Contents lists available at ScienceDirect Process Biochemistry journal homepage: www.elsevier.com/locate/procbio Turning oil palm empty fruit bunch waste into substrate for optimal lipase secretion on solid state fermentation by Trichoderma strains Haliru Musa a,b , Pang Chien Han a , Farizul Hafiz Kasim a,b, ⁎ , Subash C.B. Gopinath a , Mohd Azmier Ahmad c a School of Bioprocess Engineering, Universiti Malaysia Perlis, 02600, Arau, Perlis, Malaysia b Centre of Excellence for Biomass Utilization, School of Bioprocess Engineering, Universiti Malaysia Perlis, 02600, Arau, Perlis, Malaysia c School of Chemical Engineering, Universiti Sains Malaysia, Engineering Campus, Pulau Pinang, Malaysia ARTICLE INFO Keywords: Extracellular lipase Oil palm empty fruit bunch Trichoderma strains Hypocrea neorufa Response surface methodology ABSTRACT This study is aimed to improving extracellular lipase production by Trichoderma strains using oil palm empty fruit bunch (OPEFB) medium on solid state fermentation with the assistance of statistical optimization. Two selected Trichoderma strains (Trichoderma sp.1 and Hypocrea neorufa.1) with high lipase producing potential were employed in a stepwise optimization. Initially, the influence of nutritional (carbon, nitrogen sources, and inducers) and environmental (moisture and temperature) factors on lipase production was evaluated using One- Factor-At-A-time (OFAT) method. Next, three most influential factors (Glucose, Urea and Olive oil) resulting from OFAT were optimized for lipase production by Trichoderma sp.1 using the central composite design under response surface methodology. Experiments conducted under optimum conditions (10.38% (w/w) glucose, 0.86% (w/w) urea, and 7.38% (v/w) olive oil) were further improved the lipase production from 0.195 to 0.390 Ug -1 , which is about 2 folds greater than un-optimized condition. This study demonstrated that OPEFB can be utilized as inexpensive substrate for improving the lipase secretion by Trichoderma sp.1. 1. Introduction Palm oil industry is one of the most significant industries generating agricultural wastes, especially oil palm empty fruit bunch (OPEFB) [1]. OPEFB is an agricultural by-product of the extraction of palm oil from the fresh fruit bunches and it is the major solid waste material from the extraction process alongside other solid waste materials, which include kernel shells and mesocarp fibres. It is a lignocellulose rich crop residue with high porosity, water and nutrient holding capacity [2]. Palm oil mills in Malaysia have been reported to generate 2.4 million tons of OPEFB annually, where a little fraction of it is used as fuel for electricity and steam production and most of them dumped as waste [3]. The utilization of this waste material for lipase production via Solid State Fermentation would not only solve waste disposal problem in the in- dustry but also produce a valuable product like lipase [4]. Lipases are triacylglycerol acylhydrolases (EC 3.1.1.3), catalyze the hydrolysis of triglycerides into diglycerides, and monoglycerides, fur- ther hydrolysed to glycerol and fatty acids [5–7]. Microbial lipases occur widely in bacteria, actinomycetes [8] and yeast but fungal lipases are most favourable, because of their industrial applications. Fungi are preferably used for industrial applications because they are generally secreting extracellular enzymes [9,10] and enhance lipase recovery from the fermentation media as well as their excellent tolerance to high osmotic pressure conditions, low water activity, and colonization ability on solid substrates [11]. Although lipase could be produced by either solid state fermenta- tion (SSF) or submerged fermentation (SmF), use of agro-industrial residues for lipase secretion via SSF is preferred due to the greater stability of the enzyme, low production cost, and simplicity of the entire process [12]. SSF is the fermentation process that involves growing microorganisms on solid substrate/matrix, which is conducted in the absence (or near absence) of free water but the substrate, however, must contain enough moisture to support microbial metabolism and growth [13]. In order to achieve successful SSF process for the lipase production, some important parameters such as selection of an appro- priate microbial strain and solid support, optimization of process parameters, and selection of the most suitable downstream process for the end product recovery is pertinent [14]. Studies on the preference of appropriate substrates for SSF have been concentrated around agro-industrial wastes because of the po- tentials of filamentous fungi, with the ability to penetrate into the harder substrates, aided by the turgor pressure presence at the terminal http://dx.doi.org/10.1016/j.procbio.2017.09.002 Received 6 August 2017; Accepted 1 September 2017 ⁎ Corresponding author at: School of Bioprocess Engineering, Universiti Malaysia Perlis, 02600, Arau, Perlis, Malaysia. E-mail address: farizul@unimap.edu.my (F.H. Kasim). Process Biochemistry xxx (xxxx) xxx–xxx 1359-5113/ © 2017 Elsevier Ltd. All rights reserved. Please cite this article as: Musa, H., Process Biochemistry (2017), http://dx.doi.org/10.1016/j.procbio.2017.09.002