4.2 Mixotrophic Cultivation
In mixotrophic mode, microalgal growth happens majorly through photosynthesis
apart from the utilization of CO 2 and organic compounds [37]. As mixotrophic mode
accumulates lipid via photosynthesis and also involved in sequestering CO 2 , it was
considered good and much sustainable than heterotrophic mode [38]. Higher growth
rates were attained for some microalgae in mixotrophic than phototrophic conditions, and they produce compounds that are synthesized during both phototrophic
and heterotrophic conditions [39]. It can be considered as a potential approach for
producing wide array of economically viable microalgal products in a short span of
time. Mixotrophic cultivation can effectively be used for producing seed cells;
subsequently it can then be used as inoculums for phototrophic microalgal biomass
and lipid production.
Different culture conditions may influence the algal productivity and final composition of a microalga. Therefore a detailed investigation on all parameters relevant
to microalgal composition is crucial. Light intensity in particular represents one such
vital parameter. Most microalgae metabolites are obligate photoautotrophs; therefore
they require light (natural or artificial) to grow [15]. However some species have the
ability in consuming the carbon resources in the medium to gain energy for their
metabolism, according to a heterotrophic configuration.
Although various strategies like closed PBRs, open ponds, fermentation tanks,
and hybrid systems (mixotrophic and heterotrophic) are available for algae cultivation, as a piece of information, there is not a standard single approach in culturing
algae at an industrial scale. To economically produce microalgal biomass, it’s very
important to consider set of factors like algal species type and expected end products,
geographical location, and availability of resources on site for mass production.
Aside from culture management, temperature and light radiation can play important
role for algae-based biotechnology.
5 Site Selection and Resources Requirement
Microalgae can adapt their metabolism to changing environments, and it is feasible
to culture them in diverse aquatic environments like sea and fresh water, metropolitan wastewaters, and industrial wastewaters, providing that there are sufficient
measures of carbon (C) (natural or inorganic), nitrogen (N) (urea, ammonium, or
nitrate), and phosphate (P), and additionally other essential components available in
the growing medium [40]. When compared to sea and fresh waters, wastewaters
have more nutrients appropriate for microalgae cultivation [40, 41]. The choice of
cultivation site is also an important requirement for the algal growth and biomass
production. The production costs may be decreased notably by positioning the plant
close to the easy availability of other resources such as CO 2 , nutrients, water,
Algal Biomass for Biofuels and Bioproducts
147
In mixotrophic mode, microalgal growth happens majorly through photosynthesis
apart from the utilization of CO 2 and organic compounds [37]. As mixotrophic mode
accumulates lipid via photosynthesis and also involved in sequestering CO 2 , it was
considered good and much sustainable than heterotrophic mode [38]. Higher growth
rates were attained for some microalgae in mixotrophic than phototrophic conditions, and they produce compounds that are synthesized during both phototrophic
and heterotrophic conditions [39]. It can be considered as a potential approach for
producing wide array of economically viable microalgal products in a short span of
time. Mixotrophic cultivation can effectively be used for producing seed cells;
subsequently it can then be used as inoculums for phototrophic microalgal biomass
and lipid production.
Different culture conditions may influence the algal productivity and final composition of a microalga. Therefore a detailed investigation on all parameters relevant
to microalgal composition is crucial. Light intensity in particular represents one such
vital parameter. Most microalgae metabolites are obligate photoautotrophs; therefore
they require light (natural or artificial) to grow [15]. However some species have the
ability in consuming the carbon resources in the medium to gain energy for their
metabolism, according to a heterotrophic configuration.
Although various strategies like closed PBRs, open ponds, fermentation tanks,
and hybrid systems (mixotrophic and heterotrophic) are available for algae cultivation, as a piece of information, there is not a standard single approach in culturing
algae at an industrial scale. To economically produce microalgal biomass, it’s very
important to consider set of factors like algal species type and expected end products,
geographical location, and availability of resources on site for mass production.
Aside from culture management, temperature and light radiation can play important
role for algae-based biotechnology.
5 Site Selection and Resources Requirement
Microalgae can adapt their metabolism to changing environments, and it is feasible
to culture them in diverse aquatic environments like sea and fresh water, metropolitan wastewaters, and industrial wastewaters, providing that there are sufficient
measures of carbon (C) (natural or inorganic), nitrogen (N) (urea, ammonium, or
nitrate), and phosphate (P), and additionally other essential components available in
the growing medium [40]. When compared to sea and fresh waters, wastewaters
have more nutrients appropriate for microalgae cultivation [40, 41]. The choice of
cultivation site is also an important requirement for the algal growth and biomass
production. The production costs may be decreased notably by positioning the plant
close to the easy availability of other resources such as CO 2 , nutrients, water,
Algal Biomass for Biofuels and Bioproducts
147