Calculation of fermentation parameters from the results of a batch test taking account of the volume of biomass in the fermenting medium
The values of fermentation parameters calculated from the measured concentrations of substrates and/or products may be significantly affected by the volume of biomass in the fermenting medium. Corrections proposed in this paper should be evaluated and, depending on their magnitude, considered in order to obtain more representative results.
Searching the best operational strategies for Rhizopus oryzae lipase production in Pichia pastoris Mut+ phenotype: Methanol limited or methanol non-limited fed-batch cultures?
Abstract Two different operational strategies, methanol limited (MLFB) and methanol non-limited fed-batch (MNLFB) cultures, have been compared for the production of the recombinant Rhizopus oryzae lipase (ROL) expressed in Pichia pastoris Mut + phenotype. Yields, productivities and specific production rate in all MLFB conditions were very low, obtaining the best results at the lower specific growth rates. Similar results were obtained for MNLFB strategy at methanol set-point concentrations up to 2 g l −1 . However, for methanol set-points higher than 2 g l −1 a significant increase in the production was observed. Methanol set-point of 3 g l −1 was the optimum to maximize product yield ( Y P/X ), both volumetric and specific productivity and mean specific production rate ( q P,mean ), although in terms of ROL production high values were obtained in the range of 3–10 g l −1 . An inhibitory effect of methanol on cell growth as well as slowness on ROL production during early induction phase was observed at concentration of 10 g l −1 .
Ocean thermal energy conversion: The promise of a clean future
Due to the world's heavy dependence on fossil fuels for electricity, pollution and global warming is on the rise. However, numerous countries are still relying on diesel generators as their main source of energy. There is a lack of practical alternative energy source that can meet the global energy demand without posing any threat to the natural environment. Ocean Thermal Energy Conversion (OTEC) is a concept that has the potential to address this growing issue. It is basically a mechanism that exploits the temperature difference between warm surface seawater and cold deep ocean water, to produce electricity. Although OTEC has a low energy density, the thermal energy in the ocean is vastly abundant. OTEC development has been dormant for a long time since it was first proposed in 1881. However, it has now regained recognition worldwide as a realistic solution to our world energy issue. Instead of having a great potential for power generation, it also carries the ability to produce high value products from the large volume of Deep Sea Water (DSW) that can be released as byproducts of OTEC plant operation. These products can hold a very profitable place in industries such as pharmaceutical, food, cosmetics and mineral water production. Further research on ocean current and DSW properties can someday lead to the commercial used of OTEC. This paper is a review of the basic concept, present status and future prospects of OTEC around the world.