Mixotrophic Cultivation of Microalgae Using Biogas as the Substrate

Abstract

Biogas utilization through biotechnology represents a potential and novel technology. We propose the microalgal mixotrophic cultivation to convert biogas to microalgae-based biodiesel, in which methanotroph was co-cultured to convert CH4 to organic intermediate (and CO2) for microalgal mixotrophic growth. This study constructed a co-culture of Methylocystis bryophila (methanotroph) and Scenedesmus obliquus (microalgae) with biogas feeding. Compared with the single culture of S. obliquus, higher microalgal biomass but a lower chlorophyll concentration was observed. The organic metabolism-related genes were upregulated, verifying microalgal mixotrophic growth. The stoichiometric calculation of M. bryophila culture shows that M. bryophila tends to release organic matter rather than grow under a low O2 content. M. bryophila rarely grew under five different light intensities, indicating that M. bryophila acts as a biocatalyst in the co-culture. The organic intermediate released by methanotroph increased the maximum biomass of microalgal culture, accelerated nitrogen absorption, accumulated more monounsaturated fatty acids, and improved the adaptation to light. The co-culture of microalgae and methanotroph may provide new opportunities for microalgae-based biodiesel production using biogas as a substrate.

Microalgal-Based Bioenergy: Strategies, Prospects, and Sustainability

“…Some processes that undergo a thermochemical transformation include gasification (syngas production), thermal liquefaction (bio-oil production), pyrolysis (bio-oil, syngas, charcoal production, etc. ), and direct burning or combustion (heat and electricity generation). , The biochemical reaction illustrates the natural bioprocessing of biomass to produce biofuels. Anaerobic digestion (biogas generation), alcoholic fermentation (bioethanol production), and photobiological hydrogen production are all examples of biochemical transformations (production of biohydrogen) .…”

Spirulina Cultivation Using Biogas CO2 as the Carbon Source: Preliminary Study on Biomass Growth and Productivity

“…al., [15] have employed microalgae for simultaneous biogas upgrading and nutrient removal from a digester centrate in an outdoor high-rate algal pond. Also, it was reported that compared with air sparing, biogas sparging could significantly increase biomass productivity because of high CO2 availability [16]. The atmospheric level of CO2 is very low (0.0387% (v/v)) and is insufficient to achieve a high rate microalgal biorefinery [17].…”

Exploring the Role of NH₄Cl Supplementation on Triacylglycerol Production by <em>Chlamydomonas reinhardtii </em>under Mixotrophic Cultivation using a Proteomics Approach

“…Under carbon supplementation, the ammonium assimilation is increased leading to reduced ammonium toxicity. Moreover, mixotrophic cultivation with ammonium could greatly enhance microalgal growth, biomass, total lipid, and particularly TAG content [13,14].…”