Aridity modulates belowground bacterial community dynamics in olive tree

Aridity negatively affects the diversity and abundance of edaphic microbial communities and their multiple ecosystem services, ultimately impacting vegetation productivity and biotic interactions. Investigation about how plant-associated microbial communities respond to increasing aridity is of particular importance, especially in light of the global climate change predictions. To assess the effect of aridity on plant associated bacterial communities, we investigated the diversity and co-occurrence of bacteria associated with the bulk soil and the root system of olive trees cultivated in orchards located in higher, middle and lower arid regions of Tunisia. The results indicated that the selective process mediated by the plant root system is amplified with the increment of aridity, defining distinct bacterial communities, dominated by aridity-winner and aridity-loser bacteria negatively and positively correlated with increasing annual rainfall, respectively. Aridity regulated also the co-occurrence interactions among bacteria by determining specific modules enriched with one of the two categories (aridity-winners or aridity-losers), which included bacteria with multiple PGP functions against aridity. Our findings provide new insights into the process of bacterial assembly and interactions with the host plant in response to aridity, contributing to understand how the increasing aridity predicted by climate changes may affect the resilience of the plant holobiont

Environmental micro-niche filtering shapes bacterial pioneer communities during primary colonization of a Himalayas' glacier forefield

The pedogenesis from the mineral substrate released upon glacier melting has been explained with the succession of consortia of pioneer microorganisms, whose structure and functionality are determined by the environmental conditions developing in the moraine. However, the microbiome variability that can be expected in the environmentally heterogeneous niches occurring in a moraine at a given successional stage is poorly investigated. In a 50 m2 area in the forefield of the Lobuche glacier (Himalayas, 5050 m above sea level), we studied six sites of primary colonization presenting different topographical features (orientation, elevation and slope) and harbouring greyish/dark biological soil crusts (BSCs). The spatial vicinity of the sites opposed to their topographical differences, allowed us to examine the effect of environmental conditions independently from the time of deglaciation. The bacterial microbiome diversity and their co-occurrence network, the bacterial metabolisms predicted from 16S rRNA gene high-throughput sequencing, and the microbiome intact polar lipids were investigated in the BSCs and the underlying sediment deep layers (DLs). Different bacterial microbiomes inhabited the BSCs and the DLs, and their composition varied among sites, indicating a niche-specific role of the micro-environmental conditions in the bacterial communities' assembly. In the heterogeneous sediments of glacier moraines, physico-chemical and micro-climatic variations at the site-spatial scale are crucial in shaping the microbiome microvariability and structuring the pioneer bacterial communities during pedogenesis

The stage of soil development modulates rhizosphere effect along a High Arctic desert chronosequence

In mature soils, plant species and soil type determine the selection of root microbiota. Which of these two factors drives rhizosphere selection in barren substrates of developing desert soils has, however, not yet been established. Chronosequences of glacier forelands provide ideal natural environments to identify primary rhizosphere selection factors along the changing edaphic conditions of a developing soil. Here, we analyze changes in bacterial diversity in bulk soils and rhizospheres of a pioneer plant across a High Arctic glacier chronosequence. We show that the developmental stage of soil strongly modulates rhizosphere community assembly, even though plant-induced selection buffers the effect of changing edaphic factors. Bulk and rhizosphere soils host distinct bacterial communities that differentially vary along the chronosequence. Cation exchange capacity, exchangeable potassium, and metabolite concentration in the soil account for the rhizosphere bacterial diversity. Although the soil fraction (bulk soil and rhizosphere) explains up to 17.2% of the variation in bacterial microbiota, the soil developmental stage explains up to 47.7% of this variation. In addition, the operational taxonomic unit (OTU) co-occurrence network of the rhizosphere, whose complexity increases along the chronosequence, is loosely structured in barren compared with mature soils, corroborating our hypothesis that soil development tunes the rhizosphere effect

Biomasse in agricoltura. Caratterizzazione e utilizzo sostenibile.

