Two-Stage Aeration Fermentation Strategy to Improve Bioethanol Production by Scheffersomyces stipitis

Hardwood spent sulfite liquor (HSSL) is a by-product from pulp industry with a high concentration of pentose sugars, besides some hexoses suitable for bioethanol production by Scheffersomyces stipitis. The establishment of optimal aeration process conditions that results in specific microaerophilic conditions required by S. stipitis is the main challenge for ethanol production. The present study aimed to improve the ethanol production from HSSL by S. stipitis through a two-stage aeration fermentation. Experiments with controlled dissolved oxygen tension (DOT) in the first stage and oxygen restriction in the second stage were carried out. The best results were obtained with DOT control at 50% in the first stage, where the increase of oxygen availability provided faster growth and higher biomass yield, and no oxygen supply with an agitation rate of 250 rpm, in the second stage allowed a successful induction of ethanol production. Fermentation using 60% of HSSL (v/v) as substrate for S. stipitis provided a maximum specific growth rate of 0.07 h−1, an ethanol productivity of 0.04 g L h−1 and an ethanol yield of 0.39 g g−1, respectively. This work showed a successful two-stage aeration strategy as a promising aeration alternative for bioethanol production from HSSL by S. stipitis.

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Hemicellulosic Bioethanol Production from Fast-Growing Paulownia Biomass

Processes ◽

10.3390/pr9010173 ◽

2021 ◽

Vol 9 (1) ◽

pp. 173

Author(s):

Elena Domínguez ◽

Pablo G. del Río ◽

Aloia Romaní ◽

Gil Garrote ◽

Lucília Domingues

Keyword(s):

Ethanol Production ◽

Ethanol Concentration ◽

Ethanol Yield ◽

Xylose Reductase ◽

Energy Crop ◽

Scheffersomyces Stipitis ◽

Fractionation Process ◽

Renewable Source ◽

Fast Growing ◽

Engineered Strain

In order to exploit a fast-growing Paulownia hardwood as an energy crop, a xylose-enriched hydrolysate was obtained in this work to increase the ethanol concentration using the hemicellulosic fraction, besides the already widely studied cellulosic fraction. For that, Paulownia elongata x fortunei was submitted to autohydrolysis treatment (210 °C or S0 of 4.08) for the xylan solubilization, mainly as xylooligosaccharides. Afterwards, sequential stages of acid hydrolysis, concentration, and detoxification were evaluated to obtain fermentable sugars. Thus, detoxified and non-detoxified hydrolysates (diluted or not) were fermented for ethanol production using a natural xylose-consuming yeast, Scheffersomyces stipitis CECT 1922, and an industrial Saccharomyces cerevisiae MEC1133 strain, metabolic engineered strain with the xylose reductase/xylitol dehydrogenase pathway. Results from fermentation assays showed that the engineered S. cerevisiae strain produced up to 14.2 g/L of ethanol (corresponding to 0.33 g/g of ethanol yield) using the non-detoxified hydrolysate. Nevertheless, the yeast S. stipitis reached similar values of ethanol, but only in the detoxified hydrolysate. Hence, the fermentation data prove the suitability and robustness of the engineered strain to ferment non-detoxified liquor, and the appropriateness of detoxification of liquor for the use of less robust yeast. In addition, the success of hemicellulose-to-ethanol production obtained in this work shows the Paulownia biomass as a suitable renewable source for ethanol production following a suitable fractionation process within a biorefinery approach.

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Two-stage alkaline and acid pretreatment applied to sugarcane bagasse to enrich the cellulosic fraction and improve enzymatic digestibility

Detritus ◽

10.31025/2611-4135/2020.14005 ◽

2020 ◽

pp. 106-113

Author(s):

Longinus Ifeanyi Igbojionu ◽

Cecilia Laluce ◽

Edison Pecoraro

Keyword(s):

