scholarly journals The Improvement of Bioethanol Production by Pentose-Fermenting Yeasts Isolated from Herbal Preparations, the Gut of Dung Beetles, and Marula Wine

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Mahlatse Ellias Moremi ◽  
Elbert Lukas Jansen Van Rensburg ◽  
Daniël Coenrad La Grange
Keyword(s):  
Acetic Acid ◽  
Carbon Source ◽  
Parental Strain ◽  
Ethanol Yield ◽  
Dung Beetles ◽  
Adaptation Process ◽  
Bioethanol Production ◽  
Herbal Preparations ◽  
Efficient Conversion ◽  
Pentose Sugars

Efficient conversion of pentose sugars to ethanol is important for an economically viable lignocellulosic bioethanol process. Ten yeasts fermenting both D-xylose and L-arabinose were subjected to an adaptation process with L-arabinose as carbon source in a medium containing acetic acid. Four Meyerozyma caribbica-adapted strains were able to ferment L-arabinose to ethanol in the presence of 3 g/L acetic acid at 35°C. Meyerozyma caribbica Mu 2.2f fermented L-arabinose to produce 3.0 g/L ethanol compared to the parental strain with 1.0 g/L ethanol in the absence of acetic acid. The adapted M. caribbica Mu 2.2f strain produced 3.6 and 0.8 g/L ethanol on L-arabinose and D-xylose, respectively, in the presence of acetic acid while the parental strain failed to grow. In a bioreactor, the adapted M. caribbica Mu 2.2f strain produced 5.7 g/L ethanol in the presence of 3 g/L acetic acid with an ethanol yield and productivity of 0.338 g/g and 0.158 g/L/h, respectively, at a KLa value of 3.3 h−1. The adapted strain produced 26.7 g/L L-arabitol with a yield of 0.900 g/g at a KLa value of 4.9 h−1.

Evaluating the Effect of Residual Lignin Contents and Fermentation Systems on Bioethanol Production

2021 ◽  
Vol 15 (3) ◽  
pp. 312-322
Author(s):  
Yanzhi You ◽  
Changhe Ding ◽  
Jinlong Li ◽  
Jun Meng ◽  
Xiankun Zhang ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Ethanol Yield ◽  
Lignin Content ◽  
Tween 80 ◽  
Cost Effective ◽  
Bioethanol Production ◽  
Residual Lignin ◽  
Buffer Solution ◽  
Citrate Buffer ◽  
Process Route

Peroxide-acetic acid (Peroxide-HAc) pretreatment is a simplified and cost-effective technology due to its mild conditions without the catalysis of strong acids, which was introduced to treat sugarcane bagasse (SCB) in this paper. Then pretreated SCB was used to produce bioethanol using thermophilic Saccharomyces cerevisiae in deionized water (DW) and sodium citrate buffer solution (SCS) fermentation systems, respectively. Results: showed that peroxide-HAc pretreatment can selectively remove lignin and change morphological structures, thus positively increasing saccharification and fermentation efficiency downstream. SCB pretreated at 100 °C obtained the lowest residual lignin content of 2.88% and achieved the highest ethanol yield of 92.10% (0.45 g/g-biomass) in DW system. In particular, SCS can decrease the residual sugars content of pretreated SCB during simultaneous saccharification and co-fermentation (SSCF) process. The addition of Tween 80 improved SSCF of SCB pretreated at 80 °C likely because Tween 80 can block residual lignin adsorption with enzymes. The concentration of acetic acid and glycerol byproducts from SCB pretreated at 80 °C can be decreased by SCS and DW systems, respectively, comparing to SCS and DW systems with additing Tween 80. This study provided a systematic process route for the bioethanol production by mild pretreatment method.

scholarly journals Genome shuffling enhances stress tolerance of Zymomonas mobilis to two inhibitors

2019 ◽  
Vol 12 (1) ◽  
Author(s):  
Weiting Wang ◽  
Bo Wu ◽  
Han Qin ◽  
Panting Liu ◽  
Yao Qin ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Cell Growth ◽  
Stress Tolerance ◽  
Parental Strain ◽  
Zymomonas Mobilis ◽  
De Novo ◽  
Ethanol Yield ◽  
Genome Shuffling ◽  
De Novo Mutation ◽  
Fermentation Time

Abstract Background Furfural and acetic acid are the two major inhibitors generated during lignocellulose pretreatment and hydrolysis, would severely inhibit the cell growth, metabolism, and ethanol fermentation efficiency of Zymomonas mobilis. Effective genome shuffling mediated by protoplast electrofusion was developed and then applied to Z. mobilis. Results After two rounds of genome shuffling, 10 different mutants with improved cell growth and ethanol yield in the presence of 5.0 g/L acetic acid and 3.0 g/L furfural were obtained. The two most prominent genome-shuffled strains, 532 and 533, were further investigated along with parental strains in the presence of 7.0 g/L acetic acid and 3.0 g/L furfural. The results showed that mutants 532 and 533 were superior to the parental strain AQ8-1 in the presence of 7.0 g/L acetic acid, with a shorter fermentation time (30 h) and higher productivity than AQ8-1. Mutant 533 exhibited subtle differences from parental strain F34 in the presence of 3.0 g/L furfural. Mutations present in 10 genome-shuffled strains were identified via whole-genome resequencing, and the source of each mutation was identified as either de novo mutation or recombination of the parent genes. Conclusions These results indicate that genome shuffling is an efficient method for enhancing stress tolerance in Z. mobilis. The engineered strains generated in this study could be potential cellulosic ethanol producers in the future.

