Abstract
Palm kernel cake (PKC) has been largely produced in Malaysia as one of the cheap and abundant agro-waste by-products from the palm oil industry and it contains high fiber (mannan) content. The present study aimed to produce β-mannanase by Bacillus subtilis ATCC11774 via optimization of the medium composition using palm kernel cake as substrate in semi-solid fermentation. The fermentation nutrients such as PKC, peptone, yeast extract, sodium chloride, magnesium sulphate (MgSO2), initial culture pH and temperature were screened using a Plackett-Burman design. The three most significant factors identified, PKC, peptone and NaCl, were further optimized using central composite design (CCD), a response surface methodology (RSM) approach, where yeast extract and MgSO2 were fixed as a constant factor. The maximum β-mannanase activity predicted by CCD under the optimum medium composition of 16.50 g/L PKC, 19.59 g/L peptone, 3.00 g/L yeast extract, 2.72 g/L NaCl and 0.2 g/L MgSO2 was 799 U/mL. The validated β-mannanase activity was 805.12 U/mL, which was close to the predicted β-mannanas activity. As a comparison, commercial media such as nutrient broth, M9 and Luria bertani were used for the production of β-mannanase with activities achieved at 204.16 ± 9.21 U/mL, 50.32 U/mL and 88.90 U/mL, respectively. The optimized PKC fermentation medium was four times higher than nutrient broth. Hence, it could be a potential fermentation substrate for the production of β-mannanase activity by Bacillus subtilis ATCC11774.
Highlights
Bioprocess Technology, School of Industrial Technology, Universiti Sains Malaysia, Halal Products Research Institute, Universiti Putra Malaysia UPM, Serdang 43400, Selangor, Malaysia; Protein and Food Technology Unit, Product Development and Advisory Services Department, Milling and Processing Unit, Engineering and Processing Division, Malaysia Palm Oil Board, Academic Editors: Anna Andolfi and Maria Michela Salvatore
Liquid cultures were used in this research because it is easier to control the environmental factors required for the optimum growth of B. subtilis and β-mannanase production and it allows control over the agitation speed, pH and temperature of the medium
Several carbon sources consisting of locust bean gum (LBG), azo-carob, xylose, glucose and sucrose were examined as carbon sources in comparison to that of Palm kernel cake (PKC) for β-mannanase production by
Summary
Bioprocess Technology, School of Industrial Technology, Universiti Sains Malaysia, Halal Products Research Institute, Universiti Putra Malaysia UPM, Serdang 43400, Selangor, Malaysia; Protein and Food Technology Unit, Product Development and Advisory Services Department, Milling and Processing Unit, Engineering and Processing Division, Malaysia Palm Oil Board, Academic Editors: Anna Andolfi and Maria Michela Salvatore. ATCC11774 via optimization of the medium composition using palm kernel cake as substrate in semi-solid fermentation. The fermentation nutrients such as PKC, peptone, yeast extract, sodium chloride, magnesium sulphate (MgSO2 ), initial culture pH and temperature were screened using a Plackett-Burman design. The maximum β-mannanase activity predicted by CCD under the optimum medium composition of 16.50 g/L PKC, 19.59 g/L peptone, 3.00 g/L yeast extract, 2.72 g/L NaCl and 0.2 g/L MgSO2 was 799 U/mL. The optimized PKC fermentation medium was four times higher than nutrient broth. It could be a potential fermentation substrate for the production of β-mannanase activity by Bacillus subtilis ATCC11774. Among different Bacillus species, Bacillus subtilis has been shown to produce highly active β-mannanase [3]
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