Feasibility of a two-step culture method to improve the CO2-fixing efficiency of nonphotosynthetic microbial community and simultaneously decrease the spontaneous oxidative precipitates from mixed electron donors

Effect of electron donors on CO2 fixation from a model cement industry flue gas by non-photosynthetic microbial communities in batch and continuous reactors

The aim of this work was to evaluate the effect of different inorganic compounds as electron donors for the capture of CO2 from a model cement flue gas CO2 /O2 /N2 (4.2:13.5:82.3% v/v) using a non-photosynthetic microbial community. The inoculum obtained from a H2 -producing reactor was acclimated to CO2 consumption achieving 100% of CO2 removal after 45 days. Na2 S, MnCl2 , NaNO2 , NH4 Cl, Na2 S2 O3 , and FeCl2 were used as energy source for CO2 fixation by the acclimated microbial community showing different efficiencies, being Na2 S the best electron donor evaluated (100% of CO2 consumption) and FeCl2 the less effective (28% of CO2 consumption). In all treatments, acetate and propionate were the main endpoint metabolites. Moreover, scaling the process to a continuous laboratory biotrickling filter using Na2 S as energy source showed a CO2 consumption of up to 77%. Analysis of the microbial community showed that Na2 S and FeCl2 exerted a strong selection on the microbial members in the community showing significant differences (PERMANOVA, p = 0.0001) compared to the control and the other treatments. Results suggest that the CO2 fixing pathways used by the microbial community in all treatments were the 3-hydroxypropionate-4-hydroxybutyrate cycle and the Wood-Ljungdahl pathway.

Microbial community design: methods, applications, and opportunities

Microbial communities can perform a variety of behaviors that are useful in both therapeutic and industrial settings. Engineered communities that differ in composition from naturally occurring communities offer a unique opportunity for improving upon existing community functions and expanding the range of microbial community applications. This has prompted recent advances in various community design approaches including artificial selection procedures, reduction from existing communities, combinatorial evaluation of potential microbial combinations, and model-based in silico community optimization. Computational methods in particular offer a likely avenue toward improved synthetic community development going forward. This review introduces each class of design approach and surveys their recent applications and notable innovations, closing with a discussion of existing design challenges and potential opportunities for advancement.

Characterization of a designed synthetic autotrophic–heterotrophic consortia for fixing CO2 without light

CO₂ fixation efficiency of the devised synthetic microbial consortia with both autotrophic–autotrophic and autotrophic–heterotrophic microbial interactions were higher than the sum of theoretical CO₂ fixation efficiency of the microbial components.