@misc{ZyakunNiiAnnangFrankeetal., author = {Zyakun, Anatoly and Nii-Annang, Seth and Franke, Gabriele and Fischer, Thomas and Buegger, Franz and Dilly, Oliver}, title = {Microbial Actvity and 13C/12C Ratio as Evidence of N-Hexadecane and N-Hexadecanoic Acid Biodegradation in Agricultural and Forest Soils}, series = {Geomicrobiology Journal}, volume = {28}, journal = {Geomicrobiology Journal}, number = {7}, issn = {1521-0529}, doi = {10.1080/01490451.2010.489922}, pages = {632 -- 647}, abstract = {The dynamics of microbial degradation of exogenous contaminants, n-hexadecane and its primary microbial oxidized metabolite, n-hexadecanoic (palmitic) acid, was studied for topsoils, under agricultural management and beech forest on the basis the changes in O2 uptake, CO2 evolution and its associated microbial and non-microbial carbon isotopic signature, the respiratory quotient (RQ) and the priming effect (PE) of substrates. Soil microbial communities in agricultural soil responded to the n-hexadecane addition more rapidly compared to those of forest soil, with lag-periods of about 23 ± 10 and 68 ± 13 hours, respectively. Insignificant difference in the lag-period duration was detected for agricultural (tlag = 30 ± 13 h) and forest (tlag = 30 ± 14 h) soils treated with n-hexadecanoic (palmitic) acid. These results demonstrate that the soil microbiota differed in metabolic activities for using n-hexadecane as a reductive hydrocarbon and n-hexadecanoic acid as a partly oxidized hydrocarbon. The corresponding δ13C of respired CO2 after the addition of the hydrocarbon contaminants to soils indicates a shift in microbial activity towards the consumption of exogenous substrates with a more complete degradation of n-hexadecane in the agricultural soil, for which some initial contents of hydrocarbons are inherent. It was reflected in the carbon isotope signature of microbial biomass. It is supposed that the observed deviation of RQ from theoretically calculated value under microbial substrate mineralization is determined by difference in the time (Δti) of registration of CO2 production and O2 consumption. Positive priming effect (PE) of n-hexadecane and negative PE of n-hexadecanoic (palmitic) acid were detected in agricultural and forest soils. It is suggested that positive PE of n-hexadecane is conditioned by the induction of microbial enzymes that perform hydroxylation/oxygenation of stable SOM compounds mineralized by soil microbiota to CO2. The microbial metabolism coupled with oxidative decarboxylation of n-hexadecanoic acid is considered as one of the most probable causes of the revealed negative PE value.}, language = {en} } @misc{DillyNiiAnnangFrankeetal., author = {Dilly, Oliver and Nii-Annang, Seth and Franke, Gabriele and Fischer, Thomas and Buegger, Franz and Zyakun, Anatoly}, title = {Resilience of microbial respiration, respiratory quotient and stable isotope characteristics to soil hydrocarbon addition}, series = {Soil Biology and Biochemistry}, volume = {43}, journal = {Soil Biology and Biochemistry}, number = {9}, issn = {0038-0717}, doi = {10.1016/j.soilbio.2010.09.026}, pages = {1808 -- 1811}, abstract = {On the basis of CO2 evolution rate, O2 uptake rate, and 13C isotopic signature of respired CO2, the metabolic response to the addition of 13C labelled n-hexadecane and palmitic acid each with supplementary nitrogen was studied for two topsoils, one under continuous agricultural management and the other under beech forest. The CO2 evolution rate was immediately stimulated in the agricultural soil and the respiratory quotient (RQ) decreased from 0.8 to 0.4 mol CO2 evolution rate per mol O2 uptake rate, which was below the theoretically expected value of 0.65 and 0.70 for the degradation of n-hexadecane and palmitic acid, respectively. The microbial response was delayed in the forest soil, but developed better than in the agricultural soil throughout the subsequent 2-4 weeks. Consequently, the respiration rate returned earlier to the initial level for the beech forest soil and the δ13C of respired CO2 and RQ approached values before hydrocarbon addition. Based on the link among respiration rates, RQ and 13C-CO2 value, the added oil-analogue compounds induced a more rapid response in the agricultural soil and were degraded more completely in the forest soil. We concluded that the resilience, which we defined here as the capacity of the soil microbiota to buffer perturbance and to reorganise in response to change resulting in a more desirable system, was higher in our forest soil than for the agricultural soil.}, language = {de} } @misc{DillyFrankeNiiAnnangetal., author = {Dilly, Oliver and Franke, G. and Nii-Annang, Seth and Weber, K. and Freese, Dirk and Zyakun, Anatoly and H{\"u}ttl, Reinhard F.}, title = {Soil respiratory indicators including carbon isotope characteristics in response to copper}, series = {Geomicrobiology Journal}, volume = {25}, journal = {Geomicrobiology Journal}, number = {7-8}, issn = {1521-0529}, doi = {10.1080/01490450802402992}, pages = {390 -- 395}, language = {en} } @misc{DillyZyakun, author = {Dilly, Oliver and Zyakun, Anatoly}, title = {Priming Effect and Respiratory Quotient in a Forest Soil Amended with Glucose}, series = {Geomicrobiology Journal}, volume = {25}, journal = {Geomicrobiology Journal}, number = {7-8}, issn = {1521-0529}, doi = {10.1080/01490450802403099}, pages = {425 -- 431}, language = {en} }