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BACKGROUND: Spot blotch is a serious foliar disease of barley (Hordeum vulgare L.) plants caused by Bipolaris sorokiniana, which is a hemibiotrophic ascomycete that has a global impact on productivity. Some Trichoderma spp. is a promising candidate as a biocontrol agent as well as a plant growth stimulant. Also, the application of nanomaterials in agriculture limits the use of harmful agrochemicals and helps improve the yield of different crops. The current study was carried out to evaluate the effectiveness of Trichoderma. cf. asperellum and the biosynthesized titanium dioxide nanoparticles (TiO2 NPs) to manage the spot blotch disease of barley caused by B. sorokiniana and to assess the plant's innate defense response. RESULTS: Aloe vera L. aqueous leaf extract was used to biosynthesize TiO2 NPs by reducing TiCl4 salt into TiO2 NPs and the biosynthesized NPs were detected using SEM and TEM. It was confirmed that the NPs are anatase-crystalline phases and exist in sizes ranging from 10 to 25 nm. The T. cf. asperellum fungus was detected using morphological traits and rDNA ITS analysis. This fungus showed strong antagonistic activity against B. sorokiniana (57.07%). Additionally, T. cf. asperellum cultures that were 5 days old demonstrated the best antagonistic activity against the pathogen in cell-free culture filtrate. Also, B. sorokiniana was unable to grow on PDA supplemented with 25 and 50 mg/L of TiO2 NPs, and the diameter of the inhibitory zone increased with increasing TiO2 NPs concentration. In an in vivo assay, barley plants treated with T. cf. asperellum or TiO2 NPs were used to evaluate their biocontrol efficiency against B. sorokiniana, in which T. cf. asperellum and TiO2 NPs enhanced the growth of the plant without displaying disease symptoms. Furthermore, the physiological and biochemical parameters of barley plants treated with T. cf. asperellum or TiO2 NPs in response to B. sorokiniana treatment were quantitively estimated. Hence, T. cf. asperellum and TiO2 NPs improve the plant's tolerance and reduce the growth inhibitory effect of B. sorokiniana. CONCLUSION: Subsequently, T. cf. asperellum and TiO2 NPs were able to protect barley plants against B. sorokiniana via enhancement of chlorophyll content, improvement of plant health, and induction of the barley innate defense system. The present work emphasizes the major contribution of T. cf. asperellum and the biosynthesized TiO2 NPs to the management of spot blotch disease in barley plants, and ultimately to the enhancement of barley plant quality and productivity.

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Pseudomonas protegens (strain DSMZ 13134) is a biocontrol agent with promising antagonistic activity hinging on antibiosis against the fungal forest pathogens Heterobasidion spp. Here, by using High-Performance Liquid Chromatography coupled to Mass Spectrometry (HPLC-MS), we assessed whether monocultures of P. protegens (strain DSMZ 13134) produce the three major determinants of biocontrol activity known for the genus Pseudomonas: 2,4-diacetylphloroglucinol (2,4-DAPG), pyoluteorin (PLT), and pyrrolnitrin (PRN). At the tested culture conditions, we observed the production of PLT at concentrations ranging from 0.01 to 10.21 mg/L and 2,4-DAPG at a concentration not exceeding 0.5 mg/L. Variations of culture conditions involving culture medium, incubation temperature, and incubation period had no consistent influence on PLT production by the bacterium. Assays using culture medium amended with PLT at the same concentration of that present in cell-free filtrate of the bacterium, i.e., 3.77 mg/L, previously documented as effective against Heterobasidion spp., showed a remarkable activity of PLT against genotypes of all the four Heterobasidion species present in Europe, including the non-native invasive H. irregulare. However, such antifungal activity decreased over time, and this may be a constraint for using this molecule as a pesticide against Heterobasidion spp. When the bacterium was co-cultured in liquid medium with genotypes of the different Heterobasidion species, an increased production of PLT was observed at 4 °C, suggesting the bacterium may perform better as a PLT producer in field applications under similar environmental conditions, i.e., at low temperatures. Our results demonstrated the role of PLT in the inhibition of Heterobasidion spp., although all lines of evidence suggest that antibiosis does not rely on a single constitutively produced metabolite, but rather on a plethora of secondary metabolites. Findings presented in this study will help to optimize treatments based on Pseudomonas protegens (strain DSMZ 13134) against Heterobasidion spp.

