Abstract
The objective of this study was to determine the potential of different filamentous fungi to degrade cellulose in rice husk pre-treated with steam explosion or alkaline hydrolysis. A preliminary test performed with carboxymethyl cellulose and nine fungi (Trichoderma 1, 2, 3, 4, 5; Trichoderma reesei; Aspergillus niger; Rhizopus oryzae and an isolated fungus from rice husk) allowed the selection of the fungi that can degrade cellulose the most. Subsequently, the fastest growing fungi on the substrate (carboxymethyl cellulose) were subjected to a fermentation bioreactor (18 mL of the fungus with 2 mL of conidial suspension at a concentration of 5 x 106 conidia mL-1). Their potential to degrade cellulose was determined. This was done by measuring the amount of total carbohydrate and reducing sugars using the anthrone method and 3,5 dinitrosalicylic acid respectively. On the other hand, the endoglucanase, exoglucanase and β-glucosidase activity of the two most promising fungus (Trichoderma sp. 1 and Aspergillus sp.) was evaluated. Statistical analysis revealed no significant differences; however, the rice husk pre-treated with steam explosion before the fungal strains had the greatest amount of total carbohydrates; it produces 2.9 and 1.4 times more than those not treated with alkaline hydrolysis. Moreover, fungi Trichoderma sp. 1 and Aspergillus sp. had higher number of total released carbohydrate and reducing respectively, which demonstrated the difference in the enzyme system of the two microorganisms. Endoglucanase and exoglucanase activities had similar performance for Aspergillus sp., and Trichoderma sp. 1, during the 288 h of the test. Likewise, β-glucosidase activity was similar. After 192 h, values of 0.150 and 0.140 IU mL-1 were obtained for Aspergillus sp. and Trichoderma sp. 1, respectively. Finally, the applicability of rice husk in agribusiness as a raw material for subsequent fermentation and for obtaining added-value compounds is shown. Key words: Enzymatic activity, rice husk, fermentable sugar, agroindustrial wastes, filamentous fungi.
Highlights
Cellula ase acttivity of o filam mentou us fung gi indu uced by y rice husk
A preliminary y test perform med with carboxymetthyl cellulos se and nine fungi
Trichoderma a reesei; As spergillus niger; Rhizopus oryzae e and an isolated fungus s from rice h husk) allowe ed the selecttion of the fu ungi that can degrade cellulose th he most
Summary
Dieg go Fernand do Oliveros s1*, Nathalie Guarnizzo[1], Elizabe eth Murillo Perea[1,2] and Walter Murillo. The Trichoderma genus was analyzed because of its ability to produce high cellulolytic enzymes activity (Miettinen-Oinonen and Suominen, 2002), that allows the transformation of plant cell-wall constituents or wastes, such as husk, into simple sugars that may become alcohols after the fermentation process. The search for native microorganisms from substrates could be an alternative for obtaining fungal strains with high potential for a cleaner conversion of lignocellulosic materials, and the use of physical and chemical pretreatments will generate cleaner, cheaper processes and without demanding specialized infrastructure (Llacza and Castellanos, 2012; Martínez-Anaya et al., 2008) In this regard, the objective of this study is to compare the cellulolytic activity of fungal reference strains against those isolated from rice husk, identifying the potential of converting this residue into fermentable sugars
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
