A novel lignocellulolytic bacterium for bioconversion of rice straw. | [Pakistan Journal of Agricultural Sciences • 2016]

Author(s):

1. H. Kausar: Laboratory of Food Crops, Institute of Tropical Agriculture, Universiti Putra Malaysia, Serdang, Selangor, Malaysia

2. Mohd Razi Ismail: Laboratory of Food Crops, Institute of Tropical Agriculture, Universiti Putra Malaysia, Serdang, Selangor, Malaysia

3. Halimi Mohd Saud: Department of Agriculture Technology, Faculty of Agriculture, Universiti Putra Malaysia, 43400, Serdang, Selangor, Malaysia

4. S. H. Habib: Department of Agriculture Technology, Faculty of Agriculture, Universiti Putra Malaysia, 43400, Serdang, Selangor, Malaysia

5. R. Othman: Laboratory of Food Crops, Institute of Tropical Agriculture, Universiti Putra Malaysia, Serdang, Selangor, Malaysia

6. Gous Miah: Laboratory of Food Crops, Institute of Tropical Agriculture, Universiti Putra Malaysia, Serdang, Selangor, Malaysia

Abstract:

Large amounts of straw accumulate as a by-product of paddy cultivation. However, proper management of bulky straw has become a concern worldwide. We therefore explored potential bacterial isolate(s) for rice straw bioconversion. A study comprising several experiments was conducted at Composting Unit and Laboratory of Food Crops of Universiti Putra Malaysia under controlled condition. In total, 33 bacterial isolates were obtained from various sources of decomposed rice straw, such as composts or soil. The results showed that isolates UPMB7, UPMB8, UPMB10, UPMB17, and UPMB25, tested on ricestraw-powder amended media, exhibited optimum lignocellulolytic activities. UPMB7 and UPMB25 were further screened for rice straw bioconversion. Finally, the most optimal lignocellulolytic bacterial isolate, UPMB25, was identified as Bacillus subtilis using 16S rRNA sequencing and tested for in vivo rice straw bioconversion. UPMB 25 (B. subtilis) decomposed rice straw at a significantly higher rate than the control, with respect to both in-vitro and in-vivo bioconversion. At day 7, UPMB 25-inoculated compost showed optimum lignin peroxidase (LiP) activity of 6.06 μmol veratraldehyde•min-1 •G-1 , endoglucanase activity of 7.37 CMC•G-1 , exoglucanase activity of 3.79 FPA•G-1 , and fluorescein diacetate (FDA) hydrolysis activity of 1428.8 µg fluorescein•min-30•G-1 at day 14. After 4 weeks, the germination index of tomato seeds was found to be 80%, indicating the potential of UPMB25, B. subtilis, to be used as an efficient lignocellulolytic bacterium for large scale composting of rice straw.

Page(s): 523-533

DOI: DOI not available

Published: Journal: Pakistan Journal of Agricultural Sciences, Volume: 53, Issue: 3, Year: 2016

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