1,354,149 research outputs found
Volatile-mediated inhibitory activity of the biocontrol agent Lysobacter capsici AZ78 as a result of multiple factors interaction
No full textPlant beneficial rhizobacteria are able to inhibit the growth of soilborne phytopathogenic microorganisms through the release of a relevant number of volatile compounds. Based on this, we investigated the ability of the biocontrol agent Lysobacter capsici AZ78 (AZ78) to produce volatile organic compounds (VOCs) that may contribute to its efficacy in controlling soilborne phytopathogenic microorganisms. AZ78 significantly reduced the growth of Pythium ultimum, Rhizoctonia solani and Sclerotinia minor in split Petri dish assays. The GC-MS analysis revealed that AZ78 produce 22 VOCs and most of them were putatively identified as mono- and dialkylated methoxypyrazines. Exposure to 2,5-dimethylpyrazine, 2-ethyl-3-methoxypyrazine and 2-isopropyl-3-methoxypyrazine determined a drastic reduction of Pythium ultimum, Rhizoctonia solani and Sclerotinia minor mycelium growth in split Petri dish assays. However, the discrepancy of the toxicity between the quantity of pyrazines and the AZ78 lead us to further investigate the volatile-mediated inhibitory activity of the biocontrol bacterium. Further experiments revealed the ability of AZ78 cells to produce ammonia that caused the alkalinization of the physically separated culture medium in split Petri dishes assays. Results achieved in this work clearly demonstrated that VOCs, ammonia and the alkalinization of growth medium contribute to the overall inhibitory activity of AZ78 against soilborne phytopathogenic microorganisms
MODULATING HEAVY METAL ACCUMULATION IN PLANTS: OVEREXPRESSION OF THE PSEUDOMONAS PUTIDA EFFLUX COMPLEX CZCCBA
No full textNegli ultimi decenni aree sempre maggiori sono state sfruttate, degradate ed inquinate dalle attività antropiche. Tra gli inquinanti più pericolosi rilasciati nell’ambiente vi sono i metalli pesanti. Questi vengono dispersi nell’ambiente attraverso processi industriali, rilascio di fanghi di depurazione, attività minerarie e pratiche agricole (Hüttermann et al., 1999; Shull, 1998). Queste attività causano un accumulo nell’ambiente di metalli pesanti che sono già naturalmente presenti nei suoli (Godbold and Hüttermann, 1985; Breckle, 1991; Nies, 1999). I metalli pesanti grazie alle loro caratteristiche chimiche–fisiche sono stabili e persistenti nell’ambiente e spesso non sono sensibili a degradazioni chimiche o microbiologiche (Gisbert et al., 2003). Alte concentrazioni di metalli pesanti nel suolo causano una forte riduzione della crescita delle piante e quelli più solubili in acqua, diffondono nell’ambiente ed entrano facilmente nella catena alimentare, diventando un serio problema per la salute umana. Negli organismi viventi, la tossicità dei metalli pesanti è legata ai danni che provocano a livello cellulare, quali l’induzione di stress ossidativo, gli effetti negativi sulla permeabilità ed integrità di membrana, l’inibizione delle attività enzimatiche e l’interferenza con il folding proteico (Schützendübel and Polle, 2002). Piante e microorganismi per sopravvivere in ambienti inquinati da metalli pesanti hanno evoluto meccanismi di controllo dell’omeostasi dei metalli, evolvendo tolleranza o resistenza (Ramos et al., 2001; Moore and Helmann, 2005; Clemens 2001). I meccanismi generalmente sfruttati dai batteri sono la produzione di molecole chelanti (peptidi, proteine, polisaccaridi), l’attivazione di enzimi di detossificazione e di meccanismi di efflusso, intesi come il trasporto attivo dei metalli al di fuori della cellula. Quest’ultimo meccanismo è uno dei più utilizzati dai batteri per sfuggire alla tossicità dei metalli pesanti (Nies, 2003).
Al fine di ottenere produzioni agricole più sicure è possibile trasferire meccanismi batterici di efflusso dei metalli pesanti in piante di interesse agrario. L’obiettivo è quello di coltivare, su terreni leggermente contaminati, piante caratterizzate da un ridotto assorbimento di metalli pesanti.
