Drought is a major threat to crop productivity and causes decreased plant growth, poor yields, and crop failure. Nevertheless, the frequency of droughts is expected to increase in the coming decades. The microbial communities associated with crop plants can influence how plants respond to various stresses; hence, microbiome manipulation is fast becoming an effective strategy for improving the stress tolerance of plants. The effect of drought stress on the root microbiome of perennial woody plants is currently poorly understood. Using Populus trees as a model ecosystem, we found that the diversity of the root microbial community decreased during drought treatment and that compositional shifts in microbes during drought stress were driven by the relative abundances of a large number of dominant phyla, including Actinobacteria, Firmicutes, and Proteobacteria. A subset of microbes, including Streptomyces rochei, Bacillus arbutinivorans, B. endophyticus, B. megaterium, Aspergillus terreus, Penicillium raperi, Trichoderma ghanense, Gongronella butleri, and Rhizopus stolonifer, was isolated from the drought-treated poplar rhizosphere soils, which have potentially beneficial to plant fitness. Further controlled inoculation experiments showed that the isolated bacterial and fungal isolates positively impacted plant growth and drought tolerance. Collectively, our results demonstrate the impact of drought on root microbiome structure and provide a novel example of manipulating root microbiomes to improve plant tolerance.

Fungal endophytes are considered one of the most important reservoirs of bioactive compounds which defeat resistant microbes. In our study, endophyticAlternaria alternatawas isolated fromZiziphus spina-christiand identified morphologically and genetically with accession number OM 331,682. Preliminary phytochemical screening of ethyl acetate (EA) crude extract ofA. alternatarevealed that this extract contains alkaloids, tannins, flavonoids, glycosides, phenols, and terpenoids. Moreover, the extract was analyzed using gas chromatography-mass spectrometry (GC–MS) which verified the presence of numerous bioactive compounds. Antimicrobial results illustrated that EA crude extract exhibited promising antimicrobial activity against Gram-negative bacteria (Escherichia coliATCC 11229,Proteus vulgarisRCMB 004,Pseudomonas aeruginosaATCC 27853, andKlebsiella pneumoniaRCMB 003), Gram-positive bacteria (Bacillus subtilisRCMB 015,Staphylococcus aureusATCC 25923, andStaphylococcus epidermidisATCC 14990), and unicellular fungi (Candida albicansATCC 90028). Ultrastructure study of treatedK. pneumoniashowed remarkably elucidated destruction of the cell wall and cell membrane and leakage of cytoplasmic materials. Furthermore, the extract has potential antioxidant activity where IC₅₀was 409 µg/mL. Moreover, this extract did not show any toxicity on Vero normal cell line. These findings confirmed that the endophyticA. alternatafromZ. spina-christiis a promising source of bioactive compounds which can be used in different biological applications.

The emergence of bacteria that are resistant to several antibiotics has represented a serious hazard to human health globally. Bioactive metabolites from medicinal plants have a wide spectrum of therapeutic possibilities against resistant bacteria. Therefore, this study was performed to investigate the antibacterial efficacy of various extracts of three medicinal plants as Salvia officinalis L., Ziziphus spina-christi L., and Hibiscus sabdariffa L. against pathogenic Gram-negative Enterobacter cloacae (ATCC13047), Pseudomonas aeruginosa (RCMB008001), Escherichia coli (RCMB004001), and Gram-positive Staphylococcus aureus (ATCC 25923), bacteria using the agar-well diffusion method. Results revealed that, out of the three examined plant extracts, the methanol extract of H. sabdariffa L. was the most effective against all tested bacteria. The highest growth inhibition (39.6 ± 0.20 mm) was recorded against E. coli. Additionally, the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) of the methanol extract of H. sabdariffa were detected in the case of all tested bacteria. Moreover, an antibiotic susceptibility test revealed that all tested bacteria showed multidrug resistance (MDR). While 50% of tested bacteria were sensitive and 50% were intermediately sensitive to piperacillin/tazobactam (TZP) based on the inhibition zone but still less than the extract. Synergistic assay demonstrated the promising role of using a combination of H. sabdariffa L. and (TZP) against tested bacteria. A surface investigation using a scanning electron microscope of the E. coli treated with TZP, extract, or a combination of the two revealed extremely considerable bacterial cell death. In addition, H. sabdariffa L. has a promising anticancer role versus Caco-2 cells with IC₅₀ of 17.51 ± 0.07 µg/mL and minimal cytotoxicity upon testing versus Vero cells with CC₅₀ of 165.24 ± 0.89 µg/mL. Flow cytometric analysis confirmed that H. sabdariffa extract significantly increased the apoptotic rate of Caco-2-treated cells compared to the untreated group. Furthermore, GC-MS analysis confirmed the existence of various bioactive components in the methanol hibiscus extract. Utilizing molecular docking with the MOE-Dock tool, binding interactions between n-Hexadecanoic acid, hexadecanoic acid-methyl ester, and oleic acid, 3-hydroxypropyl ester were evaluated against the target crystal structures of E. coli (MenB) (PDB ID:3T88) and the structure of cyclophilin of a colon cancer cell line (PDB ID: 2HQ6). The observed results provide insight into how molecular modeling methods might inhibit the tested substances, which may have applications in the treatment of E. coli and colon cancer. Thus, H. sabdariffa methanol extract is a promising candidate to be further investigated for developing alternative natural therapies for infection treatment.

