Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
9602399 | Biomolecular Engineering | 2005 | 8 Pages |
Abstract
The present study outlines a process for the cost-effective production of 13C/15N-labelled biomass of microalgae on a commercial scale. The core of the process is a bubble column photobioreactor with exhaust gas recirculation by means of a low-pressure compressor. To avoid accumulation of dissolved oxygen in the culture, the exhaust gas is bubbled through a sodium sulphite solution prior to its return to the reactor. The engineered system can be used for the production of 13C, 15N, and 13C-15N stable isotope-labelled biomass as required. To produce 13C-labelled biomass, 13CO2 is injected on demand for pH control and carbon supply, whereas for 15N-labelled biomass Na15NO3 is supplied as nitrogen source at the stochiometric concentration. The reactor is operated in semicontinuous mode at different biomass concentrations, yielding a maximum mean biomass productivity of 0.3 g Lâ1 dayâ1. In order to maximize the uptake efficiency of the labelled substrates, the inorganic carbon is recovered from the supernatant by acidification/desorption processes, while the nitrate is delivered at stochiometric concentration and the harvesting of biomass is performed when the 15NO3â is depleted. In these conditions, elemental analysis of both biomass and supernatant shows that 89.2% of the injected carbon is assimilated into the biomass and 6.9% remains in the supernatant. Based on elemental analysis, 97.8% of the supplied nitrogen is assimilated into the biomass and 1.3% remains in the supernatant. Stable isotope-labelling enrichment has been analysed by GC-MS results showing that the biomass is highly labelled. All the fatty acids are labelled; more than 96% of the carbon present in these fatty acids is 13C. The engineered system was stably operated for 3 months, producing over 160 g of 13C and/or 15N-labelled biomass. The engineered bioreactor can be applied for the labelling of various microalgae.
Related Topics
Physical Sciences and Engineering
Chemical Engineering
Bioengineering
Authors
F.G. Acién Fernández, J.M. Fernández Sevilla, T.A. Egorova-Zachernyuk, E. Molina Grima,