Streptomyces spp. From Ethiopia Producing Antimicrobial Compounds: Characterization via Bioassays, Genome Analyses, and Mass Spectrometry

Abstract

A total of 416 actinomycete cultures were isolated from various unique environments in Ethiopia and tested for bioactivity. Six isolates with pronounced antimicrobial activity were chosen for taxonomic identification and further investigation. Morphological and cultural properties of the isolates were found to be consistent with those of the genus Streptomyces, which was further confirmed by phylogenetic analysis based on 16S rRNA gene sequences. One of the isolates, designated Streptomyces sp. Go-475, which displayed potent activity against both pathogenic yeasts and Gram-positive bacteria, was chosen for further investigation. Metabolite profiles and bioactivity of Go-475 incubated on wheat bran-based solid and soya flour-based liquid media were compared using high-resolution LC-MS. This allowed identification of several known compounds, and suggested the ability of Go-475 to produce new secondary metabolites. Major anti-bacterial compounds were purified from liquid cultures of Go-475, and their structures elucidated by NMR and HRMS as 8-O-methyltetrangomycin and 8-O-methyltetrangulol. In addition, many potentially novel metabolites were detected, the majority of which were produced in solid media-based fermentation. The genome sequence of Streptomyces sp. Go-475 was obtained using a hybrid assembly approach of high quality Illumina short read and low quality Oxford Nanopore long read data. The complete linear chromosome of 8,570,609 bp, featuring a G+C content of 71.96%, contains 7,571 predicted coding sequences, 83 t(m)RNA genes, and six rrn operons. Analysis of the genome for secondary metabolite biosynthesis gene clusters further confirmed potential of this isolate to synthesize chemically diverse natural products, and allowed to connect certain clusters with experimentally confirmed molecules.

Isolation and Characterization of Urease-Producing Soil Bacteria

“…eir ability to produce urease can be exploited to enrich and isolate such bacteria from the environment for future applications [21]. While the occurrence of these bacteria and their characteristics have been explored in some regions and soil types [1,12,21,22] and other novel bacterial strains isolated from Ethiopian sediments and soils [23,24], this study is the first report on the characterization of ureolytic bacteria from Ethiopian soil. is study aimed to isolate and characterize rapid ureaseproducing bacteria from Ethiopian soils.…”

Antagonistic activity of Streptomyces (DS3) and Nocardia (DN5) isolates against selected bacteria isolated from cream samples

“…However, their isolates were not able to inhibit the growth of E. coli and P. aeruginosa [13] . Moreover, Kibret et al [14] detected 416 isolates of Streptomyces with certain bacterial members, such as their designated Go -475 isolate, with strong bioactive cross -product substances, some of them are newly identified, that decreased the livability of some fungi and Gram positive pathogenic bacteria. In addition, they found that the DNA gnomic materials have the ability to code for antimicrobial metabolites [14] .…”

Methanol-Essential Growth of Corynebacterium glutamicum: Adaptive Laboratory Evolution Overcomes Limitation due to Methanethiol Assimilation Pathway

“…If the coverage was above 10, the minimum frequency was 90% instead. Additionally, genomic DNA of C. glutamicum ∆ald ∆fadH ∆rpe strains MDS2, MDS2T8 and MDS2T14 was sequenced using Nanopore MinION sequencing technology (Oxford Nanopore Technologies Oxford, UK) as described previously [53]. After assembly, 11 contigs for MDS2, 6 contigs for MDS2T8 and 2 contigs for MDS2T14 were revealed.…”