Streptomyces spp. Isolated from Potato Scab Lesions Under Nordic Conditions in Finland.

Actinomycetes isolated from scab lesions of potato tubers in Finland (60°-68°N, 21°-31°E) were characterized using physiological tests and production of necrosis on potato minitubers. Seven strains were additionally analyzed for their whole cell fatty acid profiles. The majority of the pathogenic strains were similar to the Streptomyces scabies type strain ATCC 49173 that is characterized by gray to brown colonies, gray spores, spiral sporophores, melanin production, and utilization of the International Streptomyces Project (ISP) sugars. However, two groups of strains (designated as Group 4, 38 strains; and Group 5, nine strains), each containing several pathogenic isolates, differed from S. scabies ATCC 49173 in at least two phenotypic traits. Additionally, a single, highly virulent strain (SSC 122) differed from all other strains for its phenotypic traits. The fatty acid compositions of the three pathogenic strains of Group 4 and the strain SSC 122 differed from S. scabies ATCC 49173 and S. acidiscabies ATCC 49003. In SSC 122, the ratio of saturated and unsaturated and the iso and anteiso forms of fatty acids were different from all other streptomycetes analyzed. Thus, the strains of Group 4 and 5 and SSC 122 may represent three novel Streptomyces spp. pathogenic on potato. SSC 122 and the pathogenic strains identified to S. scabies grew at pH 5.0 but not at pH 4.6, whereas the pathogenic strains of Group 4 and 5 grew at pH 4.6 or 4.4 but not at pH 4.2.

High aromatic ring-cleavage diversity in birch rhizosphere: PAH treatment-specific changes of I.E.3 group extradiol dioxygenases and 16S rRNA bacterial communities in soil.

Genes encoding key enzymes of catabolic pathways can be targeted by DNA fingerprinting to explore genetic degradation potential in pristine and polluted soils. We performed a greenhouse microcosm experiment to elucidate structural and functional bacterial diversity in polyaromatic hydrocarbon (PAH)-polluted soil and to test the suitability of birch (Betula pendula) for remediation. Degradation of PAHs was analysed by high-performance liquid chromatography, DNA isolated from soil amplified and fingerprinted by restriction fragment length polymorphism (RFLP) and terminal restriction fragment length polymorphism (T-RFLP). Bacterial 16S rRNA T-RFLP fingerprinting revealed a high structural bacterial diversity in soil where PAH amendment altered the general community structure as well as the rhizosphere community. Birch augmented extradiol dioxygenase diversity in rhizosphere showing a rhizosphere effect, and further pyrene was more efficiently degraded in planted pots. Degraders of aromatic compounds upon PAH amendment were shown by the changed extradiol ring-cleavage community structure in soil. The RFLP analysis grouped extradiol dioxygenase marker genes into 17 distinct operational taxonomic units displaying novel phylogenetic clusters of ring-cleavage dioxygenases representing putative catabolic pathways, and the peptide sequences contained conserved amino-acid signatures of extradiol dioxygenases. A branch of major environmental TS cluster was identified as being related to Parvibaculum lavantivorans ring-cleavage dioxygenase. The described structural and functional diversity demonstrated a complex interplay of bacteria in PAH pollution. The findings improve our understanding of rhizoremediation and unveil the extent of uncharacterized enzymes and may benefit bioremediation research by facilitating the development of molecular tools to detect and monitor populations involved in degradative processes.