Defined enzyme cocktail from the anaerobic fungus Orpinomyces sp. strain C1A effectively releases sugars from pretreated corn stover and switchgrass.

Jessica M Morrison,Noha H Youssef,Mostafa S Elshahed

doi:10.1038/srep29217

Abstract

The anaerobic fungus Orpinomyces strain C1A is capable of growth on various types of lignocellulosic substrates, and harbors an impressive reservoir of carbohydrate active enzymes (CAZymes). Using a minimum enzyme cocktail strategy, we constituted a four-component lignocellulolytic cocktail derived from highly transcribed C1A, and evaluated its efficacy against pretreated corn stover and switchgrass. Hydrolysis yields ranged between 65–77.4%, depending on the lignocellulosic substrate and pretreatment applied. Addition of a highly expressed anaerobic fungal swollenin improved hydrolysis yields by up to 7%. Compared to the commercial cocktail CTec2, these anaerobic fungal cocktails provided comparable or slightly lower hydrolysis yields. Further, the differences in efficacy between commercial and anaerobic cocktails were often only realized after extended (168 hr) incubations. Under certain conditions, the hydrolysis yields of the anaerobic fungal cocktail was slightly superior to that realized by CTec2. We attribute the observed high hydrolysis yields to the high specific activity and affinity of the individual enzymes of the cocktail, as well as the high level of synergy and multi-functionality observed in multiple components. Collectively, this effort provides a novel platform for constructing highly effective enzymes for biofuel production and represents the first lignocellulolytic enzyme cocktail created from anaerobic fungal enzymes.

Highlights

Not available, it is impossible to conduct a systematic cost/yield analysis to evaluate the relative contribution of individual cocktail components to the overall hydrolysis yields and assess whether their inclusion is economically justifiable
Many of the activities reported in such commercial cocktails mediate the hydrolysis of polymers that are present in exceedingly low levels in common lignocellulosic substrates e.g. mannan (0.3–0.4% in corn stover and switchgrass)[6] and pectin (2–10% in corn stover and switchgrass)[7]
We concur with Meyers et al.[3] that the construction and optimization of a defined, highly effective, and minimal component enzymatic cocktail that solely targets the key abundant polymers in lignocellulosic biomass represents an extremely promising approach for the development of a highly effective and lower cost lignocellulosic enzyme cocktail

Summary

Introduction

Not available, it is impossible to conduct a systematic cost/yield analysis to evaluate the relative contribution of individual cocktail components to the overall hydrolysis yields and assess whether their inclusion is economically justifiable. The economic justification for the inclusion of multiple accessory enzymes has recently come into question[1,3,4,8], since commonly utilized plant biomass pretreatment approaches often achieve the same outcome. Based on these arguments, we concur with Meyers et al.[3] that the construction and optimization of a defined, highly effective, and minimal component enzymatic cocktail that solely targets the key abundant polymers (cellulose and hemicellulose) in lignocellulosic biomass represents an extremely promising approach for the development of a highly effective and lower cost lignocellulosic enzyme cocktail. The high hydrolysis yields obtained, coupled with the simplicity and defined nature of these preparations, renders them a promising alternative to commercial preparations and highlights the value of bioprospecting for novel enzymes in poorly studied lignocellulolytic microorganisms

Methods

Results

Conclusion