Isolation and screening of thermophilic and thermotolerant fungi for production of hemicellulases from heated environments

Abstract

Thermostable hemicellulases have potential to improve the quality of products of various industries including pulp and paper, food and feed, textile, etc. This study was aimed to isolate, screen, and identify potential xylanase and mannanase producers from heated environments. Sixty-eight thermophilic and thermotolerant fungi were isolated from various self-heated habitats based on their ability to grow at 45°C. With the aid of cultural and morphological observations, the fungi were identified and grouped into 19 fungal species. The enzyme production was evaluated by cultivating isolated fungi in submerged fermentation using wheat bran as carbon source. Screening of these isolates for hydrolysis of xylan and mannan was confirmed by Congo red plate assay method followed by assessment of xylanase and mannanase activity. Based on experimental analysis, we have found that all the isolates have exhibited xylanase activity, whereas only 22 isolates have found positive for mannanase activity. The highest xylanase and mannanase production was obtained by the cultivation of Malbranchea cinnamomea NFCCI 3724 (242 and 27 nkat/ml) followed by Melanocarpus albomyces (195 and 24 nkat/ml), Aspergillus terreus (165 and 21 nkat/ml), and Myceliophthora thermophila NFCCI 3725 (130 and 18 nkat/ml), respectively.

Keywords

• Thermophilic fungi
• xylanase
• mannanase
• enzymatic activity
• submerged fermentation