Optimized membrane process to increase hemicellulosic ethanol production from pretreated rice straw by recombinant xylose-fermenting Saccharomyces cerevisiae

Sasaki, Kengo; Tsuge, Yota; Sasaki, Daisuke; Hasunuma, Tomohisa; Sakamoto, Takatoshi; Sakihama, Yuri; Ogino, Chiaki; Kondo, Akihiko

doi:10.1016/j.biortech.2014.06.101

Cited by 20 publications

(17 citation statements)

References 24 publications

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“…Although we cannot stringently reject a purely neutral explanation, the directly opposing effects of these alleles on growth and survival corresponds to an evolutionary trade-off between the two key determinants of fitness and makes it tempting to invoke selection to explain this divergence. Domestication to distinct human made niches (Sake and grape-wine), including different substrates of fermentation (Giudici & Zambonelli, 1992; Sasaki et al, 2014), may be the ultimate explanation for this divergence with drug resistance as a side-effect caused by TOR pleiotropy. More broadly, this is reminiscent of methicillin-resistant and penicillin-resistant strains emerging long before the introduction of these antibiotics in the clinic because of other irrelevant selections (Baker et al, 2014; D’Costa et al, 2011; Harkins et al, 2017).…”

Section: Discussionmentioning

confidence: 99%

Patterns of selection reveal shared molecular targets over short and long evolutionary timescales

Vázquez-García

Persson

et al. 2017

Preprint

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1Standing and de novo genetic variants can both drive adaptation to environmental changes, but 2 their relative contributions and interplay remain poorly understood. Here we investigated the 3 dynamics of drug adaptation in yeast populations with different levels of standing variation by 4 experimental evolution coupled with time-resolved sequencing and phenotyping. We found a 5 doubling of standing variation alone boost the adaptation by 64.1% and 51.5% in hydroxyuea and 6 rapamycin respectively. The causative standing and de novo variants were selected on shared 7 targets of RNR4 in hydroxyurea and TOR1, TOR2 in rapamycin. The standing and de novo TOR 8 variants map to different functional domains and act via distinct mechanisms. Interestingly, 9 standing TOR variants from two domesticated strains exhibited opposite resistance effects, 10 reflecting lineage-specific functional divergence. This study provides a dynamic view on how 11 standing and de novo variants interactively drive adaptation and deepens our understanding of 12 clonally evolving diseases.13 8 This adaptive gain was directly comparable to those of NA endpoint populations, and thus 1 capable of fully explaining their adaptive gains. (Figure S4B). 2 3 De novo mutations in TOR1, TOR2 and FPR1 drive rapamycin adaptation in heterogeneous 4 populations 5Both de novo and standing variants could contribute to adaptation in the four-parent populations. 6Given that they were derived from four parents, the frequency spectrum of each parental allele is 7 centered around a median frequency of 0.21 (WA), 0.26 (NA), 0.26 (WE) and 0.26 (SA) at T0 8 (Cubillos et al., 2013). In comparison, the initial frequency of de novo mutations is extremely low, 9 arising during the crossing or selection phases (Vázquez-García et al., 2017). We called de novo 10 driver mutations in genes that were recurrent mutation targets in the eight four-parent populations 11 and found that FPR1, TOR1 and TOR2 harbor such mutations ( Figure 3A). Identical FPR1 12 mutations occurred in all the replicated populations derived from one intercrossed population 13 F12_1 and the same TOR1 mutations were found in all the replicated population derived from the 14 other intercrossed population F12_2; thus these drivers emerged during the shared crossing phase 15 and then expanded independently during the selection phase. Validating this assumption, the 16 same haplotype blocks increased in frequency in the replicated populations derived from the same 17 intercrossed population, reflecting expansion of the same clones present at T0 ( Figure S6). 18Similar to the isogenic lines, we found recurrent mutations at the TOR1 1972 and 2038 amino 19 acid sites, further confirming that these were the primary RM selection targets and that they arise 20 independently of the genetic context. In one population (F12_2_RM_4) we also found a TOR2 21 Ser1975Ile mutation rising to high frequency ( Figure 3A). TOR2 Ser1975 is located in the RM-22

