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Background. Astaxanthin is the most important and expensive carotenoid pigment used in aquaculture. Its commercial attractiveness is also related with its antioxidant potential. Xanthophyllomyces dendrorhous yeast is considered to be promising for commercial production of astaxanthin. The aim of this study was to investigate the possibility of the growth and astaxanthin production by X. dendrorhous strains on media containing xylose under different illumination. Material and methods. X. dendrorhous DSM 5626 and its mutants: 10BE and 26UV were used in this study. The cultures were carried out on hydrolysed rye stillage (HS) and YM medium with xylose (YM-K). Celi concentration, total carotenoid and astaxanthin yields were assessed in 5-day cultures. The effect of illumination in the range of 0-5,000 lx on growth and on astaxanthin production of yeasts in cultures run on YM-K medium was also examined. Resuits. For the tested yeast strains better growth parameters and astaxanthin yields were obtained on the YM-K medium, on which for all strains the highest pigment yields were recorded at 600-1,000 lx. The highest concentration of astaxanthin in cells was recorded for 26UV in a culture at 1,000 lx (0.51 g kg1 DCW). The volume yield of the pigment regardless of strain was highest in cultures at 600 lx. In this case 10BE was found to be the best astaxanthin producer with a yield of 2.15 mg dm'3. Conclusions. Astaxanthin synthesis in X. dendrorhous DSM 5626 and its mutants was better on YM-K medium comparing to hydrolysed rye stillage. Moreover, carotenogenesis in the studied yeast strains was subjected to marked photoregulation. Illumination within the range of 600-1,000 lx promotes carotenogenesis and astaxanthin production, while exceeding a certain light capacity resuits in microbial celi death.
Astaxanthin is a xanthophill pigment with commercial application in the aquaculture, pharmaceutical, food and cosmetic industries. The red yeast Xanthophyllomyces dendrorhous is one of the most promising microorganisms for its industrial production. However, astaxanthin content in wild yeast strains is low. Pigment production by X. dendrorhous can be improved by mutagenesis. The aim of the study was to assess the efficiency of four mutagens: UV radiation, benomyl, ethyl methanesulfonate and ethidium bromide in generating asthaxanthinhyperproducing strains of the yeast Xanthophyllomyces dendrorhous DSM 5626. Mutations with benomyl, ethidium bromide and UV radiation generated a group of hyperpigmented mutants exhibiting increases up to 100% in astaxanthin content. Ethyl methanesulfonate turned out to be useless in this respect.
Background. Carotenoids are components playing an important role in biological Systems, starting with light protection, immunoenhancement, protection against carcinogens and finishing with antioxidant activity. Food additives market is based mainly on synthetic additives; however, higher consumer awareness has resulted in an increased use of natural substances. One of the potentially antioxidant compounds could be a lipid soluble carotenoid - astaxanthin (xanthophyll), found in the microbial world. The aim of this study was to evaluate the antioxidant potential of carotenoid extract from Phaffia rhodozyma extract. Material and methods. Carotenoids extracted from Phaffia rhodozyma and the astaxanthin standard was selected for the investigations. Antioxidant potential was evaluated by radical scavenging activity (DPPH' and ABTS'+ radicals) and in lipid oxidative stability measurements (Rancimat, Oxidograph and Schaal oven tests). Results. It was found that the examined extracts presented a significantly higher ability to scavenge the DPPH' radical in comparison to the ABTS’+ radical. Evaluations of linoleic acid emulsion oxidative stability showed a higher antioxidant effect of the Phaffia rhodozyma extract than that of astaxanthin during 19 h of incubation. That potential how- ever, was not detected in linoleic acid emulsion incubated for 96 h, where both additives accelerated oxidation process. In bulk sunflower oil a protective effect of Phaffia rhodozyma extract was observed. In both Rancimat and Oxidograph tests antioxidant activity measured using the induction period was evaluated. However, results of the Schaal oven test indicated that a 144 h incubation of sunflower oil offered a significantly better protection of the lipid against oxidation when the Phaffia rhodozyma extract was added. Conclusions. On the basis of recorded results it was found that the Phaffia rhodozyma carotenoid extract showed moderate antioxidant properties, depending on the environmental conditions of methods used.