scholarly journals Saccharomyces cerevisiae Fermentation of 28 Barley and 12 Oat Cultivars

Fermentation ◽  
2021 ◽  
Vol 7 (2) ◽  
pp. 59
Author(s):  
Timothy J. Tse ◽  
Daniel J. Wiens ◽  
Jianheng Shen ◽  
Aaron D. Beattie ◽  
Martin J. T. Reaney
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Acetic Acid ◽  
Lactic Acid ◽  
Succinic Acid ◽  
Alcoholic Fermentation ◽  
Ethanol Yield ◽  
Cereal Crops ◽  
Fermentation Products ◽  
Barley Cultivars ◽  
Oat Cultivars

As barley and oat production have recently increased in Canada, it has become prudent to investigate these cereal crops as potential feedstocks for alcoholic fermentation. Ethanol and other coproduct yields can vary substantially among fermented feedstocks, which currently consist primarily of wheat and corn. In this study, the liquified mash of milled grains from 28 barley (hulled and hull-less) and 12 oat cultivars were fermented with Saccharomyces cerevisiae to determine concentrations of fermentation products (ethanol, isopropanol, acetic acid, lactic acid, succinic acid, α-glycerylphosphorylcholine (α-GPC), and glycerol). On average, the fermentation of barley produced significantly higher amounts of ethanol, isopropanol, acetic acid, succinic acid, α-GPC, and glycerol than that of oats. The best performing barley cultivars were able to produce up to 78.48 g/L (CDC Clear) ethanol and 1.81 g/L α-GPC (CDC Cowboy). Furthermore, the presence of milled hulls did not impact ethanol yield amongst barley cultivars. Due to its superior ethanol yield compared to oats, barley is a suitable feedstock for ethanol production. In addition, the accumulation of α-GPC could add considerable value to the fermentation of these cereal crops.

scholarly journals Evaluation of polyploid miscanthus lines usage efficiency as a feedstock for bioethanol production

2021 ◽  
Vol 29 ◽  
pp. 13-19
Author(s):  
R. Y. Blume ◽  
O.V. Melnychuk ◽  
S.P. Ozheredov ◽  
D.B. Rakhmetov ◽  
Y.B. Blume
Keyword(s):  
Sweet Sorghum ◽  
Second Generation ◽  
Ethanol Yield ◽  
Bioenergy Crops ◽  
Control Line ◽  
Bioethanol Production ◽  
Second Generation Bioethanol ◽  
Giant Miscanthus ◽  
First And Second Generation ◽  
Bioethanol Yield

Aim. Main aim of this research was the evaluation of theoretical bioethanol yield (per ha) from hexaploid giant miscanthus (Miscanthus х giganteus) and further comparison with conventional triploid form as well as with other bioethanol crops. Methods. Several mathematic functions were determined that describe yearly yield dynamics and equations, which were used in calculations of theoretical bioethanol yield. Results. The theoretical bioethanol yield was evaluated for different hexaploid miscanthus lines. The most productive in terms of ethanol yield were lines 108 and 202, from which potential bioethanol yield was found to be higher than in control line (6451 L/ha) by 10.7 % and 14.2% respectively and can reach 7144 L/ha and 7684 L/ha. Conclusions. It was determined that the most productive lines of polyploid miscanthus (lines 108 and 202) are able to compete with other plant cellulosic feedstocks for second-generation bioethanol production in Ukraine. However, these lines show bioethanol productivity than sweet sorghum, in the case when sweet sorghum is processed for obtainment of both first- and second-generation bioethanol. Keywords: bioenergy crops, biofuels, giant miscanthus, Miscanthus, polyploidy, second-generation bioethanol.

scholarly journals Evaluation of Copper-Contaminated Marginal Land for the Cultivation of Vetiver Grass (Chrysopogon zizanioides) as a Lignocellulosic Feedstock and its Impact on Downstream Bioethanol Production

2019 ◽  
Vol 9 (13) ◽  
pp. 2685 ◽  
Author(s):  
Emily M. Geiger ◽  
Dibyendu Sarkar ◽  
Rupali Datta
Keyword(s):  
Contaminated Soil ◽  
Ethanol Yield ◽  
Dilute Acid Pretreatment ◽  
Cellulose Content ◽  
Bioethanol Production ◽  
Vetiver Grass ◽  
Acid Pretreatment ◽  
Biofuel Feedstock ◽  
Lignocellulosic Feedstock ◽  
The Impact

