Integrated approach on the rhizosphere response to Nickel in a facultative hyperaccumulator species

The contamination of metals like Nickel (Ni) in the soil represents a serious threat worldwide. To counteract this phenomenon, hyperaccumulator plant species, able to remove metal from soil and store it at high concentration in shoots, are employed for metal phytoremediation purposes. Native microbial communities occurring in the rhizosphere of hyperaccumulators often promote plant growth and metal uptake. So far, each abiotic and biotic rhizospheric components (soil, root system and microbiota) have been used without considering the reciprocal interactions and the responses to Ni stress as a whole. The present study aims to develop for the first time an innovative and multidisciplinary approach to examine the rhizosphere of Ni-hyperaccumulators as a holistic model, promoting the plant development and the Ni uptake. This integrated system is feasible owing to the collaboration with the Laboratory of Micology and the Laboratory of Microbiology of Department of Earth, Environmental and Life Sciences (DISTAV), University of Genoa. Among metalliferous soils, specific attention was given to serpentinitic soil which display extremely hostile conditions (nutrient shortage and concentration of metals - e.g., Ni - highly toxic) for most plants except for some hyperaccumulator species. Early response to Ni in plant development was assessed with micro- and mesocosm germination tests under Ni stress in the Ni-hyperaccumulator species Alyssoides utriculata (L.) Medik, Noccaea caerulescens (J. Presl & C. Presl) F. K. Mey. and Odontarrhena bertolonii (Desv.) L. Cecchi & Selvi and on the related non-accumulator species Alyssum montanum L. and Thlaspi arvense L., used for comparison. Afterwards, the response to increasing Ni concentrations in terms of root surface area, root and shoot biomass and photosynthetic efficiency was evaluated. Subsequently, A. utriculata was selected as a good candidate to study rhizospheric components because of its Ni-facultative hyperaccumulation traits and its ability to thrive in harsh metalliferous soils. Related rhizosphere and bare soil samples were collected from serpentine and non-serpentine sites. Plant and soil samples were processed and analysed with specific attention to isolation and identification of culturable microbiota, then selected for their Ni-tolerance and Plant Growth Promoting (PGP) traits. Later, most performing Ni tolerant bacterial and fungal strains were tested by means of co-growth methods to estimate their reciprocal behaviour in a mixed culture to be used as inoculum in the rhizosphere of A. utriculata. Results demonstrate that increasing Ni concentrations can induce marked inhibition of germination in hyperaccumulator species, despite their accumulation ability. However, hyperaccumulator species exhibit a positive response in terms of root surface area, biomass and photosynthetic efficiency, compared to non-hyperaccumulator species in which there is a dose-response effect by Ni, except for T. arvense in pot test. In particular, A utriculata reveals an increased aboveground biomass and sample vitality in pot test, suggesting an adaptation to harsh environmental conditions. Microbiota isolates are more abundant in non-serpentinitic and rhizospheric soil, without selectivity between microorganisms and Ni. Some bacterial and fungal strains (Pseudomonas sp. SERP1, Streptomyces sp. SERP4 and Penicillium ochrochloron Biourge Serp03S, Trichoderma harzianum Rifai Serp05S respectively) reveal high Ni tolerance (up to 20 nM) and PGP traits. In particular SERP1 and Serp03S display a mutual synergism in co-growth methods and they could be promising candidates as natural chelators in the rhizosphere of A. utriculata, to enhance plant development and Ni uptake. This research represents the first step of integrated plant-microbiota tool, in the perspective to improve Ni uptake from polluted soil, using native Ni-hyperaccumulator species and associated rhizobiota, although further investigations are required to ascertain the efficiency of the field application

The rapid spread of SARS-COV-2 Omicron variant in Italy reflected early through wastewater surveillance

The SARS-CoV-2 Omicron variant emerged in South Africa in November 2021, and has later been identified worldwide, raising serious concerns. A real-time RT-PCR assay was designed for the rapid screening of the Omicron variant, targeting characteristic mutations of the spike gene. The assay was used to test 737 sewage samples collected throughout Italy (19/21 Regions) between 11 November and 25 December 2021, with the aim of assessing the spread of the Omicron variant in the country. Positive samples were also tested with a real-time RT-PCR developed by the European Commission, Joint Research Centre (JRC), and through nested RT-PCR followed by Sanger sequencing. Overall, 115 samples tested positive for Omicron SARS-CoV-2 variant. The first occurrence was detected on 7 December, in Veneto, North Italy. Later on, the variant spread extremely fast in three weeks, with prevalence of positive wastewater samples rising from 1.0% (1/104 samples) in the week 5–11 December, to 17.5% (25/143 samples) in the week 12–18, to 65.9% (89/135 samples) in the week 19–25, in line with the increase in cases of infection with the Omicron variant observed during December in Italy. Similarly, the number of Regions/Autonomous Provinces in which the variant was detected increased fromone in the first week, to 11 in the second, and to 17 in the last one. The presence of the Omicron variant was confirmed by the JRC real-time RT-PCR in 79.1% (91/115) of the positive samples, and by Sanger sequencing in 66% (64/97) of PCR amplicons

The rapid spread of SARS-COV-2 Omicron variant in Italy reflected early through wastewater surveillance