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The Heterobasidion annosum species complex includes major fungal pathogens of conifers worldwide. State-of-the-art preventative stump treatments with urea or with commercial formulations of the fungal biological control agent Phlebiopsis gigantea (i.e., Rotstop®) may become no longer available or are not approved for use in many areas of Europe infested by the three native Heterobasidion species and by the North American invasive H. irregulare, making the development of new treatments timely. The efficacy of Proradix® (based on Pseudomonas protegens strain DSMZ 13134), the cell-free filtrate (CFF) of the same bacterium, a strain of P. gigantea (MUT 6212) collected in the invasion area of H. irregulare in Italy, Rotstop®, and urea was comparatively investigated on a total of 542 stumps of Abies alba, Picea abies, Pinus pinea, and P. sylvestris in forest stands infested by the host-associated Heterobasidion species. Additionally, 139 logs of P. pinea were also treated. Results support the good performances of Rotstop®, and especially of urea against the native Heterobasidion species on stumps of their preferential hosts and, for the first time, towards the invasive North American H. irregulare on stumps of P. pinea. In some experiments, the effectiveness of Proradix® and of the strain of P. gigantea was weak, whereas the CFF of P. protegens strain DSMZ 13134 performed as a valid alternative to urea and Rotstop®. The mechanism of action of this treatment hinges on antibiosis; therefore, further improvements could be possible by identifying the active molecules and/or by optimizing their production. Generally, the performance of the tested treatments is not correlated with the stump size.

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A novel technique for removing metals from water, by converting them into nanoparticles using the culture filtrate of Fusarium solani YMM20, followed by their removal by centrifugation was developed in this study. It is a promising, simple, and eco-friendly process for the bioremediation of wastewater. This method is built on the reduction of metal ions by cell-free fungal filtrate protein(s). The chitosan and chitosan nanoparticles were used as adsorbents for the removal of Cu2+ , Pb2+ , Co2+ , Cd2+ , Ni2+ , and Fe2+ , separately. In addition, fungal filtrate and chitosan nanoparticles loaded with fungal filtrate were used for the biosynthesis of metal nanoparticles of Cu2+ , Pb2+ , Co2+ , Cd2+ , Ni2+ , and Fe2+ , separately for their removal. The fungal filtrate approach has the highest metal removal (%) for most metals. Among the six metal ions, the fungal filtrate, chitosan nanoparticles loaded with fungal filtrate, chitosan, and chitosan nanoparticles showed the highest removal (%) for Pb2+ and the lowest removal (%) for Co2+ . Techniques such as transmission electron microscopy, scanning electron microscopy, and Zeta potential measurements were used to characterize the obtained nanoparticles. The average size of the spherical nanoparticles observed by transmission electron microscopy was from 18.938 ± 2.269 nm to 60.175 ± 4.973 nm.

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In this paper, the bioactivity of cell-free extracts obtained by dairy propionibacteria strains was investigated. Probiotic bifidobacteria and lactobacilli were used as microbial targets. The extracellular filtrates were added as ingredient (1% v/v) into the growth medium; the effect of cell-free filtrates was evaluated through viable count of microbial targets on appropriate media, monitoring the response of target microorganisms both in growth and death phase. The Gompertz equation was used to model the experimental data. Kinetics and time parameters were estimated in order to quantify the effectiveness of cell-free filtrates effect. To emphasize the results about the bioactivity of cell-free extract, supporting a complete picture of response, a new approach was developed: Probiotic Stability Time was calculated. This temporal parameter, defined as the time over that the cell load preserve a living value upper than 10(7) cfu ml(-1), was very useful to evaluate the probiotic capability and effectiveness. A stimulant effect was registered on growth and a positive one was recordered on survival of both bifidobacteria and lactobacilli strains, and the results obtained suggest that a prebiotic activity by dairy propionibacteria cell-free filtrates could be supposed. The cell-free filtrate obtained from Propionibacterium freudenreichii subsp. shermanii was the most effective, in our experimental conditions. Although bifidobacteria were the most sensitive to the effect of cell-free filtrates, lactobacilli have been showed a similar probiotic stability time, showing a high sensitivity to the filtrates. This paper is the first report of a positive bioactivity by propionibacteria cell-free filtrates on lactobacilli.

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An endophytic fungus isolated from Camellia sinensis, Assam, Northeastern India was identified as Colletotrichum gloeosporioides on the basis of morphological characteristics and rDNA ITS analysis. This endophytic fungus was evaluated for growth inhibition against tea pathogens Pestalotiopsis theae and Colletotrichum camelliae. One isolate of C. gloeosporioides showed strong antagonistic activity against Pestalotiopsis theae (64 %) and moderate activity against C. camelliae (37 %). Fifty percent cell-free culture filtrate from 5-day-old cultures showed highest antagonistic activity against both the pathogens although the inhibition percent was less as compared to dual culture. In the experiment of volatile compounds none of the isolates of C. gloeosporioides strains showed visible inhibition against P. theae and C. camelliae. The activity of extracellular hydrolytic enzymes chitinase and protease was also high in this culture fluid and measured 10 and 4.3 IU/µl, respectively.