Screening of Fungal Resources for the Production of Cellulases and Xylanases

Aims: The final screening of fungal isolates aimed at applications based tertiary screening i.e. deinking of mixed office waste paper and saccharification of pearl millet stover and cellulases from selected fungal isolates were characterized.

Study Design: An experimental study.

Methodology: Samples from soil, compost and decaying wood were collected from different habitats and were screened based on growth over CMC-agar medium (primary screening), zone ratios and enzyme activities (secondary screening) and applications such as bio-deinking of mixed office paper and saccharification of pearl millet stover (tertiary screening).

Results: 134 fungal isolates were selected during primary screening based on their growth. In secondary screening, fungal strains showing zone ratio of 3.0 or more were selected for application based tertiary screening. Two fungal isolates AKB-24 and AKB-25 were selected based on their applications in deinking of mixed office waste and saccharification of pearl millet stover after tertiary screening. Fungal isolates AKB-25 and AKB-24 were identified as Aspergillus nidulans and Penicillium sp. Optimum pH for FPase, endoglucanase, and glucosidase activities were 5.0 for both the fungal strains. Cellulases from A. nidulans AKB-25 were found moderately thermo-stable with optimum endoglucanase activity at 65ºC and optimal FPase and β-glucosidase activities at 60ºC. The maximal endoglucanase, FPase and β-glucosidase activities were observed at 55ºC for fungal strain Penicillium sp. AKB-24. Cellulases from both fungal strains were found stable up to 48 h at 50ºC.

Conclusion: Aspergillus nidulans AKB-25 and Penicillium sp. AKB-24 were selected based on an extensive screening and enzymes from both fungal strains were found effective in bio-deinking of mixed office waste paper. Enzyme from Aspergillus nidulans AKB-25 was also found effective in saccharification of pearl millet stover.