algae exposed to high salinities produce high amounts of carotenoids for protection
(Orosa et al. 2001). Wei et al. (2011) used different monosaccharides for hydrogen
generation. Glucose, fructose, galactose, and sucrose substrates at a concentration of
200 mg/L were used by Chen et al. (2020) in Anabaena sp. strain to investigate the
biogas production. Chlamydomonas reinhardtii could produce hydrogen at a rate of
1.7 mol/mol with acetate as carbon source (Show et al. 2011). Bala Amutha and
Murugesan (2011) have observed that Chlorella vulgaris MSU 01 strain isolated
from a pond produced hydrogen. They optimized the media with different carbohydrates and amino acids. Feedstock of corn stalk was studied for growing algae and
generation of hydrogen. Antal et al. (2020) have studied the role of hydrogen
generation under sulfur limitation in the acclimation of Chlamydomonas reinhardtii
CC-425 cells and compared it with hydEF-1 mutant lacking hydrogenase activity.
They suggested that under sulfur deprivation, the active hydrogenase plays a key
role in the algae acclimation to anaerobic phase by modulating intracellular redox
and maintaining pH. Fakhimi et al. (2020) reported synergistic hydrogen production
using co-cultures of bacteria and algae. They have observed an enhancement of
about 60% hydrogen when photobiological and fermentative production was combined in Chlamydomonas and Escherichia coli co-cultures using glucose substrate.
Kannah et al. (2019) pretreated rice straw and used modeling approaches for
hydrogen production.
7.6.4 Light Intensity
When the light intensity is high, the overexcitation of the chemistry equipment takes
place resulting in the formation of reactive chemical element species (ROS). High
strength causes injury to PSII by inhibiting the synthesis of the D1 supermolecule of
the PSII reaction center (Nishiyama et al. 2006). Krzemińska et al. (2014) investigated the influence of sunlight on the expansion rate and algal biomass formation.
Modeling of the outdoor or indoor algal culture system light intensity plays a
significant role (Huesemann et al. 2013) in optimizing hydrogen production. Alabi
et al. (2009) found that at different light intensities, microalgae cannot grow to their
full potential. Enhanced hydrogen production after 4 h light exposure in anaerobic
condition was seen by Tsygankov et al. (2006c). The role of light in hydrogen
production is still being debated (Uyar et al. 2007). Kim et al. (2006) found that
hydrogen production depends on the rate of consumption of sulfate by algae. They
observed that the consumption of sulfur was maximum at a light intensity of
200 mmol/m
2 /s. The effects of light on microalgae biohydrogen needs to be explored
at various stages of the process (Rashid et al. 2013). Phlips and Mitsui (1983) have
studied the effects of environmental factors in Oscillatoria sp. strain Miami BG7 and
reported that biohydrogen production is greatly influenced by light intensity. Nitrogen depletion was essential for the initiation of hydrogen production which was
observed at the linear phase of growth. Phlips and Mitsui (1983) observed that the
200
R. Kumar et al.
(Orosa et al. 2001). Wei et al. (2011) used different monosaccharides for hydrogen
generation. Glucose, fructose, galactose, and sucrose substrates at a concentration of
200 mg/L were used by Chen et al. (2020) in Anabaena sp. strain to investigate the
biogas production. Chlamydomonas reinhardtii could produce hydrogen at a rate of
1.7 mol/mol with acetate as carbon source (Show et al. 2011). Bala Amutha and
Murugesan (2011) have observed that Chlorella vulgaris MSU 01 strain isolated
from a pond produced hydrogen. They optimized the media with different carbohydrates and amino acids. Feedstock of corn stalk was studied for growing algae and
generation of hydrogen. Antal et al. (2020) have studied the role of hydrogen
generation under sulfur limitation in the acclimation of Chlamydomonas reinhardtii
CC-425 cells and compared it with hydEF-1 mutant lacking hydrogenase activity.
They suggested that under sulfur deprivation, the active hydrogenase plays a key
role in the algae acclimation to anaerobic phase by modulating intracellular redox
and maintaining pH. Fakhimi et al. (2020) reported synergistic hydrogen production
using co-cultures of bacteria and algae. They have observed an enhancement of
about 60% hydrogen when photobiological and fermentative production was combined in Chlamydomonas and Escherichia coli co-cultures using glucose substrate.
Kannah et al. (2019) pretreated rice straw and used modeling approaches for
hydrogen production.
7.6.4 Light Intensity
When the light intensity is high, the overexcitation of the chemistry equipment takes
place resulting in the formation of reactive chemical element species (ROS). High
strength causes injury to PSII by inhibiting the synthesis of the D1 supermolecule of
the PSII reaction center (Nishiyama et al. 2006). Krzemińska et al. (2014) investigated the influence of sunlight on the expansion rate and algal biomass formation.
Modeling of the outdoor or indoor algal culture system light intensity plays a
significant role (Huesemann et al. 2013) in optimizing hydrogen production. Alabi
et al. (2009) found that at different light intensities, microalgae cannot grow to their
full potential. Enhanced hydrogen production after 4 h light exposure in anaerobic
condition was seen by Tsygankov et al. (2006c). The role of light in hydrogen
production is still being debated (Uyar et al. 2007). Kim et al. (2006) found that
hydrogen production depends on the rate of consumption of sulfate by algae. They
observed that the consumption of sulfur was maximum at a light intensity of
200 mmol/m
2 /s. The effects of light on microalgae biohydrogen needs to be explored
at various stages of the process (Rashid et al. 2013). Phlips and Mitsui (1983) have
studied the effects of environmental factors in Oscillatoria sp. strain Miami BG7 and
reported that biohydrogen production is greatly influenced by light intensity. Nitrogen depletion was essential for the initiation of hydrogen production which was
observed at the linear phase of growth. Phlips and Mitsui (1983) observed that the
200
R. Kumar et al.