Sugarcane Bagasse ◽

Maleic Acid ◽

Ethanol Yield ◽

High Yield ◽

Enzymatic Digestibility ◽

Acid Pretreatment ◽

Two Stage ◽

Second Stage ◽

One Stage ◽

Naoh Pretreatment

Sugarcane bagasse (SB) is made up of cellulose (32-43%), hemicellulose (19-34%) and lignin (14-30%). Due to high recalcitrant nature of SB, pretreatment is required to deconstruct its structure and enrich the cellulosic fraction. A two-stage NaOH and maleic acid pretreatment was applied to SB to enrich its cellulosic fraction. SB used in the present study is composed of cellulose (40.4 wt%), hemicellulose (20.9 wt%), lignin (22.5 wt%) and ash (4.0 wt%). After one-stage NaOH pretreatment, its cellulosic fraction increased to 61.8 wt% and later increased to 80.1 wt% after the second-stage acid pretreatment. Lignin fraction decreased to 3.0 wt% after one-stage NaOH pretreatment and remained unaffected after the acid pretreatment step. Hemicellulose fraction decreased substantially after the second-stage pretreatment with maleic acid. Pretreated SB displayed high crystallinity index and improved enzymatic digestibility. Hydrolysates of pretreated SB contained very low amount of xylose and subsequent fermentation by Saccharomyces cerevisiae -IQAr/45-1 resulted to ethanol level of 8.94 g/L. Maximal ethanol yield of 0.49 g/g (95.8% of theoretical yield) and productivity of 0.28 g/L/h was attained. At the same time, biomass yield and productivity of 0.47 g/g and 0.27 g/L/h respectively were obtained. Two-stage NaOH and maleic acid pretreatment led to ~ two-fold increase in cellulosic fraction and enhanced the enzymatic digestibility of SB up to 70.4%. The resulted enzymatic hydrolysate was efficiently utilized by S. cerevisiae -IQAr/45-1 to produce high yield of ethanol. Thus, optimization of enzymatic hydrolysis at low enzyme loading is expected to further improve the process and reduce cost.

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Enhanced fuel ethanol production from rice straw hydrolysate by an inhibitor-tolerant mutant strain of Scheffersomyces stipitis

RSC Advances ◽

10.1039/c7ra04049k ◽

2017 ◽

Vol 7 (50) ◽

pp. 31180-31188 ◽

Cited By ~ 5

Author(s):

Kedong Ma ◽

Mingxiong He ◽

Huiyan You ◽

Liwei Pan ◽

Guoquan Hu ◽

...

Keyword(s):

Ethanol Production ◽

Lignocellulosic Biomass ◽

Rice Straw ◽

Mutant Strain ◽

Continuous Fermentation ◽

Bioethanol Production ◽

Scheffersomyces Stipitis ◽

Rice Straw Hydrolysate ◽

Cell Recycling ◽

Tolerant Mutant

A novel process for bioethanol production from lignocellulosic biomass using an inhibitor-tolerant mutant strain of Scheffersomyces stipitis and cell-recycling continuous fermentation.

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Bioethanol Production by Using Detoxified Sugarcane Bagasse Hydrolysate and Adapted Culture of Candida tropicalis

Current Biochemistry ◽

10.29244/cb.2.1.1-12 ◽

2016 ◽

Vol 2 (1) ◽

pp. 1-12

Author(s):

Inda Setyawati ◽

Laksmi Ambarsari ◽

Siti Nur'aeni ◽

Suryani Suryani ◽

Puspa Julistia Puspita ◽

...

Keyword(s):

