Similar Methanogenic Shift but Divergent Syntrophic Partners in Anaerobic Digesters Exposed to Direct versus Successive Ammonium Additions

Hardy, Julie; Bonin, Patricia; Lazuka, Adèle; Gonidec, Estelle; Guasco, Sophie; Valette, Corinne; Lacroix, Sébastien; Cabrol, Léa

doi:10.1128/spectrum.00805-21

Cited by 16 publications

(6 citation statements)

References 91 publications

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Section: ■ Results and Discussionmentioning

confidence: 99%

“…Meanwhile, the relative abundance of Sporanaerobacter sp. (carbohydrate hydrolysis-related bacteria), which could accelerate carbohydrate hydrolysis and convert carbohydrates to butyric acid, was improved from 0.36 to 9.61% after enzymatic pretreatment. Since the pH values of all reactors were controlled at 6 and the content of soluble reducing sugar (the representative carbohydrate) in the mixed enzymatic pretreatment reactor (41352 mg/L) was significantly higher than that in the unpretreated reactor (14536 mg/L), these conditions might be beneficial for the enrichment of these VFA formation-related bacteria, resulting in remarkable VFA promotion.…”

Section: Resultsmentioning

confidence: 99%

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Enhanced Volatile Fatty Acid Production from Food Waste Fermentation via Enzymatic Pretreatment: New Insights into the Depolymerization and Microbial Traits

Zhu

et al. 2022

ACS EST Eng.

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Food waste (FW) has been considered a potential carbon reservoir and can be used for high-value volatile fatty acid (VFA) production via anaerobic fermentation. Nevertheless, more work is needed to unravel how to regulate the structural defects of FW and enhance microbial metabolisms for improving VFA production through pretreatment methods. This work investigated the enhancement of VFA production from FW fermentation through enhancing depolymerization and stimulating microbial traits via enzymatic pretreatment. The results exhibited that, after pretreatment, VFA production was improved by 50.1% compared to the unpretreated group, and the concentrations of bioavailable substrates (e.g., reducing sugar and soluble chemical oxygen demand) increased significantly. Further analysis proved that the enzymatic pretreatment could highly reduce the particle sizes of FW by 69.3% and thus promoted the solubilization of substrates and lipids. Meanwhile, the ratio of α-helix/(β-sheet + random coil) in the protein secondary structure of FW decreased from 0.32 to 0.23 after enzymatic pretreatment, indicating that the pretreatment process accelerated the FW depolymerization. Furthermore, the organic substrates after the pretreatment were favorable for enriching the bacteria involved in hydrolysis and acidification (e.g., Olsenella sp. and Sporanaerobacter sp.), upregulating the gene expressions involved in hydrolysis, pyruvate metabolism, and fatty acid biosynthesis (e.g., malZ, PK, accA, and accC), and stimulating the enzymatic activities involved in acetate and butyrate formation (e.g., AK, PTA, BK, and PTB), which was in accordance with the enhanced VFA generation from FW fermentation via enzymatic pretreatment.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Enhanced Volatile Fatty Acid Production from Food Waste Fermentation via Enzymatic Pretreatment: New Insights into the Depolymerization and Microbial Traits

Zhu

et al. 2022

ACS EST Eng.

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“…5 ). It has been reported that low formate concentrations (2 mM) can have notorious effects on microbial growth and activity [ 58 , 60 ]; but also microbial acclimation after short-term sequential batch incubation [ 61 ] could have played a role in the observed differences between phase II-A and II-C in the treatments of experiment II. More experimental work including incubations in parallel is required to differentiate effects associated with formate addition and microbial acclimation.…”

Section: Discussionmentioning

confidence: 99%

“…Sequential batch experiments were carried out to investigate the effect of successive changes in operational conditions (e.g., high S/X ratio and addition of formate as external electron donor) on carboxylates and CH 4 production under elevated pCO 2 (5 bar). Batch incubation modality was selected based on the premise of anticipated differentiated microbial community responses depending on the way the stress condition is applied (direct vs. successive), as reported for other stressors such as high NH 4 + concentrations [ 61 ]. An operational pressure of 5 bar pCO 2 was selected as a boundary condition between extended lag-phases and noticeable CO 2 effects on substrate conversion based on previous work [ 29 , 55 ].…”

Section: Methodsmentioning

confidence: 99%

Steering the product spectrum in high-pressure anaerobic processes: CO2 partial pressure as a novel tool in biorefinery concepts

