Mushroom spent straw: a potential substrate for an ethanol-based biorefinery (original) (raw)
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Enzymatic saccharification of pretreated rice straw and biomass production
Biotechnology and Bioengineering, 1986
A comparative study on the saccharification of pretreated rice straw was brought about by using cellulase enzyme produced by Aspergillus terreus ATCC 52430 and its mutant strain UNGIBO. The effect of enzyme and substrate concentrations on the saccharification rate at 24 and 48 were studied. A syrup with 7% sugar concentration was obtained with a 10% substrate concentration for t h e mutant case, whereas a syrup with 6.8% sugar concentration was obtained with 3.5 times concentrated enzyme from the wild strain. A high saccharification value was obtained with low substrate concentration; the higher the substrate concentration used, the lower the percent saccharification. The glucose content in the hydrolysate comprised 8O-82% of total reducing sugars; the remainder was cellobiose and xylose together. The hydrolysate supported the growth of yeasts Candida utilis and Saccharomyces cerevisiae ATCC 52431. A biomass with a 48% protein content was obtained. The essential amino acid composition of yeast biomass was determined.
Journal of Fungi, 2021
The utilization of rice straw for biofuel production is limited by its composition. The pretreatment process is required to improve the enzymatic accessibility of polysaccharides in the biomass prior to enzymatic saccharification. In this study, simultaneous biological pretreatment and saccharification (SPS) of rice straw starting from laccase production by Panus neostrigosus I9 was operated in a 2-L fermenter. It was found that fungal physiology was strongly influenced by the agitation, and that the highest laccase production was obtained at an agitation speed of 750 rpm (209.96 ± 0.34 U/L). The dilution rate of 0.05 h−1 was set in continuous fermentation which resulted in laccase activity of 678.49 ± 20.39 U/L, approximately three times higher than that in batch culture. Response surface methodology (RSM) was applied to achieve the condition for maximum percentage of delignification. The maximum percentage of delignification of 45.55% was accomplished after pretreatment of rice st...
Reducing sugar production of 3 species mushrooms spent media for bioethanol
INTERNATIONAL ENERGY CONFERENCE ASTECHNOVA 2019, 2020
Using lignocellulose materials as bioethanol feed stocks requires an efficient pretreatment process to reduce cellulose resistance. Among various types of pretreatment, biological pretreatment is a low-cost pretreatment technique. The edible white-rot fungus is a promising candidate for pretreatment of lignocellulosic biomass. This research used media waste from 3 types of edible mushrooms namely Ear, Lingzhi, and Oyster which has been cultivated for 90, 100, 110 days. The experiment results showed that the cultivation process can decrease the media weight up to 24.22% as well as reduce the content of chemical media components significantly. The interaction between the types of fungi and cultivation period provides a significant interaction on the extractive levels of ethanol-toluene, holocellulose, α-cellulose, hemicellulose, and acid soluble lignin. A hydrolysis rate of cultivation media waste on acid hydrolysis method is 0.28-28.7% while enzyme hydrolysis 9.3-25.64%. The results of t-test analysis between acid hydrolysis method and an enzyme showed significant difference in reducing sugar content. The average yield of reducing sugar levels of acid hydrolysis method (1.18 mg/ml) is lower than reducing sugar levels of enzyme hydrolysis method (3.5 mg/ml). The highest reducing sugar content was produced from Lingzhi mushroom waste media with cultivation period of 100 days and enzyme hydrolysis method, which amounted to 4.34 mg/ml.
Fungal pretreatment: An alternative in second-generation ethanol from wheat straw
Bioresource Technology, 2011
The potential of a fungal pretreatment combined with a mild alkali treatment to replace or complement current physico-chemical methods for ethanol production from wheat straw has been investigated. Changes in substrate composition, secretion of ligninolytic enzymes, enzymatic hydrolysis efficiency and ethanol yield after 7, 14 and 21 days of solid-state fermentation were evaluated. Most fungi degraded lignin with variable selectivity degrees, although only eight of them improved sugar recovery compared to untreated samples. Glucose yield after 21 days of pretreatment with Poria subvermispora and Irpex lacteus reached 69% and 66% of cellulose available in the wheat straw, respectively, with an ethanol yield of 62% in both cases. Conversions from glucose to ethanol reached around 90%, showing that no inhibitors were generated during this pretreatment. No close correlations were found between ligninolytic enzymes production and sugar yields.
2015
A B S T R A C T Cellulases are a group of hydrolytic enzymes and are capable of degrading lignocellulosic materials. Cellulases have wide range of applications. This work focuses on factors relevant for improvement of enzymatic hydrolysis of rice straw by using isolated fungal strain from compost pit. Different cultural conditions were examined to assess their effect in optimizing enzyme production as well as for characterization of enzyme after partial purification. In comparison with WR (White rot fungi), our isolated strain 2b reports higher production of cellulases. K e y w o r d s Fungal cellulase, Lignocellulolytic agrowaste, Enzymatic saccharification
Molecules
A large amount of agro-industrial waste is produced worldwide in various agricultural sectors and by different food industries. The disposal and burning of this waste have created major global environmental problems. Agro-industrial waste mainly consists of cellulose, hemicellulose and lignin, all of which are collectively defined as lignocellulosic materials. This waste can serve as a suitable substrate in the solid-state fermentation process involving mushrooms. Mushrooms degrade lignocellulosic substrates through lignocellulosic enzyme production and utilize the degraded products to produce their fruiting bodies. Therefore, mushroom cultivation can be considered a prominent biotechnological process for the reduction and valorization of agro-industrial waste. Such waste is generated as a result of the eco-friendly conversion of low-value by-products into new resources that can be used to produce value-added products. Here, we have produced a brief review of the current findings th...
Bioresources, 2015
This work aimed at improving the hydrolysis and fermentation processes of rice straw through different ammonia-based pretreatments to aid in bioethanol production. For this purpose, pretreatment was performed at 70 °C for 12 h, followed by enzymatic hydrolysis at 50 °C for 24 h and 72 h using 15 FPU cellulase and 30 CBU cellobiase. The best hydrolysis yield, based on the production yield and rate, for the 24-h digestion period was samples that had been soaked in methanolic aqueous ammonia (SMAA), with 72% of the theoretical maximum. However, for the 72-h digestion period, soaking in ethanolic aqueous ammonia (SEAA) was the best method, with 88% yield. In the case of ethanol production after 24 h, the SMAA pretreatment and SSF resulted in the highest yield at 72%. However, after 72 h of simultaneous saccharification and fermentation (SSF), SMAA-pretreated rice straw showed a yield of 85%, while the SEAA-pretreated sample resulted in a noteworthy yield of 89% of the theoretical maximum. However, with regard to the production yield and rate and pretreatment cost, the best method for ethanol production was judged to be the SMAA with 5% methanol, particularly after 24 h of SSF.
Practical use of the polysaccharidic fraction of lignocellulosic material is limi- ted by its high lignin content. In this study the lignin-degrading white-rot fungus Trametes trogii Berk. in Trog. was used in the solid-state pre-treatment of wheat straw and the effi- ciency of the enzymatic hydrolysis of the residual cellulose after pre-treatment was analy- sed. Glucose, mineral nitrogen and yeast extract were used to supplement the pre-treatment minimal medium. Results were determined on the basis of levels of glucose and total redu- cing sugars released after batch incubation with foreign cellulases. The principal effect of medium components, as well as the effects of their interaction, were investigated using a two-level full factorial analysis in function of pre-treatment and hydrolysis times. Eviden- ce is provided to show that better results are obtained in the presence of glucose, while the presence of nitrogen sources results in lower yields irrespective of the time course ...