The SARS-CoV-2 Omicron variant emerged in South Africa in November 2021, and has later been identified worldwide, raising serious concerns. A real-time RT-PCR assay was designed for the rapid screening of the Omicron variant, targeting characteristic mutations of the spike gene. The assay was used to test 737 sewage samples collected throughout Italy (19/21 Regions) between 11 November and 25 December 2021, with the aim of assessing the spread of the Omicron variant in the country. Positive samples were also tested with a real-time RT-PCR developed by the European Commission, Joint Research Centre (JRC), and through nested RT-PCR followed by Sanger sequencing. Overall, 115 samples tested positive for Omicron SARS-CoV-2 variant. The first occurrence was detected on 7 December, in Veneto, North Italy. Later on, the variant spread extremely fast in three weeks, with prevalence of positive wastewater samples rising from 1.0% (1/104 samples) in the week 5-11 December, to 17.5% (25/143 samples) in the week 12-18, to 65.9% (89/135 samples) in the week 19-25, in line with the increase in cases of infection with the Omicron variant observed during December in Italy. Similarly, the number of Regions/Autonomous Provinces in which the variant was detected increased from one in the first week, to 11 in the second, and to 17 in the last one. The presence of the Omicron variant was confirmed by the JRC real-time RT-PCR in 79.1% (91/115) of the positive samples, and by Sanger sequencing in 66% (64/97) of PCR amplicons. In conclusion, we designed an RT-qPCR assay capable to detect the Omicron variant, which can be successfully used for the purpose of wastewater-based epidemiology. We also described the history of the introduction and diffusion of the Omicron variant in the Italian population and territory, confirming the effectiveness of sewage monitoring as a powerful surveillance tool

Cronotipologia al tempo del web 2.0: banca dati e mappa online dei portali di Genova.

The article describes the construction of a territorial database that collects information about the 14th century portals of the city of Genoa, in the historic downtown of the area inside the defensive walls. The project focuses on dating some significant elements and demonstrating their importance compared to other elements of the building and the portal itself. Decorative aspects, especially the aesthetic ones, are less significant compared to the thicknesses and shapes of the fixed frame stone of the portals. So the essential characteristics for defining the portal chronotype are the proportions and the thickness of the jamb portal in relation to the width of the net size. The territorial database was created with the aim of collecting information on all portals within the established boundaries. An important contribution to the research planning consists in the CIVIS project: a system in which information collected converged, leading to the production of digital cartography and computer data, available from all over the web. Moreover, the authors illustrate another territorial database produced thanks to a research conducted by ISCUM, which led to cataloguing the chronotypology of the portals in rural areas. In ISCUM databases there are already 2560 rural portals, for the most part located in north-western Italy

Root and Shoot Response to Nickel in Hyperaccumulator and Non-Hyperaccumulator Species

The soil–root interface is the micro-ecosystem where roots uptake metals. However, less than 10% of hyperaccumulators’ rhizosphere has been examined. The present study evaluated the root and shoot response to nickel in hyperaccumulator and non-hyperaccumulator species, through the analysis of root surface and biomass and the ecophysiological response of the related aboveground biomass. Ni-hyperaccumulators Alyssoides utriculata (L.) Medik. and Noccaea caerulescens (J. Presl and C. Presl) F.K. Mey. and non-hyperaccumulators Alyssum montanum L. and Thlaspi arvense L. were grown in pot on Ni-spiked soil (0–1000 mg Ni kg−1, total). Development of root surfaces was analysed with ImageJ; fresh and dry root biomass was determined. Photosynthetic efficiency was performed by analysing the fluorescence of chlorophyll a to estimate the plants’ physiological conditions at the end of the treatment. Hyperaccumulators did not show a Ni-dependent decrease in root surfaces and biomass (except Ni 1000 mg kg−1 for N. caerulescens). The non-hyperaccumulator A. montanum suffers metal stress which threatens plant development, while the excluder T. arvense exhibits a positive ecophysiological response to Ni. The analysis of the root system, as a component of the rhizosphere, help to clarify the response to soil nickel and plant development under metal stress for bioremediation purposes

Prove di phytoremediation nell'ottica di un approccio integrato piante-funghi-batteri

La rizosfera, come interfaccia suolo-radice, svolge un ruolo significativo nella phytoremediation di suoli contaminati da metalli. Si tratta di un micro-ecosistema in cui le radici hanno accesso agli elementi del suolo (Alford et al. 2010) e rappresenta la prima area di potenziale captazione di metallo in piante iperaccumulatrici. Nonostante sia noto da letteratura che le comunità microbiche presenti a livello rizosferico siano potenzialmente in grado di incrementare le performance di phytoremediation (Jing et al. 2007), le interazioni fra le componenti rizosferiche di taxa iperaccumulatori restano ancora in gran parte inesplorate. I nostri studi e sperimentazioni sono volti a valutare la risposta delle piante ai metalli con particolare riferimento al nichel (Ni) in termini di sviluppo di biomassa e superficie radicale, e selezionare il microbioma rizosferico idoneo per incrementare l’accumulo di metalli. Le piante iperaccumulatrici di Ni Alyssoides utriculata (L.) Medik., Noccaea caerulescens (J.Presl & C.Presl) F.K.Mey. e i non iperaccumulatori Alyssum montanum L. e Thlaspi arvense L. sono stati selezionati quali specie test in micro- e mesocosmo e trattati su suoli contaminati con differenti concentrazioni di Ni (0-1000 mg kg-1 ). Parallelamente si è proceduto ad isolare la componente batterica e fungina da campioni di suolo rizosferico di A. utriculata (Rosatto et al. 2017). Si prevede di utilizzare il microbioma isolato a livello della rizosfera di piante iperaccumulatrici per ottenere una bioaugmentation. Ciò consentirà la messa a punto di un sistema integrato pianta-funghi-batteri in cui il microbioma del suolo può agire come chelante naturale nei confronti dei metalli al fine di alleviarne lo stress e incrementarne l’accumulo, promuovendo attivamente la ricolonizzazione di suoli disturbati