The Influence of Hydrocarbon-Oxidizing Auxin-Producing Bacteria on the Growth, Biochemical Parameters, and Hormonal Status of Barley Plants in the Process of Bioremediation of Oil-Contaminated Soil

Взаимосвязи бактерий и растений в процессе биоремедиации почв, загрязненных нефтью, уделяется много внимания, однако воздействие бактерий-деструкторов нефти, синтезирующих фитогормоны, на содержание и распределение этих соединений в самих растениях, исследовано слабо. Целью полевого опыта было изучение влияния углеводородокисляющих бактерий, продуцирующих ауксины, на ростовые, биохимические показатели и гормональный статус растений ячменя в присутствии нефти и перспективы применения их ассоциаций для очистки почвы, содержащей нефть (в среднем 2,7 %). Обработка растений штаммами Enterobacter sp. UOM 3 и Pseudomonas hunanensis IB C7 приводила к увеличению длины и массы корней и побегов, индекса листовой поверхности и улучшению показателей элементов структуры урожая, которые были угнетены под воздействием поллютанта. В результате бактеризации повышалось содержание хлорофилла, флавоноидов и снижалось количество пролина. Наиболее заметным проявлением влияния бактерий на гормональную систему растений было уменьшение накопления абсцизовой кислоты. Полученные данные свидетельствуют о том, что интродукция микроорганизмов ослабляла для растений негативные последствия абиотического стресса, вызванного присутствием нефти. Совместное применение бактерий-нефтедеструкторов и растений эффективнее снижало содержание углеводородов в почве и увеличивало ее микробиологическую активность по сравнению с использованием их по отдельности. Изученные микробно-растительные комплексы признаны перспективными для биоремедиации нефтезагрязненных почвExtensive research has been done to investigate the relationship between bacteria and plants in the process of bioremediation of soils contaminated with oil, but the effect of oil-degrading bacteria that synthesize phytohormones on the content and distribution of these compounds in plants has been poorly studied. The aim of the field experiment was to study the effect of hydrocarbon-oxidizing bacteria producing auxins on the growth, biochemical parameters, and hormonal status of barley plants in the presence of oil and the prospects for using bacterial-plant associations for treating soil that contains oil (2.7 %, on average). Treatment of plants with cultures of Enterobacter sp. UOM 3 and Pseudomonas hunanensis IB C7 led to an increase in the length and mass of roots and shoots and the leaf surface index and an improvement in the parameters of the components of the crop structure that were suppressed by the pollutant. As a result of bacterization, the contents of chlorophyll and flavonoids increased, and the amount of proline decreased. The most noticeable effect of bacteria on the hormonal system of plants was a decrease in the accumulation of abscisic acid. The data obtained indicate that the treatment of plants with bacterial cultures alleviated the negative consequences of abiotic stress caused by the presence of oil for plants. The use of oil-degrading bacteria and plants in combination rather than separately more effectively reduced the content of hydrocarbons in the soil and increased its microbiological activity. The microbial-plant combinations studied in this work are regarded as promising for the bioremediation of oil-contaminated soil

Adaptive Changes in the Vestibular System of Land Snail to a 30-Day Spaceflight and Readaptation on Return to Earth

The vestibular system receives a permanent influence from gravity and reflexively controls equilibrium. If we assume gravity has remained constant during the species' evolution, will its sensory system adapt to abrupt loss of that force? We address this question in the land snail Helix lucorum exposed to 30 days of near weightlessness aboard the Bion-M1 satellite, and studied geotactic behavior of postflight snails, differential gene expressions in statocyst transcriptome, and electrophysiological responses of mechanoreceptors to applied tilts. Each approach revealed plastic changes in the snail's vestibular system assumed in response to spaceflight. Absence of light during the mission also affected statocyst physiology, as revealed by comparison to dark-conditioned control groups. Readaptation to normal tilt responses occurred at ~20 h following return to Earth. Despite the permanence of gravity, the snail responded in a compensatory manner to its loss and readapted once gravity was restored