No abstract

Contamination with harmful chemical substances, including organic compounds of the BTEX and PAH groups, constitutes one of the major threats to the functioning of soil habitat. Excessive contents of the above substances can exert adverse effects on soil organisms, reduce biodiversity, and thus deteriorate soil quality. The threat to soil ecosystems within areas particularly exposed to contamination with accumulating chemical compounds was assessed using the Ecological Risk Assessment (ERA) with a multi-stage Triad (triage rapid initial assessment) procedure (taking into account the different lines of evidence). The article presents the results of chemical and ecotoxicological study of soils sampled at sites affected by contamination from petrochemical industry. The study results provided foundations for developing the site specific ERA framework for the area examined.

Drought is one of the major environmental factors limiting biomass and seed yield production in agriculture. In this research, we focused on plants from the Fabaceae family, which has a unique ability for the establishment of symbiosis with nitrogen-fixing bacteria, and are relatively susceptible to water limitation. We have presented the changes in nitrogenase activity and global gene expression occurring in Medicago truncatula and Lotus japonicus root nodules during water deficit. Our results proved a decrease in the efficiency of nitrogen fixation, as well as extensive changes in plant and bacterial transcriptomes, shortly after watering cessation. We showed for the first time that not only symbiotic plant components but also Sinorhizobium meliloti and Mesorhizobium loti bacteria residing in the root nodules of M. truncatula and L. japonicus, respectively, adjust their gene expression in response to water shortage. Although our results demonstrated that both M. truncatula and L. japonicus root nodules were susceptible to water deprivation, they indicated significant differences in plant and bacterial response to drought between the tested species, which might be related to the various types of root nodules formed by these species.

A b s t r a c tA total of 181 cultivable endophytic bacterial isolates were collected from stems of 13 species of herbs inhabiting Europe (Poland): Chelido nium majus L., Elymus repens L., Erigeron annuus L., Euphrasia rostkoviana Hayne, Foeniculum vulgare L., Geranium pratense L., Humulus lupulus L., Matricaria chamomilla L., Mentha arvensis L., Papaver rhoeas L., Rosmarinus officinalis L., Solidago gigantea L. and Vinca minor L. The isolates were screened for their antifungal activity and fifty three were found to inhibit fungal growth. Of these, five had strong antifungal properties. These selected isolates were identified as: Pseudomonas azotoformans, P. cedrina, Bacillus subtilis group and Erwinia persicina. 370In the past few years the search for endophytes inhabiting medicinal plants intensified. It is now recognized that herbs are a very rich source of microorganisms with different biochemical properties. Numerous recent studies have been devoted to the identification of endophytes colonizing herbs from Asian countries. One study isolated 18 endophytic bacteria from herbal plants in Indonesia, such as citrus, turmeric, Androgra phis paniculata and Piper crocatum (Soka et al., 2012). Another study obtained 19 bacterial endophytes and 113 fungal endophytes from plants grown in India: Digitalis lanata, Digitalis purpurea, Plantago ovata and Dioscorea bulbifera (Ahmed et al., 2012). Indian herbs were also investigated by Amirita and colleagues, who managed to isolate 334 fungal strains inhabiting the internal tissues of Adhatoda vasica, Costus igneus, Coleus aromaticus and Lawsonia (Amirita et al., 2012). Another study of medicinal plants grown in Taiwan isolated 156 fungal endophytes from 20 species from the Lauraceae and Rutaceae family (Ho et al., 2012). In 2014 our team presented endophytic microflora of Hypericum perforatum (Rekosz-Burlaga et al., 2014). From stems and leaves of the tested plants four bacterial strains were isolated.The aim of the present study was to describe the endophytic microflora of selected medicinal plants inhabiting European countries. Isolated bacteria were tested for their antifungal properties against a plant pathogenic fungi and strains displaying the greatest antifungal activity have been classified according to their morphological, physiological and molecular characteristics.Plant samples were collected from two areas in central Poland, near Kozienice town (51.575°N, 21.750°E) and in Warsaw city (52.259°N, 21.020°E), during the vegetative seasons of 2007 and 2008. Bacterial endophytes were isolated from stems of 13 native growing herbal plant species: Chelidonium majus L., Elymes repens L., Erigeron annuus L., Euphrasia rostkoviana Hayne, Foeniculum vulgare L., Geranium pratense L., Humulus lupulus L., Matricaria chamomilla L., Mentla arvensis L., Papaver rhoeasL., Rosmarinus officinalis L. Solidago gigantea L. and Vinca minor L. Bacterial isolation from plant material was performed according to the procedure of Hung and Annapurna (2004). Five plants of each species were...

Endophytes produce a wide range of compounds with high application potential, mainly in medicine and agriculture. In this study, we test the hypothesis that endophytic bacteria produce indole-3-acetic acid (IAA), have positive influence on plant root development and are possible to application as plant-growth promoters. Endophytic bacteria were isolated from 3 native growing plant species: Chelidonium majus L., Elymus repens L., Solidago gigantea L. All endophytic strains produced IAA and the highest levels of IAA were observed for Pseudomonas azotoformans P3 strain. Triticale seed bacterization did not affect the seed germination, but had significant influence on root length and the longest roots were obtained after seed treatment with Pseudomonas sp. strains. Triticale roots were longer only in seedlings grown from seeds treated with endophytic strains producing high IAA levels (more than 22 µg ml -1 ). Our results suggest that endophytic Pseudomonas sp. strains isolated from Elymus repens L. can be used as plant-growth promoter.