Ceron-Chafla

Vrieze²,

Rabaey³

et al. 2023

Biotechnol Biofuels

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Background Elevated CO2 partial pressure (pCO2) has been proposed as a potential steering parameter for selective carboxylate production in mixed culture fermentation. It is anticipated that intermediate product spectrum and production rates, as well as changes in the microbial community, are (in)directly influenced by elevated pCO2. However, it remains unclear how pCO2 interacts with other operational conditions, namely substrate specificity, substrate-to-biomass (S/X) ratio and the presence of an additional electron donor, and what effect pCO2 has on the exact composition of fermentation products. Here, we investigated possible steering effects of elevated pCO2 combined with (1) mixed substrate (glycerol/glucose) provision; (2) subsequent increments in substrate concentration to increase the S/X ratio; and (3) formate as an additional electron donor. Results Metabolite predominance, e.g., propionate vs. butyrate/acetate, and cell density, depended on interaction effects between pCO2–S/X ratio and pCO2–formate. Individual substrate consumption rates were negatively impacted by the interaction effect between pCO2–S/X ratio and were not re-established after lowering the S/X ratio and adding formate. The product spectrum was influenced by the microbial community composition, which in turn, was modified by substrate type and the interaction effect between pCO2–formate. High propionate and butyrate levels strongly correlated with Negativicutes and Clostridia predominance, respectively. After subsequent pressurized fermentation phases, the interaction effect between pCO2–formate enabled a shift from propionate towards succinate production when mixed substrate was provided. Conclusions Overall, interaction effects between elevated pCO2, substrate specificity, high S/X ratio and availability of reducing equivalents from formate, rather than an isolated pCO2 effect, modified the proportionality of propionate, butyrate and acetate in pressurized mixed substrate fermentations at the expense of reduced consumption rates and increased lag-phases. The interaction effect between elevated pCO2 and formate was beneficial for succinate production and biomass growth with a glycerol/glucose mixture as the substrate. The positive effect may be attributed to the availability of extra reducing equivalents, likely enhanced carbon fixating activity and hindered propionate conversion due to increased concentration of undissociated carboxylic acids.

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“…Briefly, hydrolytic and acidogenic bacteria break down complex organic molecules into volatile fatty acids (VFAs, e.g., butyric acid, propionic acid, acetic acids, etc. ), dihydrogen (H 2 ), and carbon dioxide (CO 2 ) via hydrolysis, acidogenesis, and acetogenesis ( Hardy et al, 2021 ). Then, acetoclastic (e.g., Methanosaetaceae , Methanosarcinaceae ) and hydrogenotrophic (e.g., Methoanomicrobiales , Methanobacteriales ) methanogenic archaea produce CH 4 from acetate and H 2 /CO 2 , respectively.…”

Section: Introductionmentioning

confidence: 99%

Key players in syntrophic propionate oxidation revealed by metagenome-assembled genomes from anaerobic digesters bioaugmented with propionic acid enriched microbial consortia

Kim

Rhee²,

Wells³

et al. 2022

Front. Microbiol.

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Propionic acid (HPr) is frequently accumulated in anaerobic digesters due to its thermodynamically unfavorable degradation reaction. Here, we identify key players in HPr oxidation and organic overloading recovery from metagenome-assembled genomes (MAGs) recovered from anaerobic digesters inoculated with HPr-enriched microbial consortia before initiating organic overloading. Two independent HPr-enrichment cultures commonly selected two uncultured microorganisms represented with high relative abundance: Methanoculleus sp002497965 and JABUEY01 sp013314815 (a member of the Syntrophobacteraceae family). The relative abundance of JABUEY01 sp013314815 was 60 times higher in bioaugmented bioreactors compared to their unaugmented counterparts after recovery from organic overloading. Genomic analysis of JABUEY01 sp013314815 revealed its metabolic potential for syntrophic propionate degradation when partnered with hydrogenotrophic methanogens (e.g., Methanoculleus sp002497965) via the methylmalonyl-CoA pathway. Our results identified at least two key species that are responsible for efficient propionate removal and demonstrate their potential applications as microbial cocktails for stable AD operation.

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Similar Methanogenic Shift but Divergent Syntrophic Partners in Anaerobic Digesters Exposed to Direct versus Successive Ammonium Additions

Abstract: Anaerobic digestion (AD) is an attractive biotechnological process for wastewater bioremediation and bioenergy production in the form of methane-rich biogas. However, AD can be inhibited by ammonium generated by protein-rich effluent, commonly found in agro-industrial activities.

Cited by 16 publications

References 91 publications

Enhanced Volatile Fatty Acid Production from Food Waste Fermentation via Enzymatic Pretreatment: New Insights into the Depolymerization and Microbial Traits

Enhanced Volatile Fatty Acid Production from Food Waste Fermentation via Enzymatic Pretreatment: New Insights into the Depolymerization and Microbial Traits

Steering the product spectrum in high-pressure anaerobic processes: CO2 partial pressure as a novel tool in biorefinery concepts

Key players in syntrophic propionate oxidation revealed by metagenome-assembled genomes from anaerobic digesters bioaugmented with propionic acid enriched microbial consortia

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