Tolerance of Pichia farinosa KCTC27753 Isolated from Nuruk to Fermentation Inhibitors

Abstract Background Presence of inhibitory chemicals in lignocellulose hydrolysates is a major hurdle for production of second-generation bioethanol. Especially cheaper pre-treatment methods that ensure an economical viable production process generate high levels of these inhibitory chemicals. The effect of several of these inhibitors has been extensively studied with non-xylose-fermenting laboratory strains, in synthetic media, and usually as single inhibitors, or with inhibitor concentrations much higher than those found in lignocellulose hydrolysates. However, the relevance of individual inhibitors in inhibitor-rich lignocellulose hydrolysates has remained unclear. Results The relative importance for inhibition of ethanol fermentation by two industrial second-generation yeast strains in five lignocellulose hydrolysates, from bagasse, corn cobs and spruce, has now been investigated by spiking higher concentrations of each compound in a concentration range relevant for industrial hydrolysates. The strongest inhibition was observed with industrially relevant concentrations of furfural causing partial inhibition of both D-glucose and D-xylose consumption. Addition of 3 or 6 g/L furfural strongly reduced the ethanol titer obtained with strain MD4 in all hydrolysates evaluated, in a range of 34 to 51% and of 77 to 86%, respectively. This was followed by 5-hydroxymethylfurfural, acetic acid and formic acid, for which in general, industrially relevant concentrations caused partial inhibition of D-xylose fermentation. On the other hand, spiking with levulinic acid, 4-hydroxybenzaldehyde, 4-hydroxybenzoic acid or vanillin caused little inhibition compared to unspiked hydrolysate. The further evolved MD4 strain generally showed superior performance compared to the previously developed strain GSE16-T18. Conclusion The results highlight the importance of individual inhibitor evaluation in a medium containing a genuine mix of inhibitors as well as the ethanol that is produced by the fermentation. They also highlight the potential of increasing yeast inhibitor tolerance for improving industrial process economics.

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Biodegradation of 5-(Hydroxymethyl)-furfural and Furan Derivatives

Proceedings ◽

10.3390/proceedings2201283 ◽

2018 ◽

Vol 2 (20) ◽

pp. 1283 ◽

Cited By ~ 2

Author(s):

María Isabel Igeño ◽

Rubén Sánchez-Clemente ◽

Ana G. Población ◽

M. Isabel Guijo ◽

Faustino Merchán ◽

...

Keyword(s):

Furan Ring ◽

Degradation Products ◽

Chemical Compounds ◽

Aldehyde Group ◽

Bacterial Strains ◽

Fermentation Inhibitors ◽

Furan Derivatives ◽

Hydroxymethyl Furfural ◽

Common Thread ◽

Lignocellulose Hydrolysates

Furfural and 5-hydroxymethylfurfural (HMF) are degradation products of lignocellulose during pretreatment operations. Furfural compounds are a group of chemical compounds whose common thread is an aldehyde group attached to a furan ring, and they constitute a problem for the development of second-generation biofuels because they act as fermentation inhibitors of the lignocellulose hydrolysates. Up to date, very few bacteria have been described to be able to eliminate them. The objective of this work was to isolate and characterize bacterial strains able to use, as the sole carbon source, 5-(hydroxymethyl)-furfural (HMF) and furan derivatives.

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Changes of Nitrogen Compounds During Ensiling of High Protein Herbages – A Review

Annals of Animal Science ◽

10.1515/aoas-2015-0008 ◽

2015 ◽

Vol 15 (2) ◽

pp. 289-305 ◽

Cited By ~ 20

Author(s):

Maja Fijałkowska ◽

Barbara Pysera ◽

Krzysztof Lipiński ◽

Danuta Strusińska

Keyword(s):

Protein Synthesis ◽

Protein Degradation ◽

Crude Protein ◽

Raw Material ◽

Nitrogen Compounds ◽

Microbial Protein ◽

Fermentation Inhibitors ◽

Protein Nitrogen ◽

Microbial Protein Synthesis ◽

Positive Effects

Abstract Losses of crude protein during ensiling of herbages, in contrast to carbohydrates, do not affect the reduction of its content; their form is changed into greater solubility non-protein compounds and also highly degraded forms, which lower the efficiency of the microbial protein synthesis in the rumen. These processes are accompanied by a change of amino acid composition of herbage protein and decrease in intestinal digestibility of protein from feeds as a result of the formation of indigestible complexes with carbohydrates (ADIN). Reduction of protein degradation in silages is achieved by accelerated acidity through addition of acids or dominance of homofermentative bacteria. The positive effects of fermentation inhibitors or sorbents use, as well as the wilting of raw material on the level and rate of protein degradation were demonstrated by many researchers. A greater contribution of protein nitrogen and reduction of deamination in silages can also be obtained by using bacteria inoculants. Increasing the proportion of protein nitrogen is accompanied by the improved efficiency of microbial protein synthesis.

