Development of redox potential-controlled schemes for very-high-gravity ethanol fermentation

Liu, Chen‐Guang; Lin, Yen‐Han; Bai, Feng‐Wu

doi:10.1016/j.jbiotec.2011.03.007

Cited by 31 publications

(12 citation statements)

References 26 publications

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“…For the aeration rate tested, S. cerevisiae NP 01 showed the highest P value (125.86 g L −1 , k 3 ) at the aeration rate of 2.5 vvm. Aeration is indispensible for yeast to synthesize sterols and unsaturated fatty acids, which are essential to assure cell membrane integrity [38][39][40]. Additionally, aeration helps vent CO 2 that inhibits the yeast growth [41].…”

Section: Impact Of Multi-factors On Ethanol Concentrationmentioning

confidence: 99%

Optimization of Agitation and Aeration for Very High Gravity Ethanol Fermentation from Sweet Sorghum Juice by Saccharomyces cerevisiae Using an Orthogonal Array Design

et al. 2012

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Optimization of three parameters: agitation rate (A; 100, 200 and 300 rpm), aeration rate (B; 0.5, 1.5 and 2.5 vvm) and aeration timing (C; 2, 4 and 6 h), for ethanol production from sweet sorghum juice under very high gravity (VHG, 290 g L−1 of total sugar) conditions by Saccharomyces cerevisiae NP 01 was attempted using an L9 (34) orthogonal array design. The fermentation was carried out at 30 °C in a 2-L bioreactor and the initial yeast cell concentration was approximately 2 × 107 cells mL−1. The results showed that the optimum condition for ethanol fermentation should be A2B3C2 corresponding to agitation rate, 200 rpm; aeration rate, 2.5 vvm and aeration timing, 4 h. The verification experiments under the optimum condition clearly indicated that the aeration and agitation strategies improved ethanol production. The ethanol concentration (P), productivity (Qp) and ethanol yield (Yp/s) were 132.82 ± 1.06 g L−1, 2.55 ± 0.00 g L−1h−1 and 0.50 ± 0.00, respectively. Under the same condition without aeration (agitation rate at 200 rpm), P and Qp were only 118.02 ± 1.19 g L−1 and 2.19 ± 0.04 g L−1h−1, respectively while Yp/s was not different from that under the optimum condition.

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Section: Impact Of Multi-factors On Ethanol Concentrationmentioning

confidence: 99%

Optimization of Agitation and Aeration for Very High Gravity Ethanol Fermentation from Sweet Sorghum Juice by Saccharomyces cerevisiae Using an Orthogonal Array Design

et al. 2012

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“…Controlling ORP during fermentation has been verified as an effective strategy to alter metabolic flux distribution towards desired metabolic products 9 10 11 12 . Although some work has been done to demostrate the effect of ORP on ethanol fermentation under limited oxygen environment 13 14 15 16 , the effect of a full spectrum of oxygen level, from no aeration to fully aerated, on flocculating yeast during ethanol fermentation is lacking.…”

mentioning

confidence: 99%

Redox potential driven aeration during very-high-gravity ethanol fermentation by using flocculating yeast

Liu

Xuemi

Lin

et al. 2016

Sci Rep

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Ethanol fermentation requires oxygen to maintain high biomass and cell viability, especially under very-high-gravity (VHG) condition. In this work, fermentation redox potential (ORP) was applied to drive the aeration process at low dissolved oxygen (DO) levels, which is infeasible to be regulated by a DO sensor. The performance and characteristics of flocculating yeast grown under 300 and 260 g glucose/L conditions were subjected to various aeration strategies including: no aeration; controlled aeration at −150, −100 and −50 mV levels; and constant aeration at 0.05 and 0.2 vvm. The results showed that anaerobic fermentation produced the least ethanol and had the highest residual glucose after 72 h of fermentation. Controlled aerations, depending on the real-time oxygen demand, led to higher cell viability than the no-aeration counterpart. Constant aeration triggered a quick biomass formation, and fast glucose utilization. However, over aeration at 0.2 vvm caused a reduction of final ethanol concentration. The controlled aeration driven by ORP under VHG conditions resulted in the best fermentation performance. Moreover, the controlled aeration could enhance yeast flocculating activity, promote an increase of flocs size, and accelerate yeast separation near the end of fermentation.

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“…During ethanol fermentation by Z. mobilis ZM4, the ORP value of broth kept decreasing in the initial 36 h, followed by a slightly recovery until 48 h ( Figure 1A). It has been reported that the glucose consumption rate was the main cause for the altered ORP [20]. Before 36 h, rapid glucose consumption, attributed to active metabolism, tended to release and accumulate the reducing power from the substrate, which consequently pull down the ORP value.…”

Section: Electricity Generation By Z Mobilis Zm4mentioning

confidence: 99%

Potential of Zymomonas mobilis as an electricity producer in ethanol production

Geng

Cao

et al. 2019

Preprint

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Background Microbial fuel cell (MFC) convokes microorganism as workhorse to convert biomass into electricity. However, most well-known electrogenic strains can not directly use glucose to produce valuable products. Zymomonas mobilis , a promising bacterial for ethanol production, owns special Entner-Doudoroff pathway with less ATP and biomass produced and the low energy-coupling respiration, making Z. mobilis a potential exoelectrogen. Results A glucose-consumed MFC is constructed by inoculating Z. mobilis . The electricity with power density 2.0 mW m -2 is derived from the difference of oxidation-reduction potential (ORP) between anode and cathode chambers. Besides, two-type electricity generation is observed as glucose-independent process and glucose-dependent process. For the sake of enhancing MFC efficiency, extracellular and intracellular strategies are implemented. Biofilm removal and addition of c -type cytochrome benefits electricity performance and Tween 80 accelerates the electricity generation. Perturbation of cellular redox balance compromises the electricity output, indicating that redox homeostasis is the principal requirement to reach idea voltage. Conclusion This study identifies potential feature of electricity activity for Z. mobilis and provides multiple strategies to enhance the electricity output. Therefore, additional electricity generation will benefit the techno-economic viability of the commercial bulk production for biochemicals or biofuels in an efficient and environmentally sustainable manner.

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Development of redox potential-controlled schemes for very-high-gravity ethanol fermentation

Cited by 31 publications

References 26 publications

Optimization of Agitation and Aeration for Very High Gravity Ethanol Fermentation from Sweet Sorghum Juice by Saccharomyces cerevisiae Using an Orthogonal Array Design

Optimization of Agitation and Aeration for Very High Gravity Ethanol Fermentation from Sweet Sorghum Juice by Saccharomyces cerevisiae Using an Orthogonal Array Design

Redox potential driven aeration during very-high-gravity ethanol fermentation by using flocculating yeast

Potential of Zymomonas mobilis as an electricity producer in ethanol production

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