Mixotrophic Algae Cultivation for Energy Production and Other Applications

Abstract

Micro-algae offer potentially significant advantages over other approaches to overcome the current challenges of energy shortages and for pollution control. In addition major new directions in the genetic manipulation of algae and in new bioreactor design have been initiated in an effort to design new systems and approaches for this purpose. However, significant barriers for the commercialization of microalgae still exist including economic barriers, the level of technology readiness and lack of established co-products to make the overall process of energy from algae attractive. Mixotrophic algae cultivation offers the benefits of high biomass productivity and allows for integrated approaches which combine both photosynthetic and heterotrophic components during the diurnal cycle. This chapter focuses mainly on mixotrophic algae, the different methods of cultivation and different roles of algae in energy production. The large number of algal species and their versatile habitats and adaptability make mixotrophic microalgae serious candidates for applied research and development and for commercialization of new technologies. Approaches based on mixotrophic cultivation of algae will continue to play a role in efforts to mitigate the above mentioned challenges.

Effect of Different Cultivation Modes (Photoautotrophic, Mixotrophic, and Heterotrophic) on the Growth of Chlorella sp. and Biocompositions

“…In addition, the content of useful substances, including lipids and pigment, can be enhanced (Ip et al, 2004;Liang et al, 2009). The application of the organic carbon source can be divided into two types depending on the presence (mixotrophic) or absence (heterotrophic) of light (Liang et al, 2009;Bassi et al, 2014). Mixotrophic cultivation is preferred due to several drawbacks with heterotrophic cultivation (Liu et al, 2009;Perez-Garcia et al, 2011;Wang et al, 2014).…”

“…Therefore, it is possible to culture microalgae to high densities, leading to enhanced biomass productivity (Chen and Zhang, 1997;Kong et al, 2013). Although heterotrophic and mixotrophic conditions both improve biomass productivity compared to photoautotrophic conditions, mixotrophic cultivation is preferred as it has greater biomass productivity (Liang et al, 2009;Bassi et al, 2014;Lowrey et al, 2015).…”

“…In previous studies, two cultivation methods that provided organic carbon sources were applied to various microalgae (Bassi et al, 2014;Engin et al, 2018). It was shown that this method had economically efficient culture conditions for microalgae in a process that was aimed toward the production of bioresource and fatty acid for bioenergy development (Bassi et al, 2014;Engin et al, 2018). Currently, microalgae are utilized for bioenergy, food supplement, and medicinal compound production (López et al, 2019;Menegol et al, 2019).…”

Using chlorella vulgaris for nutrient removal from hydroponic wastewater: experimental investigation and economic assessment

“…Mixotrophic and heterotrophic, however, may represent an alternative strategy for large-scale operation of microalgal biofuels as they offer a reasonable amount of biomass and lipid and remove nutrients from wastewater. A multiplicity of biofuels and other valuable products can be obtained by cultivating microalgae mixotrophically and heterotrophically (Bassi et al 2014). The heterotrophic mode of cultivation offers various products, from cellular storage compounds, such as lipids and starch, to a vast number of hydrocarbons and polysaccharides that can boost the prospect for commercialization.…”

Microalgae Cultivation for the Biotransformation of Birch Wood Hydrolysate and Dairy Effluent

“…Although this growth regime is less studied, most microalgal species investigated so far have been shown to produce higher biomass yields along with higher lipid, starch, and protein productivities compared with photoautotrophic regimes [11,16,17]. Therefore, the production of mixotrophic microalgae allows for the integration of photosynthetic and heterotrophic metabolisms during the diurnal cycle, thus reducing the impact of biomass loss during dark-respiration, and decreasing the costs of the organic substances utilised during growth in daylight [18]. For these reasons, mixotrophic cultivation should be preferred within the microalgae-to-biofuels process.…”