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Pervaporation for Ethanol-Water Separation and Effect of Fermentation Inhibitors

Membrane Processes ◽

10.1002/9781119418399.ch3 ◽

2018 ◽

pp. 89-122

Author(s):

Anjali Jain ◽

Sushant Upadhyaya ◽

Ajay K. Dalai ◽

...

Keyword(s):

Fermentation Inhibitors ◽

Water Separation

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Characterization of a novel Aspergillus niger beta-glucosidase tolerant to saccharification of lignocellulosic biomass products and fermentation inhibitors

Chemical Papers ◽

10.1515/chempap-2015-0111 ◽

2015 ◽

Vol 69 (8) ◽

Cited By ~ 10

Author(s):

Alesandra Oriente ◽

Robson Tramontina ◽

Diandra de Andrades ◽

Caroline Henn ◽

Jose L. C. Silva ◽

...

Keyword(s):

Aspergillus Niger ◽

Lignocellulosic Biomass ◽

Culture Conditions ◽

Industrial Wastes ◽

Fermentation Inhibitors ◽

State Culture ◽

Solid State Culture ◽

Atlantic Rainforest Biome ◽

Beta Glucosidase

AbstractProperties of beta-glucosidase produced by Aspergillus niger URM 6642 recently isolated from the Atlantic rainforest biome and its potential tolerance to saccharification of lignocellulosic biomass products and fermentation inhibitors was evaluated. The fungus was cultivated under solid state culture conditions at 37°C with different agro-industrial wastes. High levels of beta-glucosidase (3778.9 U g

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Study of Carbohydrate Hydrolysis From Arracacha Roots (Arracacia Xanthorriza Bancroft) to Produce Fermentable Sugars

Ingeniería e Investigación ◽

10.15446/ing.investig.v41n2.87365 ◽

2021 ◽

Vol 41 (2) ◽

pp. e87365

Author(s):

Darwin Carranza Saavedra ◽

Jorge Andrés Alvarado Nuñez ◽

José Fernando Solanilla Duque ◽

Claudia Patricia Valenzuela Real

Keyword(s):

Acetic Acid ◽

Sulfuric Acid ◽

Mechanical Damage ◽

Maximum Level ◽

Raw Material ◽

Saturated Steam ◽

Fermentation Inhibitors ◽

Carbohydrate Hydrolysis ◽

Fermentable Carbohydrates ◽

High Yields

In Colombia, approximately 855 840 tons of arracacha are produced each year. The unsalable postharvest arracacha root (Arracacia xanthorriza Bancroft) is not commercialized, mainly due to mechanical damage or small and misshapen roots. In this work, dry samples were characterized and subjected to two treatments: one using thermal hydrolysis, applying saturated steam at pressures of 0,1034 MPa, 0,2068 MPa, and 0,4137 MPa; and another one using hydrolysis with sulfuric acid in concentrations between 0,252,00 M. Then, the cake resulting from the hydrolysis and filtration process was enzymatically hydrolyzed (Liquozyme SC DS, Novozymes) at 1,5, 5 and 10 KNU/g (pH 6, 80 _C, 2 h). Fermentation inhibitors (acetic acid and furfural) were evaluated in the best pretreatment. The results showed that the treatment with sulfuric acid at 1,00 M (2 h) has high yields in reducing sugars added to enzymatic hydrolysis. The maximum level of fermentable carbohydrates per gram of dry sample (1,04 g/g) was also reached. Regarding the fermentation inhibitors of the reducing sugar, a higher concentration of acetic acid was found with a lower furfural content. Therefore, arracacha discards are a promising raw material to increase the supply of bioethanol.

