Microbial infections pose a significant global health threat, affecting millions of individuals and leading to substantial mortality rates. The increasing resistance of microorganisms to conventional treatments requires the development of novel antimicrobial agents. Pyrroloquinoline quinone (PQQ), a natural medicinal drug involved in various cellular processes, holds promise as a potential antimicrobial agent. In the present study, our aim was, for the first time, to explore the antimicrobial activity of PQQ against 29 pathogenic microbes, including 13 fungal strains, 8 Gram-positive bacteria, and 8 Gram-negative bacteria. Our findings revealed potent antifungal properties of PQQ, particularly against Syncephalastrum racemosum, Talaromyces marneffei, Candida lipolytica, and Trichophyton rubrum. The MIC values varied between fungal strains, and T. marneffei exhibited a lower MIC, indicating a greater susceptibility to PQQ. In addition, PQQ exhibited notable antibacterial activity against Gram-positive and -negative bacteria, with a prominent inhibition observed against Staphylococcus epidermidis, Proteus vulgaris, and MRSA strains. Remarkably, PQQ demonstrated considerable biofilm inhibition against the MRSA, S. epidermidis, and P. vulgaris strains. Transmission electron microscopy (TEM) studies revealed that PQQ caused structural damage and disrupted cell metabolism in bacterial cells, leading to aberrant morphology, compromised cell membrane integrity, and leakage of cytoplasmic contents. These findings were further affirmed by shotgun proteomic analysis, which revealed that PQQ targets several important cellular processes in bacteria, including membrane proteins, ATP metabolic processes, DNA repair processes, metal-binding proteins, and stress response. Finally, detailed molecular modeling investigations indicated that PQQ exhibits a substantial binding affinity score for key microbial targets, including the mannoprotein Mp1P, the transcriptional regulator TcaR, and the endonuclease PvuRTs1I. Taken together, our study underscores the effectiveness of PQQ as a broad-spectrum antimicrobial agent capable of combating pathogenic fungi and bacteria, while also inhibiting biofilm formation and targeting several critical biological processes, making it a promising therapeutic option for biofilm-related infections.

Fungi are responsible for many plant infections. Indeed, fungi are responsible for most plant spoilage that occurs in the field or in storage, causing symptoms of dieback, leaf spot, rot, rust and wilt. A more serious issue is that fungi produce mycotoxins, which can contaminate crops. Samples of leaf, fruit and root tissues were collected from sick crops, pre- and post-harvest within Al-Baha region. Using molecular markers, twenty fungal isolates were identified that represent eight genera and thirteen species. The most common species were Penicillium spp. (45%), followed by Aspergillus spp. (25%). The remaining 30% were comprised of multiple species (Alternaria alternata, Fusarium oxysporum, Geotrichum candidum, Lasiodiplodia theobromae, Megasporoporia minor and Rhizopus arrhizu). The majority of these isolates are recognised as spoilers of crops and producers of mycotoxins. The study evaluated which temperatures optimised fungal growth. Half of the isolates thrived best at 25 °C; six isolates favoured 30 °C, whilst four isolates grew best at 20 °C. The study also evaluated the optimal water activity (a_w) for fungal growth, at four points (0.995, 0.99, 0.90 and 0.85 a_w). The isolates were categorised as being either xerophilic, mesophilic or hydrophilic. The majority of isolates (70%) were xerophilic (Aspergillus and Penicillium spp.), 10% were mesophilic (Alternaria alternata and Rhizopus oryzae spp.) and 20% were hydrophilic (Lasiodiplodia theobromae, Geotrichum candidum, Megasporoporia minor and Fusarium oxysporum spp). The information derived from this study will assist in building effective strategies to control these pathogens, minimising crops losses and mycotoxin contamination.