Ethanol Production ◽

Sugarcane Bagasse ◽

Ethanol Yield ◽

Renewable Resource ◽

Bioethanol Production ◽

Fermentation Inhibitors ◽

Renewable Materials ◽

Promising Alternative ◽

Fermentation Time ◽

Sugarcane Bagasse Hydrolysate

Ethanol is considered as the most promising alternative fuel, since it can be produced from a variety of agriculturally-based renewable materials, such as sugarcane bagasse. Lignocellulose as a major component of sugarcane bagasse is considered as an attractive renewable resource for ethanol production due to its great availability and relatively low cost. The major problem of lignocellulose is caused by its need for treatment to be hydrolyzed to simple sugar before being used for bioethanol production. However, pretreatment using acid as hydrolyzing agent creates some inhibitor compounds that reduce ethanol production because these compounds are potential fermentation inhibitors and affect the growth rate of the yeast. Reduction of these by-products requires a conditioning (detoxification and culture starter adaptation). Thus, the aim of this study was to evaluate bioethanol production by fermentation with and without detoxified sugarcane bagasse acid hydrolysate using adapted and non-adapted culture of C. tropicalis. According to this study, the highest ethanol amount was obtained about 0.43 % (v/v) with an ethanol yield of 2.51 % and theoretical yield of 4.92 % by fermentation of sugarcane bagasse hydrolysate with detoxification using the adapted strain of C. tropicalis at 72 hours fermentation time. Furthermore, the addition of 3 % glucose as co-substrate on detoxified-hydrolysate media only achieved the highest ethanol concentration 0.21 % after 24 hours fermentation with the ethanol yield 0.69 % and theoretical ethanol yield 1.35 %, thus it can be concluded that the addition of glucose could not increase the ethanol production.

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Improvement in Ethanol Yield from Lignocellulo-Starch Biomass using Saccharomyces cerevisiae alone or its Co-culture with Scheffersomyces stipitis

Current Biotechnology ◽

10.2174/2211550109666200311111119 ◽

2020 ◽

Vol 9 (1) ◽

pp. 57-76

Author(s):

Madhanamohanan G. Mithra ◽

Gouri Padmaja

Keyword(s):

Saccharomyces Cerevisiae ◽

Ethanol Production ◽

Ethanol Yield ◽

Relative Advantage ◽

Vegetable Crops ◽

Fed Batch ◽

Scheffersomyces Stipitis ◽

Separate Hydrolysis And Fermentation ◽

Ethanol Yields ◽

Sugar Levels

Background: Literature on ethanol production from Lignocellulo-Starch Biomass (LCSB) containing starch besides cellulose and hemicellulose, is scanty. Fed-Batch Separate Hydrolysis And Fermentation (F-SHF) was earlier found more beneficial than Fed-Batch Simultaneous Saccharification and Fermentation (F-SSF). Objective: The study aimed at modification of the saccharification and fermentation strategies by including a prehydrolysis step prior to the SSF and compared the ethanol yields with co-culture fermentation using hexose-fermenting Saccharomyces cerevisiae and pentose-fermenting Scheffersomyces stipitis. Methods: Fed-batch hybrid-SSF and Fed-Batch Separate Hydrolysis and Co-culture Fermentation (F-SHCF) in improving ethanol yield from Steam (ST) or Dilute Sulfuric Acid (DSA) pretreated LCSBs (peels of root and vegetable crops) were studied. Results: There was a progressive build-up of ethanol during F-HSSF up to 72h and further production up to 120h was negligible, with no difference among pretreatments. Despite very high ethanol production in the initial 24h of fermentation by S.cerevisiae under F-SHCF, the further increase was negligible. A rapid hike in ethanol production was observed when S. stipitis was also supplemented because of xylose conversion to ethanol. Conclusion: While ST gave higher ethanol (296-323 ml/kg) than DSA under F-HSSF, the latter was advantageous under F-SHCF for certain residues. Prehydrolysis (24h; 50°C) enhanced initial sugar levels favouring fast fermentation and subsequent saccharification and fermentation occurred concurrently at 37°C for 120h, thus leading to energy saving and hence F-HSSF was advantageous. Owing to the low hemicellulose content in LCSBs, the relative advantage of co-culture fermentation over monoculture fermentation was not significant.