Il concetto di qualità, per una biomassa, può assumere declinazioni diverse in funzione di quello che sarà il suo utilizzo. In termini generali, quando ci riferiamo ad una biomassa, il termine “qualità” deve assumere una connotazione quantitativa basata cioè su parametri misurabili dal momento che, quando se ne prevede la valorizzazione in ambiti agricoli o di altro tipo, essa perde il suo status di rifiuto per assumere quello di “prodotto”, di un bene cioè in grado di soddisfare un determinato bisogno. In tale senso possiamo fare riferimento a Kant che, nella Critica del Giudizio, affermava che “solo la conoscenza implica l’esistenza di un oggetto percepibile e una funzione, a priori, intrinseca e in grado di organizzare la percezione dell’oggetto”. Esempio: “il bello non è una proprietà delle cose, ma nasce dal rapporto tra le cose e noi e, precisamente, dal rapporto fra la loro immagine e il nostro sentimento”. Dal pensiero di Kant si origina il concetto di qualità nella storia contemporanea. Juran (1951) definisce la qualità come “idoneità all’uso” e, più di recente, possiamo fare riferimento alla norma UNI EN ISO 8402 (1995) che definisce la qualità “l’insieme delle proprietà e delle caratteristiche di un prodotto o servizio che gli conferiscono l’attitudine a soddisfare bisogni espressi o impliciti”. Applicato alle biomasse è quindi possibile attribuire ad esse un differente livello di qualità in base all’utilizzo che ne verrà fatto

Hydrophilic and hydrophobic fractions of water-soluble organic matter in digestates obtained from different organic wastes

Up to now, it is unknown how anaerobic digestion of biowastes affects the chemical composition of water-soluble organic matter (WSOM) in the digestate and, thus, the potential distribution and mobility of hydrophobic organic contaminants. The aim of the present work was to estimate the proportions of hydrophilic (HI) and hydrophobic (HO) fractions of WSOM in anaerobic digestates obtained from different mixtures of biomass. The overall goal was correlating proportions of HI and HO fractions to the different chemical characteristics of the biowastes subjected to anaerobic digestion. More than 70% of WSOM was with the HI fractions of digestates derived from 1:1 mixtures of the organic part of municipal solid wastes and sewage sludge. Larger HO fractions were observed for digestates derived from energy crop plus smaller contributions of poultry manure, stomach residue, and apple residues, likely due to the concentration of fibers during the digestion. Ratios between HO fractions in digestates and in their corresponding ingestates were used as indicators of the transformation of WSOM during the process. © 2014 Elsevier Ltd

Sugars production for green chemistry from 2nd\ua0generation crop (Arundo donax L.): a full field approach

Arundo donax L. (giant cane) is a suitable feedstock for sugar production because of its high biomass yield and low agronomic input requirement. Eight A. donax clones were studied at full field scale for sugars production. 1-ethyl-3-methylimidazolium acetate - [CCim][OAc] - and enzymatic treatments were used to obtain the sugars. Highest glucose yields were obtained for pretreatment performed at 160 °C for 3 hours, with glucan conversion yields from 40.8 % to 76.2 % for most productive A. donax clones (AD10 and AD 20). Differences in cell wall structure measured by micropore surface area (pores of 0.3 - 1.5 nm) explained both ionic liquids and enzymatic performances of clones. Structural differences were due to the guaiacyl (G) and syringyl (S) units that determined different lignin cross-linking affecting cell wall microporosity and so enzyme accessibility. Total glucose and xylose yields (11 Mg Ha and 4.84 Mg Ha, clone AD20), were impressive and about 3.5 to 4.5 times more than those obtainable from switchgrass and corn stover

Nitrogen fertilising products based on manure and organic residues : supporting literature of the SYSTEMIC factsheets