Lo scopo di questo progetto di dottorato è quello di trasferire in pianta il trasportatore di efflusso di Pseudomonas putida CzcCBA, per cercare di modulare il contenuto dei metalli pesanti nella pianta trasformata. Il complesso di efflusso CzcCBA utilizzato in questo lavoro è stato isolato da un ceppo di P. putida individuato nella rizosfera autoctona di un ecotipo di A. halleri cresciuto su un suolo contaminato da Cd, Zn e Pb (Farinati et al., 2011), questo ceppo è stato denominato P. putida Cd001. Il trasportatore di efflusso è risultato sovra espresso in P. putida Cd001 in condizioni di stress da metalli pesanti (CdSO4 250 μM) (Manara et al., 2012). CzcCBA è una pompa di efflusso tripartita appartenente ad una famiglia di trasportatori che basano il loro funzionamento sulla proteina trans-membrana RND (Nies et al., 1989). Esso è in grado di trasportare Zn2+, Co2+ e Cd2, al di fuori della cellula, sfruttando un meccanismo di efflusso in antiporto di tipo protone/catione (Goldberg et al., 1999; Nies, 1995). Il complesso è formato da tre componenti CzcA, CzcB and CzcC, rispettivamente la proteina RND, la proteina di fusione di membrana e il fattore della membrana esterna. Il primo attraversa la membrana interna e trasporta i cationi metallici dal citosol allo spazio periplasmico, il componente CzcB funziona da connettore e direziona gli ioni verso il terzo componente CzcC, che apre un canale nella membrana esterna permettendo l’estrusione dei metalli al di fuori della cellula (Rensing et al., 1997).
I geni codificanti per questi tre trasportatori sono stati amplificati a partire dal DNA genomico di P. putida Cd001 e clonati in vettori di espressione adatti all’espressione in pianta, sotto il controllo del promotore costitutivo 35SCaMV. Sono state scelte tre specie modello per le trasformazioni, Arabidopsis, tabacco e pomodoro. Per ciascuna specie sono state ottenute diverse linee transgeniche stabilmente trasformate con ciascuno dei tre trasportatori. Incrociando successivamente i singoli trasformati sono state ottenute piante che esprimono parzialmente (CzcA/CzcB) o per intero il complesso (CzcCBA).
Le analisi di Real Time PCR sui transgeni hanno evidenziato diversi livelli di espressione tra piante trasformate appartenenti allo stesso genotipo. Si è evidenziato inoltre un livello di espressione maggiore per il gene CzcB quando risulta espresso simultaneamente a CzcA, o a CzcA e CzcC. La modulazione del contenuto di metalli pesanti nelle piante transgeniche è stata verificata attraverso esperimenti di accumulo. Le piante trasformate sono state trasferite da condizioni in vitro e cresciute in soluzione idroponica in condizioni controllate, utilizzando piante wild-type come controllo. L’aggiunta del Cd (CdSO4) è stata diversificata nelle tre specie analizzate Arabidopsis, tabacco e pomodoro che sono state trattate rispettivamente con concentrazioni di 0,45, 0,7 e 5 μM. Dopo 22 giorni di crescita la parte aerea è stata campionata ed il contenuto di Cd analizzato. Le piante transgeniche di tabacco mostrano una riduzione del contenuto di Cd in confronto alle piante wild-type. La riduzione aumenta quando nella pianta vengono sovra espressi più componenti del sistema di efflusso CzcCBA. L’espressione singola di CzcA determina una riduzione media del contenuto di Cd (considerando tutte le linee testate) pari al 30% rispetto al wild-type, la contemporanea presenza di CzcA e CzcB determina una riduzione media del 39%. In presenza dell’intero sistema di efflusso i tabacchi riducono il contenuto di Cd nella parte aerea mediamente del 55%.
In Arabidopsis la sola presenza di CzcA o CzcB non determina un chiaro effetto sul contenuto di Cd mentre la loro contemporanea espressione causa una riduzione media dei livelli di Cd nelle parte aerea delle piante pari al 23% rispetto al wild-type. Né in tabacco né in Arabidopsis la sola espressione di CzcC è in gradi di modulare il contenuto di Cd rispetto alle piante di controllo. Poiché in P. putida il sistema CzcCBA trasporta oltre al Cd anche lo Zn, piante di tabacco sovra esprimenti l’intero complesso CzcCBA sono state testate per il contenuto di quest’ultimo metallo. Differenze molto basse nel contenuto di Zn sono state rilevate tra piante trasformate e di controllo.
