1,080 research outputs found
Biodiversity of fungi as bioresources to face diversity of soil threats
No full textDegradation threats affect soils and ecosystems, providing fundamental services for humans and living organisms. Contamination represents a major soil threat and can impair several soil functions, such as biomass production, storage, filtration and transformation of nutrients and water, and biodiversity pool (1). Despite in a smaller measure than in the past, agriculture is one of the major drivers of soil contamination, contributing with pesticides, herbicides and fertilizers added to improve crop yield. More than 3000 different types of pesticides have been used in the European agroecosystems in the past 50 years and less than 0.1% of applied pesticide to crops are estimated to reach target pests while the rest enters the environment (1). Even if contamination can reduce soil biodiversity, in microbial communities tolerant microorganisms can develop (1). Several studies have demonstrated the efficacy of indigenous fungi as a promising tool for soil bioremediation and as bioresources to reverse contamination processes in mid-term (2). The application of fungi as bioresources can also help to prevent or at least reduce the application of agrochemicals, improving at the same time quality and quantity of the yields in the contest of sustainable agricultural practices. Indeed, several soil fungi can act as plant growth promoters, both improving nutrition and stimulating protection against pests (3). Considering the pivotal role of developing nature-based solutions in coping with future challenges (e.g. world population increase, rock phosphate exhaustion), in the last years the Fungal Biodiversity Laboratory of Sapienza University of Rome focused its research mainly on selecting suitable fungal strains as bioresources for agriculture and bioremediation. The biological characterization of historically contaminated sites by DDT and HCH, respectively in Poland and in the Czech Republic, allowed to individuate indigenous fungi suitable for integrated, sustainable and cost-effective solutions for future applications in bioremediation of persistent chlorinated compounds. While, investigations on the ability of saprotrophic fungi to solubilize inorganic phosphates allowed to screen and individuate, among several strains preserved in the culture collection of Fungal Biodiversity Laboratory, a pool of strains applicable to improve phosphorus plant nutrition (4). As appear clear from these experiences, culture collections play a pivotal role in finding and screening microorganisms, which possess interesting traits as bioresources. In fact, the conservation of organisms isolated from specific environments in fungal collections, even after years, can provide useful tools and bioresources to develop new cost-effective and environmentally friendly biotechnologies and improve new feasible practices in a context of sustainable bioeconomy. References 1. Stolte, J., Tesfai, M., Øygarden, L., Kværnø, S., Keizer, J., Verheijen, F., Panagos,P., Ballabio, C. & Hessel, R., 2015. Soil threats in Europe. 2. Ceci, A., Pinzari, F., Russo, F., Persiani, A. M. & Gadd, G. M., 2019. Appl. Microbiol. Biotechnol. 103, 53–68. 3. Owen, D., Williams, A. P., Griffith, G. W. & Withers, P. J. A., 2015. Appl. Soil Ecol. 86, 41–54. 4. Ceci, A., Pinzari, F., Russo, F., Maggi, O. & Persiani, A. M., 2018. Ambio. 47, 30–40
Fungi and arsenic: tolerance and bioaccumulation by soil saprotrophic strains
No full textArsenic, a common metalloid, is worldwide recognised as important toxic element for human beings and
living organisms (1,2). Natural processes as well as anthropogenic activities contribute to its diffusion and
occurrence in the environment (1,2). Fungi, as geoactive agents, can play very important geological roles in
several processes, including decomposition, biogeochemical cycling, element biotransformations, metal and
mineral transformations, bioweathering and soil formation (3,4). Fungi can tolerate and accumulate high
concentration of arsenic and for some species, biovolatilization via methylation was reported (5).
In this research, relationships between some soil saprotrophic microfungi and arsenic in relation to growth
responses and bioaccumulation were investigated. In particular, Absidia spinosa Lendn., Purpureocillium
lilacinum (Thom) Luangsa-ard, Houbraken, Hywel-Jones & Samson (formerly Paecilomyces lilacinus),
Metarhizium marquandii (Massee) Kepler, S.A. Rehner & Humber (formerly Paecilomyces marquandii) and
Cephalotrichum nanum (Ehrenb.) S. Hughes (formerly Doratomyces nanus), previously isolated from areas
with high natural As concentrations, were studied in two different cultural media, namely Malt Extract Agar
and Czapek-Dox Agar, and three different concentrations (10, 20 and 50 mg/L) of sodium arsenite (NaAsO2)
were tested. Metabolic responses and fungal tolerance to As have been investigated by tolerance indices,
namely Rt:Rc (%) and T.I. (%), based on growth data, diametric extension and dry weights, respectively.
