Gasification and synthesis gas fermentation: an alternative route to biofuel production

Slivka, Rachel Marie; Chinn, Mari S.; Grunden, Amy M.

doi:10.4155/bfs.11.108

Cited by 23 publications

(13 citation statements)

References 65 publications

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“…Ethanol constitutes the main targeted product of syngas fermentation because of its availability for a wide spectrum of applications, hence several factors of the fermentation process have been studied and are in depth reviewed [15,27,28,34,[65][66][67]. In short, the most crucial ones are: bioreactor configuration and operational parameters such as pressure, temperature and pH.…”

Section: Production Of Ethanol And/or Acetatementioning

confidence: 99%

“…Those disadvantages highlight the need for alternative ways to be sought. One promising alternative is the combination of thermochemical and biological processing of biomass [27]. The greatest merits of the fermentation processes are the mild conditions needed that entail low energy and infrastructure costs along with the high selectivity of the microbes.…”

Section: Introductionmentioning

confidence: 99%

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Reactor systems for syngas fermentation processes: A review

Asimakopoulos

Skiadas²

2018

Chemical Engineering Journal

152

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Section: Production Of Ethanol And/or Acetatementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Reactor systems for syngas fermentation processes: A review

Asimakopoulos

Skiadas²

2018

Chemical Engineering Journal

152

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“…Due to the extremely low solubility of CH 4 and O 2 , which are both required for cell growth and lipid production, the cultivation of methanotrophs can be severely limited by the gas transfer efficiency [ 30 , 31 ]. Increasing the agitation rate is the simplest way to improve gas transfer efficiency in a continuous stirred tank bioreactor (CSTR), in which a sparger at the bottom of the CSTR delivers gases into the liquid phase [ 32 ].…”

Section: Resultsmentioning

confidence: 99%

Enhanced biological fixation of methane for microbial lipid production by recombinant Methylomicrobium buryatense

Fei

Puri

Smith

et al. 2018

Biotechnol Biofuels

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BackgroundDue to the success of shale gas development in the US, the production cost of natural gas has been reduced significantly, which in turn has made methane (CH4), the major component of natural gas, a potential alternative substrate for bioconversion processes compared with other high-price raw material sources or edible feedstocks. Therefore, exploring effective ways to use CH4 for the production of biofuels is attractive. Biological fixation of CH4 by methanotrophic bacteria capable of using CH4 as their sole carbon and energy source has obtained great attention for biofuel production from this resource.ResultsIn this study, a fast-growing and lipid-rich methanotroph, Methylomicrobium buryatense 5GB1 and its glycogen-knock-out mutant (AP18) were investigated for the production of lipids derived from intracellular membranes, which are key precursors for the production of green diesel. The effects of culture conditions on cell growth and lipid production were investigated in high cell density cultivation with continuous feeding of CH4 and O2. The highest dry cell weight observed was 21.4 g/L and the maximum lipid productivity observed was 45.4 mg/L/h obtained in batch cultures, which corresponds to a 2-fold enhancement in cell density and 3-fold improvement in lipid production, compared with previous reported data from cultures of 5GB1. A 90% enhancement of lipid content was achieved by limiting the biosynthesis of glycogen in strain AP18. Increased CH4/O2 uptake and CO2 evaluation rates were observed in AP18 cultures suggesting that more carbon substrate and energy are needed for AP18 growth while producing lipids. The lipid produced by M. buryatense was estimated to have a cetane number of 75, which is 50% higher than biofuel standards requested by US and EU.ConclusionsCell growth and lipid production were significantly influenced by culture conditions for both 5GB1 and AP18. Enhanced lipid production in terms of titer, productivity, and content was achieved under high cell density culture conditions by blocking glycogen accumulation as a carbon sink in the strain AP18. Differences observed in CH4/O2 gas uptake and CO2 evolution rates as well as cell growth and glycogen accumulation between 5GB1 and AP18 suggest changes in the metabolic network between these strains. This bioconversion process provides a promising opportunity to transform CH4 into biofuel molecules and encourages further investigation to elucidate the remarkable CH4 biofixation mechanism used by these bacteria.

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“…For this purpose, Vega et al [119] demonstrated a strong connection between mass transfer, kinetics, cell growth, and production of the desired products. Because of high cell densities in mixed culture, growth will depend on the mass transfer rate [120]. Therefore, diffusion limitations at high cell densities resulted in overall lower productivity.…”

Section: Advantages and Challengesmentioning

confidence: 99%