Al fine di caratterizzare il meccanismo di efflusso del sistema CzcCBA in pianta, la localizzazione sub-cellulare dei tre componenti è stata studiata. Sono stati creati tre costrutti di fusione sotto il controllo del promotore 35SCaMV: CzcA::eGFP, CzcB::dsRED, CzcC::eYFP e sono stati utilizzati per la trasformazione stabile di tabacco e successivamente per la trasformazione transiente di protoplasti. In entrambi i casi i campioni sono stati osservati al microscopio confocale. La trasformazione dei protoplasti con i tre costrutti di fusione è stata combinata con la co-espressione di marcatori di comparti sub-cellulari per approfondire il grado di specificità della localizzazione. Le analisi microscopiche hanno indicato una localizzazione a livello del reticolo endoplasmico per CzcA; la proteina non sembra tuttavia essere indirizzata verso il vacuolo litico. I risultati preliminari suggeriscono che CzcB tende a formare aggregati a livello citosolico. CzcC appare localizzato in maniera diffusa nel citosol. Ulteriori analisi sono necessarie per stabilire l’eventuale co-localizzazione dei tre componenti del complesso CzcCBA.
In conclusione, i risultati presentati dimostrano che l’espressione dei singoli componenti ed ancor più dell’intero sistema di efflusso batterico CzcCBA determinano una riduzione del contenuto di Cd a livello della porzione aerea delle piante trasformate in confronto alle piante wild-type.In the last years, more and more areas were exploited, degraded and polluted by antropic activities. Among the different pollutants released into the environment, heavy metals are one of the most life-threatening, being diffused into the environment through a great variety of activities and industrial processes, such as release of sewage sludge, mining, agricultural practices, and usage of contaminated fertilizers (Hüttermann et al., 1999; Shull, 1998). As, Hg, Ag, Cd e Pb, are examples of heavy metals with no biological functions and toxic to all living organisms even at low concentrations, they can be considered very dangerous to human health (Godbold and Hüttermann, 1985; Breckle, 1991; Nies, 1999). Due to their chemical and physical properties, heavy metals are highly stable and persistent for long periods in the environment. The majority is poorly sensitive to microbial or chemical degradation and usually cannot be biologically destroyed but only modified from one oxidation state or organic complex to another (Garbisu and Alkorta, 2001; Gisbert et al., 2003). Excess concentrations of heavy metals in soil cause strong declines in plant growth and these elements (due to their solubility in water) can easily enter the food-chain, becoming a serious problem to human health. Heavy metal toxicity shows its effect by causing damages at cellular level, leading, for instance, to oxidative stress, perturbation of membrane integrity and permeability, inhibition of enzymatic activities, and interference with protein folding (Schützendübel and Polle, 2002).
Plants and microorganisms developed several strategies to survive in dynamic environments and to face different unfavourable conditions, being able to continuously adapt to rapid changes in the environment. During evolution same bacterial and plant species have developed metal homeostasis mechanisms allowing the achievement of tolerance and resistance conditions in order to survive in heavy metals polluted environments (Ramos et al., 2001; Moore and Helmann, 2005; Clemens, 2001). Bacterial resistance mechanisms include the synthesis of metal-chelating molecules (peptides, proteins or polysaccharides), active metal efflux outside the cell and induction of detoxification enzymes that modify a toxic ion into a less toxic or less available form. One of the most important mechanisms of metal resistance is the translocation of toxic ions towards the outside of the cell. Efflux transporters participate in the reduction of heavy metals content into the cell (Nies, 2003).
An interesting biotechnological application aimed at improving safe crop production, is the transfer of bacterial mechanisms deputed to extrude heavy metals into plants, that can be evaluated for metal accumulation when grown on slightly polluted soils.
In this project, the Pseudomonas putida CzcCBA efflux system (membrane exporter of Cd2+, Zn2+, Co2+), was transferred into plant, in order to modulate heavy metals content. The CzcCBA complex was isolated from P. putida Cd001, a strain of Pseudomonas inhabiting the rhizosphere of an ecotype of A. halleri growing in soils contaminated by high concentrations of Cd, Zn and Pb (Farinati et al., 2009).
