Biosynthetic Potential of a Novel Antarctic Actinobacterium Marisediminicola antarctica ZS314T Revealed by Genomic Data Mining and Pigment Characterization.

Li Liao,Bin Zhao,Shiyuan Su,Bo Chen,Huirong Li,Jin Zhang,Chengqi Fan

doi:10.3390/md17070388

Abstract

Rare actinobacterial species are considered as potential resources of new natural products. Marisediminicola antarctica ZS314T is the only type strain of the novel actinobacterial genus Marisediminicola isolated from intertidal sediments in East Antarctica. The strain ZS314T was able to produce reddish orange pigments at low temperatures, showing characteristics of carotenoids. To understand the biosynthetic potential of this strain, the genome was completely sequenced for data mining. The complete genome had 3,352,609 base pairs (bp), much smaller than most genomes of actinomycetes. Five biosynthetic gene clusters (BGCs) were predicted in the genome, including a gene cluster responsible for the biosynthesis of C50 carotenoid, and four additional BGCs of unknown oligosaccharide, salinixanthin, alkylresorcinol derivatives, and NRPS (non-ribosomal peptide synthetase) or amino acid-derived compounds. Further experimental characterization indicated that the strain may produce C.p.450-like carotenoids, supporting the genomic data analysis. A new xanthorhodopsin gene was discovered along with the analysis of the salinixanthin biosynthetic gene cluster. Since little is known about this genus, this work improves our understanding of its biosynthetic potential and provides opportunities for further investigation of natural products and strategies for adaptation to the extreme Antarctic environment.

Highlights

Actinobacteria are considered as one of the most important producers of natural products for drug discovery
To get an idea of the average genome size of the phylum Actinobacteria, a total of 1674 genomes available in the GenBank database were analyzed
M. antarctica ZS314T was isolated on Marine Agar 2216 (Difco) from intertidal sediments of the coast off the Chinese Antarctic Zhongshan Station in East Antarctica

Summary

Introduction

Actinobacteria are considered as one of the most important producers of natural products for drug discovery. More than half of antibiotics were produced by the genus Streptomyces [1]. The re-discovery of known natural products, especially from the genus Streptomyces due to the so-called diminishing marginal effect, has become an issue [1,2]. The increased prevalence of multi-drug resistance pathogens and the emergence of cross-resistance to antibiotics have driven researchers to seek for novel natural products [3]. Rare actinobacteria (non-Streptomyces), especially those from underexplored extreme environments, draw increasing attention for discovering. Mar. Drugs 2019, 17, 388; doi:10.3390/md17070388 www.mdpi.com/journal/marinedrugs

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