Trichoderma species are known as excellent biocontrol agents against soil-borne pathogens that cause considerable crop losses. Eight strains of Trichoderma were isolated from five Egyptian regions. They identified based on translation elongation factor-1α (TEF1) sequencing as four different Trichoderma species: Trichoderma asperellum, Trichoderma harzianum, Trichoderma viride, and Trichoderma longibrachiatum. Optimal growth conditions (temperature and media), and the phosphate solubilization capability of Trichoderma strains were evaluated in vitro. Further, the ability of these strains to antagonize Fusarium solani, Macrophomina phaseolina, and Fusarium graminearum was also evaluated. The results revealed that Trichoderma harzianum (Th6) exhibited the highest antagonistic ability against F. solani, M. phaseolina and F. graminearum with inhibition rates of 71.42%, 72.97%, and 84.61%, respectively. Trichoderma viride (Tv8) exhibited the lowest antagonism against the same pathogens with inhibition rates of 50%, 64% and 69.23%, respectively. Simple-sequence repeats (SSRs) and random amplified polymorphic DNA (RAPD) markers were used to evaluate the genetic variability of the Trichoderma strains. The results revealed that of 45 RAPD amplified bands, 36 bands (80%) were polymorphic and of SSRs amplified 36 bands, 31 bands (86.11%) were polymorphic. The amplification of calmodulin and β-1,3-endoglucanase was noted at 500 bp and 230 bp, respectively. Data indicated that T. viride (Tv8) had the highest phosphate solubilization index (10.0 mm), while T. harzianum (Th6) had the lowest phosphate solubilization index (4.0 mm). In conclusion, T. harzianum (Th6) had the highest antagonistic activity in dual culture assay along with the growth rate; while T. viride (Tv8) had the highest phosphate solubilization activity. There are still gaps in obtaining new formulations, selecting potent Trichoderma strains to confirm disease control in planta. For improving Trichoderma recommendation in the organic agricultural system and sustaining the fertility of the soil, the field application of highly antagonistic biocontrol agents in different types of soil and plant species will be the first approach toward bio-pesticide treatments along with bio-fertilizer inoculation. Furthermore, secondary metabolites will be investigated for the most promising strains with the combination of different pathogens and application timing.
Background: The problem of heavy metal contamination is a global issue, and the challenge is to develop methods to remove heavy metals from soil and water. Recently, biosurfactants are one of the compounds that provide an attractive eco-friendly alternative to the physicochemical process in alleviating the heavy metals. Results: Sixty bacterial isolates were isolated from Al-Rahawy drain sediments and screened for biosurfactant production. Only 10 isolates were recoded as biosurfactant producers by the oil spreading and emulsifying assays in addition to the ability of biosurfactant on heavy metal removal in wastewater. The most potent isolate was identified using morphological, cultural, biochemical characteristics, antibiotics susceptibility, and 16 s rRNA technique as Citrobacter freundii MG812314.1. Conclusions: The produced biosurfactant was found to be more effective in removing heavy metals from wastewater, viz 80, 67, 66, 55, 45, 44, and 41% of aluminum, lead, zinc, cadmium, iron, copper, and manganese, respectively, under two inoculum potentials and two contact time. The interaction of heavy metals with biosurfactant was monitored using scanning electron microscope (SEM), energy dispersive X-ray spectra (EDX), and Fourier-transform infrared spectroscopy (FTIR) analyses.
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