The complete genome sequence of Propionibacterium acnes, a commensal of human skin

Propionibacterium acnes is a major inhabitant of adult human skin, where it resides within sebaceous follicles, usually as a harmless commensal although it has been implicated in acne vulgaris formation. The entire genome sequence of this Gram-positive bacterium encodes 2333 putative genes and revealed numerous gene products involved in degrading host molecules, including sialidases, neuraminidases, endoglycoceramidases, lipases, and pore-forming factors. Surface-associated and other immunogenic factors have been identified, which might be involved in triggering acne inflammation and other P. acnes-associated diseases.     

Fibroblast adhesion on unidirectional polymeric nanofilms

Nanotextured polymeric surfaces with inclined rods reveal highly anisotropic properties concerning wetting and adhesion. In this work, we report on the interaction of fibroblast cells with these highly anisotropic materials. The authors quantified removal of adherent cells from such surfaces by a laminar flow. The critical shear force needed for cell removal from the surface depends on the inclination direction. Based on electron microscopy cross sections we deduce that interactions of cellular filopodia extending into the nanotextured surface are causing the direction depending removal.     

Simulating the production potential and net energy yield of maize-ethanol in the southeastern USA

The interest in producing ethanol from maize has increased during recent years. However, the potential for maize-ethanol production is restricted to the extent of the feedstock production and the feedstock collection radius around an ethanol processing plant. The harvested acreage of maize in Alabama, Florida and Georgia has varied from 115,000 ha to 1.4 million ha during the last 50 years. One basic criterion for a sustainable production of renewable bio-ethanol is a positive net energy yield (NEY), i.e. more energy must be produced than the non-renewable energy that is used in the energy production chain, including the feedstock production and transportation and the biofuel processing. The goal of this study was to evaluate the potential to produce renewable energy the form of maize-ethanol in a region with typical southeastern USA maize cropping conditions. Two maize production acreages, which represent current and historical large acreages, and two feedstock collection radii of 100 and 200 km around an ethanol plant in southwest Georgia were evaluated. Maize growth and yield were simulated with the Cropping System Model (CSM)-CERES-Maize model to account for climate and soil variability. The simulations included weather data for 68 years. The potential ethanol production and NEY were calculated based on the simulated yields and energy requirements for the production. The ethanol production potential was 30–40 times greater for the large production acreage than for the small acreage. The average NEY across all simulated years was positive for all evaluated production acreages and collection radii. However, it was negative for the large production acreage under certain weather conditions. This study showed the potential to provide for an increase in renewable ethanol production from maize in the southeastern USA to meet the demand of the ethanol processing infrastructure.     

How does silviculture affect storm damage in forests of south-western Germany? Results from empirical modeling based on long-term observations

Storms represent the most important disturbance factor in forests of Central Europe. Using data from long-term growth and yield experiments in Baden-Wuerttemberg (south-western Germany), which permit separation of storm damage from other causes of mortality for individual trees, we investigated the influence of soil, site, forest stand, and tree parameters on storm damage, especially focusing on the influence of silvicultural interventions. For this purpose, a four-step modeling approach was applied in order to extract the main risk factors for (1) the general stand-level occurrence of storm damage, (2) the occurrence of total stand damage, and (3) partial storm damage within stands. The estimated stand-level probability of storm damage obtained in step 3 was then offset in order to describe the damage potential for the individual trees within each partially damaged stand (4). Generalized linear mixed models were applied. Our results indicate that tree species and stand height are the most important storm risk factors, also for characterizing the long-term storm risk. Additionally, data on past timber removals and selective thinnings appear more important for explaining storm damage predisposition than for example stand density, soil and site conditions or topographic variables. When quantified with a weighting method (summarizing the relative weight of single predictors or groups of predictors), removals could explain up to 20% of storm risk. The stepwise modeling approach proved an important methodological feature of the analysis, since it enabled consideration of the large number of observations without damage (“zero inflation”) in a statistically correct way. These results form a reliable basis for quantifying forest management’s direct impact on the risk of storm damage.     

A potential novel Brucella species isolated from mandibular lymph nodes of red foxes in Austria

The wild red fox (Vulpes vulpes) is a known indicator species for natural foci of brucellosis. Here, we describe phenotypic and molecular characteristics of two atypical Brucella strains isolated from two foxes hunted 2008 in Eastern Austria. Both strains agglutinated with monospecific anti-Brucella A serum and were positive in ELISA with monoclonal antibodies directed against various Brucella lipopolysaccharide epitopes. However, negative nitrate reductase- and negative oxidase-reaction were atypical traits. Affiliation to the genus Brucella was confirmed by 16S rRNA gene sequencing and by detection of the Brucella specific insertion element IS711 and gene bcsp31 using real-time PCR. Both fox strains showed identical IS711 Southern blot profiles but were distinct from known brucellae. The number of IS711 copies detected was as high as found in B. ovis or marine mammal Brucella strains. Molecular analyses of the recA and omp2a/b genes suggest that both strains possibly represent a novel Brucella species.     

Microbial community composition affects soil organic carbon turnover in mineral soils

Soil organic carbon (SOC) turnover is the most ubiquitous and ecologically fundamental process in soils. It is generally assumed that SOC is utilised by functionally redundant soil-specific microbial communities which do not differ in their capability to mineralise soil organic matter. To challenge this assumption, incubation experiments were conducted to analyse the community-specific effects on SOC turnover for six mineral soils under different land-use. Comparisons of respiration by a native soil community and an alien community both inoculated to sterilised soils revealed 29 ± 18% higher respiration by the native community (‘home-field advantage’). Increased soil microbial community diversity, as generated by mixing several microbial inoculants, did not result in increased mineralisation rates. Even under impaired conditions, in the presence of aged engine oil as a less decomposable substance, communities with higher diversity did not show higher respiration rates. Also, in non-sterilised soils, we detected the influence of the microbial community composition on respiration rates: Investigations on the effect of mixing two communities in a 50:50 untreated soil mixture showed declining respiration in three out of six cases (by 23.9 ± 5.9%) and increased respiration in one case (by 57%) compared to the mean respiration of the two unmixed soils. These effects were highly related to the microbial community capability, with only communities with low capability profiting from mixing with a second community. Our results question the assumption of redundancy of microbial community’s functionality for SOC mineralisation in soils.