Biochemical methane potential of microalgae biomass using different microbial inocula.
Gonzalez-Fernandez C, Barreiro-Vescovo S, de Godos I, Fernandez M, Zouhayr A, Ballesteros M
Biotechnol Biofuels. 2018. doi: 10.1186/s13068-018-1188-7
COMMENT: Anaerobic digestion (AD) is a proven technology for obtaining biogas via conversion of organic matter. Microalgae biomass is regarded as a potential feedstock for bioenergy purposes through AD. Even though AD is a well-proven technology, the use of new feedstocks requires in-depth studies. A lot of research has been conducted assessing methane yield without paying attention to the anaerobic microbiome and their activities.
For such a goal, in this article Gonzalez-Fernadez and coworkers study the link between methane yield and two sludge characteristics. The authors tested different anaerobic sludge sources, namely adapted to microalgae biomass and adapted to sewage sludge. Despite the registered differences for the anaerobic microbiome analysis and specific methane activities towards model substrates, sludge adapted to digest sewage sludge did not affect the methane yield of Chlorella sorokiniana and Scenedesmus sp. Opposite to that, sludge samples adapted to digest microalgae exhibited a concomitant increase in methane yield together with increasing digestion temperatures.
While psycro- and mesophilic digestion supported similar yields (most probably linked to their anaerobic microbiome resemblance), the values attained for thermophilic digestion evidenced the usefulness of having a highly specific microbiome. The relative abundance of Firmicutes, particularly Clostridia, and Proteobacteria together with an important abundance of hydrogenotrophic methanogens was highlighted in this inoculum.
Finally, the authors conclude that:
Linking process engineering to microbial community in AD reactors could bring new insights to pay the way out to a better digester performance and avoid pretreatments by working with a highly specific anaerobic microbiome.