Isolation of highly thermostable β-xylosidases from a hot spring soil microbial community using a metagenomic approach. (7th August 2017)

• Record Type: Journal Article
• Authors: Sato, Masaru; Suda, Migiwa; Okuma, Jiro; Kato, Tomohiko; Hirose, Yoshitsugu; Nishimura, Asuka; Kondo, Yasuhiko; Shibata, Daisuke
• Is Part Of: DNA research. Volume 24:Number 6(2017:Dec.)
• Page Start: 649
• Page End: 656
• Publication Date: 2017-08-07
• Subjects: thermostable enzyme, β-xylosidase, metagenome, xylan-degradation; Genes -- Periodicals; Genomes -- Periodicals; Genes -- Research -- Periodicals; Genomics -- Periodicals; DNA -- Research -- Periodicals; 572.86072
• DOI: 10.1093/dnares/dsx032
• Languages: English
• ISSNs: 1340-2838

Abstract

Abstract: The DNA extracted from a high-temperature environment in which micro-organisms are living will be a good source for the isolation of thermostable enzymes. Using a metagenomic approach, we aimed to isolate thermostable β-xylosidases that will be exploited for biofuel production from lignocellulosic biomass. DNA samples obtained from the soil near a spout of a hot spring (70°C, pH7.2) were subjected to sequencing, which generated a total of 84.2 Gbp with 967, 925 contigs of >500 bp in length. Similarity search for β-xylosidase in the contigs revealed the presence of 168 candidate sequences, each of which may have arisen from more than one gene. Individual genes were amplified by PCR using sequence-specific primers. The resultant DNA fragments were cloned and introduced into Escherichia coli BL21 Star(DE3). Consequently, 269 proteins were successfully expressed in the E. coli cells and then examined for β-xylosidase activity. A total of 82 proteins exhibited β-xylosidase activity at 50°C, six of which retained the activity even at 90°C. Out of the six, three proteins were originated from a single candidate sequence, AR19M-311. An amino acid sequence comparison suggested the amino acid residues that appeared to be crucial for thermal stability of the enzymes.