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The potential of sweet potato biorefinery and development of alternative uses

SN Applied Sciences ◽

10.1007/s42452-021-04369-y ◽

2021 ◽

Vol 3 (3) ◽

Author(s):

Joana Antunez Rizzolo ◽

Adenise Lorenci Woiciechowski ◽

Antonio Irineudo Magalhães Júnior ◽

Luis Alberto Zevallos Torres ◽

Carlos Ricardo Soccol

Keyword(s):

Volatile Organic Compounds ◽

Ethanol Production ◽

Sweet Potato ◽

Organic Compounds ◽

Potato Variety ◽

Ethanol Yield ◽

Alcoholic Beverage ◽

Bioethanol Production ◽

Sweet Potatoes ◽

Volatile Organic

AbstractThe bioethanol production from the sweet potato variety BRS Cuia using three different strains of Saccharomyces cerevisiae (LPB1-93, ATCC-26602, and CA-11) was carried out in this research. Comparative analyses of consumed sugar, ethanol yield, and productivity (in tons per hectare) increased along with the concentration of cells in the inoculum. Additionally, to verify the aromatic quality of a potential sweet potato distilled spirit, volatile organic compounds were analyzed. The results showed a yield of over 90% ethanol. It was observed that the sugar consumption and ethanol production rates can be increased with a higher initial concentration of cells. This resulted in higher concentrations of ethanol in shorter times. From 100 g of the sweet potato variety BRS Cuia, the highest concentration of ethanol obtained was 25.74 g L−1 using the LPB1-93 strain. The estimated bioethanol production is about 10,000 L ha−1, with two sweet potatoes crops in a year. The ethanol production from the sweet potato variety BRS Cuia is viable, representing a sustainable alternative to fuel bioethanol, as well as an alcoholic beverage due to the volatile organic compounds present in the distilled fraction.

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Chemical mutagenesis of Saccharomyces cerevisiae for enhancing bioethanol production with fermentation at very high sugar concentration

BioResources ◽

10.15376/biores.15.1.1354-1369 ◽

2020 ◽

Vol 15 (1) ◽

pp. 1354-1369

Author(s):

Nadeem I. Elhussieny ◽

Marwah M. Bakri ◽

Magdah Ganash ◽

Tarek M. Abdel Ghany

Keyword(s):

Saccharomyces Cerevisiae ◽

Ethanol Production ◽

Incubation Period ◽

Dna Analysis ◽

Ethanol Yield ◽

Random Amplified Polymorphic Dna ◽

Chemical Mutagenesis ◽

Bioethanol Production ◽

High Sugar ◽

Very High

Saccharomyces cerevisiae is one of the most promising unicellular fungi on account of its vital applications in biotechnology as well as bioethanol production. Improvement of ethanol production via very high-gravity (VHG) fermentation (fermentation at high sugar levels) was successfully developed using the ethidium bromide (EtB) mutagenesis of S. cerevisiae. This study found two developed mutants of S. cerevisiae (EtB20a and EtB20b) with varied capacity for ethanol production using EtB, depending on random amplified polymorphic DNA analysis. Mutant EtB20b showed improved ethanol yield (19.5%) compared with the wild-type (18.0%), while the other mutant EtB20a exhibited retarded ethanol production (9.1%). Optimization of ethanol production by mutant EtB20b was performed under other conditions including temperature, pH, inoculum size, and incubation period. The highest production capacity of the yeasts was 20.8, 19.9, 19.5, and 19.5% at an optimum temperature of 30 °C, pH 6.0, incubation period of 72 h, and 1 mL of yeast suspension (optical density at 600 nm) with glucose utilization of 42.6, 40.7, 39.8, and 39.9%, respectively.

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Bio-ethanol production from Elephant grass using co-cultures of Aspergillus niger and Saccharomyces cerevisiae in simultaneous saccharification and fermentation

South Asian Journal of Experimental Biology ◽

10.38150/sajeb.3(4).p152-157 ◽

2013 ◽

Vol 3 (4) ◽

pp. 152-157

Author(s):

T. C. Agbodike ◽

S. A. Ado ◽

I. O. Abdullahi

Keyword(s):

