Agnese Bellabarba

Real-time monitoring of soil gaseous emissions is important for understanding nitrogen transformations and associated emissions of reactive and greenhouse gases. In this study, controlled soil microcosms were used to investigate changes in gas emissions, volatile profiles, and microbial functional markers under control and denitrification-promoting conditions, and to explore the ability of an IoT-enabled metal oxide (MOX) gas sensor array to monitor dynamic changes in the overall soil headspace through multivariate resistance-response patterns. The experimental workflow included preliminary Fourier transform infrared (FTIR) gas analysis on dedicated microcosms to verify the response induced by the BOOST treatment and identify relevant monitoring windows. Separate microcosms were subsequently investigated by solid-phase microextraction gas chromatography–mass spectrometry (SPME–GC–MS), qPCR targeting key nitrogen-cycling functional genes, and MOX-based headspace monitoring. BOOST microcosms, amended with mineral nitrogen and glucose and maintained at 100% field capacity, exhibited an early increase in N₂O emissions, with the highest measured concentration observed at 24 h, together with changes in bacterial abundance and nitrogen-cycling functional gene profiles. Volatilome analysis revealed a broader distribution of detected VOCs among chemical classes under BOOST conditions, with marked temporal changes and the emergence or enrichment of specific VOC classes, particularly at intermediate sampling times. MOX measurements captured concurrent changes in the overall headspace response and generated distinct resistance-based response patterns across treatments and sampling times. Exploratory multivariate analysis showed separated response clusters, which were interpreted alongside the temporal changes independently observed by FTIR and GC–MS. Overall, the findings indicate that MOX sensor arrays can rapidly capture complex and time-dependent response patterns associated with changes in the overall soil headspace under controlled conditions.

Plastic mulching provides clear benefits for strawberry cultivation but pose risks of long-term environmental pollution. However, a comprehensive investigation on how different plastic materials may impact the overall strawberry cultivation, from soil health to crop productivity, is lacking. This study investigates the influence of conventional and degradable mulching films on substrate microbial ecology, concurrently evaluating plant performance and fruit quality in a strawberry cultivation. Different mulch films were applied and compared to unmulched control: polyethylene (PE), oxo-degradable (OxoPE), polybutylene adipate terephthalate corn starch-blended (PBAT), polypropylene (PP). Substrate physicochemical analysis and 16S rRNA gene high-throughput sequencing were performed, along with plant morphological and physiological analysis, strawberries yield and quality. PBAT promotes substrate nitrogen enrichment, whereas PE induced an increase in available micronutrients. Bacterial community α-diversity increased in the presence of OxoPE, PE, and PP films, while β-diversity analysis revealed a distinct clustering based on film type, with the biodegradable PBAT communities separating from the others materials. This separation was driven by gradients of humidity and nitrate, with OxoPE, PE, and PP communities positively correlated with higher humidity. Functional predictions suggest that PE mulches boost nitrogen-fixing communities, whereas PBAT promotes nitrification and complex carbon catabolism. At plant level, OxoPE and PP significantly increased fruit yield up to 29% compared to the control, while physiological and growth traits remained consistent across treatments, as well as fruit quality and nutraceutical properties. This study demonstrates that distinct mulches uniquely promote substrate biodiversity by shaping specialized, functional bacterial communities.

Background and Aim. Traditional plastic mulching provides clear benefits for strawberry cultivation but pose risks of long-term environmental pollution. Besides, a comprehensive investigation on how different mulch materials may impact the overall strawberry cultivation, from crop productivity and quality to soil health, is still lacking. With this aim, this study investigates the influence of conventional and biodegradable mulching films on plant performance, fruit quality, and substrate microbial ecology in a strawberry cultivation. Methods. Four different mulch films were applied and compared to unmulched control: polyethylene (PE), oxo-degradable (OxoPE), polybutylene adipate terephthalate corn starch-blended (PBAT), polypropylene (PP). Assessments included plant morphological and physiological analysis, strawberries yield and quality, substrate physicochemical analysis and substrate bacterial community characterization by high throughput sequencing of the 16S rRNA gene. Results. OxoPE and PP significantly increased fruit yield up to 29% compared to the control, while physiological and growth traits remained unvaried. Fruit quality and nutraceutical properties were consistent across treatments. PBAT promotes nitrogen enrichment, whereas PE is associated with an increase in available micronutrients. Mulching enhanced bacterial community evenness and diversity, and community structural analysis revealed that each material recruits unique microbial niches leading to distinct bacterial community structures driven by humidity and nitrate gradients. Functional predictions suggest that PE mulches boost nitrogen-fixing communities, whereas PBAT promotes nitrification and complex carbon catabolism. Conclusion. PBAT and OxoPE represent effective alternatives to traditional PE, preserving high productivity and fruit quality while promoting specialized substrates bacterial communities, thus enhancing overall sustainability within strawberry production frameworks.

