Effect of seedbed steaming on Cylindrocladium floridanum, soil microbes and the development of white pine seedlings

Dans une pépinière forestière à racines nues, l'appareil Egedal® de traitement à la valeur des plates-bandes, a produit suffisamment de chaleur pour détruire les microsclérotes du Cylindrocladium floridanum à 5 et 10 cm de profondeur. À une autre pépinière, l'inoculum dans le sol ne fut détruit qu'à une profondeur de 5 cm. Le traitement à la vapeur du sol n'a pas affecté les microsclérotes situés à 15 cm. Le traitement a réduit les populations des pseudomonas fluorescents à des niveaux non détectables jusqu'à une profondeur de 20 cm et les populations des espèces de Trichoderma furent réduites significativement dans les 10 cm supérieurs de la plate-bande. Quatre mois après le traitement, la densité des semis de pin blanc semés dans les plates-bandes traitées était significativement plus élevée (P= 0,05), et leur hauteur, leur diamètre au collet, le poids de leurs tiges et celui de leurs racines étaient significativement plus grands (P= 0,05) que ceux des semis témoins provenant des plates-bandes non traitées.The Egedal® bed steamer produced sufficient heat to kill mierosclerotia of Cylindrocladium floridanum at 5 and 10 cm soil depths in one bareroot forest seedling nursery. At a second nursery, the buried inoculum was killed only to a depth of 5 cm. Soil steaming did not affect the mierosclerotia at 15 cm. The steaming reduced populations of fluorescent pseudomonas to undetectable levels to a depth of 20 cm and populations of Trichoderma species were significantly reduced in the upper 10 cm of the seedbed. Density of white pine seedlings sown in the steamed beds was significantly higher (P= 0.05), and height, root collar diameter, shoot weight and root weight were significantly greater (P= 0.05) 4 months after steaming than that of control seedlings sown in unsteamed beds

Einfluss von Zuckerrübenblatt auf N2O-Emissionen in der Nachernteperiode - Erste Ergebnisse

Praxisüblich verbleibt die gesamte Blattmasse der Zuckerrübe auf dem Feld und kann durch das enge C/N-Verhältnis rasch mineralisiert werden. Bei der mikrobiellen Umsetzung kann u.a. die reaktive Stickstoffverbindung N2O als Nebenprodukt der Nitrifikation, aber vor allem bei der Denitrifikation entstehen. Negative Umweltwirkungen wie die Eutrophierung von Biotopen oder ein vermehrter Ozonabbau können die Folge sein. Wie hoch allerdings die N2O-Emissionen durch Blattverbleib bei Zuckerrüben tatsächlich sind und inwieweit diese durch verschiedene Anbaumaßnahmen beeinflusst werden, ist derzeit unklar. Daher wurden 2016 auf zwei Standorten in der Nähe von Göttingen Versuche zur Ermittlung der N2O-Emissionen während der Nachernteperiode angelegt. Als mögliche Einflussgrößen auf die N2O-Freisetzung wurden variiert: Blattmasse und -zusammensetzung (N-Düngung zu Zuckerrüben gering, hoch), Blatteinarbeitung (mit, ohne), Erntezeitpunkt (Mitte September, Mitte Oktober). Darüber hinaus wurden die Umweltparameter Temperatur (Luft, Boden), Niederschlag, Bodenwassergehalt sowie der Boden-Nmin-Gehalt kontinuierlich erfasst. Die N2O-Messungen erfolgten mit geschlossenen Hauben nach dem Prinzip der statischen Messkammer (Closed-Chamber-Method). Erste Ergebnisse werden auf dem Poster vorgestellt

Microbial metabolism in soil at subzero temperatures: Adaptation mechanisms revealed by position-specific ¹³C labeling

