Identification of Fusarium oxysporum Genes Associated with Lignocellulose Bioconversion Competency

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Identification of Fusarium oxysporum Genes Associated with Lignocellulose Bioconversion Competency Shahin S. Ali & Mojibur Khan & Ewen Mullins & Fiona M. Doohan

# Springer Science+Business Media New York 2013

Abstract Fusarium oxysporum can convert straw to ethanol via consolidated bioprocessing (CBP)—a two-stage process that firstly involves aerobic saccharification and thereafter an oxygen-limiting fermentation phase. The efficacy of CBP is dependent upon the fungal strain used. Using suppression subtractive hybridisation (SSH), a total of 210 transcripts were identified as being overexpressed in a high as compared to low efficacy CBP strain in the aerobic and oxygenlimiting growth stages on a straw/bran mix. These transcripts encode proteins assigned to various categories, including carbohydrate metabolism, energy, protein and sugar transport and detoxification. Real-time RT-PCR analysis of 12 transcripts, including an endoglucanase III (EGIII), a novel ricin toxin A1 chain-like protein (RTA1), and two unknown transcripts (JX308289 and JX308290) validated the SSH findings. Post-transcriptional silencing of EGIII, RTA1 and an unknown transcript JX308289 in F. oxysporum strain 11C

Electronic supplementary material The online version of this article (doi:10.1007/s12155-013-9353-0) contains supplementary material, which is available to authorized users. S. S. Ali : M. Khan : F. M. Doohan Molecular Plant-Microbe Interactions Laboratory, School of Biology and Environmental Science, University College Dublin, Dublin 4, Ireland S. S. Ali (*) USDA/ARS Sustainable Perennial Crops Lab, BARC-West Bldg 001, Beltsville, MD 20705, USA e-mail: [email protected] E. Mullins Department of Crop Science, Teagasc Crop research Centre, Oak Park, Carlow, Ireland Present Address: M. Khan Institute of Advanced Study in Science and Technology, Guwahati-35, India

significantly reduced the capacity of the fungus to produce ethanol from a straw/bran mix. Thus these and other genes identified in this study are likely factors that determine the efficacy of CBP and such genes can be used as candidates for enhancing microbial ethanol production from straw and other lignocellulosic substrates. Keywords Ethanol . Fungi . Transcriptome . Lignocellulose . Straw . RTA1-like protein

Introduction Industry and researchers are trying continually to reduce the cost of ethanol production from lignocellulosic materials. Lignocellulosic wheat straw is one of the most abundant lignocellulosic crop by-products and it could potentially yield up to 104 hm3 per year of ethanol and thus make a significant contribution to our energy needs [1]. The current technology for lignocellulosic ethanol production involves several steps: feedstock pre-treatment, hydrolytic enzyme production, saccharification, fermentation and product recovery. In recent years there has been much research focused on understanding and improving the efficacy of microbial bioconversion of lignocellulose to ethanol. There is a great diversity among microbes in terms of their capacity t