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Hydrolytic potential of Trichoderma sp. strains evaluated by microplate-based screening followed by switchgrass saccharification

Paper ID Volume ID Publish Year Pages File Format Full-Text
17141 42646 2012 7 PDF Available
Title
Hydrolytic potential of Trichoderma sp. strains evaluated by microplate-based screening followed by switchgrass saccharification
Abstract

Bioconversion of lignocellulosic biomass to fuel requires a hydrolysis step to obtain fermentable sugars, generally accomplished by fungal enzymes. Large-scale screening of different microbial strains would provide optimal enzyme cocktails for any target feedstock. The aim of this study was to screen a large collection of Trichoderma sp. strains for the hydrolytic potential towards switchgrass (Panicum virgatum L.). Strains were cultivated in a small-scale system and assayed in micro-plates for xylanase and cellulase activities. The population distributions of these traits are reported after growth on switchgrass in comparison with cellulose. The distribution profiles suggest that the growth on switchgrass strongly promotes xylanase production. The IK4 strain displayed the highest xylanase activity after growth on switchgrass (133 U/mL). Enzymes (10 FPU/g substrate) from IK4 were compared with those from 2 cellulolytic Trichoderma strains and a commercial enzyme in saccharification time-course experiments on untreated and pretreated switchgrass and on an artificial substrate. Samples were analysed by DNS assay and by an oxygraphic method for sugar equivalent or glucose concentration. On the untreated substrate, IK4 enzymes even outperformed a 5-fold load of commercial enzyme, suggesting that xylanase or accessory enzymes are a limiting factor on this type of recalcitrant substrate. On the other substrates, IK4 preparations showed intermediate behaviour if compared with the commercial enzyme at 10 FPU/g substrate and at 5-fold load. IK4 also nearly halved the time to release 50% of the hydrolysable sugar equivalents (T50%), with respect to the other preparations at the same enzymatic load. DNS assay and oxygraphic method gave highly correlated results for the 3 saccharified substrates. The study suggests that accessory enzymes like xylanase play a key role in improving the performance of cellulase preparations on herbaceous lignocellulosic feedstocks like switchgrass.

► Hydrolytic potential of wild-type Trichoderma isolates was evaluated on switchgrass in miniaturised systems. ► Saccharification was performed in 96 well-plates at the same cellulase load showing relevant differences among isolates. ► One xylanolytic isolate outperformed a 5-fold load commercial enzyme on untreated switchgrass. ► Screenings for improved strains should involve evaluation of both xylanases and cellulases.

Keywords
Lignocellulosic biomass; Biofuel; Cellulase; Xylanase; Switchgrass; Trichoderma
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Hydrolytic potential of Trichoderma sp. strains evaluated by microplate-based screening followed by switchgrass saccharification
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Publisher
Database: Elsevier - ScienceDirect
Journal: Enzyme and Microbial Technology - Volume 50, Issues 6–7, 10 May 2012, Pages 304–310
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us