Most of fungi resulted tolerant to all tested As concentrations, and values of tolerance indices varied
according to cultural media and As concentrations. pH medium after fungal growth was measured to study
pH variation and metabolic responses. As bioaccumulation in all fungi was observed with chemical analyses
by hydride generation atomic fluorescence spectrometry. As tolerance and bioaccumulation by fungi and
their metabolic responses shed further light in fungal geoactive roles in the environmental fate of As and
provide potential applications in bioremediation.
1) R. Singh, S. Singh, P. Parihar, V. P. Singh, S. M. Prasad (2015) Ecotox. Environ. Safe., 112, 247-270
2) A. Sarkar, B. Paul (2016) Chemosphere, 158, 37-49
3) A. Ceci, M. Kierans, S. Hillier, A. M. Persiani, G. M. Gadd (2015) Appl. Environ. Microbiol., 81, 4955-4964
4) A. Ceci, F. Pinzari, F. Russo, A. M. Persiani, G. M. Gadd (2019) Appl. Microb. Biotechnol., 103, 53-68
5) M. Singh, P.K. Srivastava, P.C. Verma, R.N. Kharwar, N. Singh, R.D. Tripathi (2015) J. Appl. Microb., 119, 1278-
129
Fungi as bioresources for remediation of HCH-contaminated soils: from microbial community-level physiological profile to selective isolation in enrichment
No full textThe interaction between human activities and global change (including persistent chemicals
pollution) poses severe threats for the soil microbiota thus reducing the provision of ecosystem
services1. In this context -, -, and -hexachlorocyclohexane (HCH) are highly persistent organic
pollutants ofglobal concern, and a severe risk for human health and ecosystem functioning.
Soil fungi, thanksto the ability to tolerate, bioaccumulate and biodegrade HCH, are important
bioresources as biobased solutions for HCH-contaminated soil remediation. The study area
was selected within the National Priority Site “Bacino del Fiume Sacco” in the Metropolitan
City of Rome (Italy). Soil cores, up to 1 m of depth, were collected from 2 plots and later
divided in topsoil (TS: 0-10 cm) and subsoil (SS: 10-100 cm) samples. The first goal was to
characterize the microbial community level physiological profile, so the soil samples were
analysed by the Biolog EcoPlateTM Technique2 to compare metabolic activities of the
communities at different depths (TS and SS). Moving on, the project focused on the fungal
fraction of the microbial community, evaluating the fungal loaddifferences between TS and
SS, through the count of the colony forming units (CFUs/dry soil weight). The CFUs results
show a higher fungal load in topsoil than that in subsoil by one order of magnitude. To isolate
fungal bioresources suitable for HCH degradation, a selective enrichment procedure with a high
concentration HCH mixture as the only carbon source, was carried out. At the end of the
procedure several species, mainly belonging to Fusarium and Alternaria genera,were isolated
and are currently preserved in the Culture Collection of the Fungal Biodiversity Laboratory
(FBL) of the Department of Environmental Biology of Sapienza University of Rome. The
isolated fungi represent useful bioresources for further studies aimed at the development of
mycoremediation application for HCH contaminated soil remediation
Unravelling the role of the mitochondrial protein C1QBP in mammalian adaptation to environmental stressors
No full textGli stress ambientali o stressors sono i principali fattori che obbligano gli individui a modificare i loro comportamenti e la loro fisiologia al fine di adattarsi a nuove condizioni. L'adattamento a questi stress porta ad alterazioni nella morfologia, fisiologia o comportamento, migliorando in definitiva la sopravvivenza e il successo riproduttivo dell'organismo (o del gruppo di organismi). Di conseguenza, esercitano un impatto significativo sui processi evolutivi ed ecologici che influenzano l'evoluzione delle specie. I mitocondri svolgono un ruolo fondamentale nell’adattamento agli stress ambientali negli eucarioti, come, ad esempio, la carenza di ossigeno, la disponibilità di nutrienti e le variazioni di temperatura. Questo è dovuto alla capacità di questi organelli di adattarsi velocemente alle necessità metaboliche della cellula. Funzionando come la centrale elettrica della cellula, i mitocondri sono parte integrante di processi essenziali, tra cui la produzione di ATP, la regolazione intracellulare del Ca2+, la produzione e