Taxonomic Characterization and Secondary Metabolite Analysis of NEAU-wh3-1: An Embleya Strain with Antitumor and Antibacterial Activity

Abstract

Cancer is a serious threat to human health. With the increasing resistance to known drugs, it is still urgent to find new drugs or pro-drugs with anti-tumor effects. Natural products produced by microorganisms have played an important role in the history of drug discovery, particularly in the anticancer and anti-infective areas. The plant rhizosphere ecosystem is a rich resource for the discovery of actinomycetes with potential applications in pharmaceutical science, especially Streptomyces. We screened Streptomyces-like strains from the rhizosphere soil of wheat (Triticum aestivum L.) in Hebei province, China, and thirty-nine strains were obtained. Among them, the extracts of 14 isolates inhibited the growth of colon tumor cell line HCT-116. Strain NEAU-wh-3-1 exhibited better inhibitory activity, and its active ingredients were further studied. Then, 16S rRNA gene sequence similarity studies showed that strain NEAU-wh3-1 with high sequence similarities to Embleya scabrispora DSM 41855T (99.65%), Embleya hyalina MB891-A1T (99.45%), and Streptomyces lasii 5H-CA11T (98.62%). Moreover, multilocus sequence analysis based on the five other house-keeping genes (atpD, gyrB, rpoB, recA, and trpB) and polyphasic taxonomic approach comprising chemotaxonomic, phylogenetic, morphological, and physiological characterization indicated that the isolate should be assigned to the genus Embleya and was different from its closely related strains, therefore, it is proposed that strain NEAU-wh3-1 may be classified as representatives of a novel species of the genus Embleya. Furthermore, active substances in the fermentation broth of strain NEAU-wh-3-1 were isolated by bioassay-guided analysis and identified by nuclear magnetic resonance (NMR) and mass spectrometry (MS) analyses. Consequently, one new Zincophorin analogue together with seven known compounds was detected. The new compound showed highest antitumor activity against three human cell lines with the 50% inhibition (IC50) values of 8.8–11.6 μg/mL and good antibacterial activity against four pathogenic bacteria, the other known compounds also exhibit certain biological activity.

Whole genome analysis of Streptomyces sp. RerS4, a Rehmannia glutinosa rhizosphere microbe producing a new lipopeptide

“…The new compound and doxorubicin, which was used as a positive control dissolved in DMSO (dimethyl sulfoxide), were added to the medium and incubated for 48 h. Then, the cell counting kit-8 (CCK-8, Dojindo, Kumamoto, Japan) reagent was added to the medium followed by further incubation for 3 h. A SpectraMax M5 microplate reader (Molecular Devices Inc., Sunnyvale, CA, USA) was used to measure the absorbance at 450 nm with a 600 nm reference. The half-maximal inhibitory concentration (IC 50 ) values were measured based on Wang and Sun's method [ 49 ]. Cell solutions containing 0.5% DMSO were tested as a negative control, and all experiments were carried out in triplicate.…”

In Depth Natural Product Discovery from the Basidiomycetes Stereum Species

“…Natural products deriving from microorganisms are one of the most valuable sources for medicinal and agricultural applications [ 1 , 2 , 3 ]. Basidiomycetes, as producers of bioactive secondary metabolites, provide an exciting opportunity to obtain new natural products with high application potential [ 4 ].…”

Special Issue: “Actinobacteria and Myxobacteria—Important Resources for Novel Antibiotics”

“…This issue gathers 16 papers including 11 articles, 4 reviews and 1 communication. Six of them describe novel species or isolates and their characterization by the use of a polyphasic approach [ 7 , 8 , 9 , 10 , 11 , 12 ] as well as their secondary metabolites. Two of the articles describe Actinobacteria from uncommon habitats like the Western Ghats region in India [ 13 ] and endophytic ones [ 14 ].…”