Characterization of Core Microbiomes and Functional Profiles of Mesophilic Anaerobic Digesters Fed With Chlorella vulgaris Green Microalgae and Maize Silage

Abstract

Microalgal biomass is an alternative feedstock for biogas production although its C/N ratio is usually lower than optimal, therefore co-fermentation is recommended. Biogas production from photoautotrophically grown Chlorella vulgaris (C. vulgaris) biomass (240 mL CH 4 g oTS −1 ) and co-fermentation with maize silage (330 mL CH 4 g oTS −1 ) has been studied in semi continuous laboratory biogas fermenters. Maize silage control yielded 310 mL CH 4 g oTS −1 . The microbial community and the read-based functional profiles, derived from these data, were examined during the process by using next-generation metagenome Ion Torrent sequencing technology. The read-based core microbiome consisted of 92 genera from which 60 abundant taxa were directly associated with the microbial methane producing food chain. The data-set was also analyzed in a genome-based approach. Sixty-five bins were assembled, 52 of them belonged in the core biogas producing genera identified by the read-based metagenomes. The read-based and genome-based approaches complemented and verified each other. The functional profiles indicated a variety of glycoside hydrolases. Substantial rearrangements of the methanogen functions have also been observed. Co-fermentation of algal biomass and plant biomass can be carried out for an extended period of time without process failure. The microbial members of the inoculum are well-conserved, feedstock composition changes caused mostly relative abundance alterations in the core microbiome.

Chlorella vulgaris and Its Phycosphere in Wastewater: Microalgae-Bacteria Interactions During Nutrient Removal

“…The Ion Torrent PGM TM platform was used for shotgun sequencing, the manufacturer’s recommendations were followed (Life Technologies, United States). Sample preparation, quantification and barcoding were described previously ( Wirth et al, 2019 ). Sequencing was performed with Ion PGM 200 Sequencing kit (4474004) on Ion Torrent PGM 316 chip.…”

“…For total community DNA isolation 2 mL of samples were used from each cultivation media type. DNA extraction and quality estimation were performed according Wirth et al (2019).…”

Early response of methanogenic archaea to H2 as evaluated by metagenomics and metatranscriptomics

“…Four metagenome (MG) sequencing datasets were combined to assemble a fairly large number of bins (84 bins: 7 Archaea, 61 Bacteria and 16 unclassi ed bins). The non-H 2 -adapted, "raw" biogas forming microbial community was essentially the same in structure and composition as the ones sampled previously from the same industrial biogas plant fed with manure and maize silage [44,45]. This community switched to H 2 consumption and biomethane production almost immediately following H 2 injection, although feeding of the entire community with alpha-cellulose substrate continued as before.…”

A multivariate method to correct for batch effects in microbiome data

“…The families of these taxa included Ruminococcaceae (2), Syntrophomonadaceae (1), Peptococcaceae (1) and and two unknown families. All known families have been found to play a key role in AD process, ranging from the degradation of cellulose to acetogenesis, and to syntrophic acetate oxidation (Tian et al, 2014, Poirier et al, 2016, Wirth et al, 2019. To summarise, from the data corrected with our PLSDA-batch and sPLSDA-batch approaches, we identified more taxa within the order Clostridiales, while with remove-BatchEffect and ComBat we identified more taxa from the order Bacteroidales.…”