l'eliminazione di specie reattive dell'ossigeno e la regolazione della morte cellulare per apoptosi. Inoltre, negli endotermi, i mitocondri svolgono un ruolo fondamentale nell’adattamento alle basse temperature prendendo parte al processo di termogenesi adattativa che avviene principalmente nel tessuto adiposo bruno (BAT, Brown Adipose Tissue), ma anche nel muscolo scheletrico. Recentemente, è stato dimostrato che le cellule rispondono agli stress ambientali anche rilasciando vescicole extracellulari (EVs, Extracellular Vesicles) contenenti varie biomolecole, inclusi acidi nucleici, proteine e lipidi, che agiscono come mediatori di stress ambientali e metabolici. Diversi studi hanno dimostrato che fattori di stress non solo alterano la secrezione di EVs, ma modificano anche la loro composizione, influenzando così la funzione di mediazione di queste vescicole. Pertanto, le EVs possono essere potenti mediatori degli stress ambientali. Basandomi su queste evidenze, l’obiettivo principale del mio progetto di dottorato è stato quello di trovare nuovi mediatori mitocondriali per l'adattamento agli stress ambientali, in particolare allo stress da freddo, nei mammiferi. I mammiferi rispondono alle basse temperature attraverso il processo di termogenesi non da brivido, che avviene nel BAT e nel muscolo scheletrico, e di termogenesi da brivido nel muscolo scheletrico. In questo lavoro abbiamo dimostrato che, in seguito a esposizione al freddo, gli adipociti bruni rilasciano EVs arricchite di proteine mitocondriali danneggiate. Tra le proteine sovraespresse in tali EVs abbiamo focalizzato la nostra attenzione sulla proteina mitocondriale C1QBP. Sebbene C1QBP sia riconosciuta tra le proteine caratterizzanti il BAT, la sua funzione non è ancora completamente nota. Abbiamo studiato la possibile funzione di C1QBP nell’adattamento al freddo in modelli cellulari in vitro e in modelli animali (M. musculus). I risultati ottenuti nei modelli in vitro hanno dimostrato che l’espressione di C1QBP aumenta durante il differenziamento degli adipociti (adipogenesi) e in seguito a stimolazione termogenica e che la proteina si accumula nei mitocondri degli adipociti bruni sia in condizioni basali che di stress. Queste evidenze, nel complesso, indicano che C1QBP possa svolgere un ruolo chiave durante il processo di termogenesi. Successivamente, abbiamo analizzato i livelli di C1QBP e quelli di altre proteine mitocondriali, sia in termini di mRNA sia di proteina, nei depositi adiposi e nel muscolo scheletrico di topi esposti al freddo. Una sovraespressione di C1QBP e di altre proteine coinvolte nel metabolismo mitocondriale e nel processo di termogenesi è stata riscontrata nei depositi adiposi, ma non nel muscolo scheletrico di topi esposti al freddo, suggerendo che C1QBP possa essere coinvolta nella risposta al freddo specificamente nel tessuto adiposo. Per comprendere se C1QBP potesse avere un ruolo limitatamente alla risposta allo stress da freddo, abbiamo analizzato la sua espressione in risposta ad altri tipi di stress ed in particolare a una dieta ricca in grassi (HFD; High Fat Diet). I risultati ottenuti hanno dimostrato una sovraespressione di C1QBP nei depositi adiposi, ma non nel muscolo scheletrico dei topi sottoposti ad HFD. C1QBP è una proteina evolutivamente conservata e geni omologhi sono stati identificati in diversi eucarioti. L'analisi filogenetica ha rivelato che la sequenza proteica di C1QBP è conservata in tutti gli eucarioti, dal lievito all'uomo, suggerendo che questa proteina possa avere un ruolo importante nel funzionamento mitocondriale. Poiché C1QBP è conservata anche negli ectotermi, abbiamo studiato la sua possibile funzione in D. rerio, comunemente noto come pesce zebra. Più approfonditamente, abbiamo analizzato i livelli di mRNA di C1QBP nei principali tessuti coinvolti nella risposta agli stress nei pesci, come il muscolo scheletrico ed il cuore, in condizioni di bassa temperatura dell’acqua. Nel pesce zebra, non si è riscontrato alcun effetto sull'espressione di C1QBP, sebbene alcuni geni associati al potenziamento dell'attività ossidativa mitocondriale e alla risposta allo stress fossero sovraespressi dall'esposizione al freddo nel cuore. In conclusione, i nostri studi hanno rivelato che C1QBP, una proteina mitocondriale evolutivamente conservata, può svolgere un ruolo fondamentale nel funzionamento mitocondriale e