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Section: Discussionmentioning

confidence: 99%

Patterns of selection reveal shared molecular targets over short and long evolutionary timescales

Vázquez-García

Persson

et al. 2017

Preprint

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“…The fermentation of hemicellulosic hydrolysates which contains pentose sugars needs for a recombinant yeast that may not be as effi cient as usual Saccharomyces cerevisiae 6,7 . In Iran, ethanol is produced mostly from molasses than any other substrates.…”

Section: -5mentioning

confidence: 99%

Performance Evaluation of Sweet Sorghum Juice and Sugarcane Molasses for Ethanol Production

Hatamipour

Almodares

Ahi

et al. 2015

Polish Journal of Chemical Technology

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Sweet sorghum juice and traditional ethanol substrate i.e. sugarcane molasses were used for ethanol production in this work. At the end of the fermentation process, the sweet sorghum juice yielded more ethanol with higher ethanol concentration compared to sugarcane molasses in all experiments. The sweet sorghum juice had higher cell viability at high ethanol concentrations and minimum sugar concentration at the end of the fermentation process. The ethanol concentration and yield were 8.9% w/v and 0.45 g/g for sweet sorghum in 80 h and 6.5% w/v and 0.37 g/g for sugarcane molasses in 60 h, respectively. The fi ndings on the physical properties of sweet sorghum juice revealed that it has better physical properties compared to sugarcane molasses, resulting to enhanced performance of sweet sorghum juice for ethanol production

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“…Membrane technologies are used for the downstream processing of biological processes, due to their simple operation and their ease of scaling up (Sasaki et al, 2014). In particular, the pressure-driven membrane is effective and has a good performance for industrial production processes (Zhou et al, 2013b;Nguyen et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

Membrane-Based Downstream Processing of Microbial Xylitol Production

Desiriani¹,

Kresnowati²,

Wenten³

2017

IJTech

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Xylitol is a sugar alcohol used as a sweetener in the food industry. Xylitol can be produced from D-xylose using a fermentation process, but it then needs to be separated from the other components of the fermentation broth (e.g., metabolic products, residual substances, biomass cells, and mineral salts), before being purified as xylitol crystals. Therefore, to obtain high purity xylitol, various separation processes are required. One very promising downstream processing method is membrane separation. This study evaluated membrane-based processes for the separation of biomass cells and other impurities, determined the concentration of xylitol produced from Debaryomyces hansenii yeast fermentation broth, and proposed a polysulfone ultrafiltration (UF) membrane for biomass-cell separation followed by polyamide nanofiltration (NF) to remove low-molecular-weight compounds (e.g., acetic acids) from sugars. The effects of operating pressure were examined using a fermentation broth model solution. The results showed that a higher pressure caused a higher permeate flux; however, the permeate flux's rate flow decreased over time due to concentration polarization, and fouling in the UF and NF membranes. Nevertheless, at all pressures, UF achieved a 99% rejection of biomass cells. In addition, microscope analysis showed that no biomass cells were detected in the permeates of UF. The resulting NF concentrates revealed high xylitol retention and a beneficially lower concentration of acetic acids. The operating pressures of the UF test conditions were 1 barg and 1.5 barg, illustrating that, at a pressure of 5.5 barg, the experiments achieved reasonably high xylitol retention (above 90%) indicating negligible losses of sugar in the permeate port. Moreover, this was proven to be a feasible way to concentrate xylitol up to three times from the initial concentration of the model fermentation broth (MFB). Therefore, the results demonstrated that a two-stage combination of UF and NF is a promising system for the downstream processing of microbial xylitol production.

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Optimized membrane process to increase hemicellulosic ethanol production from pretreated rice straw by recombinant xylose-fermenting Saccharomyces cerevisiae

Cited by 20 publications

References 24 publications

Patterns of selection reveal shared molecular targets over short and long evolutionary timescales

Patterns of selection reveal shared molecular targets over short and long evolutionary timescales

Performance Evaluation of Sweet Sorghum Juice and Sugarcane Molasses for Ethanol Production

Membrane-Based Downstream Processing of Microbial Xylitol Production

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