Biochemical Engineering Journal 48 (2009) 51–57 Contents lists available at ScienceDirect Biochemical Engineering Journal journal homepage: www.elsevier.com/locate/bej Enhanced production of xylanase by a newly isolated Aspergillus terreus under solid state fermentation using palm industrial waste: A statistical optimization Garapati Suvarna Lakshmi a , Chaganti Subba Rao a , Ravella Sreenivas Rao b , Phil J. Hobbs b , Reddy Shetty Prakasham a,∗ a Bioengineering and Environmental Centre, Indian Institute of Chemical Technology, Habsiguda, Hyderabad, Andhra Pradesh 500 607, India b North Wyke Research, Okehampton, Devon EX20 2SB, UK article info Article history: Received 18 March 2009 Received in revised form 14 July 2009 Accepted 15 August 2009 Keywords: Xylanase Hemicellulosic material hydrolyzing enzyme Aspergillus terreus Optimization Solid state fermentation Taguchi methodology abstract Xylanase production by a newly isolated Aspergillus terreus MTCC 8661 was optimized using palm fiber in solid state fermentation (SSF). Different fermentation parameters such as incubation temperature, moisture content, medium pH, particle size, incubation time, inoculum, xylose and sodium nitrate con- centrations were investigated at the individual and interactive level by the Taguchi methodology. All selected fermentation parameters influenced xylanase production. Moisture content, incubation time and inoculum concentration were the major [∼85%] influential parameters on xylanase production at the individual level. At the interactive level, inoculum concentration was important and accounted for more than 50% of the severity index with particle size and incubation temperature. Xylanase produc- tion improved from 41,000 to 115,000 U/g indicating 227% improvement after optimization suggesting that this fungal strain, A. terreus MTCC 8661, has the commercial potential for hemicellulosic enzyme production. © 2009 Published by Elsevier B.V. 1. Introduction Xylan is an integral part of lignocellulosic structure, which is the most abundant and renewable biomass available on earth [1]. It is an heterogeneous polysaccharide consisting of -1,4-linked d-xylosyl residues along with a small fraction of arabinose, glu- curonic and arabinoglucuronic acids linked to the d-xylose back bone [2]. Several industrial processes have been developed that utilize agro-industrial biomass residues as raw materials for the production of bulk chemicals such as ethanol and single-cell protein and enzymes. In fact, use of agro-industrial residues in bioprocesses is effective as alternative bio-substrates, and may reduce pollution problems caused by their disposal [3]. Xylanases [EC.3.2.1.8] are responsible for hydrolysis of xylan; they first attack the internal main-chain linkages and subsequently releasing xylosyl residues by endwise attack of xylooligosaccharides [4]. These enzymes have recently attracted considerable attention due to their application potential in hydrolysis or bioconversion of lignocelluloses to sugars. In addition, xylanases also have application potential in indus- tries involved in clarification of juices, extraction of plant oils and extracellular polymeric substances [EPS]. They have been known ∗ Corresponding author. Tel.: +91 40 27191664; fax: +91 40 27193159. E-mail address: prakasam@iict.res.in (R.S. Prakasham). to improve the nutritional value of silage, green feed, coffee, starch and as bleaching agents in pulp and paper industry [5–8]. A variety of microorganisms including bacteria, yeast and fila- mentous fungi have been reported to produce xylanolytic enzymes [9–11]. The research indicated that xylanase production differed with different strains and was regulated by the physiological, nutri- tional, and biochemical nature of the microbes employed [4,8–10]. Notable environmental and fermentation factors that influence metabolism-mediated production yields include pH, temperature, aeration, agitation, carbon and nitrogen sources, metal ion require- ment, incubation time, initial inoculum size, etc., [12–15]. Hence, for commercial production, optimization of medium composition is one of the essential steps to minimize the amount of unuti- lized components for a cost-effective yield. In general, no defined medium has been established for the best production of any metabolite because the genetic diversity present in different micro- bial sources causes each organism or strain to have its own special conditions for maximum yield of production [15]. Therefore, it is highly imperative to optimize all fermentation parameters includ- ing medium composition, which further facilitates economic design of the full-scale operation system for newly isolated microbial strains. However, it is impractical to optimize all fermentation parameters in conventional methodology to establish the optimum conditions by understanding the interactions of all parameters, as this involves numerous experiments if all possible combina- 1369-703X/$ – see front matter © 2009 Published by Elsevier B.V. doi:10.1016/j.bej.2009.08.005