Obesity and associated metabolic disorders have become highly prevalent diseases worldwide, and the human gut microbiota, due to its influence on host energy metabolism, has been attributed an important role therein. This pilot study explores host-microbiota relationships in men and women affected by various types of glucose metabolism disorder. Among 20 individuals aged 58 to 71 years with either normal glucose tolerance, prediabetes, or type 2 diabetes mellitus the gut bacterial communities were compared based on barcoded 454 sequencing of 16S rRNA genes amplified from stool samples. We found that specific microbiota groups were relatively enriched or reduced in different metabolic states. Further, positive or negative associations with clinical manifestations of metabolic disease suggest that these organisms indicate and possibly contribute to metabolic impairment or health. For instance, a higher prevalence of Erysipelotrichaceae and Lachnospiraceae was found associated with metabolic disorders, and the Holdemania and Blautia genera correlated with clinical indicators of an impaired lipid and glucose metabolism. The Bacteroidetes and groups therein, by contrast, displayed inverse relationships with metabolic disease parameters and were found relatively enriched in participants not diagnosed with metabolic syndrome or obesity. Further, the prevalence of specific Clostridia and Rikenellaceae members also pointed towards a healthier metabolic state. Links with diet as an intermediate factor included positive and negative associations of Lachnospiraceae with relative consumption rates of fat and carbohydrates, respectively, and positive associations of Turicibacteraceae with the consumption of protein. Identifying critical roles of major gut microbiota components in metabolic disorders has important translational implications regarding the prevention and treatment of metabolic diseases by means of preventing or reversing dysbiosis and by controlling exacerbating diet and life style factors particularly in sensitive population groups.

Complete cycling of mineral nitrogen (N) in soil requires the interplay of microorganisms performing nitrification and denitrification, whose activity is increasingly affected by extreme rainfall or heat brought about by climate change. In a pristine forest soil, a gradual increase in soil temperature from 5 to 25 degrees C in a range of water contents stimulated N turnover rates, and N gas emissions were determined by the soil water-filled pore space (WFPS). NO and N(2)O emissions dominated at 30% WFPS and 55% WFPS, respectively, and the step-wise temperature increase resulted in a threefold increase in the NO(3)(-) concentrations and a decrease in the NH(4)(+) concentration. At 70% WFPS, NH(4)(+) accumulated while NO(3)(-) pools declined, indicating gaseous N loss. AmoA- and nirK-gene-based analysis revealed increasing abundance of bacterial ammonia oxidizers (AOB) with increasing soil temperature and a decrease in the abundance of archaeal ammonia oxidizers (AOA) in wet soil at 25 degrees C, suggesting the sensitivity of the latter to anaerobic conditions. Denitrifier (nirK) community structure was most affected by the water content and nirK gene abundance rapidly increased in response to wet conditions until the substrate (NO(3)(-)) became limiting. Shifts in the community structure were most pronounced for nirK and most rapid for AOA, indicating dynamic populations, whereas distinct adaptation of the AOB communities required 5 weeks, suggesting higher stability.

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The diversity and composition of soil bacterial communities were compared among six Austrian natural forests, including oak-hornbeam, spruce-fir-beech, and Austrian pine forests, using terminal restriction fragment length polymorphism (T-RFLP, or TRF) analysis and sequence analysis of 16S rRNA genes. The forests studied differ greatly in soil chemical characteristics, microbial biomass, and nutrient turnover rates. The aim of this study was to relate these differences to the composition of the bacterial communities inhabiting the individual forest soils. Both TRF profiling and clone sequence analysis revealed that the bacterial communities in soils under Austrian pine forests, representing azonal forest types, were distinct from those in soils under zonal oak-hornbeam and spruce-fir-beech forests, which were more similar in community composition. Clones derived from an Austrian pine forest soil were mostly affiliated with high-G؉C gram-positive bacteria (49%), followed by members of the ␣-Proteobacteria (20%) and the Holophaga/Acidobacterium group (12%). Clones in libraries from oak-hornbeam and spruce-fir-beech forest soils were mainly related to the Holophaga/Acidobacterium group (28 and 35%), followed by members of the Verrucomicrobia (24%) and the ␣-Proteobacteria (27%), respectively. The soil bacterial communities in forests with distinct vegetational and soil chemical properties appeared to be well differentiated based on 16S rRNA gene phylogeny. In particular, the outstanding position of the Austrian pine forests, which are determined by specific soil conditions, was reflected in the bacterial community composition.

The soil microbiome plays an important role in the establishment of weeds and invasive plants. They associate with microorganisms supporting their growth and health. Weed management strategies, like tillage and herbicide treatments, to control weeds generally alter soil structure going alongside with changes in the microbial community. Once a weed population establishes in the field, the plants build up a close relationship with the available microorganisms. Seeds or vegetative organs overwinter in soil and select early in the season their own microbiome before crop plants start to vegetate. Weed and crop plants compete for light, nutrition and water, but may differently interact with soil microorganisms. The development of new sequencing technologies for analyzing soil microbiomes has opened up the possibility for in depth analysis of the interaction between 'undesired' plants and crop plants under different management systems. These findings will help us to understand the functions of microorganisms involved in crop productivity and plant health, weed establishment and weed prevention. Exploitation of the knowledge offers the possibility to search for new biocontrol methods against weeds based on soil and plant-associated microorganisms. This review discusses the recent advances in understanding the functions of microbial communities for weed/invasive plant establishment and shows new ways to use plant-associated microorganisms to control weeds and invasive plants in different land management systems.