The CzcCBA complex was chosen among several membrane transporter specifically induced by Cd stress (Manara et al., 2012). Such system is a trans-envelope efflux pump, belonging to the heavy metal efflux family of the Gram-negative bacteria RND-driven tripartite protein complexes (Nies et al., 1989 ). This transporter utilizes the proton motive force, pumping the substrate across the membranes, through a proton/cation antiporter (Goldberg et al., 1999; Nies, 1995). The complex is made up of three proteins defined CzcA, CzcB and CzcC, respectively the RND protein, the Membrane Fusion Protein, and the Outer Membrane Factor. The first is localized at the inner membrane of the cell and allows the movement of metal cations from the cytosol to the periplasmic space, whereas the B component is located in the periplasmic space, directing ions towards the third element, located in the outer membrane, that opens a membrane channel in order to extrude ions from the bacterium (Rensing et al., 1997). The sequences encoding for CzcA, CzcB and CzcC were amplified from the genomic DNA of P. putida Cd001 and cloned into constructs enabling their overexpression in plants under the control of a plant-specific strong promoter. Arabidopsis thaliana, Nicotiana tabacum and Lycopersicon esculentum were used as test species for transformation. Several stable transgenic lines were obtained for each construct. Singly transformed plants were crossed in order to obtain plants expressing partial (CzcA/CzcB) or whole complex (CzcCBA.).
The expression levels of transgenes were analyzed by Real Time PCR. Among transgenic lines of the same genotype, different levels of expression were identified. Worth to note that in both Arabidopsis and tobacco plants overexpressing CzcA/CzcB or CzcA/CzcB/CzcC, the expression level of CzcB is always higher in comparison to the other transgenes.
The modulation of metal content in transgenic plants was analyzed carrying out accumulation experiments. Transformed plants were cultured hydroponically and treated with 0.45, 0.7, 5 μM (CdSO4) for Arabidopsis, tobacco and tomato plants respectively. Cd accumulated in shoot was analyzed, after 22 days of treatment by comparing transgenic and wild-type plants. Tobacco transgenic lines showed a reduced Cd content in comparison to wild-type plants. Such reduction in Cd level is enhanced progressively in plants overexpressing simultaneously more components of the CzcCBA system. The single expression of CzcA causes (considering all transgenic lines tested) a Cd reduction on average equal to the 30% in comparison to wild-type, while the concomitant presence of CzcA and CzcB led to 39% reduction. Finally, the overexpression of the whole efflux system, result on average in a 55% reduction in shoot Cd content.
In Arabidopsis, the presence of CzcA or CzcB alone does not have a clear effect on Cd content into shoot. Differently, the simultaneous presence of both the components, CzcA and CzcB, results on average in a 23% reduction into shoot in comparison to wild-type. The presence of CzcC does not influence Cd accumulation nor in tobacco neither in Arabidopsis transgenic plants. Since in bacteria the CzcCBA transport system is able to export Cd and Zn, the content of the latter was analyzed in tobacco transgenic lines overexpressing the whole complex CzcCBA. Transgenic lines do not show strong differences in Zn content in comparison to wild-type.
In order to better characterize the efflux mechanism of CzcCBA in plant, the sub-cellular localization of the three components was analyzed. The following fusion constructs under the control of the 35SCaMV promoter were obtained: CzcA::eGFP, CzcB::dsRED, CzcC::eYFP. These constructs were used both for stable transformation of tobacco and for protoplast transfection. In both cases samples were observed by confocal microscopy.
Tobacco protoplast were transiently transformed with the construct of the three proteins fused to fluorescent reporter, and together with sub-cellular markers, in order to identify the precise location. Microscopy analysis indicates a localization on endoplasmic reticulum for CzcA-GFP; however, the protein seems not to be addressed to the lytic vacuole. Preliminary results suggest that CzcB-RFP forms aggregates with cytosolic localization. CzcC-YFP seems to localize diffusely in the cytosol. Further analyses are necessary to determine the possible co-localization of the three components of the CzcCBA system.
