562
Alexandra Galetovi´ c C. and L. Dufossé
The last studies about phycobiliproteins have been focused on the prevention of
the loss of color due to PC degradation. In this regard several preservative substances
were tested such as citric acid, fructose, beet pectin, crosslinking with methylglyoxal
(MGO) and anionic micelles. The PC from Spirulina platensis improved the stability
in presence of citric acid (4 mg/mL) at 35 °C during 15 days. It has showed a
correlation between sugars (mainly fructose) and PC stability, but the use is limited
for pastry and confectionery due to the high sugar content. On the other hand SDS
micelles stabilize the non-protonated (blue) forms of PC and prevent the formation
of protonated forms (green) at low pH (Martelli et al. 2014; Falkeborg et al. 2018).
In this chapter, the structural characteristics of phycobiliproteins, chromophores,
and phycobilisomes are related to the stability of these structures, mainly at pH and
temperature. In addition, the biochemical differences found between phycobiliproteins of mesophilic and thermophilic organisms and the potential use in biotechnological applications are analyzed. Likewise, is considered the use of food grade
phycobiliproteins as additive and on stability studies at pH, temperature, light, as
well as the use of preservatives and microencapsulation to increase the stability of
these pigments.
22.2 Structural Characteristics of Phycobiliproteins
The cyanobacteria are located in diverse environments such as the desert, sea water,
Antarctic region, lakes, soils, lithic substrates (halite and quartz), and their adaptation
is due to the synthesis of compounds (polysaccharides, osmolytes, and pigments
among others) that serve as a survival strategy, to tolerate a wide range of factors such
as temperature, pH, ultraviolet radiation, and salinity (Rippka et al. 1979; Tandeau de
Marsac and Houmard 1993). Several studies have been dedicated to test the stability
of phycobiliproteins in high-temperature environments and compare it with those
of microorganisms in moderate temperature environments. The following question
arises: are there differences in the structure and stability of the phycobiliproteins of
thermophilic and mesophilic cyanobacteria?
In this sense, the presence of cyanobacteria in environments with high temperatures such as hot springs and geysers (Pumas et al. 2012; Rahman et al. 2017) has been
widely reported and studies have focused mainly on C-phycocyanin cyanobacteria
isolated from thermal environments.
The cyanobacterium Synechoccoccus lividus isolated from thermal alkaline hot
springs of Yellowstone National Park grows at 73 °C and produces C-phycocyanin,
which denaturates at a higher temperature than mesophilic microorganisms. Unlike
other phycocyanins, this pigment has a maximum absorption at 608 nm, which may be
due to a biline-apoprotein interaction, which is different from that found in mesophilic
phycocyanins. A second strain of this cyanobacterium grows at 55 °C and at temperatures of 49 °C, the aggregation increases, it needs a higher temperature to acquire the
native structure. The aggregation of phycobiliprotein monomers has been associated
Alexandra Galetovi´ c C. and L. Dufossé
The last studies about phycobiliproteins have been focused on the prevention of
the loss of color due to PC degradation. In this regard several preservative substances
were tested such as citric acid, fructose, beet pectin, crosslinking with methylglyoxal
(MGO) and anionic micelles. The PC from Spirulina platensis improved the stability
in presence of citric acid (4 mg/mL) at 35 °C during 15 days. It has showed a
correlation between sugars (mainly fructose) and PC stability, but the use is limited
for pastry and confectionery due to the high sugar content. On the other hand SDS
micelles stabilize the non-protonated (blue) forms of PC and prevent the formation
of protonated forms (green) at low pH (Martelli et al. 2014; Falkeborg et al. 2018).
In this chapter, the structural characteristics of phycobiliproteins, chromophores,
and phycobilisomes are related to the stability of these structures, mainly at pH and
temperature. In addition, the biochemical differences found between phycobiliproteins of mesophilic and thermophilic organisms and the potential use in biotechnological applications are analyzed. Likewise, is considered the use of food grade
phycobiliproteins as additive and on stability studies at pH, temperature, light, as
well as the use of preservatives and microencapsulation to increase the stability of
these pigments.
22.2 Structural Characteristics of Phycobiliproteins
The cyanobacteria are located in diverse environments such as the desert, sea water,
Antarctic region, lakes, soils, lithic substrates (halite and quartz), and their adaptation
is due to the synthesis of compounds (polysaccharides, osmolytes, and pigments
among others) that serve as a survival strategy, to tolerate a wide range of factors such
as temperature, pH, ultraviolet radiation, and salinity (Rippka et al. 1979; Tandeau de
Marsac and Houmard 1993). Several studies have been dedicated to test the stability
of phycobiliproteins in high-temperature environments and compare it with those
of microorganisms in moderate temperature environments. The following question
arises: are there differences in the structure and stability of the phycobiliproteins of
thermophilic and mesophilic cyanobacteria?
In this sense, the presence of cyanobacteria in environments with high temperatures such as hot springs and geysers (Pumas et al. 2012; Rahman et al. 2017) has been
widely reported and studies have focused mainly on C-phycocyanin cyanobacteria
isolated from thermal environments.
The cyanobacterium Synechoccoccus lividus isolated from thermal alkaline hot
springs of Yellowstone National Park grows at 73 °C and produces C-phycocyanin,
which denaturates at a higher temperature than mesophilic microorganisms. Unlike
other phycocyanins, this pigment has a maximum absorption at 608 nm, which may be
due to a biline-apoprotein interaction, which is different from that found in mesophilic
phycocyanins. A second strain of this cyanobacterium grows at 55 °C and at temperatures of 49 °C, the aggregation increases, it needs a higher temperature to acquire the
native structure. The aggregation of phycobiliprotein monomers has been associated