Saccharomyces Cerevisiae ◽

Aspergillus Niger ◽

Ethanol Production ◽

Simultaneous Saccharification And Fermentation ◽

Ethanol Yield ◽

Pennisetum Purpureum ◽

Plant Sample ◽

Agitation Rate ◽

Elephant Grass ◽

Simultaneous Saccharification

Elephant grass (Pennisetum purpureum) was evaluated for its ethanol production potential using co-cultures of Aspergillus niger and Saccharomyces cerevisiae. Proximate and lignocellulose analysis carried out on the plant sample showed that it had crude fibre, lignin, hemicellulose and cellulose contents of 31.5%, 26.78%, 18.76% and 34.16% respectively. A. niger strain (AN-15) used for the simultaneous saccharification and fermentation (SSF) of the plant sample was isolated from soil and selected upon subsequent screening because it gave highest yield of cellulase enzyme (0.1792 IU/ml/min). S. cerevisiae strain (PW-4) used for the SSF was isolated from palm wine and selected upon subsequent screening after showing ability to assimilate more sugars compared to other isolates. Fermentation of plant sample was carried out at different substrate concentrations ranging from 2-10% and highest ethanol yield (1.68g/100ml) was observed at 6% substrate concentration though lesser than that observed for glucose at same concentration (8.38g/100ml). Optimization of culture parameters for ethanol production showed maximum ethanol yield at pH 5, 35oC and agitation rate of 300 rpm.

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An Enhanced Two Stage MMSE Equalizer for Coded FBMC/OQAM Systems

International Journal of Embedded and Real-Time Communication Systems ◽

10.4018/ijertcs.2019010104 ◽

2019 ◽

Vol 10 (1) ◽

pp. 69-82 ◽

Cited By ~ 2

Author(s):

Mohammad Rizk Assaf ◽

Abdel-Nasser Assimi

Keyword(s):

Error Propagation ◽

Channel Model ◽

Error Correcting Codes ◽

Two Stage ◽

Probability Of Error ◽

Second Stage ◽

Different Types ◽

Mmse Equalizer ◽

And Performance ◽

Ici Cancellation

In this article, the authors investigate the enhanced two stage MMSE (TS-MMSE) equalizer in bit-interleaved coded FBMC/OQAM system which gives a tradeoff between complexity and performance, since error correcting codes limits error propagation, so this allows the equalizer to remove not only ICI but also ISI in the second stage. The proposed equalizer has shown less design complexity compared to the other MMSE equalizers. The obtained results show that the probability of error is improved where SNR gain reaches 2 dB measured at BER compared with ICI cancellation for different types of modulation schemes and ITU Vehicular B channel model. Some simulation results are provided to illustrate the effectiveness of the proposed equalizer.

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Enzymatic Process for Cystoseira barbata Valorization: Ethanol Production and Additional By-Products

Processes ◽

10.3390/pr9050741 ◽

2021 ◽

Vol 9 (5) ◽

pp. 741

Author(s):

Doinita-Roxana Cioroiu Tirpan ◽

Ancaelena Eliza Sterpu ◽

Claudia Irina Koncsag ◽

Alina Georgiana Ciufu ◽

Tănase Dobre

Keyword(s):

Ethanol Production ◽

Alcoholic Fermentation ◽

Ethanol Yield ◽

Product Yield ◽

Liquid Ratio ◽

Experimental Conditions ◽

Factors Affecting ◽

Cystoseira Barbata ◽

Main Factors ◽

Process Factors

The aim of this study is to evaluate the potential of dried Cystoseira barbata alga for ethanol production through alcoholic fermentation. The influence of the main factors affecting the fermentation are studied in the frame of a 23 factorial experimental plan. The main factors influencing the process are the fermentation temperature (t from 25 °C to 35 °C), the solid to liquid ratio (S/L from 0.040 g/g to 0.080 g/g), and the cellulase ratio (R from 8 U/g d.m to 16 U/g d.m.). The maximum volatile compounds yield of 0.2808 g/g d.m and ethanol yield of 0.0158 g/g d.m were favored by the following experimental conditions: process temperature of 35 °C, solid to liquid ratio of 0.0415, and enzyme ratio of 16 U/g d.m. A statistical model was used to correlate the product yield with the process factors. Additionally, 19 interesting bioactive compounds were found in the enzymatic hydrolysis and alcoholic fermentation broths which seem likely to maintain natural defence mechanisms against diseases and physical disorders.

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