The extreme physical properties of the CoRoT-7b super-Earth

International audience► Here, we discuss the extreme physical properties possible for the first characterized rocky super-Earth, CoRoT-7b ( = 1.58 , = 5.7 ). ► We make the working hypothesis that the planet is rocky with no volatiles in its atmosphere, and derive the physical properties that result. ► The dayside is very hot (2500 K at the sub-stellar point) while the nightside is very cold (∼ 50 K). The sub-stellar point is as hot as the tungsten filament of an incandescent bulb, resulting in the melting and distillation of silicate rocks and the formation of a lava ocean. ► These possible features of CoRoT-7b should be common to many small and hot planets, including Kepler-10b. They define a new class of objects that we propose to name ''Lava-ocean planets''

Phenotypic characterization of Brettanomyces bruxellensis strains for the tolerance to stresses encountered during second generation bioethanol production

Brettanomyces (teleomorph Dekkera) bruxellensis has been generally considered a spoilage yeast in fuel ethanol production plants. However, due to its peculiar carbon- and nitrogen metabolism, the yeast is also believed to hold great potential for bioethanol production in continuous reactors. Nevertheless, before actually being useful in the production of second generation bioethanol there are still some challenges to overcome. For example, the use of lignocellulosic biomass results in the need for an extensive pretreatment process during which often several inhibiting compounds are released, leading to less efficient or stuck fermentations. The objective of this study was to phenotypically characterize B. bruxellensis strains for tolerance to stresses typically encountered during second generation bioethanol fermentation and to develop a screening plate for the evaluation of yeast strains against stresses relevant for the second generation bioethanol production. To this end, a plate was developed containing a dose range of different inhibitors (i.e. vanillin, catechol, levulinic acid, formic acid, furfural, ethanol, low pH, and high osmotic pressure). Further the plate included a negative and positive control well. Subsequently, several B. bruxellensis strains from different ecological niches were screened using the developed plate. Plates were incubated for eight days at 25 °C and analyzed by the OmniLog incubator/reader (Biolog, Hayward, CA, USA). All analysis were performed in duplicate. The different B. bruxellensis strains were ranked by calculating the average well colour development (AWCD). Additionally, each strain was scored for its tolerance to the tested inhibitory conditions. This resulted in a huge variation among strains, demonstrating the need for screening a large collection of strains to identify superior yeast strains. Highly ranked B. bruxellensis strains can then be further tested for tolerance against a mixture of inhibitors and real hydrolyzed biomass fermentation broths. Additionally, features such as ethanol yield and performance in pilot plants should be evaluated to truly see its potential for industrial second generation bioethanol production.status: publishe