PRODUCTION OF THERMOSTABLE PULLULANASE 383 Jurnal Teknologi, 49(F) Dis. 2008: 383–396 © Universiti Teknologi Malaysia PRODUCTION OF THERMOSTABLE PULLULANASE FROM Bacillus Flavothermus KWF-1: MEDIUM DEVELOPMENT USING EXPERIMENTAL DESIGN WITH DATA TRANSFORMATION ROZAIMI ABU SAMAH 1 , NIK AZMI NIK MAHMOOD 2 , GOH KIAN MAU 3 , OSMAN HASSAN 4 & ROSLI MD ILLIAS 5* Abstract. The extracellular production of pullulanase from Bacillus flavothermus KWF-1 using experimental design was studied. Two-level full factorial design was applied to enhance these nutrient constituents with respect to pullulanase production. Statistical analysis (ANOVA) have identified that tapioca starch was the most significant factor affecting the enzyme production. Diagnostic plots obtained from ANOVA revealed abnormalities with respect to the response data. Therefore, data transformation was advantageous in order to make the distribution of the response variable closer to the normal distribution and to stabilize the variance of the response, as well as to improve the fit of the model to the data. An improved model was attained with higher coefficient of determination (R 2 = 0.9523) compared to original R 2 of 0.9280. The enhanced medium consisted of (% w/v): 3.0 tapioca starch, 0.11 peptone from casein, 0.08 KH 2 PO 4 , 0.02 MnSO 4 and an initial pH of 9.0, produced 3.498 U/ml pullulanase, which was approximately 4.5 fold increment than that obtained from initial medium (0.791 U/ml). Keywords: Medium development; full factorial design; data transformation; pullulanase; bacillus flavothermus Abstrak. Kajian ini dilaksanakan untuk meningkatkan penghasilan pullulanase melalui kaedah reka bentuk eksperimen. Dengan bantuan perisian Design-Expert 6.0.4, peningkatan penghasilan enzim dilakukan menerusi reka bentuk penuh faktorial dua peringkat. Analisis statistik (ANOVA) mengenal pasti bahawa kanji ubi kayu adalah faktor yang memberikan kesan yang paling besar di dalam penghasilan enzim ini. Menerusi plot-plot diagnostik, didapati bahawa terdapat masalah terhadap kenormalan dan kesamaan variasi data. Penjelmaan data secara log membolehkan model yang lebih tepat diperolehi (R 2 = 0.9523). Medium yang terdiri daripada 3.0% (b/i) kanji ubi kayu, 0.11% (b/i) pepton dari kasein, 0.08% (b/i) KH 2 PO 4 , 0.02% (b/i) MnSO 4 and pH awalan 9.0 berjaya meningkatkan penghasilan enzim pullulanase sebanyak kira-kira 4.5 kali kali ganda berbanding penggunaan medium asal. Kata kunci: Pullulanase; medium pengkulturan; bacillus flavothermus KWF-1 1 Faculty of Chemical Engineering & Natural Resources, Universiti Malaysia Pahang, Lebuhraya Tun Razak, 26300 Kuantan, Pahang, Malaysia 2&5 Faculty of Chemical Engineering and Natural Resources Engineering, Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor Bahru, Malaysia 3 Faculty of Bioscience and Bioengineering, Universiti Teknologi Malaysia, 81310 Skudai, Johor, Malaysia 4 School of Chemical Sciences and Food Technology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor, Malaysia * Corresponding author: Tel: +6075535564, Fax: +6075581463. Email: r-rosli@utm.my