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Pretreatment of lignocellulosic material with fungi capable of higher lignin degradation and lower carbohydrate degradation improves substrate acid hydrolysis and the eventual conversion to ethanol

Canadian Journal of Microbiology ◽

10.1139/w08-003 ◽

2008 ◽

Vol 54 (4) ◽

pp. 305-313 ◽

Cited By ~ 75

Author(s):

Sarika Kuhar ◽

Lavanya M. Nair ◽

Ramesh Chander Kuhad

Keyword(s):

Phanerochaete Chrysosporium ◽

Lignin Degradation ◽

Ethanol Yield ◽

Fungal Isolate ◽

Fermentation Inhibitors ◽

Pycnoporus Cinnabarinus ◽

Acid Hydrolysate ◽

Carbohydrate Degradation ◽

Fungal Pretreatment ◽

Acid Load

Phanerochaete chrysosporium , Pycnoporus cinnabarinus ,and fungal isolates RCK-1 and RCK-3 were tested for their lignin degradation abilities when grown on wheat straw (WS) and Prosopis juliflora (PJ) under solid-state cultivation conditions. Fungal isolate RCK-1 degraded more lignin in WS (12.26% and 22.64%) and PJ (19.30% and 21.97%) and less holocellulose in WS (6.27% and 9.39%) and PJ (3.01% and 4.58%) after 10 and 20 days, respectively, than other fungi tested. Phanerochaete chrysosporium caused higher substrate mass loss and degraded more of holocellulosic content (WS: 55.67%; PJ: 48.89%) than lignin (WS: 18.89%; PJ: 20.20%) after 20 days. The fungal pretreatment of WS and PJ with a high-lignin-degrading and low-holocellulose-degrading fungus (fungal isolate RCK-1) for 10 days resulted in (i) reduction in acid load for hydrolysis of structural polysaccharides (from 3.5% to 2.5% in WS and from 4.5% to 2.5% in PJ), (ii) an increase in the release of fermentable sugars (from 30.27 to 40.82 g·L–1in WS and from 18.18 to 26.00 g·L–1in PJ), and (iii) a reduction in fermentation inhibitors (total phenolics) in acid hydrolysate of WS (from 1.31 to 0.63 g·L–1) and PJ (from 2.05 to 0.80 g·L–1). Ethanol yield and volumetric productivity from RCK-1-treated WS (0.48 g·g–1and 0.54 g·L–1·h–1, respectively) and PJ (0.46 g·g–1and 0.33 g·L–1·h–1, respectively) were higher than untreated WS (0.36 g·g–1and 0.30 g·L–1·h–1, respectively) and untreated PJ (0.42 g·g–1and 0.21 g·L–1·h–1, respectively).

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Novel Approach in the Construction of Bioethanol-Producing Saccharomyces cerevisiae Hybrids

Food Technology and Biotechnology ◽

10.17113/ftb.57.01.19.5685 ◽

2019 ◽

Vol 57 (1) ◽

pp. 5-16 ◽

Cited By ~ 1

Author(s):

Anamarija Štafa ◽

Andrea Pranklin ◽

Ivan Krešimir Svetec ◽

Božidar Šantek ◽

Marina Svetec Miklenić ◽

...

Keyword(s):

Saccharomyces Cerevisiae ◽

Gene Targeting ◽

Co2 Production ◽

Production Test ◽

Fermentation Inhibitors ◽

Lignocellulosic Hydrolysates ◽

Novel Approach ◽

Ethanol Producer ◽

High Ethanol ◽

Selection Of

Bioethanol production from lignocellulosic hydrolysates requires a producer strain that tolerates both the presence of growth and fermentation inhibitors and high ethanol concentrations. Therefore, we constructed heterozygous intraspecies hybrid diploids of Saccharomyces cerevisiae by crossing two natural S. cerevisiae isolates, YIIc17_E5 and UWOPS87-2421, a good ethanol producer found in wine and a strain from the flower of the cactus Opuntia megacantha resistant to inhibitors found in lignocellulosic hydrolysates, respectively. Hybrids grew faster than parental strains in the absence and in the presence of acetic and levulinic acids and 2-furaldehyde, inhibitors frequently found in lignocellulosic hydrolysates, and the overexpression of YAP1 gene increased their survival. Furthermore, although originating from the same parental strains, hybrids displayed different fermentative potential in a CO2 production test, suggesting genetic variability that could be used for further selection of desirable traits. Therefore, our results suggest that the construction of intraspecies hybrids coupled with the use of genetic engineering techniques is a promising approach for improvement or development of new biotechnologically relevant strains of S. cerevisiae. Moreover, it was found that the success of gene targeting (gene targeting fidelity) in natural S. cerevisiae isolates (YIIc17_E5α and UWOPS87-2421α) was strikingly lower than in laboratory strains and the most frequent off-targeting event was targeted chromosome duplication.

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