Monday, April 30, 2007

Fungal co-cultivation: An approach for simultaneous production of xylanase and laccase under submerged fermentation using Parthenium sp. as a novel plant biomass

P Dwivedi, V Vivekanand, N Sabharwal, and R. P. Singh. Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee, 247 667, India

Xylanase and laccase are known for their application to the pulp and paper industries. Several advantages like pulping, bleaching, process economization and improved paper properties may be obtained by synergistic action of xylanase and laccase and thus fungal co-cultivation may be a promising approach for achieving the same. P. oxalicum SAUE-3.510 was developed through mixed mutagenesis of P. oxalicum SA-8 ITCC 6024, isolated from wastes of soda ash industry. Significant levels of xylanase (735.7 ± 17.3 IU ml-1) was produced when Parthenium sp. (congress grass) was used as carbon source. Three white rot fungal cultures Pleurotus ostreatus MTCC 1804, Trametes hirsuta MTCC 136 and Pycnoporus MTCC 137 which are laccase producers were procured from Institute of Microbial Technology, Chandigarh, India. Compatibility of these fungi with mutant P. oxalicum SAUE-3.510 was observed by their co-cultivation on potato dextrose agar media, which indicated that P. ostreatus MTCC 1804 had growth compatibility with mutant P. oxalicum SAUE-3.510.  In addition, interaction among two selected fungi was also detected by scanning electron microscopy. Further, analysis of laccase production by P. ostreatus MTCC 1804 had indicated maximal levels (22.8 ± 1.8 IU ml-1) following 12th days of incubation along with lower levels of xylanase. Penicillium oxalicum SAUE-3.510 and P. ostreatus MTCC 1804 when cultured under co-cultivation condition had resulted into increased levels of xylanase (58.2%, 1208 ± 15.0 IU ml-1) and laccase (32.8%, 30.3 ± 2.6 IU ml-1) production. Various critical fermentation parameters were analyzed to derive co-cultivation strategy for simultaneous production of enzymes.