enzymologie MeSH
- Rhodotorula účinky léků enzymologie MeSH
- vibrace ultrazvukové MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- srovnávací studie MeSH
Enhancement of the immune response leading to protection against bacterial and fungal infections was shown using different schedules of immunization with microbial pigments and a polysaccharide. The group of mice given carotenoids of Rhodotorula glutinis (preparation I) and polysaccharide of Spitulina platensis (IV) survived for 2 weeks after Pseudomonas aeruginosa infection. The groups of mice given carotenoids (I), polysaccharide (IV), I+IV and with the crude phycocyanin of S. platensis (III)+IV survived for 2 weeks after Candida albicans infection. All other groups recorded a maximum level of mortality reaching 2 mice per group either after immunization or post-infection. Adding the carotenoids, phycocyanin and polysaccharides to food as additives might therefore enhance the human immune response against microbial infections.
- MeSH
- analýza přežití MeSH
- Candida albicans imunologie MeSH
- časové faktory MeSH
- imunologické faktory aplikace a dávkování izolace a purifikace MeSH
- kandidóza imunologie prevence a kontrola MeSH
- karotenoidy farmakologie izolace a purifikace MeSH
- myši MeSH
- pseudomonádové infekce imunologie prevence a kontrola MeSH
- Pseudomonas aeruginosa imunologie MeSH
- Rhodotorula chemie MeSH
- Spirulina chemie MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- myši MeSH
- ženské pohlaví MeSH
- zvířata MeSH