© 2017 Bore, Apostel, Halicki, Kuzyakov and Dippold.Although biogeochemical models designed to simulate carbon (C) and nitrogen (N) dynamics in high-latitude ecosystems incorporate extracellular parameters, molecular and biochemical adaptations of microorganisms to freezing remain unclear. This knowledge gap hampers estimations of the C balance and ecosystem feedback in high-latitude regions. To analyze microbial metabolism at subzero temperatures, soils were incubated with isotopomers of position-specifically 13C-labeled glucose at three temperatures: +5 (control), -5, and -20°C. 13C was quantified in CO2, bulk soil, microbial biomass, and dissolved organic carbon (DOC) after 1, 3, and 10 days and also after 30 days for samples at -20°C. Compared to +5°C, CO2 decreased 3- and 10-fold at -5 and -20°C, respectively. High 13C recovery in CO2 from the C-1 position indicates dominance of the pentose phosphate pathway at +5°C. In contrast, increased oxidation of the C-4 position at subzero temperatures implies a switch to glycolysis. A threefold higher 13C recovery in microbial biomass at -5 than +5°C points to synthesis of intracellular compounds such as glycerol and ethanol in response to freezing. Less than 0.4% of 13C was recovered in DOC after 1 day, demonstrating complete glucose uptake by microorganisms even at -20°C. Consequently, we attribute the fivefold higher extracellular 13C in soil than in microbial biomass to secreted antifreeze compounds. This suggests that with decreasing temperature, intracellular antifreeze protection is complemented by extracellular mechanisms to avoid cellular damage by crystallizing water. The knowledge of sustained metabolism at subzero temperatures will not only be useful for modeling global C dynamics in ecosystems with periodically or permanently frozen soils, but will also be important in understanding and controlling the adaptive mechanisms of food spoilage organisms

Scale Invariance of Principle of Equivalent Utility under Cumulative Prospect Theory

In 1984 A. Reich proved that under Expected Utility Theory, a scale invariance of the Principle of Equivalent Utility just for two particular values of parameters implies its scale invariance. In this paper, we extend this result onto the Principle of Equivalent Utility under Cumulative Prospect Theory

Structural and physiological adaptations of soil microorganisms to freezing revealed by position-specific labeling and compound-specific ¹³C analysis

© 2019, Springer Nature Switzerland AG. Psychrotolerant microbes are crucial for carbon cycling and biotechnological applications. Nonetheless, the mechanisms enabling their survival and functioning in frozen environments remain unclear. To elucidate adaptations of microbial cell membranes to freezing, we incubated soils with position-specific 13C labeled glucose at + 5 (control), − 5 and − 20 °C and quantified 13C in CO2 and phospholipid fatty acids. High oxidation of glucose C-1 at + 5 °C revealed a transformation via the pentose phosphate pathway. At subzero temperatures, however, the preferential oxidation of C-4 position suggested a switch to glycolysis. The threefold increase of Gram-negative phospholipid fatty acids in soil incubated at − 5 °C was accompanied by a twofold increase in 13C incorporation. This unequal increase of phospholipid fatty acids and incorporated 13C can be explained by simultaneous desaturation of existing fatty acid chains and the de novo synthesis of monounsaturated fatty acids, which indicates microbial growth. In contrast, Gram-positive bacteria incorporated 2 times higher 13C into their phospholipid fatty acids at − 20 °C than at − 5 and + 5 °C without a significant increase in their fatty acid contents. This reflects intensive repair of membranes damaged at − 20 °C without microbial growth. The fungal/bacterial ratio was 1.5 times lower at subzero temperatures than at + 5 °C, reflecting a shift in microbial community structure towards bacteria. Accordingly, soil microorganisms adapted to freezing by (1) switching their metabolic pathway from the pentose phosphate pathway to glycolysis, (2) modifying phospholipid fatty acids by desaturation and, (3) shifting microbial community structure towards Gram-negative bacteria by reducing the fungal population

Structural and physiological adaptations of soil microorganisms to freezing revealed by position-specific labeling and compound-specific ¹³C analysis

© 2019, Springer Nature Switzerland AG. Psychrotolerant microbes are crucial for carbon cycling and biotechnological applications. Nonetheless, the mechanisms enabling their survival and functioning in frozen environments remain unclear. To elucidate adaptations of microbial cell membranes to freezing, we incubated soils with position-specific 13C labeled glucose at + 5 (control), − 5 and − 20 °C and quantified 13C in CO2 and phospholipid fatty acids. High oxidation of glucose C-1 at + 5 °C revealed a transformation via the pentose phosphate pathway. At subzero temperatures, however, the preferential oxidation of C-4 position suggested a switch to glycolysis. The threefold increase of Gram-negative phospholipid fatty acids in soil incubated at − 5 °C was accompanied by a twofold increase in 13C incorporation. This unequal increase of phospholipid fatty acids and incorporated 13C can be explained by simultaneous desaturation of existing fatty acid chains and the de novo synthesis of monounsaturated fatty acids, which indicates microbial growth. In contrast, Gram-positive bacteria incorporated 2 times higher 13C into their phospholipid fatty acids at − 20 °C than at − 5 and + 5 °C without a significant increase in their fatty acid contents. This reflects intensive repair of membranes damaged at − 20 °C without microbial growth. The fungal/bacterial ratio was 1.5 times lower at subzero temperatures than at + 5 °C, reflecting a shift in microbial community structure towards bacteria. Accordingly, soil microorganisms adapted to freezing by (1) switching their metabolic pathway from the pentose phosphate pathway to glycolysis, (2) modifying phospholipid fatty acids by desaturation and, (3) shifting microbial community structure towards Gram-negative bacteria by reducing the fungal population

