Thermodynamics and economic feasibility of acetone production from syngas using the thermophilic production host Moorella thermoacetica

Abstract

BackgroundSyngas fermentation is a promising option for the production of biocommodities due to its abundance and compatibility with anaerobic fermentation. Using thermophilic production strains in a syngas fermentation process allows recovery of products with low boiling point from the off-gas via condensation.ResultsIn this study we analyzed the production of acetone from syngas with the hypothetical production host derived from Moorella thermoacetica in a bubble column reactor at 60 °C with respect to thermodynamic and economic feasibility. We determined the cost of syngas production from basic oxygen furnace (BOF) process gas, from natural gas, and from corn stover and identified BOF gas as an economically interesting source for syngas. Taking gas–liquid mass transfer limitations into account, we applied a thermodynamics approach to derive the CO to acetone conversion rate under the process conditions. We estimated variable costs of production of 389 $/t acetone for a representative production scenario from BOF gas with costs for syngas as the main contributor. In comparison, the variable costs of production from natural gas- and corn stover-derived syngas were determined to be higher due to the higher feedstock costs (1724 and 2878 $/t acetone, respectively).ConclusionWe applied an approach of combining thermodynamic and economic assessment to analyze a hypothetical bioprocess in which the volatile product acetone is produced from syngas with a thermophilic microorganism. Our model allowed us to identify process metrics and quantify the variable production costs for different scenarios. Economical production of bulk chemicals is challenging, making rigorous thermodynamic/economic modeling critical before undertaking an experimental program and as an ongoing guide during the program. We intend this study to give an incentive to apply the demonstrated approach to other bioproduction processes.Electronic supplementary materialThe online version of this article (doi:10.1186/s13068-017-0827-8) contains supplementary material, which is available to authorized users.

A TetR-family protein activates transcription from a new promoter motif associated with essential genes for autotrophic growth in acetogens

“…We next investigated if P cauto was represented in other industrially relevant acetogens with available genomes: Clostridium ljungdahlii , C. ragsdalei , C. coskatii , Moorella thermoacetica , and Eubacterium limosum (Bengelsdorf et al, 2016; Redl et al, 2017; Shin et al, 2016; Song et al, 2017). We performed the reverse of the methodology previously used to search for consensus sequence motifs by looking for the occurrence of P cauto 300 nt upstream of annotated genes (since no TSS data was available) using the FIMO tool (Grant et al, 2011) within MEME.…”

Modeling ethanol production through gas fermentation: a biothermodynamics and mass transfer-based hybrid model for microbial growth in a large-scale bubble column bioreactor

“…Mass balances are established around the gas fermentor for all species involved in the metabolic reactions leading to ethanol and bacterial biomass production (see Additional file 1: Table S2). Furthermore in the energy balances, the power requirement for compression of the gas feed and the offgas for gas recycle is estimated assuming adiabatic operation of compressors with a mechanical efficiency of 0.7 [28]. The heat required for gas cooling is obtained using average heat capacities within the applied temperature ranges, assuming that condensation will occur only when the final cooling temperature has been reached; a refrigeration coefficient of performance of 3.7 is assumed [87].…”

“…Such task is challenging considering the large variety of microbial strains, gas compositions, process conditions used in the reported experiments and the high strain-specificity of more complex models of microbial metabolism. Thus, a general model that focuses on the basic thermodynamic interactions driving the catabolism of CO, CO 2 and H 2 by a hypothetical strain of acetogenic bacteria (such as in [28]) might be able to consolidate the diversity of reported results.…”

“…Several types of mathematical models have been proposed for understanding and predicting the behavior of microorganisms in gas fermentations [21][22][23][24][25][26][27]; other simpler models have been used for estimating process performance [4,5,[28][29][30][31]. The most popular of the modeling strategies employed recently by researchers is the genome-scale modeling (GSM), which has been used for assessing several features of the intracellular processes in C. ljungdahlii and C. autoethanogenum during syngas fermentations, e.g, the influence of the link between energy conservation and carbon metabolism on the selectivity between ethanol and acetic acid [25,[32][33][34], the co-factor specificity of certain enzymes linked to energy conservation [32,33,35], the formation of biofilms [26], the possibility of boosting ATP production by supplying arginine [36], and the feasibility of gene knock-out to reach overproduction of native and non-native products of acetogens [37].…”

Genome-Based Comparison of All Species of the Genus Moorella, and Status of the Species Moorella thermoacetica and Moorella thermoautotrophica

“…Interest from the research community and industry in acetogenic bacteria has grown within recent years due to their potential to produce valuable compounds from syngas (Latif et al, 2014). Thermophilic acetogens are of significance, since their use would reduce gas cooling requirements, allow for cost-efficient recovery of products with relatively low boiling point (Henstra et al, 2007;Redl et al, 2017), and decrease the risk of contamination.…”