Journal of Microbiology

Research Support, Non-U.S. Gov'ts

Screening and Characterization of a Cellulase Gene from the Gut Microflora of Abalone Using Metagenomic Library: Duwoon Kim , Se-Na Kim , Keun Sik Baik , Seong Chan Park , Chae Hong Lim , Jong-Oh Kim , Tai-Sun Shin , Myung-Joo Oh , Chi Nam Seong; J. Microbiol. 2011;49(1):141-145. Published online March 3, 2011; DOI: https://doi.org/10.1007/s12275-011-0205-3

Abstract: A metagenomic fosmid library was constructed using genomic DNA isolated from abalone intestine. Screening of a library of 3,840 clones revealed a 36 kb insert of a cellulase positive clone (pAM11E10). A shotgun clone library was constructed using the positive clone (pAM11E10) and further screening of 3,840 shotgun clones with an approximately 5 kb insert size using a Congo red overlay revealed only one cellulase positive clone (pAM11L9). The pAM11L9 consisted of a 5,293-bp DNA sequence and three open reading frames (ORFs). Among the three ORFs, cellulase activity was only shown in the recombinant protein (CelAM11) coded by ORF3, which showed 100% identity with outer membrane protein A from Vibrio alginolyticus 12G01, but no significant sequence homology to known cellulases. The expressed protein (CelAM11) has a molecular weight of approximately 37 kDa and the highest CMC hydrolysis activity was observed at pH 7.0 and 37°C. The carboxymethyl cellulase activity was determined by zymogram active staining and different degraded product profiles for CelAM11 were obtained when cellotetraose and cellopentaose were used as the substrates, while no substrate hydrolysis was observed on oligosaccharides such as cellobiose and cellotriose.

Pseudoxanthomonas icgebensis sp. nov., Isolated from the Midgut of Anopheles stephensi Field-Collected Larvae§: Asha Rani , Anil Sharma , Tridibes Adak , Raj K. Bhatnagar; J. Microbiol. 2010;48(5):601-606. Published online November 3, 2010; DOI: https://doi.org/10.1007/s12275-010-0125-7

Abstract: A Gram-negative, aerobic, golden yellow, rod-shaped bacterium, a strain designated ICGEB-L15T, was isolated from the larval midgut of Anopheles stephensi captured in District Jhajjar, Haryana, India. The strain ICGEB-L15T grows at 30-50°C (optimum 30-37°C), pH 6.5-8.5 (optimum 7.0-8.0) and in the presence of 2% NaCl. The major fatty acids were iso-C15:0 (22.5% of total fatty acid), anteiso-C15:0 (16.5%), iso-C17:1ω9c (10.3%), iso-C16:0 (7.3%), C16:0 (6.1%), and iso-C11:0 (5.3%). The strain showed the highest 16S rRNA gene sequence similarities with the type strains Pseudoxanthomonas daejeonensis KCTC 12207T (97.4%), Pseudoxanthomonas kaohsiungensis J36T (97.17%), and Pseudoxanthomonas mexicana AMX 26BT (97.11%). The DNA relatedness between ICGEB-L15T and Pseudoxanthomonas daejeonensis KCTC 12207T, Pseudoxanthomonas kaohsiungensis J36T and Pseudoxanthomonas mexicana AMX 26BT was 24.5%, 28.2%, and 33.6%, respectively. The G+C content of genomic DNA was 69.9 mol%. The major isoprenoid quinone of strain ICGEB-L15T was Q-8. The strain ICGEB-L15T represents a novel species of the genus Pseudoxanthomonas based on physiological, biochemical and phylogenetic properties; therefore, the name Pseudoxanthomonas icgebensis sp. nov. is proposed. The type strain is ICGEB-L15T (=KACC 14090T =DSM 22536T).

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