Antifungal properties of nanoparticles (NPs) of copper oxide (CuO), titanium dioxide (TiO2), and silica dioxide (SiO₂) were compared to the fungicide thiophanate-methyl for controlling root rot and wilt of chickpea, caused by, respectively, Rhizoctonia solani and Fusarium oxysporum f. sp. ciceris. Different concentrations (10, 20, or 40 ppm) of the NPs were assessed for their ability to inhibit fungal growth in vitro. All the nanoparticles had antifungal activity, with greatest effects at 40 ppm. CuO NPs at 40 ppm gave 61% reduction for Rhizoctonia rot and 65% reduction for Fusarium wilt. Alterations in the ultrastructure of the fungal mycelia were observed in response to treating with CuO NPs. No differences in in vivo tests were observed between CuO NPs and thiophanate-methyl for reducing root rot or wilt. Applications of CuO NPs also enhanced growth and yield of chickpea plants. CuO NPs had antifungal properties, increased activities of peroxidase and polyphenol oxidase in chickpea plants, and increased plant phenol contents. These results indicate that CuO NPs have potential as effective, eco-friendly alternatives to conventional fungicides for controlling of root rot and wilt of chickpea.

Fungi inflict a great deal of damage to crops in fields and in storage facilities, causing issues such as leaf spot, wilt, rust, dieback and rot, as well as releasing mycotoxins that taint vegetation. In the current study, 25 de novo fungal isolates were taken from infected plant tissue (leaf, root and fruit), at pre- and post-harvest stages. Isolates were identified using molecular markers; 8 genera and 15 species were determined. The most common species was Penicillium spp. (40%), Aspergillus spp. (20%), Fusarium spp. (16%) and Alternaria alternata species (8%). The remaining 16% was comprised of various types of fungi, including Geotrichum candidum, Neofusicoccum parvum, Rhizopus stolonifera and Mucor fragilis. Many of these genera are known to cause significant crop damage and are notorious mycotoxin producers. An evaluation of the optimal growth temperature revealed the ideal temperatures were 30 °C for 56% of isolates, 25 °C for 28% of isolates and 20 °C for 16% of isolates. An assessment of water activity showed that 60% of isolates belonged to Penicillium and Aspergillus spp. and were mesophilic and xerophilic. Another 28% of isolates were Fusarium spp., Geotrichum candidum, Neofusicoccum parvum and Mucor fragilis, and hydrophilic. The remaining 12%, representing Alternaria alternata and Rhizopus stolonifera, were mesophilic. The current study provides accurate eco-physiological response data and molecular information for each isolate. The findings can assist the development of novel approaches to control the expansion of invasive fungal infections and minimise their deleterious consequences.

Plant pathogens of fungus have become of the most crucially harmful objects that may affect overall plants growth rate and crops production worldwide. This study involved the identification of six species and six genera was achieved from the ten fungal plant pathogen isolates that gathered from different sites and regions in Taif region, Saudi Arabia. The identification of these organisms was conducted using molecular markers; among the identified species, 30% were Mucor circinelloides, 20% were Penicillium crustosum, and 20% were Alternaria alternata. The remaining 30% was comprised of Cladosporium tenuissimum, Phoma macrostoma, and Fusarium equiseti. A considerable proportion of these genera are widely acknowledged for their capacity to generate mycotoxins. The linear growth regression derived by the new plant extract is higher than fungicide, it has been found that the growth inhibition percentage driven by fungicide was between (20 to 85%), whereas for plant extract was between (80 to 100%) across all isolates. This data facilitate the contributing to the exploration of a more secure alternative to fungicides. Further, it will facilitate the development of regulatory approaches aimed at alleviating the detrimental consequences of fungal infections.

Fungal agents form the principal disease-inducing pathogens affecting plants, being accountable for the majority of damage to crops occurring either in fields or in storage. Five genera and 8 species were recognized amongst 20 fungal isolates collected during this study. These were identified through molecular markers; 80% of the recognized species were Aspergillus; the remainder included B. prieskaensis, F. oxysporum, G. candidum and Actinomucor elegans. The majority of these genera are well-recognized for their ability to produce mycotoxins. The biological activity and virulence of fungi is notably impacted by environmental conditions, especially temperature and water. For the isolates investigated in the current research, 75% showed a growth preference for a temperature of 30°C; the remainder favoured 25°C. These data not only facilitate the recognition of species with phytopathogenic and mycotoxigenic properties, but also contribute to the design of regulatory strategies that will mitigate against the adverse effects of fungal infection.