Biosynthetic metals have attracted global attention because of their safety, affordability, and environmental friendliness. As a consequence, the cell-free filtrate (CFF) of Dill leaf-derived endophytic fungus Aspergillus luchuensis was employed for the extracellularly synthesis silver nanoparticles (AgNPs). A reddish-brown color shift confirmed that AgNPs were successfully produced. The obtained AgNPs were characterized by UV–Vis (ultraviolet–visible spectroscopy), Transmission electron microscopy (TEM), FTIR, EDX, and zeta potential. Results demonstrated the creation of crystalline AgNPs with a spherical shape at 427.81 nm in the UV–Vis spectrum, and size ranged from 16 to 18 nm as observed by TEM. Additionally, the biogenic AgNPs had a promising antibacterial activity versus multidrug-resistant bacteria, notably, S. aureus, E. coli, and S. typhi. The highest growth reduction was recorded in the case of E. coli. Furthermore, the biosynthesized AgNPs demonstrated potent antifungal potential versus a variety of harmful fungi. The maximum growth inhibition was evaluated from A. brasinsilles, followed by C. albicans as compared to cell-free extract and AgNO₃. In addition, data revealed that AgNPs possess powerful antioxidant activity, and their ability to scavenge radicals increased from 33.0 to 85.1% with an increment in their concentration from 3.9 to 1,000 μg/mL. Furthermore, data showed that AgNPs displayed high catalytic activity of safranin under light irradiation. The maximum decolorization percentage (100%) was observed after 6 h. Besides, the biosynthesized AgNPs showed high insecticidal potential against 3^rd larval instar of Culex pipiens. Taken together, data suggested that endophytic fungus, A. luchuensis, is an attractive candidate as an environmentally sustainable and friendly fungal nanofactory.

The escalating global challenges of antimicrobial resistance (AMR) and cancer necessitate innovative therapeutic solutions from natural sources. This study investigated the multifaceted therapeutic potential of pigment-enriched plant extracts. We screened diverse plant extracts for antimicrobial and antibiofilm activity against multidrug-resistant bacteria and fungi. Hibiscus sabdariffa emerged as the most promising, demonstrating potent broad-spectrum antimicrobial and significant antibiofilm activity. Sub-inhibitory concentrations of H. sabdariffa robustly downregulated essential bacterial virulence genes and suppressed aflatoxin gene expression. Comprehensive chemical profiling via HPLC identified major anthocyanin glucosides, while GC-MS revealed diverse non-pigment bioactive compounds, including fatty acids and alcohols. Molecular docking suggested favorable interactions of key identified compounds (Cyanidin-3-O-glucoside and 1-Deoxy-d-arabitol) with E. coli outer membrane protein A (OmpA), indicating potential antiadhesive and antimicrobial mechanisms. Furthermore, H. sabdariffa exhibited selective cytotoxicity against MCF-7 breast cancer cells. These findings establish H. sabdariffa pigment-enriched extract as a highly promising, multi-functional source of novel therapeutics, highlighting its potential for simultaneously addressing drug resistance and cancer challenges through an integrated chemical, biological, and computational approach.

Endophytic microorganisms are used as substitutes for chemical fertilizers and pesticides for increasing plant growth and productivity. In this study, we isolated 90 bacterial and 64 endophytic fungal isolates from the roots, stems, and leaves of different genotypes of Chinese white poplar (Populus tomentosa Carr.). The isolated endophytes were screened for the production of plant growth-promoting parameters, such as indole-3-acetic acid, siderophores, and inorganic phosphate solubilization. Furthermore, the endophytes were assessed for their activities of hydrolytic enzymes, such as amylase, cellulose, and pectinase. In vitro tests were conducted to visualize root colonization for the most potent isolates. Furthermore, 16S rRNA sequence analysis indicated that strains 24RB, 33RB, 59SB, 85LB, and 88LB displayed similarities to Enterobacter tabaci, Bacillus velezensis, Bacillus megaterium, Pantoea eucrina, and Bacillus aryabhattai ; these strains are deposited in GenBank under accession numbers MN540932.1, MN559965.1, MN540915.1, MN541091.1, and MN540958.1, respectively. Based on nucleotide sequencing from the internal transcribed spacer of rDNA, fungal isolate codes 17RF, 37RF, 46SF, 48SF, 52SF, and 63LF were identified as Lasiosphaeriaceae sp., Chaetomium globosum, Aspergillus niger, Peyronellaea sp., Talaromyces amestolkiae, and Alternaria sp. and deposited in GenBank with accession numbers MN541090.1, MN541117.1, MN540962.1, MN540968.1, MN540956.1, and MN541096.1, respectively. In conclusion, these strains have the potential to be commercialized for agricultural purposes.