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Lignocellulosic fermentation

Kevin T Finneran, Jovan Popovic
Xylose is the second most abundant sugar derived from lignocellulose; it is considered less desirable than glucose for fermentation, and strategies that specifically increase xylose utilization in wild type or engineered cells are goals for biofuel production. Issues arise with xylose utilization because of carbohydrate catabolite repression, which is the preferential utilization of glucose relative to xylose in fermentations with both pure and mixed cultures. Taken together the low substrate utilization rates and solvent yields with xylose compared to glucose, many industrial fermentations ignore the xylolytic portion of the reaction in lieu of methods to maintain high glucose...
August 14, 2018: Applied Microbiology and Biotechnology
Wagner Artifon, Charline Bonatto, Eduarda R Bordin, Suzana F Bazoti, Adriana Dervanoski, Sérgio L Alves, Helen Treichel
Bioethanol production has been presented as an alternative for supplying energy demand and minimizing greenhouse gases effects. However, due to abrasively conditions employed on the biomass during pretreatment and hydrolysis processes, inhibitors for fermentation phase such as acetic acid and others can be generated. Based on this problem, the aim of this work was to evaluate the adsorption of acetic acid on microporous activated carbon and investigate the stripping of the same component with dried air. For adsorption process, three concentrations of acetic acid (5, 10, and 20%) were analyzed by adsorption kinetics and adsorption isotherms (Langmuir and Freundlich models)...
2018: Frontiers in Bioengineering and Biotechnology
Mpc Volpi, V S Santos, Apb Ribeiro, Mha Santana, R G Bastos
The aim of this research was to study the production of humic acids (HA) by Trichoderma reesei from empty fruit bunches (EFBs) of palm oil processing, with a focus on the effects of lignocellulosic content and residual lipids. EFBs from two different soils and palm oil producers were previously characterized about their lignocellulosic composition. Submerged fermentations were inoculated with T. reesei spores and set up with or without residual lipids. The results showed that the soil and the processing for removal of the palm fresh fruits were crucial to EFB quality...
August 14, 2018: Applied Biochemistry and Biotechnology
Arup Jyoti Borah, Mayank Agarwal, Arun Goyal, Vijayanand S Moholkar
Invasive weeds ubiquitously found in terrestrial and aquatic ecosystems form potential feedstock for lignocellulosic ethanol production. The present study has reported a bioprocess for production of ethanol using mixed feedstock of 8 invasive weeds found in India. The feedstock was subjected to pretreatment comprising dilute acid hydrolysis (for hydrolysis of hemicellulosic fraction), alkaline delignification and enzymatic hydrolysis of cellulosic fraction. Pentose-rich and hexose-rich hydrolyzates obtained from pretreatment were fermented separately using microbial cultures of S...
August 1, 2018: Ultrasonics Sonochemistry
Ninad Kothari, Evert K Holwerda, Charles M Cai, Rajeev Kumar, Charles E Wyman
Background: The thermophilic anaerobic bacterium Clostridium thermocellum is a multifunctional ethanol producer, capable of both saccharification and fermentation, that is central to the consolidated bioprocessing (CBP) approach of converting lignocellulosic biomass to ethanol without external enzyme supplementation. Although CBP organisms have evolved efficient machinery for biomass deconstruction, achieving complete solubilization requires targeted approaches, such as pretreatment, to prepare recalcitrant biomass feedstocks for further biological digestion...
2018: Biotechnology for Biofuels
Sabeera Haris, Chuanji Fang, Juan-Rodrigo Bastidas-Oyanedel, Kristala Jones Prather, Jens Ejbye Schmidt, Mette Hedegaard Thomsen
Bacterial contamination is one of the major challenges faced by yeast fermentation industries as the contaminating microorganisms produce lactic acid and acetic acid, which reduces the viability of yeast, and hence fermentation yields. The primary bacterial contaminants of yeast fermentations are lactic acid bacteria (LAB). This study aims to identify potential natural antibacterial fractions from raw and pretreated lignocellulosic biomasses found in Abu Dhabi, UAE, in terms of LAB inhibition capacity, allowing growth of the yeast...
August 6, 2018: AMB Express
Plínio R Rodrigues, Mateus F L Araújo, Tamarah L Rocha, Ronnie Von S Veloso, Lílian A Pantoja, Alexandre S Santos
The production of lignocellulosic ethanol is one of the most promising alternatives to fossil fuels; however, this technology still faces many challenges related to the viability of the lignocellulosic alcohol in the market. In this paper the endocarp of buriti fruit was assessed for ethanol production. The fruit endocarp was characterized physically and chemically. Acid and alkaline pre-treatments were optimized by surface response methodology for removal of hemicellulose and lignin from the biomass. Hemicellulose content was reduced by 88% after acid pretreatment...
