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fatty acid composition, unsaturation, and hence the membrane fluidity (Jirků 1999).
Unfavorable environmental conditions in immobilized systems, i.e., high osmotic
pressure and nutrient limitations and/or mechanical stress, have been put forward as
a putative explanation of these modifications (Junter et al. 2002). An increase in cell
membrane permeability has also been observed for microalgae Chlamydomonas
reinhardtii entrapped in alginate beads, favoring the uptake of nitrite ions (SantosRosa et al. 1989).
7.5 Immobilized Microalgae in Biotechnology
The mainstream applications of immobilized algal cells are biomass and valueadded metabolite production, obtaining biohydrogen, and for biocapture of nutrients and metals from or destruction of the organic pollutants in wastewaters. The
immobilized microalgae are also used as biosensors to assess the degree of water
pollution (Mallick 2002; Mulbry et al. 2005; Eroglu et al. 2015). The problem of
algae biomass harvesting is one of the main challenges in photobiotechnology.
Currently employed approaches (filtration, centrifugation, flocculation) are energyand/or time-consuming. The using of immobilized cells streamlines considerably
the process of biomass harvesting. Other areas of immobilized microalgal cell
application are exemplified in the following sections.
7.5.1 Biomass and Value-Added Metabolite Production
It was proved that immobilized cells of Porphyridium cruentum were more efficient
producers of sulfated polysaccharides as compared to free cells (Gudin and
Thepenier 1986). The other prominent example is the usage of cyanobacterium
Aphanocapsa halophytia MN-11 immobilized in calcium alginate gel and coated on
light-diffusing optical fibers for sulfated polysaccharide production (Matsunaga
et al. 1996). Cyanobacterium Spirulina platensis immobilized in alginate converted
morphine to the alkaloid codeine (Rao and Hall 1984).
The NH 3 production by nitrogen-fixing cyanobacteria Anabaena azollae immobilized in polyurethane foam was enhanced during cultivation in a photobioreactor
(Kannaiyan et al. 1994). The hydrocarbon production by alginate-immobilized
Botryococcus braunii and Botryococcus protuberans was significantly increased
during stationary growth phase. Santos-Rosa et al. (1989) revealed that
Chlamydomonas reinhardtii cells immobilized in alginate beads sustained more
stable photoproduction of ammonia during their prolonged cultivation in a photobioreactor than free-living cells. Glycerol production in alginate-entrapped cells of
C. reinhardtii was doubled as compared to suspended cells.
Sustainable sources of energy such as biohydrogen produced by microalgae
draw increasing attention during the last decades. Certain microalgae species are
7 Biotechnological Applications of Immobilized Microalgae
fatty acid composition, unsaturation, and hence the membrane fluidity (Jirků 1999).
Unfavorable environmental conditions in immobilized systems, i.e., high osmotic
pressure and nutrient limitations and/or mechanical stress, have been put forward as
a putative explanation of these modifications (Junter et al. 2002). An increase in cell
membrane permeability has also been observed for microalgae Chlamydomonas
reinhardtii entrapped in alginate beads, favoring the uptake of nitrite ions (SantosRosa et al. 1989).
7.5 Immobilized Microalgae in Biotechnology
The mainstream applications of immobilized algal cells are biomass and valueadded metabolite production, obtaining biohydrogen, and for biocapture of nutrients and metals from or destruction of the organic pollutants in wastewaters. The
immobilized microalgae are also used as biosensors to assess the degree of water
pollution (Mallick 2002; Mulbry et al. 2005; Eroglu et al. 2015). The problem of
algae biomass harvesting is one of the main challenges in photobiotechnology.
Currently employed approaches (filtration, centrifugation, flocculation) are energyand/or time-consuming. The using of immobilized cells streamlines considerably
the process of biomass harvesting. Other areas of immobilized microalgal cell
application are exemplified in the following sections.
7.5.1 Biomass and Value-Added Metabolite Production
It was proved that immobilized cells of Porphyridium cruentum were more efficient
producers of sulfated polysaccharides as compared to free cells (Gudin and
Thepenier 1986). The other prominent example is the usage of cyanobacterium
Aphanocapsa halophytia MN-11 immobilized in calcium alginate gel and coated on
light-diffusing optical fibers for sulfated polysaccharide production (Matsunaga
et al. 1996). Cyanobacterium Spirulina platensis immobilized in alginate converted
morphine to the alkaloid codeine (Rao and Hall 1984).
The NH 3 production by nitrogen-fixing cyanobacteria Anabaena azollae immobilized in polyurethane foam was enhanced during cultivation in a photobioreactor
(Kannaiyan et al. 1994). The hydrocarbon production by alginate-immobilized
Botryococcus braunii and Botryococcus protuberans was significantly increased
during stationary growth phase. Santos-Rosa et al. (1989) revealed that
Chlamydomonas reinhardtii cells immobilized in alginate beads sustained more
stable photoproduction of ammonia during their prolonged cultivation in a photobioreactor than free-living cells. Glycerol production in alginate-entrapped cells of
C. reinhardtii was doubled as compared to suspended cells.
Sustainable sources of energy such as biohydrogen produced by microalgae
draw increasing attention during the last decades. Certain microalgae species are
7 Biotechnological Applications of Immobilized Microalgae