In conclusion, results of this study showed that overexpression of single components and even more of the whole efflux system CzcCBA, cause a reduction in Cd content into shoot of transformed plants in comparison to wild-type
Identification of amino acid residues of Fusarium verticillioides endo-polygalacturonase required to escape the inhibition by host plant PGIP
No full textEndopolygalacturonases (Endo-PGs) play an important role
in fungal infection since they depolymerize the pectin component
of plant cell wall. Most plant have evolved defence mechanisms
to contrast the action of endo-PGs. A direct mechanism is the interaction
with plant cell wall polygalacturonase-inhibiting proteins
(PGIPs) that block polygalacturonase activity. However,
fungal pathogens can elude the inhibition by plant PGIP, producing
PGs refractory to inhibition. Fusarium verticillioides endo-PG
is unaffected by host PGIPs (asparagus and leek) as well as by
Phaseolus vulgaris PGIP, that is the most efficient PGIP so far
characterized. Recently, we have identified a specific PG amino
acid residue responsible for the lack of recognition by bean
PGIP. Now we have mutated few amino acids of the F. verticillioides
endo-PG which allow the recognition by host PGIP. This
finding highlights the structural features of the enzyme to escape
PGIP inhibition. Moreover, this modified PG could be used to
replace native F. verticillioides PG in order to better clarify the
role of constitutive PGIP in plant defense
Wood pellets as carriers of conidia of Trichoderma atroviride SC1 for soil application
No full textThe use of biocontrol agents to control soilborne diseases is a promising alternative to chemical pesticides, however, obtaining a homogeneous distribution and incorporation of conidia of fungal biocontrol agents into the soil is often difficult. Several carriers/formulations have been proposed over time, unfortunately without offering an ultimate solution. We propose the use of wood pellets as a carrier of conidia of a saprophytic fungus that has good biodegradation and biocontrol properties (Trichoderma atroviride SC1). The coating process is based on the direct spraying of wood pellets with a conidial suspension at different rates. Beech, fir, and chestnut wood pellets were compared in terms of relevant physicochemical traits and efficacy in supporting the growth of the fungus. Beech wood pellets displayed the best characteristics in terms of water holding capacity, swelling properties, and disintegration time. T. atroviride SC1 grows best on beech and fir wood pellets and reaches a plateau after nine days of incubation, regardless of the initial coating concentrations. The addition of small quantities of a nitrogen source as tryptone or soy flour, soy proteins, and a mixture of animal proteins used as pet food to the conidial suspension can increase the growth by ten-folds on all types of wood pellets. Our results demonstrate that beech and fir wood pellets could be suitable carriers to deliver and sustain the growth of T. atroviride SC1
Volatile-mediated inhibitory activity of Rhizobacteria as a result of multiple factors interaction: the case of Lysobacter capsici AZ78
No full textPlant beneficial rhizobacteria may antagonize soilborne plant pathogens by producing a vast array of volatile organic compounds (VOCs). The production of these compounds depends on the medium composition used for bacterial cell growth. Accordingly, Lysobacter capsici AZ78 (AZ78) grown on a protein-rich medium was previously found to emit volatile pyrazines with toxic activity against soilborne phypathogenic fungi and oomycetes. However, the discrepancy between the quantity of pyrazines in the gaseous phase and the minimum quantity needed to achieve inhibition of plant pathogens observed, lead us to further investigate the volatile-mediated inhibitory activity of AZ78. Here, we show that, besides VOCs, AZ78 cells produce ammonia in increased amounts when a protein-rich medium is used for bacterial growth. The production of this volatile compound caused the alkalinization of the physically separated culture medium where Rhizoctonia solani was inoculated subsequently. Results achieved in this work clearly demonstrate that VOC, ammonia and the growth medium alkalinization contribute to the overall inhibitory activity of AZ78 against R. solani. Thus, our findings suggest that the volatile-mediated inhibitory activity of rhizobacteria in protein-rich substrates can be regarded as a result of multiple factors interaction, rather than exclusively VOCs productio
Trichoderma atroviride (cepa SC1) en la prevencion de infecciones por Phaeoacremonium y Phaeomoniella en viveros
No full textAssessment of the spectrum of activity of a new insecticide based on Clitoria ternatea extract
