Rhodosporidium toruloides cultivated in NaCl-enriched glucose-based media: adaptation dynamics and lipid production

In the present report and for the first time in the international literature, the impact of the addition of NaCl upon growth and lipid production on the oleaginous yeast Rhodosporidium toruloides was studied. Moreover, equally for first time, lipid production by R. toruloides was performed under non-aseptic conditions. Therefore, the potentiality of R. toruloides DSM 4444 to produce lipid in media containing several initial concentrations of NaCl with glucose employed as carbon source was studied. Preliminary batch-flask trials with increasing amounts of NaCl revealed the tolerance of the strain against NaCl content up to 6.0% (w/v). However, 4.0% (w/v) of NaCl stimulated lipid accumulation for this strain, by enhancing lipid production up to 71.3% (w/w) per dry cell weight. The same amount of NaCl was employed in pasteurized batch-flask cultures in order to investigate the role of the salt as bacterial inhibiting agent. The combination of NaCl and high glucose concentrations was found to satisfactorily suppress bacterial contamination of R. toruloides cultures under these conditions. Batch-bioreactor trials of the yeast in the same media with high glucose content (up to 150 g/L) resulted in satisfactory substrate assimilation, with almost linear kinetic profile for lipid production, regardless of the initial glucose concentration imposed. Finally, fed-batch bioreactor cultures led to the production of 37.2 g/L of biomass, accompanied by 64.5% (w/w) of lipid yield. Lipid yield per unit of glucose consumed received the very satisfactory value of 0.21 g/g, a value amongst the highest ones in the literature. The yeast lipid produced contained mainly oleic acid and to lesser extent palmitic and stearic acids, thus constituting a perfect starting material for “second generation” biodiese

Growth, Technological Change and Output Gap in Russia

The present paper uses the “growth accounting” methodology to estimate technological change, in an attempt to formulate an explanation of Russia’s economic decline and signs of recovery in the 1992-1999 time span, in relation to technological change. Also, the potential output and output gap is estimated using a Cobb Douglas production function and a Hodrick-Prescott filter for the Russian Economy before 2000. The results do show that, despite the general economic collapse during the 1990s, rooted in the Soviet economy’s very structure, the level of technology has, practically, remained unchanged which, in turn, prevented the Russian Economy from further deteriorating. Meanwhile, the relationship between output gap and inflation is briefly examined and the results suggest that output gap is sufficient to explain the largest part of inflation in the Russian economy. As a final conclusion, technological progress and, consequently, long-term economic growth is linked to Russia’s political and structural development

Growth, Technological Change and Output Gap in Russia

The present paper uses the “growth accounting” methodology to estimate technological change, in an attempt to formulate an explanation of Russia’s economic decline and signs of recovery in the 1992-1999 time span, in relation to technological change. Also, the potential output and output gap is estimated using a Cobb Douglas production function and a Hodrick-Prescott filter for the Russian Economy before 2000. The results do show that, despite the general economic collapse during the 1990s, rooted in the Soviet economy’s very structure, the level of technology has, practically, remained unchanged which, in turn, prevented the Russian Economy from further deteriorating. Meanwhile, the relationship between output gap and inflation is briefly examined and the results suggest that output gap is sufficient to explain the largest part of inflation in the Russian economy. As a final conclusion, technological progress and, consequently, long-term economic growth is linked to Russia’s political and structural development

Industrial derivative of tallow: a promising renewable substrate for microbial lipid, single-cell protein and lipase production by Yarrowia lipolytica

The aim of the present study was to assess the potential of valorisation of a solid industrial derivative of tallow, composed of saturated free-fatty acids ("stearin"), by fermentations carried out by the yeast Yarrowia lipolytica ACA-DC 50109 in order to produce microbial lipid, biomass and extra-cellular lipase. High quantities of biomass were produced (biomass yield of around 1.1 \ub1 0.1 g of total biomass produced per g of fat consumed) when the organism was grown in shake flasks, regardless of the concentration of extra-cellular nitrogen present. Cellular lipids accumulated in notable quantities regardless of the nitrogen availability of the medium, though this process was clearly favoured at high initial fat and low initial nitrogen concentrations. The maximum quantity of fat produced was 7.9 mg/ml corresponding to 52.0% (wt/wt) of lipid in the dry biomass. Lipase production was critically affected by the medium composition and its concentration clearly increased with increasing concentrations of fat and extra-cellular nitrogen concentration reaching a maximum level of 2.50 IU/ml. Lipase concentration decreased in the stationary growth phase. In bioreactor trials, in which higher agitation and aeration conditions were employed compared with the equivalent trial in the flasks, significantly higher quantities of biomass were produced (maximum concentration 30.5 mg/ml, yield of 1.6 g of total biomass produced per g of fat consumed) while remarkably lower quantities of cellular lipids and extra-cellular lipase were synthesised. Numerical models successfully simulated both conversion of substrate fat into biomass and production and subsequent hydrolysis of extra-cellular lipase and presented a satisfactory predictive ability verifying the potential for single-cell protein and lipase production by Yarrowia lipolytica ACA-DC 50109. In all cultures, the mycelial form of the culture was dominant with few single cells present

portable

Architectures for secur