Transcriptomic Changes in Medicago truncatula and Lotus japonicus Root Nodules during Drought Stress

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

Charakterystyka bakteriologiczna współczesnego drewna zalegającego w glebie na stanowisku archeologicznym w Biskupinie (Polska), w warunkach anoksji - Petrifilmy™ jako alternatywa względem konwencjonalnych podłoży bakteriologicznych

The paper presents results of quantitative and qualitative analyses of the composition of saprophytic and pathogenic microflora colonising contemporary wood of Scots pine (Pinus sylvestris L.) and oak (Quercus sp.), deposited for eight years in peat soil, under anoxia conditions at two measuring stations located at the fortified settlement of the Lusatian culture in Biskupin. Qualitative determinations of bacteria were performed based on the analyses of their cultural, morphological, physiological, and bio-chemical characteristics. Petrifilms™ and conventional bacteriological media were used for quantitative analyses. Bacteria in the examined wood and surrounding soil were identified as belonging to species, including those of the genera Pseudomonas, Clostridium (Cl. butyricum/beierinckii, Cl. perfringens), Bacillus, Corynebacterium, bacteria from the family Enterobacteriaceae, as well as aerobic and anaerobic cellulolytic bacteria. An important correlation between the standard pour plate method and PetrifilmTM was observed. Petrifilms are an effective alternative, in comparison with traditional methods, for the determination of total bacterial counts for wood samples.W pracy przedstawiono wyniki ilościowych i jakościowych analiz składu mikroflory saprofitycznej i patogennej zasiedlającej współczesne drewno sosny zwyczajnej (Pinus sylvestris L.) i dębu (Quercus sp.), zalegające przez okres ośmiu lat w glebie torfowej, w warunkach anoksji, na dwóch stanowiskach pomiarowych umiejscowionych na terenie grodu obronnego kultury łużyckiej w Biskupinie. Oznaczenia jakościowe bakterii przeprowadzono na podstawie analizy ich cech makro- i mikro-morfologicznych, a także fizjologicznych i biochemicznych. Do oznaczeń ilościowych użyto produktów Petrifilm™ i konwencjonalnych pożywek bakteriologicznych. Bakterie w badanym drewnie i otaczającej je glebie zidentyfikowano do gatunków, reprezentujących m.in. rodzaje Pseudomonas, Clostridium (Cl. butyricum/beierinckii, Cl. perfringens), Bacillus, Corynebacterium. Wykryto również bakterie z rodziny Enterobacteriaceae oraz tlenowe i beztlenowe bakterie celulolityczne. Zaobserwowano istotną korelację między wynikami otrzymanymi z wykorzystaniem standardowej metody płytkowej i użyciem techniki wykorzystującej produkty PetrifilmTM. Te ostatnie okazały się być skuteczną alternatywą względem tradycyjnych metod oznaczania całkowitej liczby bakterii w próbkach drewna

Ecological risk assessment for land contaminated by petrochemical industry.

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