Isolation and characterization of marine Brevibacillus sp. S-1 collected from South China Sea and a novel antitumor peptide produced by the strain.

Lanhong Zheng,Jianhua Hao,Xinwen Zhou,Mei Lv,Yuan Zheng,Jia Liu,Xiukun Lin,Junzhong Liu,Kangli Yang,Mi Sun,Yao Yi,Yiguo Hong

doi:10.1371/journal.pone.0111270

Abstract

A Gram-positive, rod-shaped bacterium, designated as S-1, was isolated from a marine sediment sample collected from South China Sea. Phylogenetic analysis based on 16S rRNA gene sequence showed that S-1 belongs to the genus Brevibacillus. A novel cytotoxic peptide was isolated from the fermentation broth of the marine-derived bacterium Brevibacillus sp. S-1, using ion-exchange chromatography and reverse-phase HPLC chromatography. The molecular weight of this peptide was determined as 1570 Da by MALDI-TOF mass spectrometry, and its structure was proposed as a cyclic peptide elucidated by MALDI-TOF/TOF mass spectrometry and de novo sequencing. 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay showed that this peptide exhibited cytotoxicity against BEL-7402 human hepatocellular carcinoma cells, RKO human colon carcinoma cells, A549 human lung carcinoma cells, U251 human glioma cells and MCF-7 human breast carcinoma cells. Additionally, SBP exhibited low cytotoxicity against HFL1 human normal fibroblast lung cells. The result suggested that the cytotoxic effect of the peptide is specific to tumor cells.

Highlights

As the leading cause of death, malignant tumors seriously threaten human health
A variety of pretreatment methods including enriching physical and chemical techniques are employed to favor the isolation of specific marine microorganisms, especially less abundant bacteria. [24,25]
Phylogenetic analysis based on the 16S rRNA sequence indicated that strain S-1 belonged to the genus Brevibacillus, with the highest sequence similarities to Brevibacillus laterosporus DSM25 (98.29%), Brevibacillus panacihumi DCY35 (97.26%), Brevibacillus invocatus NCIMB 13772 (96.99%), Brevibacillus fluminis CJ71 (96.89%) and Brevibacillus centrosporus DSM 8445 (96.78%)

Summary

Introduction

As the leading cause of death, malignant tumors seriously threaten human health. The incidence of cancer keeps growing in recent years. Recent trends in drug discovery emphasize that marine microorganisms are a potentially productive resource of novel secondary metabolites and There is a great potential to increase the number of marine natural products in clinical trials [4]. Recent advances on anticancer peptides from marine resource have provided novel information about marine bioactive peptides [9] These findings have contributed to our understanding of the relationship between chemical structure of peptides and biological activity [10]. These facts demonstrate marine peptides as a new source of obtaining lead compounds for biomedical purposes

Materials and Methods

Results and Discussion

Conclusions