A comprehensive method for organic matter characterization in solid wastes in view of assessing their anaerobic biodegradability.

The calculation of the anaerobic biodegradability requires the knowledge of the COD of the organic waste considered. Unfortunately, standard COD measurements are not available for solid wastes. In addition, sample processing generally requires a drying step (for TS and VS assessment for instance). What is shown here is that important amounts of COD might be lost upon drying (around 30% in the case of spent apples). We propose an alternate method based on the separation of the waste in two fractions: water soluble (WS) and non water soluble (NWS, particulate). The two fractions have been characterized individually and both the COD and the biodegradability could be assessed with a greater accuracy. For spent apples, the biodegradability of the NWS fraction is much lower than that of the WS fraction (36.6% vs. 95.2%), and can be well predicted from a previously established model based on the measurement of the cellulose and lignin fractions.

Cell wall invertase expression at the apical meristem alters floral, architectural, and reproductive traits in Arabidopsis thaliana.

Resource allocation is a major determinant of plant fitness and is influenced by external as well as internal stimuli. We have investigated the effect of cell wall invertase activity on the transition from vegetative to reproductive growth, inflorescence architecture, and reproductive output, i.e. seed production, in the model plant Arabidopsis thaliana by expressing a cell wall invertase under a meristem-specific promoter. Increased cell wall invertase activity causes accelerated flowering and an increase in seed yield by nearly 30%. This increase is caused by an elevation of the number of siliques, which results from enhanced branching of the inflorescence. On the contrary, as cytosolic enzyme, the invertase causes delayed flowering, reduced seed yield, and branching. This demonstrates that invertases not only are important in determining sink strength of storage organs but also play a role in regulating developmental processes.