2018: PeerJ
Javad Gharechahi, Ghasem Hosseini Salekdeh
Background: The diverse microbiome present in the rumen of ruminant animals facilitates the digestion of plant-based fiber. In this study, a shotgun metagenomic analysis of the microbes adhering to plant fiber in the camel rumen was undertaken to identify the key species contributing to lignocellulose degradation and short chain volatile fatty acids (VFA) fermentation. Results: The density of genes in the metagenome encoding glycoside hydrolases was estimated to be 25 per Mbp of assembled DNA, which is significantly greater than what has been reported in other sourced metagenomes, including cow rumen...
2018: Biotechnology for Biofuels
Vibhavee Sukruansuwan, Suchada Chanprateep Napathorn
Background: Pineapple is the third most important tropical fruit produced worldwide, and approximately 24.8 million tons of this fruit are produced annually throughout the world, including in Thailand, which is the fourth largest pineapple producer in the world. Pineapple wastes (peel and core) are generated in a large amount equal to approximately 59.36% based on raw material. In general, the anaerobic digestion of pineapple wastes is associated with a high biochemical oxygen demand and high chemical oxygen demand, and this process generates methane and can cause greenhouse gas emissions if good waste management practices are not enforced...
2018: Biotechnology for Biofuels
Shingo Miyauchi, Anaïs Rancon, Elodie Drula, Hayat Hage, Delphine Chaduli, Anne Favel, Sacha Grisel, Bernard Henrissat, Isabelle Herpoël-Gimbert, Francisco J Ruiz-Dueñas, Didier Chevret, Matthieu Hainaut, Junyan Lin, Mei Wang, Jasmyn Pangilinan, Anna Lipzen, Laurence Lesage-Meessen, David Navarro, Robert Riley, Igor V Grigoriev, Simeng Zhou, Sana Raouche, Marie-Noëlle Rosso
Background: Plant biomass conversion for green chemistry and bio-energy is a current challenge for a modern sustainable bioeconomy. The complex polyaromatic lignin polymers in raw biomass feedstocks (i.e., agriculture and forestry by-products) are major obstacles for biomass conversions. White-rot fungi are wood decayers able to degrade all polymers from lignocellulosic biomass including cellulose, hemicelluloses, and lignin. The white-rot fungus Polyporus brumalis efficiently breaks down lignin and is regarded as having a high potential for the initial treatment of plant biomass in its conversion to bio-energy...
2018: Biotechnology for Biofuels
Yuanfeng Li, Shen Jin, Denggang Wang, Shuli Liang, Suiping Zheng, Ying Lin
Displaying Candida antarctica lipase B (CALB) on the cell surface of Aspergillus niger is effectively applied for the industries of food, cosmetics, pharmaceutical and so on. Displaying CALB using induced promoter of glucoamylase on the cell surface of A. niger SH-1 has some problems such as inhibiting its expression under high concentration of glucose, mycelium cleavage and decreasing enzyme activity in the later period of fermentation process. Displaying CALB manipulated by constitutive promoter from glyceraldehyde-3-phosphate dehydrogenase instead of glucoamylase on the cell surface of A...
July 25, 2018: Sheng Wu Gong Cheng Xue Bao, Chinese Journal of Biotechnology
María Hijosa-Valsero, Ana I Paniagua-García, Rebeca Díez-Antolínez
Potato peel from a snack factory was assessed as possible feedstock for biobutanol production. This lignocellulosic biomass was subjected to various physicochemical pretreatments (autohydrolysis and hydrolysis with dilute acids, alkalis, organic solvents or surfactants) under different conditions of time, temperature and reagent concentrations, in order to favour the release of sugars and reduce the generation of fermentation inhibitors. Thereafter, the pretreated potato peel was treated enzymatically to complete the hydrolysis...
November 25, 2018: New Biotechnology
Sara L Baptista, Joana T Cunha, Aloia Romaní, Lucília Domingues
In this work, the industrial Saccharomyces cerevisiae PE-2 strain, presenting innate capacity for xylitol accumulation, was engineered for xylitol production by overexpression of the endogenous GRE3 gene and expression of different xylose reductases from Pichia stipitis. The best-performing GRE3-overexpressing strain was capable to produce 148.5 g/L of xylitol from high xylose-containing media, with a 0.95 g/g yield, and maintained close to maximum theoretical yields (0.89 g/g) when tested in non-detoxified corn cob hydrolysates...
July 20, 2018: Bioresource Technology
Gossa G Wordofa, Mette Kristensen
Background: Bio-conversion of lignocellulosic biomass to high-value products offers numerous benefits; however, its development is hampered by chemical inhibitors generated during the pretreatment process. A better understanding of how microbes naturally respond to those inhibitors is valuable in the process of designing microorganisms with improved tolerance. Pseudomonas taiwanensis VLB120 is a natively tolerant strain that utilizes a wide range of carbon sources including pentose and hexose sugars...