nella risposta adattativa ai fattori di stress ambientale, in particolare lo stress da freddo, nel tessuto adiposo dei mammiferi. Questo ruolo è sottolineato dalla sovraregolazione dell'espressione di C1QBP in risposta all'esposizione al freddo e alle diete ad alto contenuto di grassi nel BAT, ma non nel muscolo scheletrico. La conservazione di C1QBP negli eucarioti, dal lievito all'uomo, e la sua risposta specifica nel tessuto adiposo dei mammiferi rispetto agli ectotermi come il pesce zebra, suggeriscono una funzione specializzata nella termoregolazione endotermica. Ulteriori ricerche su C1QBP potrebbero fornire informazioni significative sui meccanismi molecolari dell'adattamento ambientale e sulla biologia evolutiva della termogenesi.Environmental stressors are factors that challenge individuals, compelling them to adjust their behaviour or physiology in order to cope. Adaptation to environmental stressors results in alterations in morphology, physiology, or behaviour, ultimately enhancing the survival and reproductive success of the organism or group of organisms. Consequently, they exert a significant impact on the evolutionary and ecological processes that shape species evolution. Mitochondria play a critical role in the adaptation to environmental stressors in eukaryotes, such as low oxygen availability, nutrient fluctuations, and temperature shifts. This is due to their remarkable ability to rapidly adjust to the metabolic needs of the cell. As the powerhouse of the cell, mitochondria are central to essential processes including ATP production, intracellular Ca2+ regulation, reactive oxygen species (ROS) production and scavenging, and the regulation of apoptotic cell death. For example, in endotherms, mitochondria are crucial for cold adaptation through non-shivering thermogenesis, primarily in brown adipose tissue (BAT), but also in skeletal muscle. It has recently been shown that cells respond to environmental stressors also by releasing extracellular vesicles (EVs) that carry various biomolecules, such as nucleic acids, proteins, and lipids. These acts as mediators of environmental and metabolic stress. Several studies have demonstrated that external stressors not only alter the secretion of EVs but also their composition, thereby influencing the mediating function of these vesicles. Thus, EVs can be potent mediators of environmental stimuli. The overall goal of my PhD project was to identify new factors in mitochondria that contribute to the adaptation to environmental stressors, particularly cold stress, in mammals. Mammals respond to cold exposure by non-shivering thermogenesis (NTS) in BAT and skeletal muscle as well as shivering thermogenesis (ST) in skeletal muscle. We demonstrated that after cold exposure, brown adipocytes release EVs enriched with damaged mitochondrial proteins. Among the proteins upregulated in BAT EVs exposed to cold, we focused our attention on the mitochondrial protein C1QBP, a marker of BAT, even though its function is not yet known. We investigated the possible role of C1QBP in cold adaptation using in vitro and animal models (M. musculus). The results obtained in adipose cells indicated that C1QBP expression increases during adipocyte differentiation (adipogenesis) and following thermogenic stimulation, and it accumulates in mitochondria of brown adipocytes under both basal and stressful conditions. This supports a possible role of this protein in thermogenesis. Subsequently, we analysed the mRNA and protein expression of C1QBP and other mitochondrial proteins in fat depots and skeletal muscle of mice exposed to cold. An upregulation of C1QBP expression was observed in adipose depots, but not in skeletal muscle of cold-exposed mice, suggesting that C1QBP could be involved in cold response specifically in adipose tissue. To determine whether C1QBP plays a role not only in the response to cold stress but also to other types of stress, we analysed its expression in response to other stressors, particularly a high-fat diet (HFD), in both BAT and skeletal muscle. The results showed an upregulation of C1QBP expression in adipose depots, but not in skeletal muscle of HFD mice. C1QBP is an evolutionarily conserved mitochondrial protein, and homologous genes have been identified in various eukaryotes. Phylogenetic analysis revealed that the protein sequence of C1QBP is conserved