Production Of Cellulase By Pycnoporus Sanguineus In Palm Oil Mill Effluent: Fermentation And Kinetic Studies
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Date
2011-07
Authors
Kamaluddin, Fadzilah
Journal Title
Journal ISSN
Volume Title
Publisher
Universiti Sains Malaysia
Abstract
Bioconversion of palm oil mill effluent (POME) is a novel approach in view of the increasing emphasis placed on sustainable and efficient industrial wastewater management. Biotechnological advances have seen the reuse of POME as a fermentation substrate for the production of various metabolites. In order to assess the potential of POME as substrate for cellulases production, nineteen microbial strains comprising of micro- and macrofungi were screened for cellulolytic activities. Pycnoporus sanguineus was found to be a potent producer of cellulases and laccase with maximum CMCase, FPase, β-glucosidase and laccase activities at 2.488, 1.405, 0.232 and 2.763 IU/mL, respectively.
Batch cultivations of P. sanguineus using POME as the base media were subsequently conducted in both shake flask and bioreactor. Preliminary studies in shake flask showed that pre-treatment of POME with ultrasound increased the cellulases activities 1.5-fold. The highest cell biomass (11.413 g/L) and enzymatic activities (CMCase, 6.018; FPase, 3.221; BG, 0.644; laccase, 8.149 IU/mL) were obtained with 60% (v/v) of POME concentration, pH 7 using peptone as a nitrogen source. To further improve the cellulases production, optimization of process parameters were conducted using response surface methodology (RSM) coupled with a central composite design (CCD). The optimum conditions obtained were POME concentration 70% (v/v), inoculums size 15% (v/v), cellulose (carbon) concentration 0.8% (w/v), and peptone (nitrogen) concentration 0.1% (w/v), which resulted in 10.613, 6.814, 1.040 and 10.886 IU/mL of CMCase, FPase, BG and laccase activities, respectively.
Batch culture of P. sanguineus in conventional stirred tank bioreactor (CSTB) showed that biomass and cellulase production were influenced by aeration rate and agitation speed. Aeration rate at 1.0 vvm and agitation speed 300 rpm were found to yield the highest cellulases activities and volumetric mass transfer coefficient (kLa). Optimization with CCD indicated an optimum condition at 70% (v/v) POME concentration, 350 rpm agitation speed and 1.0 vvm aeration rate with maximum enzyme activities at 16.073, 10.012, 2.348 and 12.186 IU/ml for CMCase, FPase, BG and laccase, respectively. The optimized parameters were then adapted in the studies using stirred tank bioreactor with external loop (STBEL). Enzyme productions were shown to improve with higher maximum biomass (52.75 g/L) and enzyme activities (CMCase, 18.221, FPase, 13.406, BG, 3.370 and laccase, 17.481 IU/mL) compared to CSTB.
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Keywords
Bioconversion of palm oil mill effluent , efficient industrial wastewater management