The UN General Assembly has declared 2015 the International Year of Soils to raise awareness of the vital importance of soil, which is essential not only for food security and for cultivating plants for feed, fibre, fuel and medicinal products, but also for maintaining biodiversity as it hosts countless organisms. It plays a key role in storing and filtering water, in carbon and other nutrients cycling and performs other irreplaceable ecosystem functions. The Institute of Soil Biology of the CAS Biology Centre carries out biological research into many of those functions of soil in both natural and human–affected environments, including studies of the soil microstructure, soil organism communities and their dynamics and interactions and so on. Researchers at the Institute of Soil Biology focus, among other things, on the contribution of soil fungi to nitrous oxide emissions and on the production of methane. The latter is a potent greenhouse gas and a substantial part of atmospheric methane is produced by anaerobic microorganisms called Archaea found in the soil and in animal digestive tracts, while soil is also a significant methane sink. Research is also being concentrated on the characterization and risk assessment of antibiotic resistance-reservoirs in soil, which is connected with the massive use of antibiotics in the past five decades. Scientists examine ways of preventing the antibiotic resistance spreading in the environment through food chains as well as and on the role played by the soil microflora in those processes, as Doctor Dana Elhottová explains in the corresponding article. and Jana Olivová.
Environmental pollution by antibiotics poses a potential ecological risk to aquatic photosynthetic organisms. In the present study, toxic effects of erythromycin on PSI and PSII were investigated in cyanobacteria culture medium of Microcystis aeruginosa. The activity and electron transport of both photosystems were affected by erythromycin in a concentrationdependent manner. The quantum yield of PSII (YII) was reduced at 0.1 mg L-1 of erythromycin, while the quantum yield of PSI (YI) significantly decreased at concentration of 5-25 mg L-1. The decline of YII was accompanied by an increase of nonregulated energy dissipation (YNO). At 10 mg L-1 of erythromycin, YII decreased by 55%, while YNO increased by 18%. The decrease of YI induced by erythromycin was caused by donor-side limitation of PSI (YND). YND was markedly enhanced with elevated erythromycin concentration. At 10 mg L-1 of erythromycin, YI and YNA (PSI acceptor-side limitation) decreased by 8 and 82%, respectively, while YND rose by 314%. The quantum yield of cyclic electron flow increased significantly at 0.1-1 mg L-1 of erythromycin; it decreased but remained higher than that of the control at 5-25 mg L-1 of erythromycin. The contribution of cyclic electron flow to YI, and to linear electron flow rose significantly with the increasing erythromycin concentration. The maximum values of electron transport rates in PSII and PSI decreased by 71 and 24.3%, respectively, at 25 mg L-1 of erythromycin. Compared with the untreated control, the light saturation of PSII and PSI decreased significantly with increasing erythromycin concentration. We showed that concentrations of erythromycin >- 5 mg L-1 could exert acute toxicity to cyanobacteria, whereas the chronic toxicity caused by concentrations of ng or μg L-1 needs further research., C.-N. Deng, D.-Y. Zhang, X.-L. Pan., and Obsahuje bibliografii