Streptomyces malaysiense sp. nov.: A novel Malaysian mangrove soil actinobacterium with antioxidative activity and cytotoxic potential against human cancer cell lines.

Hooi-Leng Ser,Wai-Fong Yin,Learn-Han Lee,Kok-Gan Chan,Bey-Hing Goh,Uma Devi Palanisamy

doi:10.1038/srep24247

Abstract

Actinobacteria from the unique intertidal ecosystem of the mangroves are known to produce novel, bioactive secondary metabolites. A novel strain known as MUSC 136T (=DSM 100712T = MCCC 1K01246T) which was isolated from Malaysian mangrove forest soil has proven to be no exception. Assessed by a polyphasic approach, its taxonomy showed a range of phylogenetic and chemotaxonomic properties consistent with the genus of Streptomyces. Phylogenetically, highest similarity was to Streptomyces misionensis NBRC 13063T (99.6%) along with two other strains (>98.9% sequence similarities). The DNA–DNA relatedness between MUSC 136T and these type strains ranged from 22.7 ± 0.5% to 46.5 ± 0.2%. Overall, polyphasic approach studies indicated this strain represents a novel species, for which the name Streptomyces malaysiense sp. nov. is proposed. The potential bioactivities of this strain were explored by means of antioxidant and cytotoxic assays. Intriguingly, MUSC 136T exhibited strong antioxidative activities as evaluated by a panel of antioxidant assays. It was also found to possess high cytotoxic effect against HCT-116 cells, which probably mediated through altering p53 protein and intracellular glutathione levels. Chemical analysis of the extract using GC-MS further affirms that the strain produces chemopreventive related metabolites.

Highlights

There is an enormous need for novel chemotherapeutic agents in the ongoing battle against cancer, the global burden of which is steadily increasing[1,2]
The morphological observation of a 15-day-old culture grown on ISP 2 agar revealed abundant growth of both aerial and vegetative hyphae, which were well developed and not fragmented
Cells were found to be positive for catalase but negative for hemolytic activity and melanoid pigment production

Summary

Introduction

There is an enormous need for novel chemotherapeutic agents in the ongoing battle against cancer, the global burden of which is steadily increasing[1,2]. Microorganisms are a prolific source of structurally diverse bioactive metabolites; some of which have been approved to be used as cancer chemotherapeutic agents[7,8]. Since the recognition of actinomycin D as an anticancer agent, many anticancer compounds have been isolated from Streptomyces species, including anthracyclines, bleomycin and mitosanes[7,8]. There has been increasing research investigating the biosynthetic potential of Streptomyces from underexplored areas, including mangrove forests[10,11,12]. Soil samples from the Tanjung Lumpur mangrove forest located in the east coast of Peninsular Malaysia was screened to identify novel strains exhibiting cytotoxic and antioxidant activities. The extract from this novel strain was demonstrated to have cytotoxic and antioxidant activities which was further characterized using gas chromatography-mass spectrometry (GC-MS). The findings of this research are anticipated to provide a strong basis for further in-depth molecular studies on the chemopreventive properties of the novel strain MUSC 136T

Methods

Results

Conclusion