Tsegaye Bahiru, Balomajumder Chandrajit, Roy Partha
1Department of Chemical Engineering, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand 247667 India.
2Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand 247667 India.
3 Biotech. 2018 Oct;8(10):447. doi: 10.1007/s13205-018-1471-0. Epub 2018 Oct 11.
In this study, two bacterial strains capable of degrading lignin, cellulose, and hemicellulose were isolated from wood feeding termite. The isolates were identified by 16S rRNA gene sequencing. A bacterium BMP03 capable of degrading lignin was isolated on alkali lignin medium and sp. BMP01 strain capable of degrading cellulose and hemicellulose were isolated on carboxymethyl cellulose and xylan media. The efficiency of bacterial degradation was studied by evaluating the composition of rice straw both before and after degradation. The appearance of new cellulose bands at 1382, 1276, 1200, and 871 cm, and the absence of former lignin bands at 1726, 1307, and 1246 cm was observed after biodelignification. This was further confirmed by the formation of channeling and layering of the microstructure of biodelignified rice straw observed under electron microscope. Maximum lignin removal was achieved in separate biodelignification and hydrolysis process after the 14th day of treatment by BMP03 (53.74% lignin removal). Hydrolysis of the biodelignified rice straw released 69.96% of total reducing sugars after the 14th day hydrolysis by sp. BMP01. In simultaneous delignification and hydrolysis process, about 58.67% of total reducing sugars were obtained after the 13th day of biotreatment. Separate delignification and hydrolysis process were found to be effective in lignin removal and sugar released than the simultaneous process. The bacteria, sp. BMP01, has the ability to degrade hemicellulose and cellulose simultaneously. Overall, these results demonstrate that the possibility of rice straw bioconversion into reducing sugars by bacteria from termite gut.
在本研究中，从取食木材的白蚁中分离出两种能够降解木质素、纤维素和半纤维素的细菌菌株。通过16S rRNA基因测序对分离菌株进行鉴定。在碱性木质素培养基上分离出一种能够降解木质素的细菌BMP03，在羧甲基纤维素和木聚糖培养基上分离出能够降解纤维素和半纤维素的芽孢杆菌属BMP01菌株。通过评估降解前后稻草的成分来研究细菌降解效率。生物脱木质素后，观察到在1382、1276、1200和871 cm处出现新的纤维素条带，而在1726、1307和1246 cm处先前的木质素条带消失。在电子显微镜下观察到生物脱木质素稻草微观结构的通道化和分层形成，进一步证实了这一点。在BMP03处理第14天后的单独生物脱木质素和水解过程中，木质素去除率最高（木质素去除率为53.74%）。经芽孢杆菌属BMP01水解14天后，生物脱木质素稻草释放出总还原糖的69.96%。在同时进行脱木质素和水解过程中，生物处理第13天后获得了约58.67%的总还原糖。发现单独的脱木质素和水解过程在去除木质素和释放糖方面比同时进行的过程更有效。芽孢杆菌属BMP01具有同时降解半纤维素和纤维素的能力。总体而言，这些结果证明了白蚁肠道细菌将稻草生物转化为还原糖的可能性。
