Ecological Interactions of Cyanobacteria and Heterotrophs Enhances the Robustness of Cyanobacterial Consortium for Carbon Sequestration

Abstract

Lack of robustness is a major barrier to foster a sustainable cyanobacterial biotechnology. Use of cyanobacterial consortium increases biodiversity, which provides functional redundancy and prevents invading species from disrupting the production ecosystem. Here we characterized a cyanobacterial consortium enriched from microbial mats of alkaline soda lakes in BC, Canada, at high pH and alkalinity. This consortium has been grown in open laboratory culture for 4 years without crashes. Using shotgun metagenomic sequencing, 29 heterotrophic metagenome-assembled-genomes (MAGs) were retrieved and were assigned to Bacteroidota, Alphaproteobacteria, Gammaproteobacteria, Verrucomicrobiota, Patescibacteria, Planctomycetota, and Archaea. In combination with metaproteomics, the overall stability of the consortium was determined under different cultivation conditions. Genome information from each heterotrophic population was investigated for six ecological niches created by cyanobacterial metabolism and one niche for phototrophy. Genome-resolved metaproteomics with stable isotope probing using 13C-bicarbonate (protein/SIP) showed tight coupling of carbon transfer from cyanobacteria to the heterotrophic populations, specially Wenzhouxiangella. The community structure was compared to a previously described consortium of a closely related cyanobacteria, which indicated that the results may be generalized. Productivity losses associated with heterotrophic metabolism were relatively small compared to other losses during photosynthesis.

Nutrient management and medium reuse for cultivation of a cyanobacterial consortium at high pH and alkalinity

“…Every day, three flasks were removed from the experiment and used for analysis. The consortium used in this study mainly consisted of (>90% relative DNA sequence abundance) the filamentous cyanobacterium Candidatus “Phormidium alkaliphum” ( Sharp et al, 2017 ; Ataeian et al, 2019 ; Ataeian et al, 2021 ; Ataeian et al, 2022 ). This cyanobacterial consortium was inoculated at an initial concentration of 0.43 ± 0.10 g/L AFDW (Day 0, Figure 3A ).…”

“…In either case, if the accumulation of organic compounds was the cause of the initial loss of activity, it is likely that the heterotrophic bacteria, that were also part of the cyanobacterial consortium, started to consume these organic compounds and so facilitated the acclimatization of the culture. Many of these heterotrophs can grow on cyanobacterial metabolites and components such as cell walls, proteins, lipids and fatty acids ( Ataeian et al, 2022 ).…”

“…A laboratory grown microbial consortium dominated by cyanobacteria was used in all experiments ( Ataeian et al, 2019 ; Ataeian et al, 2021 ; Ataeian et al, 2022 ). This consortium was originally enriched from photosynthetic microbial mats obtained from soda lakes located on the Cariboo Plateau (British Columbia, Canada) ( Sharp et al, 2017 ).…”

“…Cultivation of alkaliphilic, “high pH loving,” cyanobacteria has gained interest over the recent years because of their robustness and ability to capture carbon dioxide directly from the atmosphere ( Bell et al, 2016 ; Canon-Rubio, 2016 ; Sharp et al, 2017 ; Zhu et al, 2018 ; Ataeian et al, 2019 ; Chowdhury et al, 2019 ; Kim et al, 2019 ; Berthold et al, 2020 ). Previously, we enriched a consortium consisting of the alkaliphilic filamentous cyanobacterium Candidatus “Phormidium alkaliphilum” (80–90%) and associated heterotrophs ( Ataeian et al, 2021 ; Ataeian et al, 2022 ). It was enriched from soda lakes located on the Cariboo Plateau (British Columbia, Canada) and was cultivated at a pH of up to 11.2 and with 0.5 mol/L of combined carbonates.…”

A programmed response precedes cell lysis and death in a mat-forming cyanobacterium

“…1). To investigate if the rapid degradation observed in situ could be replicated in the laboratory, we used a cyanobacterial consortium previously isolated from Cariboo Plateau soda lake mats (7,8). This consortium mainly consisted of Ca.…”