Consolidated bioprocessing of raw starch with Saccharomyces cerevisiae strains expressing fungal alpha-amylase and glucoamylase combinations

Sakwa, L; Cripwell, Rosemary A.; Rose, Shaunita H.; Viljoen-Bloom, Marinda

doi:10.1093/femsyr/foy085

Cited by 35 publications

(20 citation statements)

References 45 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The estimated carbon conversion of 85% displayed by the S. cerevisiae Y294[TemG_Opt–TemA] was 31% higher than the Y294[TemG_Opt-AteA] strain, as well as the Y294[AmyA-GlaA] benchmark yeast (Table 2). The Y294[TemG_Opt–TemA] strain also showed an overall improvement in starch conversion to ethanol, compared to the previously constructed Y294[AteA-GlaA] strain [24], which produced 45.80 g l −1 ethanol after 144 h with an estimated carbon conversion of 45%.…”

Section: Resultsmentioning

confidence: 87%

Construction of industrial Saccharomyces cerevisiae strains for the efficient consolidated bioprocessing of raw starch

Cripwell

Rose

Favaro

et al. 2019

Biotechnol Biofuels

View full text Add to dashboard Cite

Background Consolidated bioprocessing (CBP) combines enzyme production, saccharification and fermentation into a one-step process. This strategy represents a promising alternative for economic ethanol production from starchy biomass with the use of amylolytic industrial yeast strains. Results Recombinant Saccharomyces cerevisiae Y294 laboratory strains simultaneously expressing an α-amylase and glucoamylase gene were screened to identify the best enzyme combination for raw starch hydrolysis. The codon optimised Talaromyces emersonii glucoamylase encoding gene ( temG_Opt ) and the native T. emersonii α-amylase encoding gene ( temA ) were selected for expression in two industrial S. cerevisiae yeast strains, namely Ethanol Red™ (hereafter referred to as the ER) and M2n. Two δ-integration gene cassettes were constructed to allow for the simultaneous multiple integrations of the temG_Opt and temA genes into the yeasts’ genomes. During the fermentation of 200 g l −1 raw corn starch, the amylolytic industrial strains were able to ferment raw corn starch to ethanol in a single step with high ethanol yields. After 192 h at 30 °C, the S. cerevisiae ER T12 and M2n T1 strains (containing integrated temA and temG_Opt gene cassettes) produced 89.35 and 98.13 g l −1 ethanol, respectively, corresponding to estimated carbon conversions of 87 and 94%, respectively. The addition of a commercial granular starch enzyme cocktail in combination with the amylolytic yeast allowed for a 90% reduction in exogenous enzyme dosage, compared to the conventional simultaneous saccharification and fermentation (SSF) control experiment with the parental industrial host strains. Conclusions A novel amylolytic enzyme combination has been produced by two industrial S. cerevisiae strains. These recombinant strains represent potential drop-in CBP yeast substitutes for the existing conventional and raw starch fermentation processes.

show abstract

Section: Resultsmentioning

confidence: 87%

Construction of industrial Saccharomyces cerevisiae strains for the efficient consolidated bioprocessing of raw starch

Cripwell

Rose

Favaro

et al. 2019

Biotechnol Biofuels

View full text Add to dashboard Cite

show abstract

“…However, the CBP applied to starch requires recombinant Saccharomyces cerevisiae strains producing sufficient quantities of raw starch hydrolyzing enzymes to ensure complete hydrolysis at a high substrate loading. This has become the primary focus of several research groups and great progress towards proof of concept in industrial strains has been made [14][15][16][17][18]. Nevertheless, engineering industrial strains for the production of amylases at titers suitable in large scale applications still remains a major challenge [14,18].…”

Section: Introductionmentioning

confidence: 99%

Delta-Integration of Single Gene Shapes the Whole Metabolomic Short-Term Response to Ethanol of Recombinant Saccharomyces cerevisiae Strains

et al. 2020

View full text Add to dashboard Cite

In yeast engineering, metabolic burden is often linked to the reprogramming of resources from regular cellular activities to guarantee recombinant protein(s) production. Therefore, growth parameters can be significantly influenced. Two recombinant strains, previously developed by the multiple δ-integration of a glucoamylase in the industrial Saccharomyces cerevisiae 27P, did not display any detectable metabolic burden. In this study, a Fourier Transform InfraRed Spectroscopy (FTIR)-based assay was employed to investigate the effect of δ-integration on yeast strains' tolerance to the increasing ethanol levels typical of the starch-to-ethanol industry. FTIR fingerprint, indeed, offers a holistic view of the metabolome and is a well-established method to assess the stress response of microorganisms. Cell viability and metabolomic fingerprints have been considered as parameters to detecting any physiological and/or metabolomic perturbations. Quite surprisingly, the three strains did not show any difference in cell viability but metabolomic profiles were significantly altered and different when the strains were incubated both with and without ethanol. A LC/MS untargeted workflow was applied to assess the metabolites and pathways mostly involved in these strain-specific ethanol responses, further confirming the FTIR fingerprinting of the parental and recombinant strains. These results indicated that the multiple δ-integration prompted huge metabolomic changes in response to short-term ethanol exposure, calling for deeper metabolomic and genomic insights to understand how and, to what extent, genetic engineering could affect the yeast metabolome.