Soil salinity poses a major challenge to the legume‐rhizobia symbiosis development, thereby affecting sustainable agriculture. Selecting NaCl‐tolerant strains and enhancing the native strains' fitness under salt stress are essential steps for the restoration of marginal areas. In this work, 49 Sinorhizobium meliloti strains, the rhizobial species forming symbiotic nitrogen‐fixing associations with alfalfa—including 21 de novo‐sequenced field isolates—were subjected to a thorough in vitro screening for salt tolerance at progressively higher NaCl concentrations. Field isolates showed genome‐based geographical clustering but contrasting salt tolerance abilities. Indeed, genome‐wide association (GWA) analysis on the strains' whole‐genome sequencing data indicated several loci associated with the variability in salt tolerance. Candidate genes were involved in various processes including cell wall organisation, LPS biosynthesis, quorum sensing, and carbohydrate transport and metabolism. The relationship with carbohydrate metabolism was further confirmed by Phenotype Microarray analysis which indicated salt‐tolerant strains having enhanced capacity in carbon source usage. These findings reveal synergistic pathways underlying salt tolerance and suggest candidate traits (e.g., quorum sensing, carbohydrate synthesis and modification) for developing bioinoculants to enhance legume performance in saline soils.

Poly(amino acids) and gold nanoparticles are stable and biocompatible materials with distinguishing features which can be used to build nanocomposite electrochemical platforms for sensing applications. This paper presents the optimization of the building steps of these nanocomposite platforms using cyclic voltammetry. Screen-printed graphite electrodes were first modified by electropolymerizing various l-amino acids and then by electrodepositing gold nanoparticles. The electroactive surface area was calculated for all platforms, which were then applied in the electrochemical oxidation of 1-naphthol as a model analyte: oxidation peaks were observed in all cases, with the current peak height increasing with increasing analyte concentration, thus demonstrating the potential of nanocomposite platforms for developing electrochemical sensors and biosensors.

Poly(amino acids) and gold nanoparticles are stable and biocompatible materials with distinguishing features which can be used to build nanocomposite electrochemical platforms for sensing applications. This communication presents the optimization of the building steps of these nanocomposite platforms using cyclic voltammetry. Screen-printed graphite electrodes were first modified by electropolymerizing various L-amino acids and then by electrodepositing gold nanoparticles. The electroactive sur-face area was calculated for all platforms, which were then applied in the electro-chemical oxidation of 1-naphthol as a model analyte: oxidation peaks were observed in all cases, with the current peak height increasing with increasing analyte concentra-tion, thus demonstrating the potential of nanocomposite platforms for developing electrochemical sensors and biosensors.

Sustainable-forage production is globally increasing, especially in marginal areas where the edaphic conditions for plant growth are not optimal. Soil salinization influences the symbiotic interaction between alfalfa and rhizobia. The efficiency of different symbiotic pairs (Sinorhizobium meliloti—Medicago sativa) was evaluated in relation to NaCl application (100 mM) on two different alfalfa cultivars (Marina and Etrusca) and 21 S. meliloti strains isolated in Algeria. At 100 mM NaCl, it was observed that there was a higher variability of plant dry weight compared to the control. The strains able to improve plant growth at 100 mM NaCl were different and specific for each alfalfa cultivar, highlighting that (symbiont) G × (host) G interaction is magnified under stressed (saline) conditions (E). Three strains were then identified as candidate inoculants for M. sativa cv Marina and used for an in-field experiment with induced stress (no irrigation), together with S. meliloti GR4 (a highly competitive strain). In-field experiments, showed a high variability, and a significant difference of plant biomass was observed only for those inoculated with S. meliloti GR4. Obtained results suggest that multiple traits should be considered for inoculant-strain selection, and for an efficient translation from lab to field, it requires extensive comprehension of the mechanisms driving G × G × E interaction.

Decoding the competitive pattern that occurs in the rhizosphere is challenging in the study of bacterial social interaction strategies. To date, the single-gene approach has mainly been used to uncover the bases of nodulation, but there is still a knowledge gap regarding the main features that a priori characterize rhizobial strains able to outcompete indigenous rhizobia.

In the past 10 years, the average demand for meat and milk across the world has significantly increased, especially in developing countries. Therefore, to support the production of animal-derived food products, a huge quantity of feed resources is needed. This paper does not present original research, but rather provides a conceptual strategy to improve primary production in a sustainable way, in relation to forthcoming issues linked to climate change. Increases in meat and milk production could be achieved by formulating balanced diets for ovines based on alfalfa integrated with local agricultural by-products. As the central component of the diet is alfalfa, one goal of the project is increasing the yield of alfalfa in a sustainable way via inoculating seeds with symbiotic rhizobia (i.e., Sinorhizobium meliloti). Seed inoculants are already present on the market but have not been optimized for arid soils. Furthermore, a part of the project is focused on the selection of elite symbiotic strains that show increased resistance to salt stress and competitiveness. The second component of the experimental diets is bio-waste, especially that obtained from olive oil manufacturing (i.e., pomace). The addition of agro-by-products allows us to use such waste as a resource for animal feeding, and possibly, to modulate rumen metabolism, thereby increasing the nutritional quality of milk and meat.

Rhizosphere and plant-associated microorganisms have been intensely studied for their beneficial effects on plant growth and health. These mainly include nitrogen-fixing bacteria (NFB) and plant-growth promoting rhizobacteria (PGPR). This beneficial fraction is involved in major functions such as plant nutrition and plant resistance to biotic and abiotic stresses, which include water deficiency and heavy-metal contamination. Consequently, crop yield emerges as the net result of the interactions between the plant genome and its associated microbiome. Here, we provide a review covering recent studies on PGP rhizobia as effective inoculants for agricultural practices in harsh soil, and we propose models for inoculant combinations and genomic manipulation strategies to improve crop yield.