New Scabimycins A-C Isolated from Streptomyces acidiscabies (Lu19992)

Peptide natural products displaying a wide range of biological activities have become important drug candidates over the years. Microorganisms have been a powerful source of such bioactive peptides, and Streptomyces have yielded many novel natural products thus far. In an effort to uncover such new, meaningful compounds, the metabolome of Streptomyces acidiscabies was analyzed thoroughly. Three new compounds, scabimycins A–C (1–3), were discovered, and their chemical structures were elucidated by NMR spectroscopy. The relative and absolute configurations were determined using ROESY NMR experiments and advanced Marfey’s method.

Draft Genome Sequences of Streptomyces scabiei S58, Streptomyces turgidiscabies T45, and Streptomyces acidiscabies a10, the Pathogens of Potato Common Scab, Isolated in Japan: TABLE 1

The draft genome sequences of the three pathogens of potato common scab, Streptomyces scabiei S58, Streptomyces turgidiscabies T45, and Streptomyces acidiscabies a10, isolated in Japan, are presented here. The genome size of each strain is >10 Mb, and the three pathogenic strains share genes located in a pathogenicity island previously described in other pathogenic Streptomyces species.

Acidiscalide, A New Glycosylated Macrolide from the Marine Actinomycete Streptomyces Acidiscabies

A new macrolide named acidiscalide (2), and a known protein synthesis inhibitor, cycloheximide (1), were isolated from the culture broth of a strain of actinomycete, Streptomyces acidiscabies, coded SCTA0002 collected from the coast of Okinawa. The structure of acidiscalide (2) was elucidated to be a glycosylated macrolide having a 24-membered ring on the basis of spectroscopic analysis. Although the stereochemistry could not be determined due to decomposition in the course of the study, it was confirmed that acidiscalide (2) possessed a new molecular scaffold.

First Report Regarding Potato Scab Caused by Streptomyces acidiscabies in Uruguay

Potato scab disease is caused by gram-positive filamentous bacteria in the genus Streptomyces. A great variety of species cause this disease, but Streptomyces scabies is the most ancient of these pathogens and can be found in a worldwide distribution, whereas S. turgidiscabies and S. acidiscabies are newly emerged pathogens (2). During the autumn of 2010, potato (Solanum tuberosum) crops had large economic losses by common scab, corresponding to 29% of the total potato-cultivation area (according to our survey), which was unusual in Uruguay. Specifically, the disease was very aggressive and the tubers showed particularly deep scab lesions. We isolated the Streptomyces species present in these particular scab lesions of tubers collected in July 2010 from one of the three potato cultivation areas (San José). A total of 19 Streptomyces spp. strains were isolated and identified using classical and molecular techniques. Morphological characteristics of colonies and microscopic structure of the mycelium were observed (1). Molecular characterization by conventional PCR was carried out using primers directed to specific regions of the 16S rRNA gene for the genus Streptomyces, Aci1: (5′-TCACTCCTGCCTGCATGGGCG-3′) and Aci2: (5′-CGACAGCTCCCTCCCACAAG-3′). Also, regions of two pathogenicity genes, namely txtAB and nec1, were amplified and confirmed by sequencing (2). Additionally, melanin production and pathogenicity of the isolates was determined by inoculation of potato discs (1). Six of the 19 strains succeeded in PCR amplification with primers specific to Streptomyces acidiscabies, which has white, aerial hypha and flexuous spore chains. These strains did not produce melanin on tyrosine agar media. The amplified fragments for 16S rRNA and pathogenicity genes from one representative strain 61 were sequenced. BLASTn analysis of the 16S rRNA gene sequence obtained of the strain 61 (Accession No. JN206667) showed the highest similarity (100%) with S. acidiscabies type strain 84-01-182 (GenBank Accession No. FJ007427.1). Pathogenicity of the isolate was tested on tuber slices. The isolate was grown on YME for 5 to 7 days at 28°C and agar plugs from the sporulating colonies were inverted onto excised tuber tissue. Disks were incubated at 28°C in the dark and the presence of necrosis was evaluated after 5 days (1). All tuber slice assays were repeated three times. The noninoculated control tuber slices did not show any necrosis, while those inoculated with the strain did. To our knowledge, this is the first report of S. acidiscabies causing potato scab disease in Uruguay. References: (1) D. H. Park et al. Plant Dis. 87:1290, 2003. (2) L. A. Wanner. Phytopathology 96:1361, 2006.