Microbiome of fungus-growing termites: a new reservoir for lignocellulase genes.
Fungus-growing termites play an important role in lignocellulose degradation and carbon mineralization in tropical and subtropical regions, but the degradation potentiality of their gut microbiota has long been neglected. The high quality and quantity of intestinal microbial DNA are indispensable for exploring new cellulose genes from termites by function-based screening. Here, using a refined intestinal microbial DNA extraction method followed by multiple-displacement amplification (MDA), a fosmid library was constructed from the total microbial DNA isolated from the gut of a termite growing in fungi. Functional screening for endoglucanase, cellobiohydrolase, β-glucosidase, and xylanase resulted in 12 β-glucosidase-positive clones and one xylanase-positive clone. The sequencing result of the xylanase-positive clone revealed an 1,818-bp open reading frame (ORF) encoding a 64.5-kDa multidomain endo-1,4-β-xylanase, designated Xyl6E7, which consisted of an N-terminal GH11 family catalytic domain, a CBM_4_9 domain, and a Listeria-Bacteroides repeat domain. Xyl6E7 was a highly active, substrate-specific, and endo-acting alkaline xylanase with considerably wide pH tolerance and stability but extremely low thermostability.
Key Laboratory of Insect Developmental and Evolutionary Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, People's Republic of China.
Ning
N
Liu
Xing
X
Yan
Meiling
M
Zhang
Lei
L
Xie
Qian
Q
Wang
Yongping
Y
Huang
Xuguo
X
Zhou
Shengyue
S
Wang
Zhihua
Z
Zhou
D000818:Animals; D044602:Cellulases / Q000235:genetics*; D015723:Gene Library; D020049:Isoptera / Q000382:microbiology*; D008031:Lignin / Q000378:metabolism; D054892:Metagenome; D008969:Molecular Sequence Data; D017422:Sequence Analysis, DNA; D017385:Sequence Homology
C036909:lignocellulose; D008031:Lignin; D044602:Cellulases