Evaluation of molecular typing methods for some scab-causing Streptomyces strains from Turkey.

This study was conducted for identifying phylogenetic relationships between 15 scab-causing Streptomyces species including S. bottropensis, S. europaeiscabiei, S. scabiei, S. stelliscabiei and, other 11 Streptomyces sp. All of the strains were originally isolated from symptomatic potatoes in Erzurum Province, The Eastern Anatolia Region of Turkey. Some morphological and biochemical properties of the strains were defined in our former research. Then, 16 s rRNA regions of them were sequenced. After the sequence data assembly, phylogenetic analyzes were performed. The phylogenetic analyses revealed that the strains are involved in the same major group and, substantially similar to reference strains. Additionally, some subgroup formations were also recorded. Moreover, Repetitive element-based PCR (Rep-PCR), Enterobacterial repetitive intergenic consensus (ERIC-PCR), and BOX-PCR fingerprinting molecular typing methods were used for as molecular typing methods. According to our knowledge, this is the first report on phylogenetic relationships of scab-causing Streptomyces species from Turkey. However, the identification of most pathogenic strains remained at the species level.

Antibacterial activities of essential oils and extracts of Turkish Achillea, Satureja and Thymus species against plant pathogenic bacteria.

BACKGROUND: The aims of this study were to examine the chemical composition of the essential oils and hexane extracts of the aerial parts of Satureja spicigera (C. Koch) Boiss., Thymus fallax Fisch. & CA Mey, Achillea biebersteinii Afan, and Achillea millefolium L. by GC and GC-MS, and to test antibacterial efficacy of essential oils and n-hexane, chloroform, acetone and methanol extracts as an antibacterial and seed disinfectant against 25 agricultural plant pathogens. RESULTS: Thymol, carvacrol, p-cymene, thymol methyl ether and gamma-terpinene were the main constituents of S. spicigera and T. fallax oils and hexane extracts. The main components of the oil of Achillea millefolium were 1,8-cineole, delta-cadinol and caryophyllene oxide, whereas the hexane extract of this species contained mainly n-hexacosane, n-tricosane and n-heneicosane. The oils and hexane extracts of S. spicigera and T. fallax exhibited potent antibacterial activity over a broad spectrum against 25 phytopathogenic bacterial strains. Carvacrol and thymol, the major constituents of S. spicigera and T. fallax oils, also showed potent antibacterial effect against the bacteria tested. The oils of Achillea species showed weak antibacterial activity. Our results also revealed that the essential oil of S. spicigera, thymol and carvacrol could be used as potential disinfection agents against seed-borne bacteria. CONCLUSION: Our results demonstrate that S. spicigera, T. fallax oils, carvacrol and thymol could become potentials for controlling certain important agricultural plant pathogenic bacteria and seed disinfectant.

Control of Aspergillus flavus with essential oil and methanol extract of Satureja hortensis.

The essential oil and methanol extract of Satureja hortensis were tested for antifungal activity against Aspergillus flavus in vitro on Petri plates and liquid culture, and under storage conditions. The oil showed strong antifungal activity based on the inhibition zone and minimal inhibitory concentration values against the pathogen on Petri plates assays. The very low concentrations of them also reduced wet and dry mycelium weight of pathogen fungus in liquid culture. When the oils at 25, 12.5 and 6.25 microl/mL concentrations were applied to lemon fruits before seven days of pathogen inoculation on storage conditions, the decay on fruits caused by the pathogen could be prevented completely. The results in this study showed that the essential oil of S. hortensis had strong antifungal activity against pathogen fungi tested. So, the essential oil of S. hortensis could be used for management of this pathogen as a potential source of sustainable eco-friendly botanical fungicides.