0000000000311584
AUTHOR
Linda Rozenfelde
Immobilisation increases yeast cells' resistance to dehydration-rehydration treatment.
This study was performed with the goal of revealing if the dehydration procedure used in our new immobilisation method noticeably decreases the viability of yeast cells in immobilised preparations. Various yeasts were used in this research: Saccharomyces cerevisiae cells that were rather sensitive to dehydration and had been aerobically grown in an ethanol-containing medium, a recombinant strain of S. cerevisiae grown in aerobic conditions which were completely non-resistant to dehydration and an anaerobically grown bakers' yeast strain S. cerevisiae, as well as a fairly resistant Pichia pastoris strain. Experiments performed showed that immobilisation of all these strains essentially incre…
Anhydrobiosis in yeast: FT-IR spectroscopic studies of yeast grown under conditions of severe oxygen limitation
Anhydrobiosis is a unique state of living organisms when metabolism is temporarily and reversibly delayed in response to the extreme desiccation of cells. The production of dry active preparations of yeast grown under anaerobic conditions is not currently possible because preparations are extremely sensitive to the dehydration procedure, though they could be very helpful in different biotechnological processes, including bioethanol production. To characterize mechanisms responsible for such sensitivity to the dehydration procedure, Fourier transform infrared spectroscopy was used to study the composition of aerobically grown yeast Saccharomyces cerevisiae resistant to dehydration and grown …
Anhydrobiosis in yeasts: Glutathione synthesis by yeast Ogataea (Hansenula) polymorpha cells after their dehydration-rehydration.
The possibility of using active dry microbial preparations in biotechnological processes is essential for the development of new modern industrial technologies. In this study, we show the possibility of obtaining such preparations of the genetically engineered yeast strain Ogataea (Hansenula) polymorpha with glutathione overproduction. Special pre-treatment involving the gradual rehydration of dry cells in water vapour led to the restoration/reactivation of almost 100% of dehydrated cells. Furthermore, dry cells do not lose their viability during storage at room temperatures. Application of dry cells as the inoculum provides the same levels of glutathione synthesis as that of a native yeast…
Effect of Lignin-Containing Media on Growth of Medicinal Mushroom Lentinula Edodes
Abstract The effect of lignocellulose and lignin on growth of mycelium of mushroom Lentinula edodes and laccase activity in cultivation medium was studied. It was shown that cultivation of L. edodes mycelium in liquid nutrient medium with addition of 0.25-0.5% of kraft lignin increased mycelium biomass yield approximately two times compared with reference conditions without addition of lignin. Similar results were obtained in experiments in which 0.5% lignocellulose that remained after obtaining furfural, and 0.5% lignin that remained after obtaining furfural and glucose from wheat straw, were added to the nutrient medium. This effect was greater in the conditions of cultivation with good a…
Catalytic treatment of rapeseed straw for enhanced production of furfural and glucose for bioethanol production
Abstract Ethanol produced from renewable biomass, such as lignocellulosic feedstock, is one of the most promising future biofuels. In this paper, rapeseed straw was tested as an abundant and cost-effective renewable resource material for the production of cellulosic glucose. Pre-treatment of this material is an important step to improve the efficiency of subsequent cellulose hydrolysis. In this study, we used two pre-treatment methods – hydrothermochemical and ultrasound. Studies have shown that, in the initial hydrothermal pre-treatment of rapeseed straw, Al2(SO4)3 may be used as an efficient catalyst, at least in procedures for obtaining glucose. An increase in the amount of this catalyst…
Physiological engineering of Pseudomonas aurantiaca antimicrobial activity: effects of sodium chloride treatment
The influence of sodium chloride (NaCl) treatment on the antifungal activity of the bacterium Pseudomonas aurantiaca, a producer of biopesticide for vegetable plants, was investigated. It was shown that an increase in the NaCl concentration in incubation solutions from 1 M to 3 M led to a significant increase in the antifungal activity of this bacterium. Antifungal activity continued to increase with prolonged treatment of bacteria in fresh nutrient medium from 72 h to 96 h. These findings could be very important for the further development of biotechnological processes directed not only to the production of new active biopesticides but also of other valuable resources.
Limitēta skābekļa apstākļos kultivēta rauga anhidrobioze un tās biotehnoloģiskie pielietojumi
Promocijas darba gaitā izvērtētas iespējas uzlabot raugu Saccharomyces cerevisiae kultivētu limitēta skābekļa apstākļos izturību dehidratācijas-rehidratācijas procesā. Izpētīta dažādu vielu - antioksidantu, cukuru, sāls, poliolu - iespējamā ietekme uz šūnu rezistences palielināšanu. Tāpat parādīta iespēja izmantot celulozi saturošu substrātu pēc furfurola izdalīšanas etanola sintēzei. Pētījumos noskaidroti apstākļi enzimātiskās hidrolīzes procesam un papildus priekšapstrādes izmantošanas efektivitāte glikozes iznākuma uzlabošanai, kā arī iegūtā hidrolizāta un dehidratēto raugu izmantošanas iespējas. Promocijas darbā novērotās likumsakarības raugu šūnu atbildes reakcijās uz inkubācijas priek…
Enzymatic Hydrolysis of Lignocellulose for Bioethanol Production
Abstract The effect of temperature, time and amount of enzyme on hydrolysis of wheat straw lignocellulose remaining after furfural production was studied. The residual substrate was subjected to enzymatic hydrolysis at different temperatures — 45 °C, 50 °C and 55 °C. Hydrolysis time was 72 hours, and samples were taken every 24 hours. The maximum glucose yield (76.5% of the theoretically possible) was reached when hydrolysis temperature 50 °C was used. The production rate of glucose increased with a hydrolysis period of time. The yield of glucose significantly depended on the ratio of enzyme to substrate.