across all eukaryotes, from yeast to humans, suggesting that it may play a significant role in mitochondrial function. As C1QBP is also conserved in ectotherms, we investigated its potential function in D. rerio, commonly known as zebrafish. We specifically analysed the mRNA expression of C1QBP in skeletal muscle and heart of zebrafish subjected to cold temperatures. In contrast to mammals, while some genes involved in the enhancement of mitochondrial oxidative activity and response to stress were upregulated by cold exposure in heart of zebrafish, no effects on C1QBP expression were observed. In conclusion, our studies have revealed that C1QBP, an evolutionarily conserved mitochondrial protein, may play a pivotal role in the mitochondrial functioning and adaptive response to environmental stressors, particularly cold stress, in mammalian adipose tissue. This role is underscored by the upregulation of C1QBP expression in response to cold exposure and HFD in BAT, but not in skeletal muscle. The conservation of C1QBP across eukaryotes, from yeast to humans, and its specific response in adipose tissue of mammals as opposed to ectotherms like zebrafish, suggest a specialized function in endothermic thermoregulation. Further research into C1QBP could provide significant insights into the molecular mechanisms of environmental adaptation and the evolutionary biology of thermogenesis
Fungi in action against hexachlorocyclohexane: a focus on biosurfactants from fungal biodiversity
No full textHexachlorocyclohexane (HCH) is a highly persistent organic pollutant of global concern, involving severe
risks for human health and ecosystem functioning. Mycoremediation represents a feasible nature-based
solution for the restoration of soils polluted by HCH thanks to the ability of fungi to tolerate, bioaccumulate
and degrade it. Known for its insecticidal properties of one of its isomers (γ-HCH), it has been used for a long
time in European soils and despite the ban in the Stockholm Convention, high concentrations exceeding the
threshold values have been found in many areas. One of this is the National Priority Site “Bacino del Fiume
Sacco” within the Metropolitan City of Rome that has been selected as study area. Soil cores up to 1m of depth,
divided in topsoil and subsoil samples, were collected from 2 plots. To isolate fungi able to utilize HCH as the
sole C-source, an isolation in enrichment conditions was carried out providing an high concentration of
isomers’ mixture (α-, β-, γ- and δ-HCH). A total of 49 fungal strains was isolated, mostly belonging to
Fusarium and Alternaria genera. To evaluate the ability of these fungi to produce biosurfactants, metabolites
that enhance HCH biodegradability, three tests were carried out: oil emulsification activity test, oil
displacement test and drop collapse assay. The results of the assays showed the ability of some strains to
produce biosurfactants, making them suitable candidates for further investigation
Fungi sniffing fungi: a working expansion of the Phenotype MicroArraysTM system to assess the effects of fungal volatile organic compounds between co-occurring species.
No full textA fungal solution to a fungal problem: Chaetomium globosum and Minimedusa polyspora potential in the biocontrol of plant pathogenic fungi
No full textPlant diseases, resulting in an annual estimated loss of 10–15% of world's major crops, represent a major threat to global crops production and social and political stability of nations [1]. About 70–80% of these diseases are caused by pathogenic fungi, numbers that are expected to increase in future years due to the effect of climate change on plant-pathogens interactions [2,3]. In the effort to transition to a more sustainable and resilient agriculture, the application of biological control agents and their secondary metabolites represent a promising option to support the achievement of food security, without further compromise ecosystems’ health [4,5]. Therefore, it is important deepening the potential of known fungal biocontrol agents against the existing fungal pathogens, shedding further light on their action mechanisms and discovering new efficient fungal strains suitable for biotechnological applications. In vitro screenings, despite presenting several limitations, constitute valuable methods for the identification of potential biocontrol agents [6].
