Date: 13 Mar 2014

Solid-state fermentation of coconut kernel-cake as substrate for the production of lipases by the coconut kernel-associated fungus Lasiodiplodia theobromae VBE-1

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Abstract

Plant oil-extracted seed-cakes are good fermentation substrates for producing lipases that find application in transesterification of seed oils into biodiesel. This work describes the production of lipases by five lipolytic, oil-seed associated fungi (Aspergillus niger, Chalaropsis thielavioides, Colletotrichum gloeosporioides, Lasiodiplodia theobromae, and Phoma glomerata) by Solid-State Fermentation (SSF) on eight plant oil-seed cakes. The highest lipase activity was from the Coelomycete Lasiodiplodia theobromae VBE-1 grown on coconut kernel-cake, and was selected to optimize lipase production. The effects of supplementing coconut kernel-cake with mineral salts and coconut oil on lipase production by L. theobromae VBE-1 resulted in enhanced lipase activity. The effects of time of growth, moisture content, initial pH, temperature, as well as nutritional factors (carbon, nitrogen, vegetable oils, surfactants) when added to coconut kernel-cake, on lipase production were examined by a one-factor-at-a-time approach, and identified key variables for optimization by Response Surface Methodology (RSM). A 26 factorial central-composite experimental design with eight starting points and six replicates at the central point was used for lipase optimization. After validating the predicted levels of the factors, lipase production rose to 698 U/g Dry Substrate (DS) over un-optimized conditions (450 U/g DS).