Metal-contaminated soil could be sustainably used for biofuel feedstock production if the harvested biomass is amenable to bioethanol production. A 60-day greenhouse experiment was performed to evaluate (1) the potential of vetiver grass to phytostabilize soil contaminated with copper (Cu), and (2) the impact of Cu exposure on its lignocellulosic composition and downstream bioethanol production. Dilute acid pretreatment, enzymatic hydrolysis, and fermentation parameters were optimized sequentially for vetiver grass using response surface methodology (RSM). Results indicate that the lignocellulosic composition of vetiver grown on Cu-rich soil was favorably altered with a significant decrease in lignin and increase in hemicellulose and cellulose content. Hydrolysates produced from Cu exposed biomass achieved a significantly greater ethanol yield and volumetric productivity compared to those of the control biomass. Upon pretreatment, the hemicellulosic hydrolysate showed an increase in total sugars per liter by 204.7% of the predicted yield. After fermentation, 110% of the predicted ethanol yield was obtained for the vetiver grown on Cu-contaminated soil. By contrast, for vetiver grown on uncontaminated soil a 62.3% of theoretical ethanol yield was achieved, indicating that vetiver has the potential to serve the dual purpose of phytoremediation and biofuel feedstock generation on contaminated sites.

scholarly journals N-Acetylglucosamine Utilization by Saccharomyces cerevisiae Based on Expression of Candida albicans NAG Genes

2009 ◽  
Vol 75 (18) ◽  
pp. 5840-5845 ◽  
Author(s):  
Jürgen Wendland ◽  
Yvonne Schaub ◽  
Andrea Walther
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Candida Albicans ◽  
Carbon Source ◽  
Sole Carbon Source ◽  
De Novo ◽  
Biofuel Production ◽  
Bioethanol Production ◽  
Catabolic Pathway ◽  
Cellular Functions ◽  
Kinase A

ABSTRACT Synthesis of chitin de novo from glucose involves a linear pathway in Saccharomyces cerevisiae. Several of the pathway genes, including GNA1, are essential. Genes for chitin catabolism are absent in S. cerevisiae. Therefore, S. cerevisiae cannot use chitin as a carbon source. Chitin is the second most abundant polysaccharide after cellulose and consists of N-acetylglucosamine (GlcNAc) moieties. Here, we have generated S. cerevisiae strains that are able to use GlcNAc as a carbon source by expressing four Candida albicans genes (NAG3 or its NAG4 paralog, NAG5, NAG2, and NAG1) encoding a GlcNAc permease, a GlcNAc kinase, a GlcNAc-6-phosphate deacetylase, and a glucosamine-6-phosphate deaminase, respectively. Expression of NAG3 and NAG5 or NAG4 and NAG5 in S. cerevisiae resulted in strains in which the otherwise-essential ScGNA1 could be deleted. These strains required the presence of GlcNAc in the medium, indicating that uptake of GlcNAc and its phosphorylation were achieved. Expression of all four NAG genes produced strains that could use GlcNAc as the sole carbon source for growth. Utilization of a GlcNAc catabolic pathway for bioethanol production using these strains was tested. However, fermentation was slow and yielded only minor amounts of ethanol (approximately 3.0 g/liter), suggesting that fructose-6-phosphate produced from GlcNAc under these conditions is largely consumed to maintain cellular functions and promote growth. Our results present the first step toward tapping a novel, renewable carbon source for biofuel production.

scholarly journals Influence of Lactose Concentration in Bioethanol Production from Cheese Whey

2017 ◽  
Vol 39 (5) ◽  
pp. 533
Author(s):  
Cleidiane Samara Murari ◽  
Débora Cristina Moraes Niz da Silva ◽  
Bruna Lima da Silva ◽  
Vanildo Luiz Del Bianchi
Keyword(s):  
Alcoholic Fermentation ◽  
Cheese Whey ◽  
Ethanol Yield ◽  
Oxygen Demand ◽  
Bioethanol Production ◽  
Organic Substances ◽  
Promising Alternative ◽  
Renewable Source ◽  
Initial Concentration ◽  
Lactose Concentration

The present study aimed the utilization of the cheese whey as substrate for ethanol production by Kluyveromyces marxianus.  Was studied the effect of the initial concentration of cheese whey (M1 57,6 g L-1; M2 45,6 g L-1; M3 32,5 g L-1 e M4 18,8 g L-1) on the alcoholic fermentation. After sterilization, the medium were incubated at 30ºC for 48 hours, performing analysis of lactose, proteins, ethanol, cell growth and chemical oxygen demand. According to the results, the medium M1 (the highest concentration) showed a higher production and productivity of ethanol 16.9 g L-1 and 1.26 g L.h-1, respectively, and also obtained the highest production and productivity of cell of 5.8 g L-1 and 0.40 g L.h-1, respectively. However, in terms of ethanol yield, the most satisfactory result was obtained with the M3 medium with 82.30% in 12 hours of fermentation. The organic substances content has been reduced in relation to COD in the medium M4 in 82.28%, representing a promising alternative for valorization of cheese whey as an effective alternative to obtain a renewable source of biofuel.

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