Biodiversity And Identification Of Pha Synthase Genes From Limestone Area Through Metagenomic Approach
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Date
2015-08
Authors
Yen Teng, Tai
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Abstract
PHA synthase (PhaC) is the key enzyme in the production of biodegradable plastics known as polyhydroxyalkanoate (PHA). In this study, metagenomic approach was applied in order to identify novel PHA synthase genes (phaCs). The presence of phaCs in limestone soil was screened using primers targeting the Class I and II PHA synthases. Phylogenetic analysis has revealed that limestone area harbors a great diversity of phaCs with activities that have not yet been investigated. A total of 87 partial phaCs were obtained with identity less than 85% compare to the known bacteria. Among these, 7 partial phaC genes were selected for full length amplification through metagenome walking. One of the clones (SC8) encoded a new PHA synthase gene (phaCSC8), with an 81 % identity to the phaC of Chromobacterium violaceum ATCC 12472 based on BLASTn results. Although this gene was truncated with the absence of putative stop codon, it able to express successfully and produce up to 55 wt. % of PHA when it was cloned into a PHA-negative mutant of Cupriavidus necator PHB−4. Besides that, the PHA synthase activity of this transformant was 55 U/g protein. At the same time, the biodiversity of this limestone area was studied. Based on the 16S rDNA sequencing result, it can be seen that this location is rich in biodiversity with the presence of potentially novel organisms. Among all these organisms, bacteria are the most dominant and diverse. In conclusion, this area is a suitable and conducive environment for the living of organisms especially for the PHA producers. This study presents a pioneering study on the discovery of phaC in a limestone area using metagenomic approach.
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Biodiversity And Identification Of Pha Synthase Genes , From Limestone Area Through Metagenomic Approach