No full textClitoria ternatea L. (butterfly pea), is a plant species belonging to the Fabaceae family, which was extensively studied for its pharmacologically activities. Besides the medicinal uses, in agriculture it is considered an excellent forage legume, with very good regrowth and yields, and cover crop. Young and tender parts of the plant (shoots, leaves, flowers and pods) are edible and frequently consumed in India. Recent studies also indicate that C. ternatea possess insecticidal effects, mainly related to its content in cyclotides and flavonoids. Putative cyclotides have been now been identified in the seed, the leaf and the flower. Cyclotides are molecules composed of 28-37 amino acids in a head-to-tail cyclic backbone with three interlocking disulfide cystine bonds (cyclic cystine knot motif) and are mainly produced by plants as defence proteins. Putative mode of action is hypothesised to be similar to the endotoxin of Bacillus thuringiensis. Currently the efficacy of C. ternatea extracts as insecticide has been characterised mainly against Helicoverpa punctigera, however its spectrum of activity can be theoretically larger. The aim of this research was to explore the possible use of C. ternatea extracts against a wide range of phytophagous insects. More specifically, a formulated extract of C. ternatea was tested under controlled conditions against a leaf miner (Antispila oinophylla; Lepidoptera: Heliozelidae), an aphid (Aphis gossypii; Hemiptera: Aphididae), white flies (Trialeurodes vaporariorum; Hemiptera: Aleyrodidae), a fruit fly (Drosophila suzukii; (Diptera: Drosophilidae), trips (Frankliniella occidentalis; Thysanoptera: Thripidae), bugs (Halyomorpha halys; Hemiptera: Pentatomidae), the grapevine moth (Lobesia botrana; Lepidoptera: Tortricidae), and a leafhopper (Scaphoideus titanus; Hemiptera: Cicadellidae). The efficacy trails resulted in a good efficacy against trips and white flies, which was also confirmed by field trials. Promising results were obtain against some other species, however further analysis will be necessary to confirm the efficacy. Based on the results obtained, the formulated C. ternatea extract can be considered a new low-risk tool to be used in the integrated pest management of crops
Development and assessment of plant protein hydrolysates as biopesticides against zucchini powdery mildew
No full textCharacterization of the volatilome of Lysobacter capsici AZ78 and its bioactivity against soilborne plant pathogenic fungi and oomycetes
No full textAntibiotics, toxins and volatile organic compounds (VOCs), are some of the plethora of secondary metabolites produced by soil bacteria. These secondary metabolites have been shown to impact on microbial interactions in the soil. Here, we studied the activity and production of VOCs emitted by Lysobacter capsici AZ78, a soil bacterium, which produces non-volatile secondary metabolites toxic against plant pathogens [1]. Recently, it has been shown that VOCs produced by L. capsici DSM 19286 grown in a protein rich medium were highly active against Phytophthora infestans in vitro [2]. In contrast, the VOC-mediated inhibitory effect was attenuated when the strain was grown in a sugar rich medium. Based on these findings, we studied the effect of medium composition on the inhibition activity of L. capsici AZ78 against plant pathogens (e.g. Rhizoctonia solani). In parallel, GC-MS was combined with dynamic headspace (DHS) extraction and thermodesorption to investigate both type and relative amount of VOCs produced by the bacterium grown in media with crescent sugar (glucose) concentrations. Generally, VOC emission profiles exhibited mainly quantitative and not qualitative differences. The chemical group of pyrazines was the most abundant in the volatile profile of L. capsici AZ78 growing in the various media. We additionally conducted experiments using a setup with Petri dishes having two compartments, where we measured the VOCs profile in the one compartment when the bacterium was growing on crescent sugar concentrations in the other. We confirmed the presence of the identified VOCs, thus giving an insight into which compounds could participate in L. capsici AZ78 bioactivity, exhibited during the pathogen inhibition assay. Currently, we are examining the inhibitory effects of the identified compounds against various plant pathogens in vitro, with the aim to understand the mechanisms of VOC-mediated microbe-microbe communications and to select bioactive VOCs for the further development of novel biopesticides
Effect of a Wood-Based Carrier of <i>Trichoderma atroviride</i> SC1 on the Microorganisms of the Soil
No full textWood pellets can sustain the growth of Trichoderma spp. in soil; however, little is known about their side effects on the microbiota. The aims of this study were to evaluate the effect of wood pellets on the growth of Trichoderma spp. in bulk soil and on the soil microbial population’s composition and diversity. Trichoderma atroviride SC1 coated wood pellets and non-coated pellets were applied at the level of 10 g∙kg−1 of soil and at the final concentration of 5 × 103 conidia∙g−1 of soil and compared to a conidial suspension applied at the same concentration without the wood carrier. Untreated bulk soil served as a control. The non-coated wood pellets increased the total Trichoderma spp. population throughout the experiment (estimated as colony-forming unit g−1 of soil), while wood pellets coated with T. atroviride SC1 did not. The wood carrier increased the richness, and temporarily decreased the diversity, of the bacterial population, with Massilia being the most abundant bacterial genus, while it decreased both the richness and diversity of the fungal community. Wood pellets selectively increased fungal species having biocontrol potential, such as Mortierella, Cladorrhinum, and Stachybotrys, which confirms the suitability of such carriers of Trichoderma spp. for soil application
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