2018: Biotechnology for Biofuels
Valtcho Zheljazkov, Charles Neal Stewart, Blake Joyce, Holly Baxter, Dr Charles L Cantrell, Tess Astatkie, Ekaterina Jeliazkova, Charleson Poovaiah
Dual production of biofuels and chemicals can increase the economic value of lignocellulosic bioenergy feedstocks. We compared the bioenergy potential of several essential oil (EO) crops with switchgrass (Panicum virgatum L.), a crop chosen to benchmark biomass and lignocellulosic biofuel production. The EO crops of interest were peppermint (Mentha x piperita L.), 'Scotch' spearmint (Mentha x gracilis Sole), Japanese cornmint (Mentha canadensis L.), and sweet sagewort (Artemisia annua L.). We also assessed each crop for EO production in a marginal production environment in Wyoming, USA, with irrigation and nitrogen rates using a split-plot experimental design...
July 20, 2018: Journal of Agricultural and Food Chemistry
Lahiru N Jayakody, Timothy Lee Turner, Eun Ju Yun, In Iok Kong, Jing-Jing Liu, Yong-Su Jin
Engineered S. cerevisiae employing the xylose reductase pathway enables efficient xylose valorization to fuels and chemicals. However, toxicity of thermochemically pretreated biomass hydrolysate on S. cerevisiae is one of the key technical challenges to upgrade biomass-derived sugars including xylose and glucose into high-value products. We investigated the effect of glycolaldehyde, one of the biomass-derived highly toxic aldehyde compounds, and its combinatorial inhibitory effect with other major fermentation inhibitors commonly found in plant hydrolysate such as methylglyoxal, 5-HMF, furfural, vanillin, and acetic acid on engineered xylose-fermenting S...
July 19, 2018: Applied Microbiology and Biotechnology
Jingfeng Wang, Xixun Hao, Ming Yang, Yujie Qin, Lili Jia, Jie Chu, Junhua Zhang
This work focuses to investigate the impact of lignin content on chemical compositions, crystallinity, surface characterizations, cellulase adsorption profiles and hydrolysability of Hybrid Pennisetum (HP) after alkaline sulfite pretreatment (ASP). For the HP with lower lignin content, the increase of the cellulose content by ASP was more obvious than raw HP. ASP decreased total lignin content and surface lignin content of HP substrates. HP with lower lignin content (e.g., ∼15%) is suitable for ASP, because a pretty perfect glucose yield (91%) was obtained using a low dosage of enzyme loadings (5 FPU of cellulases/g dry matter)...
July 10, 2018: Bioresource Technology
Maarten D Verhoeven, Sophie C de Valk, Jean-Marc G Daran, Antonius J A van Maris, Jack T Pronk
d-Glucose, d-xylose and l-arabinose are major sugars in lignocellulosic hydrolysates. This study explores fermentation of glucose-xylose-arabinose mixtures by a consortium of three 'specialist' Saccharomyces cerevisiae strains. A d-glucose- and l-arabinose-tolerant xylose specialist was constructed by eliminating hexose phosphorylation in an engineered xylose-fermenting strain and subsequent laboratory evolution. A resulting strain anaerobically grew and fermented d-xylose in the presence of 20 g L-1 of d-glucose and l-arabinose...
July 16, 2018: FEMS Yeast Research
Loredana Tarraran, Roberto Mazzoli
Lactic acid bacteria (LAB) have a long history in industrial processes as food starters and biocontrol agents, and also as producers of high-value compounds. Lactic acid, their main product, is among the most requested chemicals because of its multiple applications, including the synthesis of biodegradable plastic polymers. Moreover, LAB are attractive candidates for the production of ethanol, polyhydroalkanoates, sweeteners and exopolysaccharides. LAB generally have complex nutritional requirements. Furthermore, they cannot directly ferment inexpensive feedstocks such as lignocellulose...
August 1, 2018: FEMS Microbiology Letters
Nadchanok Rodrussamee, Pachara Sattayawat, Mamoru Yamada
BACKGROUND: Efficient bioconversion of lignocellulosic biomass to bioethanol is one of key challenges in the situation of increasing bioethanol demand. The ethanologenic microbes for such conversion are required to possess abilities of utilization of various sugars including xylose and arabinose in lignocellulosic biomass. As required additional characteristics, there are a weak or no glucose repression that allows cells to simultaneously utilize various sugars together with glucose and thermotolerance for fermentation at high temperatures, which has several advantages including reduction of cooling cost...
July 13, 2018: BMC Microbiology
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