Whole Genome Sequencing And Characterization Of Microbulbifer-Like Bacterium Isolated From Mangrove Soil
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Date
2017-08
Authors
Moh, Tsu Horng
Journal Title
Journal ISSN
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Publisher
Universiti Sains Malaysia
Abstract
Mangrove forests are rich in microbial diversity with biotechnological potentials however the studies of novel bacteria isolated from mangrove are relatively fewer when compared with other ecosystem. A strain of bacterium, CCB-MM1 was isolated from estuarine sediments of Matang Mangrove Forest, Perak and preliminary 16S rRNA gene sequence analysis showed that CCB-MM1 is potentially new species of genus Microbulbifer. Based on the publications of Microbulbifer, many species of Microbulbifer produce enzymes that can degrade a great variety of carbohydrate and these enzymes have great application potential. Therefore, this study focus on the whole genome sequencing and phenotypic characterization of strain CCB-MM1 to determine its novelty and potential applications. The whole genome sequencing was done using PacBio RS II platform while the characterization was done using polyphasic approach. The 16S rRNA sequence analysis showed CCB-MM1 shares highest sequence similarity with M. rhizosphaerae Cs16bT (98.12 %), M. maritimus TF-17T (97.46 %) and M. gwangyangensis GY2T (97.33 %). In phylogenetic analysis, strain CCB-MM1 and M. rhizosphaerae Cs16bT formed a cluster in phylogenetic trees reconstructed. The genome size is 3.86 Mb and the GC content is 58.85 %. The genome consists of 3313 protein coding genes and 92 RNA genes. A total of 71 genes associated with carbohydrate active enzymes were found using dbCAN while 201 genes associated with proteases were found using MEROPS. antiSMASH 3.0 detected ectoine biosynthesis cluster including ectABC operon and ask_ect. The cells of CCB-MM1 is rod-shaped, Gram-stain-negative, halophilic and non-motile. CCB-MM1 is catalase and oxidase positive and able to degrade starch. The cells also possess a rod-coccus cell cycle in association with growth phase and form aggregates. CCB-MM1 grew optimally at 30°C and pH 7.0 with the presence of 2-3 % (w/v) NaCl. The major cellular fatty acids are iso-C17:1ω9c and iso-C15:0 while the major respiratory quinone is ubiquinone Q-8. The total polar lipid profile of CCB-MM1 consists of phosphatidylglycerol, phosphatidylethanolamine, phosphoaminolipid, two unidentified lipids, an unidentified glycolipid, an unidentified aminolipid. The gene expression study in a rod-coccus cell cycle revealed the relationship of mreB with rod-shaped cell morphology and the relationship cpsA with the cell aggregation. On the basis of phylogenetic and phenotypic analysis, strain CCB-MM1 represents a new species of the genus Microbulbifer. The name Microbulbifer aggregans was proposed for strain CCB-MM1. This study had shown that CCB-MM1 represent a new species of Microbulbifer but CCB-MM1 does not degrade a great variety of carbohydrates. This study had also revealed some of the hydrolytic enzymes (amylase, proteases, esterases) produced by strain CCB-MM1 with potential applications.
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Keywords
Mangrove forests are rich in microbial diversity , with biotechnological potentials