Project description:Oral administration of an extract of compost fermented with thermophiles to pigs reduces the incidence of stillbirth and promotes piglet growth. However, the mechanism by which compost extract modulates the physiological conditions of the animals remains largely unknown. Here, we investigate the effects of compost extract on the gene expression in the intestine of the rat as a mammalian model. Gene expression analyses of the intestine indicated that several immune-related genes were upregulated following compost exposure. Thus, thermophile-fermented compost can contain microbes and/or substances that activate the gut mucosal immune response in the rat.
Project description:Composts are the products obtained after the aerobic degradation of different types of organic matter wastes and can be used as substrates or substrate/soil amendments. There are a small but increasing number of reports that suggest that foliar diseases may be reduced when using compost as growing medium compared to standard substrates. The purpose of this study was to unravel the gene expression alteration produced by the compost to gain knowledge about the mechanisms involved in the compost-induced systemic resistance. A compost from olive marc and olive tree leaves was able to induce resistance against Botrytis cinerea in Arabidopsis compared to the standard substrate perlite. Microarray analyses revealed that 178 genes were differently expressed with a fold change cut off of 1 from which 155 were upregulated and 23 were down regulated in compost-grown compared to perlite-grown plants. Functional enrichment study of up regulated genes revealed that 38 Gene Ontology terms were significantly enriched. Response to stress, biotic stimulus, other organism, bacterium, fungus, chemical and abiotic stimulus, SA and ABA stimulus, oxidative stress, water, temperature and cold were significantly enriched terms as well as immune and defense responses, systemic acquired resistance, secondary metabolic process and oxireductase activity. Interestingly, PR1 expression, which was equally enhanced by growing the plants in compost and by B. cinerea inoculation, was further boosted in compost-grown pathogen-inoculated plants. Compost triggered a plant response that shares similarities with both systemic acquired resistance and ABA dependent/independent abiotic stress responses.
Project description:Wastewater treatment plants use a variety of bioreactor types and configurations to remove organic matter and nutrients. Little is known regarding the effects of different configurations and within-plant immigration on microbial community dynamics. Previously, we found that the structure of ammonia-oxidizing bacterial (AOB) communities in a full-scale dispersed growth activated sludge bioreactor correlated strongly with levels of NO2- entering the reactor from an upstream trickling filter (Wells et al 2009). Here, to further examine this puzzling association, we profile within-plant microbial biogeography (spatial variation) and test the hypothesis that substantial microbial immigration occurs along a transect (raw influent, trickling filter biofilm, trickling filter effluent, and activated sludge) at the same full-scale wastewater treatment plant. AOB amoA gene abundance increased >30-fold between influent and trickling filter effluent concomitant with NO2- production, indicating unexpected growth and activity of AOB within the trickling filter. Nitrosomonas europaea was the dominant AOB phylotype in trickling filter biofilm and effluent, while a distinct ‘Nitrosomonas-like’ lineage dominated in activated sludge. Prior time series indicated that this ‘Nitrosomonas-like’ lineage was dominant when NO2- levels in the trickling filter effluent (i.e., activated sludge influent) were low, while N. europaea became dominant in the activated sludge when NO2- levels were high. This is consistent with the hypothesis that NO2- production may co-occur with biofilm sloughing, releasing N. europaea from the trickling filter into the activated sludge bioreactor. Phylogenetic microarray (PhyloChip) analyses revealed significant spatial variation in taxonomic diversity, including a large excess of methanogens in the trickling filter relative to activated sludge and attenuation of Enterobacteriaceae across the transect, and demonstrated transport of a highly diverse microbial community via the trickling filter effluent to the activated sludge bioreactor. Our results provide compelling evidence that substantial immigration between coupled process units occurs and may exert significant influence over microbial community dynamics within staged bioreactors.