56
V. K. Kannaujiya et al.
3.6.2 Temperature Stress
Temperature is the most fundamental physiological factor that affects physiological, biochemical, and metabolic processes of an organism. In aquatic system, high
temperature reduces availability of free oxygen which may be a primary effect on
the photosynthesis machinery. Temperature exhibit several impacts on productivity
of PBPs in different cyanobacterial species (Pagels et al. 2019). Hemlata and Fatma
(2009) have found an optimum temperature of about 30 °C for the synthesis of PBPs
in the cyanobacterium Anabaena NCCU-9.
However, alteration in optimum temperature (30 °C) may reduce the growth
significantly with optimum yield of PBPs. Moreover, other scientists have reported
the optimum temperature to be 36 and 37 °C for Synechococcus (Sakamoto and
Bryant 1998) and Arthronema africanum (Chaneva et al. 2007), respectively. Upon
exposure to a higher temperature, heat shock proteins (HspA) are produced by the
cyanobacterium Synechococcus sp. strain PCC 7942 which interact with PC of PBPs
and suppress the inactivation of functional properties by heat-enabled denaturation
(Nakamoto and Honma 2006). They also thrive well at high temperature (Richa
and Sinha 2015). In Synechococcus sp. PCC7 942 HspA has been suggested to
protect phycobiliproteins from degradation under heat stress as well as oxidative
stress (Nakamoto et al. 2000, Nakamoto and Honma 2006). It has been found that
Spirulina platensis is able to grow efficiently in large fluctuation of temperature
except below 20 °C and greater than 40 °C (Kumar et al. 2018).
3.6.3 Salt Stress
The maintenance of salt concentration is crucial for proper cell functioning, ion
regulation, membrane potential, osmotic balance, and metabolic activity (Pandhal
et al. 2008, 2009). The consequent increase of salt concentration adversely affect
non-tolerant organism by inhibition of electron transport system. The composition
and function of PBPs in cyanobacteria changed in response to stress conditions
(Grossman et al. 1993). Salt stress mainly decreases PC concentration, and thereby
energy transfer between PBPs and PSII may be interrupted (Lu et al. 1999, Lu and
Vonshak 2002). It was found that the lowest concentration of salt (10 mM) resulted in
an increase in PBP content in cyanobacterium Anabaena sp. NCCU-9 as compared
to untreated sample, while further increase in salt concentration resulted in gradual
decline in growth (Hemlata and Fatma 2009). To increase salt concentration, the
ionic movement of sodium ions might be increased, and induced detachment of
PBPs leads to inhibition of energy transfer reaction between PBPs and PSII (Rafiqul
et al. 2003). Moreover, Spirulina fusiformis exhibit optimum growth in the absence
of salt (Rafiqul et al. 2003).
V. K. Kannaujiya et al.
3.6.2 Temperature Stress
Temperature is the most fundamental physiological factor that affects physiological, biochemical, and metabolic processes of an organism. In aquatic system, high
temperature reduces availability of free oxygen which may be a primary effect on
the photosynthesis machinery. Temperature exhibit several impacts on productivity
of PBPs in different cyanobacterial species (Pagels et al. 2019). Hemlata and Fatma
(2009) have found an optimum temperature of about 30 °C for the synthesis of PBPs
in the cyanobacterium Anabaena NCCU-9.
However, alteration in optimum temperature (30 °C) may reduce the growth
significantly with optimum yield of PBPs. Moreover, other scientists have reported
the optimum temperature to be 36 and 37 °C for Synechococcus (Sakamoto and
Bryant 1998) and Arthronema africanum (Chaneva et al. 2007), respectively. Upon
exposure to a higher temperature, heat shock proteins (HspA) are produced by the
cyanobacterium Synechococcus sp. strain PCC 7942 which interact with PC of PBPs
and suppress the inactivation of functional properties by heat-enabled denaturation
(Nakamoto and Honma 2006). They also thrive well at high temperature (Richa
and Sinha 2015). In Synechococcus sp. PCC7 942 HspA has been suggested to
protect phycobiliproteins from degradation under heat stress as well as oxidative
stress (Nakamoto et al. 2000, Nakamoto and Honma 2006). It has been found that
Spirulina platensis is able to grow efficiently in large fluctuation of temperature
except below 20 °C and greater than 40 °C (Kumar et al. 2018).
3.6.3 Salt Stress
The maintenance of salt concentration is crucial for proper cell functioning, ion
regulation, membrane potential, osmotic balance, and metabolic activity (Pandhal
et al. 2008, 2009). The consequent increase of salt concentration adversely affect
non-tolerant organism by inhibition of electron transport system. The composition
and function of PBPs in cyanobacteria changed in response to stress conditions
(Grossman et al. 1993). Salt stress mainly decreases PC concentration, and thereby
energy transfer between PBPs and PSII may be interrupted (Lu et al. 1999, Lu and
Vonshak 2002). It was found that the lowest concentration of salt (10 mM) resulted in
an increase in PBP content in cyanobacterium Anabaena sp. NCCU-9 as compared
to untreated sample, while further increase in salt concentration resulted in gradual
decline in growth (Hemlata and Fatma 2009). To increase salt concentration, the
ionic movement of sodium ions might be increased, and induced detachment of
PBPs leads to inhibition of energy transfer reaction between PBPs and PSII (Rafiqul
et al. 2003). Moreover, Spirulina fusiformis exhibit optimum growth in the absence
of salt (Rafiqul et al. 2003).