Therefore, this study, through an array of in vitro plate assays, aimed at evaluating Minimedusa polyspora (Hotson) Weresub & P. M. LeClair and Chaetomium globosum Kunze ability to inhibit the growth of Alternaria alternata (Fr.) Keissl., Berkeleyomyces basicola (Berk. & Broome) W.J. Nel, Z.W. de Beer, and Botrytis cinerea Pers.. Furthermore, this study aimed also at gaining insights on possible antimicrobial mechanism/s involved in their biological control action. More specifically, a dual culture assay, a dual culture for volatile antimicrobial compounds (performed in two different conditions), and a culture filtrate antifungal activity assay were designed to try to discriminate the impact of direct and indirect biological control mechanisms. This study’s results show that both M. polyspora and C. globosum were able to inhibit, to a different extent, all the pathogens’ growth in the dual culture assay, suggesting a mechanism of biocontrol involving competition for nutrients and space. M. polyspora, based on the culture filtrate antifungal activity assay, was found to exert its inhibition on all the pathogens thanks also to an antibiosis mechanism through the release of diffusible compounds. Moreover, M. polyspora culture filtrate resulted to be particularly effective especially against B. basicola whose growth was completely inhibited; furthermore, its high inhibition effect against this species was also observed in the dual culture for volatile antimicrobial compounds assay, suggesting that M. polyspora antagonism against B. basicola occurs through multiple or mixed mechanisms.
Therefore, based on this preliminary study’s results M. polyspora and C. globosum are promising biocontrol agents of three fungal phytopathogens of economical and agronomical relevance, and consequently species of interest for further studies in this area aimed at validating their potential as antagonists in in vivo conditions.
1) J.B. Ristaino, P.K. Anderson, D.P. Bebber, K.A. Brauman, N.J.Cunniffe, N.V. Fedoroff, C. Finegold, K.A. Garrett, C.A. Gilligan, C.M. Jones, et al. (2021). PNAS 118, 23 e2022239118.
2) A.C. Velásquez, C.D.M. Castroverde, S.Y. He (2018) Current Biology 28, 619–634.
3) S. Sarrocco, G. Vannacci (2018) Crop Protection 110, 160–170.
4) R.A.A. Khan, S. Najeeb, S. Hussain, B. Xie, Y. Li (2020) Microorganisms 8, 817.
5) Y. Peng, S.J. Li, J. Yan, Y. Tang, J.P. Cheng, A.J. Gao, X. Yao, J.J. Ruan, B.L. Xu (2021) Frontiers in Microbiology 12, 670135.
6) K. Raymaekers, L. Ponet, D. Holtappels, B. Berckmans, B.P.A. Cammue (2020) Biological Control 144, 104240
Fungal diversity for bioremediation: Tackling co-contaminations in a decomissioned military site
No full textMilitary sites, both active and decommissioned, represent a unique situation in which both biodiversity loss
and protection may occur, depending on how those sites are managed. Exclusion zones and good practices
such those provided in Natura 2000 report for military sites — can maintain or even increase the detected
biodiversity. However, potential and identified contaminations in military zones are soil threats of increasing
interest, especially when co-contaminations by organic and inorganic pollutants are established. Remediating
such complex contaminations through conventional techniques is not only economically unsustainable but
can also impact soil biodiversity. Novel methods to tackle co-contaminations may be found in
biotechnological applications of the bioresources isolated from those same contaminated sites, even though
there is a knowledge gap to be filled regarding the potentialities of autochthonous microbial communities.
Therefore, this study aimed at gaining insight on the culturable fungal community of a decommissioned
military site in Italy and the potentialities in fungal bioremediation. To reach the aims of the study, soil
samples were collected in six sampling plots and the fungal communities were isolated. Furthermore, the
fungal community associated with the rhizosphere of a specimen of Plantago lanceolata L., a wild herb
largely distributed in the site, was similarly studied for the same purposes. The results showed high
differences in species' abundances among samples with Penicillium, Aspergillus and Trichoderma as the
most abundant genera. The analysis of alpha diversity and evenness revealed that the samples with the
lowest abundance in Colony Forming Units (CFUs) showed the highest values of Shannon’s Diversity Index
(H’) and Simpson Diversity Index (D1), pointing to a lack of a dominant species among the isolates from
those samples, while in samples with higher CFU values a more varied situation arises. In fact, sample S28
had the lowest diversity indexes but also the second highest CFU abundance, pointing to a dominance of few
species, especially Penicillium S28A5, which was the most abundant species isolated from all samples. The
analysis of genera alpha diversity revealed a similar situation, except for sample S22, whose diversity of
genera showed to be the lowest among all samples, with a clear dominance of the Penicillium genus.
