Use of methylene blue uptake for assessing cell viability of colony-forming microalgae
Lemos Bicas, J. ; Kleinegris, D.M.M. ; Barbosa, M.J. - \ 2015
Algal Research 8 (2015). - ISSN 2211-9264 - p. 174 - 180.
botryococcus-braunii - yeast cells - race-b - biomass - hydrocarbons - extraction - chemicals - dyes
During the past few years, interest in microalgae has grown, mainly because of their potential for biofuel production. Botryococcus braunii, a green microalga that can accumulate more than half of its dry weight as hydrocarbons, is one of the most important examples. This microorganism grows in colonies and there has been no reliable viability protocol reported for this species as yet. Knowing the number of dead cells in cultures is essential for the development of efficient bioprocesses such as non-destructive extraction procedures (“milking”) to obtain lipid soluble substances from microalgal biomass. Our study presents a simple colorimetric method to determine the proportion of living to dead cells in cultures, based on the uptake of methylene blue in solution by dead B. braunii cells. The main parameters influencing this process were investigated and used to develop a protocol. This technique was validated using flow cytometry and Neochloris oleoabundans, and appears not to be limited to use with B. braunii.
Potential of industrial biotechnology with cyanobacteria and eukaryotic microalgae
Wijffels, R.H. ; Kruse, O. ; Hellingwerf, K.J. - \ 2013
Current Opinion in Biotechnology 24 (2013)3. - ISSN 0958-1669 - p. 405 - 413.
alga chlamydomonas-reinhardtii - botryococcus-braunii - photosynthetic production - biofuel production - protein-production - carbon-dioxide - genome - transformation - food - cell
Both cyanobacteria and eukaryotic microalgae are promising organisms for sustainable production of bulk products such as food, feed, materials, chemicals and fuels. In this review we will summarize the potential and current biotechnological developments.Cyanobacteria are promising host organisms for the production of small molecules that can be secreted such as ethanol, butanol, fatty acids and other organic acids. Eukaryotic microalgae are interesting for products for which cellular storage is important such as proteins, lipids, starch and alkanes.For the development of new and promising lines of production, strains of both cyanobacteria and eukaryotic microalgae have to be improved. Transformation systems have been much better developed in cyanobacteria. However, several products would be preferably produced with eukaryotic microalgae. In the case of cyanobacteria a synthetic-systems biology approach has a great potential to exploit cyanobacteria as cell factories. For eukaryotic microalgae transformation systems need to be further developed. A promising strategy is transformation of heterologous (prokaryotic and eukaryotic) genes in established eukaryotic hosts such as Chlamydomonas reinhardtii.Experimental outdoor pilots under containment for the production of genetically modified cyanobacteria and microalgae are in progress. For full scale production risks of release of genetically modified organisms need to be assessed.
Two-phase systems: Potential for in situ extraction of microalgal products
Kleinegris, D.M.M. ; Janssen, M.G.J. ; Brandenburg, W.A. ; Wijffels, R.H. - \ 2011
Biotechnology Advances 29 (2011)5. - ISSN 0734-9750 - p. 502 - 507.
intracellularly stored products - beta-carotene production - botryococcus-braunii - chlamydomonas-reinhardtii - dunaliella biotechnology - saccharomyces-cerevisiae - hydrocarbon recovery - biodiesel production - organic-solvents - l-phenylalanine
Algae are currently used for production of niche products and are becoming increasingly interesting for the production of bulk commodities, such as biodiesel. For the production of these goods to become economically feasible, production costs will have to be lowered by one order of magnitude. The application of two-phase systems could be used to lower production costs. These systems circumvent the costly step of cell harvesting, whilst the product is extracted and prepared for downstream processing. The mechanism of extraction is a fundamental aspect of the practical question whether two-phase systems can be applied for in situ extraction, viz, simultaneous growth, product formation and extraction, or as a separate downstream processing step. Three possible mechanisms are discussed; 1) product excretion 2) cell permeabilization, and 3) cell death. It was shown that in the case of product excretion, the application of two-phase systems for in situ extraction can be very valuable. With permeabilization and cell death, in situ extraction is not ideal, but the application of two-phase systems as downstream extraction steps can be part of a well-designed biorefinery process. In this way, processing costs can be decreased while the product is mildly and selectively extracted. Thus far none of the algal strains used in two-phase systems have been shown to excrete their product; the output has always been the result of cell death. Two-phase systems can be a good approach as a downstream processing step for these species. For future applications of two-phase in situ extraction in algal production processes, either new species that show product excretion should be discovered, or existing species should be modified to induce product excretion.