Microbial metabolism in soil at subzero temperatures: Adaptation mechanisms revealed by position-specific ¹³C labeling

© 2017 Bore, Apostel, Halicki, Kuzyakov and Dippold.Although biogeochemical models designed to simulate carbon (C) and nitrogen (N) dynamics in high-latitude ecosystems incorporate extracellular parameters, molecular and biochemical adaptations of microorganisms to freezing remain unclear. This knowledge gap hampers estimations of the C balance and ecosystem feedback in high-latitude regions. To analyze microbial metabolism at subzero temperatures, soils were incubated with isotopomers of position-specifically 13C-labeled glucose at three temperatures: +5 (control), -5, and -20°C. 13C was quantified in CO2, bulk soil, microbial biomass, and dissolved organic carbon (DOC) after 1, 3, and 10 days and also after 30 days for samples at -20°C. Compared to +5°C, CO2 decreased 3- and 10-fold at -5 and -20°C, respectively. High 13C recovery in CO2 from the C-1 position indicates dominance of the pentose phosphate pathway at +5°C. In contrast, increased oxidation of the C-4 position at subzero temperatures implies a switch to glycolysis. A threefold higher 13C recovery in microbial biomass at -5 than +5°C points to synthesis of intracellular compounds such as glycerol and ethanol in response to freezing. Less than 0.4% of 13C was recovered in DOC after 1 day, demonstrating complete glucose uptake by microorganisms even at -20°C. Consequently, we attribute the fivefold higher extracellular 13C in soil than in microbial biomass to secreted antifreeze compounds. This suggests that with decreasing temperature, intracellular antifreeze protection is complemented by extracellular mechanisms to avoid cellular damage by crystallizing water. The knowledge of sustained metabolism at subzero temperatures will not only be useful for modeling global C dynamics in ecosystems with periodically or permanently frozen soils, but will also be important in understanding and controlling the adaptive mechanisms of food spoilage organisms

Assessment of physical properties and pH of selected surface waters in the northern part of Western Siberia

One of the undisputed natural resources of Western Siberia is a countless number of surface waters. They can be found in the form of all sorts of lakes from the smallest thermokarst ones with a surface area of only 1 m2 to large post-glacial lakes or high-mountain lakes. Besides, the world’s largest wetland is the peat bogs in the Western Siberia. Other equally impressive forms of surface waters are streams and rivers with the Ob River at the head making it the seventh largest river in the world. All these water bodies pose a tremendous challenge for research into their ecology

Microbial metabolism in soil at subzero temperatures: Adaptation mechanisms revealed by position-specific ¹³C labeling

© 2017 Bore, Apostel, Halicki, Kuzyakov and Dippold.Although biogeochemical models designed to simulate carbon (C) and nitrogen (N) dynamics in high-latitude ecosystems incorporate extracellular parameters, molecular and biochemical adaptations of microorganisms to freezing remain unclear. This knowledge gap hampers estimations of the C balance and ecosystem feedback in high-latitude regions. To analyze microbial metabolism at subzero temperatures, soils were incubated with isotopomers of position-specifically 13C-labeled glucose at three temperatures: +5 (control), -5, and -20°C. 13C was quantified in CO2, bulk soil, microbial biomass, and dissolved organic carbon (DOC) after 1, 3, and 10 days and also after 30 days for samples at -20°C. Compared to +5°C, CO2 decreased 3- and 10-fold at -5 and -20°C, respectively. High 13C recovery in CO2 from the C-1 position indicates dominance of the pentose phosphate pathway at +5°C. In contrast, increased oxidation of the C-4 position at subzero temperatures implies a switch to glycolysis. A threefold higher 13C recovery in microbial biomass at -5 than +5°C points to synthesis of intracellular compounds such as glycerol and ethanol in response to freezing. Less than 0.4% of 13C was recovered in DOC after 1 day, demonstrating complete glucose uptake by microorganisms even at -20°C. Consequently, we attribute the fivefold higher extracellular 13C in soil than in microbial biomass to secreted antifreeze compounds. This suggests that with decreasing temperature, intracellular antifreeze protection is complemented by extracellular mechanisms to avoid cellular damage by crystallizing water. The knowledge of sustained metabolism at subzero temperatures will not only be useful for modeling global C dynamics in ecosystems with periodically or permanently frozen soils, but will also be important in understanding and controlling the adaptive mechanisms of food spoilage organisms