Astaksantyna należy do grupy barwników karotenoidowych. Znajduje ona powszechne zastosowanie jako niezbędny składnik pasz w przemysłowej hodowli łososi, pstrągów i krewetek, nadając tkankom tych zwierząt pożądane przez konsumenta, charakterystyczne różowoczerwone zabarwienie. Ponadto, astaksantyna charakteryzuje się dużą aktywnością przeciwutleniającą, najwyższą wśród znanych karotenoidów i 100-500-krotnie wyższą w porównaniu z α-tokoferolem. Wśród preparatów astaksantyny, występujących na światowym rynku, 95% zawiera barwnik syntetyczny - mniej stabilny od astaksantyny pozyskiwanej ze źródeł naturalnych. Ograniczony zakres stosowania astaksantyny naturalnej wynika z kosztów jej otrzymywania, głównie na drodze syntezy mikrobiologicznej z udziałem alg Haematococcus pluvialis. Potencjalnym źródłem astaksantyny naturalnej są drożdże Phaffia rhodozyma. Jako ewentualne przemysłowe źródło tego barwnika wykazują one wiele zalet. Przede wszystkim astaksantyna jest głównym produkowanym przez te drożdże karotenoidem. Phaffia rhodozyma są znacznie łatwiejsze w hodowli w porównaniu z algami. Jednak poważnym ograniczeniem w wykorzystaniu tych drożdży do syntezy astaksantyny na skalę przemysłową jest niska wydajność produkowanego przez nie barwnika, a także koszty związane z jego izolacją z komórek. W artykule przedstawiono zakres i rezultaty badań dotyczących drożdży Phaffia rhodozyma, a także możliwości i ograniczenia w wykorzystaniu tych drożdży do przemysłowej produkcji astaksantyny. Omówiono najważniejsze czynniki wpływające na proces karotenogenezy w komórkach, w tym syntezę astaksantyny. Przedstawiono również możliwości pozyskiwania szczepów Phaffia rhodozyma zdolnych do nadprodukcji astaksantyny.
The aim of this study was to evaluate the influence of light on the production of carotenoids by Phaffia rhodozyma CBS 5626 yeast. The fed-cultures at different illuminance were conducted: in the dark, at constant illuminance of 400 lux and 600 lux, at variable illuminance. It was found that illuminance and time had a significant effect on the level of carotenoids synthesized by Phaffia rhodozyma CBS 5626. But these agents had no a significant effect on yeast dry matter yield. Light stimulated carotenogenesis in cells of the tested yeast; the highest yields of carotenoids were obtained in cultures run at illuminance of 400 lux, while the lowest in cultures run in the dark.
Living cells of Propionibacterium freudenreichii ssp. shermanii 1 and 4 were immobilized in 20 g/L, 30 g/L and 40 g/L alginate gels. Ammonia consumption, glucose utilization, biosynthesis of vitamin B12, productions of propionic and acetic acids were examined. A significant increase of propionic acid production and a decrease of vitamin B12 biosynthesis were observed. The best results were obtained in the fermentation with the strains immobilized in 40 g/L alginate gel being applied for the third time.
The effect of Bacillus coagulans No. 6 strain, B. circulans No. 1, 7, 8 strains and Propionibacterium on growth of Alternaria radicina on carrot tap root was estimated in the research. Investigations were carried out in two terms. In the first test, black rot lesions on carrot tap roots were significantly reduced in size when roots were treated with Propionibacterium, Bacillus coagulans No. 6 and B. circulans No. 1, 7, 8 strains. In second test only insignificant level of fungistatic activity of all tested bacteria was observed.
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