The EU H2020 project SYSTEMIC has taken up the challenge to recover nutrients from animal manure and biowaste. Biowaste, like animal manure, sewage sludge and food and feed waste, forms the most abundant waste stream in Europe and hence the most prominent potential resource for the production of biogas and the recovery and reuse of mineral nutrients like phosphorus (P), nitrogen (N) and potassium (K). The application of nutrient recovery from waste is hindered by regulatory requirements amongst others the Nitrates Directive 91/676/EEG. This report gives an overview of the agronomic and environmental performance of nitrogen fertilising products made from manure. These products are ammonium sulphate and ammonium nitrate from air scrubbers and ammonia strippers, mineral concentrates produced by reverse osmosis, condensated ammonia water from capturing ammonia and liquid digestate produced by separation of digestate. For each fertilising product the state of the art of information on the technology, characteristics, composition, agronomic effectivity and risk assessment on contaminants, pathogens and other components is given. The information is condensed to a factsheet. These factsheets are also found at the website of the SYSTEMIC product (https://systemicproject.eu/downloads/)

The Fate of Phosphorus in Experimental Burials: Chemical and Ultramicroscopic Characterization and Environmental Control of Its Persistency

The permanence of a buried body in soil always induces the formation of a decomposition island that can serve as a significant recording location to understand how the persistence of a clandestine grave affects soil. This study aims to analyze the elemental exchange from buried bodies to soil, with a focus on phosphorus content, and to determine the effects of environmental factors on its persistency. The experiment was carried out using eleven swine carcasses buried in an open site (northern Italy). The analyses were performed using the Olsen P method, which allowed for a recognition of the trend of the amount of phosphorus over time, due to the decomposition of phospholipids, followed by the transfer of the element from bone to soil. Additionally, microanalyses performed using a scanning electron microscope (SEM-EDS) on two different soil sample specimens (i.e., “dust” and “plug”) allowed for the identification of numerous phosphatic features (i.e., coatings, infillings, impregnations, and organo-mineral associations), which are the result of the interaction between soil and body fluids and can thus be used as indicators of the former presence of decomposing body (even in its absence). The ultramicroscopic analysis also shows increasing and decreasing amounts of P2O5 over time in the soil, which could be related to environmental conditions (i.e., soil moisture), due to the leaching of phosphorus induced by the percolation of natural rainwater. The study underlines the potential use of these methods to evaluate the possibility of a cadaver–soil linkage and of assessing the burial in the soil for a variable period. Moreover, the study may aid in analyzing the dynamics of phosphorus migration from buried bodies to soil during and after the decomposition process

The Fate of Phosphorus in Experimental Burials: Chemical and Ultramicroscopic Characterization and Environmental Control of Its Persistency

The permanence of a buried body in soil always induces the formation of a decomposition island that can serve as a significant recording location to understand how the persistence of a clandestine grave affects soil. This study aims to analyze the elemental exchange from buried bodies to soil, with a focus on phosphorus content, and to determine the effects of environmental factors on its persistency. The experiment was carried out using eleven swine carcasses buried in an open site (northern Italy). The analyses were performed using the Olsen P method, which allowed for a recognition of the trend of the amount of phosphorus over time, due to the decomposition of phospholipids, followed by the transfer of the element from bone to soil. Additionally, microanalyses performed using a scanning electron microscope (SEM-EDS) on two different soil sample specimens (i.e., “dust” and “plug”) allowed for the identification of numerous phosphatic features (i.e., coatings, infillings, impregnations, and organo-mineral associations), which are the result of the interaction between soil and body fluids and can thus be used as indicators of the former presence of decomposing body (even in its absence). The ultramicroscopic analysis also shows increasing and decreasing amounts of P2O5 over time in the soil, which could be related to environmental conditions (i.e., soil moisture), due to the leaching of phosphorus induced by the percolation of natural rainwater. The study underlines the potential use of these methods to evaluate the possibility of a cadaver–soil linkage and of assessing the burial in the soil for a variable period. Moreover, the study may aid in analyzing the dynamics of phosphorus migration from buried bodies to soil during and after the decomposition process