Focusing on the rhizosphere sample, the results of alpha revealed a highly diverse community of culturable
fungi, in both species and genera. The analysis of beta diversity, using Sørensen’s index, showed that while
the samples shared few common species, the isolated genera mostly overlapped. To evaluate the
potentialities of the isolated species, a set of screenings were performed on a selected group of 30 species,
which included the most abundant species and a species for each genus isolated. The assays performed in
this study were the Remazol Brilliant Blue R (RBBR) and Fe-Chromeazurol S (Fe-CAS) decolorization
assay, which are reported in literature as proxy test to investigate the ability to degrade complex organic
compounds and to produce siderophores in response to metallic and non-metallic elements. The species
showing the best performances were further tested to assess their tolerance to zinc (Zn), lead (Pb), Polycyclic
Aromatic Hydrocarbons (PAHs) and mixtures of organic and inorganic pollutants (Zn-PAH and Pb-PAH) in
in-vitro assays. The results of the screenings pointed to Gliomastix S28RE2 and Westerdykella S28RA1
having high capacities of degrading RBBR, while Acremonium S76A16, Aspergillus S56C4 and the
aforementioned Gliomastix species showed to be able to produce high quantities of siderophores. Eleven
species were chosen to be tested in the tolerance tests on Zn and PAHs, while four strains isolated from a Pb contaminated sample were exposed to Pb and PAHs. Overall, Penicillium S56C6 showed the best results in
both test conditions, retaining more than 70% of its growth rate when compared with control, while Mucor
S56E4 showed no change in growth rate, but suffered a loss in mycelium density. To conclude, several
strains isolated from this decommissioned military site showed promising potentialities for possible
application in bioremediation and further studies are currently underway to develop microbial consortia to
enhance their performance
Veronica mas, Spirea, Barbarea
No full text1. Nome scientifico: Veronica chamaedrys L.
(Scrophulariaceae)
Nome attuale: Veronica comune
2. Nome scientifico: Spiraea hypericifolia L.
(Rosaceae)
Nome attuale: Spirea spagnola
3. Nome scientifico: Barbarea vulgaris r. Br.
(Brassicaceae, Cruciferae)
Nome attuale: Erba di Santa Barbar
Fungi handling phosphorus: soil fungi ability to solubilise inorganic phosphate and mediate secondary minerals formation
No full textPhosphorous (P) is both sequestered and mobilised in soil by biological and geochemical processes. However, it primarily tends to form insoluble complexes and minerals with calcium, aluminium, iron, and hydroxides, becoming consequently unavailable for plants. Soil microorganisms can increase the amount of bioavailable phosphorus through several biological processes as the acidification of their microenvironment, the mineralisation of organic phosphorus and the translocation of phosphates [1,2].
Saprotrophic fungi play critical geoactive roles in the P biogeochemical cycle. By leaching minerals and solubilising insoluble phosphorus, fungi determine the P concentration in the soil solution [2,3,4]. Moreover, fungal ability to store phosphorus in the biomass and pass it to plant roots may be pivotal in avoiding the loss of solubilised phosphorus. Phosphorus low mobility in soil is a limiting factor for productivity in most agricultural land. Because of the worldwide exhaustion of phosphorus mineral sources and the limited availability of fertilisers [5], the slow solubilisation of the mineral P already present in agricultural soils may be the key to ensuring sustainable and environmentally friendly crop production.
This study aimed to evaluate, in vitro, the ability of 9 selected strains of soil fungi, with different life strategies, to solubilise, assimilate and store P from the insoluble tricalcium phosphate as its only source. Chemical analyses with SEM/EDX, colorimetric methods and ICP-MS were used to quantify the P released from TCP by the fungi and P concentration in the fungal biomass. We tested for each strain the ability to release P in a liquid culture medium, store it in their biomass and mediate its precipitation in secondary minerals.
Tested fungi were able to solubilise tricalcium phosphate (TCP) to a different extent, increasing P concentration in a liquid medium and biomass and mediating new secondary minerals.
References:
[1] Alori E T et al. (2017) Front Microbiol 8:971
[2] Owen D et al. (2015) Appl Soil Ecol 86:41–54
[3] Shrivastava M et al. (2018) Springer ISBN 9789811300431 : 137–165
[4] Ceci A et al. (2018), Ambio 47:S30–S40
[5] White S and Cordell D (2017) Routledge ISBN 1-315-28161-9 : 59–7
- …