show abstract

“…Our research work is herein pertinent with the "Recent Advances" [7] in June 2020 addresses for starch-to-ethanol conversion have provided a platform for the development of raw starch consolidated bioprocessing (CBP) technologies. Several proof-of-concept studies identified improved enzyme combinations, alternative feedstocks and novel strains [8,9] for evaluation and application under fermentation conditions. However, further research efforts are required before this technology can be scaled-up to an industrial level.…”

Section: Introductionmentioning

confidence: 99%

“…In their review, different CBP approaches are defined and discussed, also highlighting the role of enzymes for a supplemented CBP process. Various achievements of amylolytic Saccharomyces cerevisiae strains [8,9] for CBP of raw starch and the remaining challenges that need to be tackled / pursued to bring yeast raw starch CBP to industrial realization are described in [7].…”

Section: Introductionmentioning

confidence: 99%

Single-Step Ethanol Production from Raw Cassava Starch Using a Combination of Raw Starch Hydrolysis and Fermentation, Scale-Up from 5-L Laboratory and 200-L Pilot Plant to 3,000-L Industrial Fermenters

Krajang

Malairuang

Sukna

et al. 2020

Preprint

View full text Add to dashboard Cite

Background: A single-step ethanol production is the combination of raw cassava starch hydrolysis and fermentation. For the development of raw starch consolidated bioprocessing (CBP) technologies, this research work was to investigate the optimum conditions and technical procedures for the production of ethanol from raw cassava starch in a single step. This resulted high yields and productivities of all the experiments from the laboratory, the pilot, through the industrial scales. The yields of ethanol concentration are comparable with those in the commercial industries that use molasses and hydrolyzed starch as the raw materials. Results: Before single-step ethanol production, the studies of raw cassava starch hydrolysis by a granular starch hydrolyzing enzyme, StargenTM002, were carefully conducted. It successfully converted 80.19% (w/v) of raw cassava starch to glucose at a concentration of 176.41 g/L with a productivity of 2.45 g/L/h when the raw starch was pretreated at 60 °C for 1 h with 0.10% (v/w dry starch basis) of Distillase ASP before hydrolysis. A single-step ethanol production at 34 °C in a 5-L fermenter showed that S. cerevisiae (Fali, active dry yeast) produced the maximum ethanol concentration, p of 81.86 g/L (10.43% v/v) with a yield coefficient, Y p/s of 0.41 g/g, a productivity or production rate, r p of 1.14 g/L/h with an efficiency, Ef of 71.44%. The scale-up experiments of the single-step ethanol production using this method, from the 5-L fermenter to the 200-L fermenter and further to the 3,000-L industrial fermenter were successfully achieved with essentially good results. The p, Y p/s , r p , and Ef values of the 200-L scale were 80.85 g/L (10.23% v/v), 0.41 g/g, 1.12 g/L/h and 72.47% , respectively ; of the 3,000-L scale were 70.74 g/L (9.01% v/v), 0.34 g/g, 0.98 g/L/h and 59.82% , respectively. Because of using raw starch, the major by-products of all the three scales were very low; glycerol lactic acid and acetic acid, in ranges of 0.94-1.14%, 0.046-0.052%, 0-0.059% (w/v), respectively, where are less than those values in the industries. Conclusions: This single-step ethanol production using a combination of raw cassava starch hydrolysis and fermentation of the three fermentation scales here is practicable and feasible for the scale-up of industrial production of ethanol from raw starch.

show abstract

Consolidated bioprocessing of raw starch with Saccharomyces cerevisiae strains expressing fungal alpha-amylase and glucoamylase combinations

Cited by 35 publications

References 45 publications

Construction of industrial Saccharomyces cerevisiae strains for the efficient consolidated bioprocessing of raw starch

Construction of industrial Saccharomyces cerevisiae strains for the efficient consolidated bioprocessing of raw starch

Delta-Integration of Single Gene Shapes the Whole Metabolomic Short-Term Response to Ethanol of Recombinant Saccharomyces cerevisiae Strains

Single-Step Ethanol Production from Raw Cassava Starch Using a Combination of Raw Starch Hydrolysis and Fermentation, Scale-Up from 5-L Laboratory and 200-L Pilot Plant to 3,000-L Industrial Fermenters

Contact Info

Product

Resources

About