The experiment reported in this research paper aimed to evaluate the effects of high-starch or starch and oil-supplemented diets on rumen and faecal bacteria, and explore links between the structure of bacterial communities and milk fatty acid (FA) profiles. We used four Holstein dairy cows in a 4 × 4 Latin square design. Cows were fed a diet rich in cereals (high-starch diet with 23% starch content on dry matter (DM) basis), a diet supplemented with saturated FA from Ca salts of palm oil + 18% DM starch, a diet with high content of monounsaturated FA (from extruded rapeseeds) + 18% DM starch or a diet rich in polyunsaturated FA (from extruded sunflower seeds) + 17% DM starch. At the end of each experimental period, cows were sampled for rumen and faecal contents, which were used for DNA extraction and amplicon sequencing. Partial least squares (PLS) regression analysis highlighted diet-related changes in both rumen and faecal bacterial structures. Sparse PLS discriminant analysis was further employed to identify biologically relevant operational taxonomical units (OTUs) driving these differences. Our results show that Butyrivibrio discriminated the high-starch diet and linked positively with higher concentrations of milk odd- and branched-chain FA. YS2-related OTUs were key taxa distinguishing diets supplemented with Ca salts of palm oil or sunflower seeds and correlated positively with linoleic acid in milk. Similarly, diets modulated faecal bacterial composition. However, correlations between changes in faecal and rumen bacteria were poor. With this work, we demonstrated that high-starch or lipid-supplemented diets affect rumen and faecal bacterial community structure, and these changes could have a knock-on effect on milk FA profiles.

A study on locally available composts in Austria, Germany, Italy and Switzerland was conducted to investigate the potential of these non-chemical based tools to increase soil health in orchards afflicted by apple replant disease (ARD). A total of 26 different composts (six to seven per country) were chosen for the study. Composts were divided into ten types according to the waste materials used as substrates in the composting process. Growth reduction is the main symptom associated with replant disease; therefore compost performance was evaluated based on the growth responses of apple rootstock plantlets in compost-amended soils in pots. These greenhouse trials were performed in one research station per country, located in an intensive apple-growing area, and soil was taken from an apple orchard affected by replanting disease. Plant growth response was measured as shoot elongation at the end of each greenhouse trial, and results showed increases in growth compared with the respective controls of 2–26% in 20 out of 26 composts evaluated. The heterogeneous nature of the composts most likely attributed to the finding that similar compost types originating from the different countries had varying effects on plant growth. Overall, no significant changes in chemical and biological properties were observed in amended soils as compared with non-amended controls. The high soil resilience was in part expected given the good organic matter content in the original soils (>2%). The bacterial communities of the composts were investigated using the COMPOCHIP microarray, and analyses showed that differences in plant growth response were mainly attributed to the microbial changes introduced into the soil through composts rather than to changes in soil chemical and biological parameters. However, the bacterial communities of composts appeared to be more influenced by geographical origin than by compost type. The results have shown that soil amendment with composts generated from locally produced wastes have the potential to reduce the effects of ARD, although the effects appear to be both compost and soil specific.

Different techniques to assess bacterial community structure and diversity were evaluated in silages prepared with four different maize cultivars, three conventional and one transgenic (cv. Tundra, event Bt-176). Plants were cultivated in the greenhouse and harvested after 30 days of growth. Silage samples were collected at successive times during fermentation and analyzed for bacterial counts and by various DNA-based fingerprinting techniques. Bacterial counts were similar between cultivars for the total culturable bacteria, sporeforming, and mesophilic and thermophilic lactic acid bacteria (LAB). Further analysis of the species composition of 388 LAB strains by intergenic transcribed spacer (ITS) PCR followed by sequencing of 16S rRNA gene did not reveal differences between cultivars. In contrast, molecular fingerprinting methods targeting whole bacterial communities, such as automated ribosomal intergenic spacers analysis (ARISA) and 16S rRNA gene length heterogeneity-PCR (LH-PCR), indicated that different maize silage batches or cultivars hosted different bacterial communities. Thus, ARISA and LH-PCR fingerprinting techniques offer a fast and sensitive method to compare bacterial communities, and to detect differences in silage bacterial communities.