Size matters: biochemical mineralization and microbial incorporation of dicarboxylic acids in soil

The transformation and turnover time of medium- to long-chain dicarboxylic acids (DCA) in soil is regulated by microbial uptake and mineralization. However, the chain length of n-alkyl lipids may have a remarkable influence on its microbial utilization and mineralization and therefore on the formation of stable soil organic carbon from e.g. leave- needle- and root-derived organic matter during decomposition. To investigate their size dependent mineralization and microbial incorporation, four DCA of different chain lengths (12–30 carbon atoms), that were 13C labeled at each of their terminal carboxylic groups, were applied to the Ah horizon of a Fluvic Gleysol. Incorporation of 13C into CO2 and in distinct microbial groups classified by phospholipid fatty acid (PLFA) analysis was investigated. Mineralization of DCA and incorporation into PLFA decreased with increasing chain length, and the mineralization rate was highest during the first days of incubation. Half-life time of DCA carbon in soil increased from 7.6 days for C12 DCA to 86.6 days for C18 DCA and decreased again to 46.2 days for C22 DCA, whereas C30 DCA had the longest half-life time. Rapid and efficient uptake of C12 DCA as an intact molecule was observable. Gram-negative bacteria incorporated higher amounts of DCA-derived 13C compared to other microbial groups, especially compared to actinomycetes and fungi during the first phase of incubation. However, the incorporation of C12 DCA derived 13C into the PLFA of actinomycetes, and fungi increased steadily during the entire incubation time, suggesting that those groups take up the 13C label from necromass of bacteria that used the C12 DCA for formation of their lipids before

Correction to: Size matters: biochemical mineralization and microbial incorporation of dicarboxylic acids in soil

The transformation and turnover time of medium- to long-chain dicarboxylic acids (DCA) in soil is regulated by microbial uptake and mineralization. However, the chain length of n-alkyl lipids may have a remarkable influence on its microbial utilization and mineralization and therefore on the formation of stable soil organic carbon from e.g. leave- needle- and root-derived organic matter during decomposition. To investigate their size dependent mineralization and microbial incorporation, four DCA of different chain lengths (12–30 carbon atoms), that were 13C labeled at each of their terminal carboxylic groups, were applied to the Ah horizon of a Fluvic Gleysol. Incorporation of 13C into CO2 and in distinct microbial groups classified by phospholipid fatty acid (PLFA) analysis was investigated. Mineralization of DCA and incorporation into PLFA decreased with increasing chain length, and the mineralization rate was highest during the first days of incubation. Half-life time of DCA carbon in soil increased from 7.6 days for C12 DCA to 86.6 days for C18 DCA and decreased again to 46.2 days for C22 DCA, whereas C30 DCA had the longest half-life time. Rapid and efficient uptake of C12 DCA as an intact molecule was observable. Gram-negative bacteria incorporated higher amounts of DCA-derived 13C compared to other microbial groups, especially compared to actinomycetes and fungi during the first phase of incubation. However, the incorporation of C12 DCA derived 13C into the PLFA of actinomycetes, and fungi increased steadily during the entire incubation time, suggesting that those groups take up the 13C label from necromass of bacteria that used the C12 DCA for formation of their lipids before

From virtual to physical environments when judging action opportunities : are diagnostics and trainings transferable?

The proper evaluation of whether our given bodily capabilities and environmental properties allow particular actions is indispensable for pertinent decisions, so-called affordance judgments. These can be impacted by older age or brain damage. Virtual Environments (VEs) may provide an efficient opportunity to offer trainings. But do people make affordance judgments in VEs in the same way that they do in Physical Environments (PEs)? And are these decisions trainable by use of VEs? We investigated 24 healthy young adults’ judgment performance of whether or not they could fit their hand into a given aperture. They were presented with a set of opening-increments and indicated their judgments by pressing a yes- or no-button. The stimuli were presented in PE using an aperture apparatus and in VE displayed by use of Oculus Rift goggles. Our results demonstrated the level of equivalence to be specific to the variable: While we found equivalence between VE and PE for the accuracy parameter, results were uncertain or non-equivalent for perceptual sensitivity and for judgment tendency, respectively. When applying training in VE, judgment accuracy improved significantly when tested subsequently within VE. Improvement appeared detectable in PE only on a descriptive level. Furthermore, equivalence testing post-training revealed that perceptual sensitivity performance in VE approached a PE-level. Promisingly, the VE training approach appeared applicable and efficacious within the VE. Future studies need to specify factors that enhance equivalence for detection theory variables and that facilitate transfer from VEs to PEs when judging action opportunities.publishe