Browsing by Subject "Streptomyces"

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  • Vaario, Lu-Min; Asamizu, Shumpei; Sarjala, Tytti; Matsushita, Norihisa; Onaka, Hiroyasu; Xia, Yan; Kurokochi, Hiroyuki; Morinaga, Shin-Ichi; Huang, Jian; Zhang, Shijie; Lian, Chunlan (2020)
    Tricholoma matsutake is known to be the dominant fungal species in matsutake fruitbody neighboring (shiro) soil. To understand the mechanisms behind matsutake dominance, we studied the bacterial communities in matsutake dominant shiro soil and non-shiro soil, isolated the strains of Streptomyces from matsutake mycorrhizal root tips both from shiro soil and from the Pinus densiflora seedlings cultivated in shiro soil. Further, we investigated three Streptomyces spp. for their ability to inhibit fungal growth and Pinus densiflora seedling root elongation as well as two strains for their antifungal and antioxidative properties. Our results showed that Actinobacteria was the most abundant phylum in shiro soil. However, the differences in the Actinobacterial community composition (phylum or order level) between shiro and non-shiro soils were not significant, as indicated by PERMANOVA analyses. A genus belonging to Actinobacteria, Streptomyces, was present on the matsutake mycorrhizas, although in minority. The two antifungal assays revealed that the broths of three Streptomyces spp. had either inhibitory, neutral or promoting effects on the growth of different forest soil fungi as well as on the root elongation of the seedlings. The extracts of two strains, including one isolated from the P. densiflora seedlings, inhibited the growth of either pathogenic or ectomycorrhizal fungi. The effect depended on the medium used to cultivate the strains, but not the solvent used for the extraction. Two Streptomyces spp. showed antioxidant activity in one out of three assays used, in a ferric reducing antioxidant power assay. The observed properties seem to have several functions in matsutake shiro soil and they may contribute to the protection of the shiro area for T. matsutake dominance.
  • Hiltunen, Lea H.; Tarvainen, Oili; Kelloniemi, Jani; Tanskanen, Jaakko; Karhu, Jouni; Valkonen, Jari P. T. (2021)
    Disease suppressive soils are important for managing soil-borne diseases that cannot be controlled with chemicals. One such disease is the potato common scab caused by Streptomyces species. Suppressiveness against common scab can develop spontaneously in fields where potato is grown for years without interruption, and this has been attributed to non-pathogenic Streptomyces strains. Streptomyces spp. have been used as inoculants in biological control, but their long-term effects have gained less attention. In our previous studies, a nonpathogenic Streptomyces strain (Str272) isolated from a potato common scab lesion suppressed common scab in field trials lasting over 5 years. In this study, bacterial communities in the tuberosphere i.e. in the soil adjacent to potato tubers, were analysed by next generation sequencing (NGS). The aim was to compare bacterial communities in untreated control plots to those in which seed tubers were treated with Str272 in one or several growing seasons. Str272 applications increased soil bacterial diversity and affected the bacterial composition in the potato tuberosphere. The most pronounced differences were observed between the untreated control and the treatments in which the antagonist had been applied in three or four consecutive years. The differences remained similar until the following growing season. Bacterial composition after repeated antagonist applications was associated with lower common scab severity. The antagonist applications had no or only slight effect on the number or abundance of OTUs belonging to Actinobacteria or Streptomyces, and no differences in quantities of pathogenic Streptomyces populations were detected by qPCR. This indicates that suppression of common scab by Str272 may not be based on direct effect on the common scab pathogens but is more likely to be associated with the alterations of the soil bacterial community. The most abundant bacteria phyla in the potato tuberosphere were Actinobacteria, Proteobacteria and Acidobacteria. However, the OTUs responding greatest to the antagonist treatments belonged to Bacterioidetes and Gemmatimonadetes. Results indicate that repeated applications of Str272 can change the bacterial community in the potato tuberosphere and lead to development of soil that is suppressive against potato common scab for several growing seasons after the last application.
  • Ojanperä, Taru (Helsingfors universitet, 2008)
    The causal agents of Potato scab, S. scapies, S. turbidiscapies and S. aureofaciens spoil the quality of tubers, slow down the formation of potato seedlings, increase the number of small sized tubers and therefore can have a significant impact on the potato harvest. Sometimes the technical methods applied in the potato farming are not effective enough and there are no chemical means available to prevent potato scab. In this work the properties of selected Finnish Actinomyces-isolates were studied from the point of view of biological control. Both potato scab forming and stains that do not cause visible signs of potato scab in tubers were selected for the study. The purpose was to study the ability of the stains to inhibit the growth of potato scab bacteria in different pH-conditions. In addition the ability of Streptomyces-strains to inhibit the growth of silver scurf, stem cancer and black scurf was studied. The competitive balance between different Actinomyces and fungal strains was tested on plates. Greenhouse tests were used to study the root infesting of Actinomyces strains. Streptomyces strains inhibited each others growth. This inhibition was not linked to scab. All strains tested prevented the growth of silver scurf and ps pathogens but strains S.griseoviridis ja 16IV turned out being especially effective in preventing. All strains grew in pH-conditions 5.5-8.0. An unknown Streptomyces strain 16IV did not grow well in pH 5.5 and S. turbidiscapies which is known to persist in acidic conditions grew well also in pH 8.0. All tested strains colonized potato root. The study showed that some of the isolates had potential for future studies in biological control. More research is needed to study the root colonization and the antagonism properties of selected strains in root conditions. The causal agents of Potato scab, S. scapies, S. turbidiscapies and S. aureofaciens spoil the quality of tubers, slow down the formation of potato seedlings, increase the number of small sized tubers and therefore can have a significant impact on the potato harvest. Sometimes the technical methods applied in the potato farming are not effective enough and there are no chemical means available to prevent potato scab. In this work the properties of selected Finnish Actinomyces-isolates were studied from the point of view of biological control. Both potato scab forming and stains that do not cause visible signs of potato scab in tubers were selected for the study. The purpose was to study the ability of the stains to inhibit the growth of potato scab bacteria in different pH-conditions. In addition the ability of Streptomyces-strains to inhibit the growth of silver scurf, stem cancer and black scurf was studied. The competitive balance between different Actinomyces and fungal strains was tested on plates. Greenhouse tests were used to study the root infesting of Actinomyces strains. Streptomyces strains inhibited each others growth. This inhibition was not linked to scab. All strains tested prevented the growth of silver scurf and ps pathogens but strains S.griseoviridis ja 16IV turned out being especially effective in preventing. All strains grew in pH-conditions 5.5-8.0. An unknown Streptomyces strain 16IV did not grow well in pH 5.5 and S. turbidiscapies which is known to persist in acidic conditions grew well also in pH 8.0. All tested strains colonized potato root. The study showed that some of the isolates had potential for future studies in biological control. More research is needed to study the root colonization and the antagonism properties of selected strains in root conditions.