A Novel Alkaliphilic Streptomyces Inhibits ESKAPE Pathogens

Abstract

In an effort to stem the rising tide of multi-resistant bacteria, researchers have turned to niche environments in the hope of discovering new varieties of antibiotics. We investigated an ethnopharmacological (cure) from an alkaline/radon soil in the area of Boho, in the Fermanagh Scarplands (N. Ireland) for the presence of <i>Streptomyces</i>, a well-known producer of antibiotics. From this soil we isolated a novel (closest relative 57% of genome relatedness) <i>Streptomyces</i> sp. capable of growth at high alkaline pH (10.5) and tolerant of gamma radiation to 4 kGy. Genomic sequencing identified many alkaline tolerance (antiporter/multi-resistance) genes compared to <i>S. coelicolor</i> M145 (at 3:1), hence we designated the strain <i>Streptomyces</i> sp. myrophorea, isolate McG1, from the Greek, myro (fragrance) and phorea (porter/carrier). <i>In vitro</i> tests demonstrated the ability of the <i>Streptomyces</i> sp. myrophorea, isolate McG1 to inhibit the growth of many strains of ESKAPE pathogens; most notably carbapenem-resistant <i>Acinetobacter baumannii</i> (a critical pathogen on the WHO priority list of antibiotic-resistant bacteria), vancomycin-resistant <i>Enterococcus faecium</i>, and methicillin-resistant <i>Staphylococcus aureus</i> (both listed as high priority pathogens). Further <i>in silico</i> prediction of antimicrobial potential of <i>Streptomyces</i> sp. myrophorea, isolate McG1 by anti-SMASH and RAST software identified many secondary metabolite and toxicity resistance gene clusters (45 and 27, respectively) as well as many antibiotic resistance genes potentially related to antibiotic production. Follow-up <i>in vitro</i> tests show that the <i>Streptomyces</i> sp. myrophorea, isolate McG1 was resistant to 28 out of 36 clinical antibiotics. Although not a comprehensive analysis, we think that some of the Boho soils' reputed curative properties may be linked to the ability of <i>Streptomyces</i> sp. myrophorea, isolate McG1 to inhibit ESKAPE pathogens. More importantly, further analysis may elucidate other key components that could alleviate the tide of multi-resistant nosocomial infections.