Production and characterization of melanin pigment from black fungus Curvularia soli AS21 ON076460 assisted gamma rays for promising medical uses.

Owing to the growing need for natural materials in different fields, studying melanin production from biological sources is imperative. In the current study, the extracellular melanin pigment was produced by the fungus Curvularia soli AS21 ON076460. The factors that affect the production of melanin were optimized by the Plackett-Burman design (P-BD). The effect of gamma irradiation on melanin productivity was investigated. The maximum melanin yield (3.376 mg/L) was elicited by a stimulus of gamma irradiation at 1.0 kGy. The results evoked that, Curvularia soli AS21 ON076460 melanin exhibited excellent antimicrobial activity against all tested bacteria and fungi. Klebsiella pneumoniae ATCC 13883 and P. digitatum were mostly affected by melanin registering the inhibition zone diameters of 37.51 ± 0.012 and 44.25 ± 0.214 mm, respectively. Moreover, Curvularia soli AS21 ON076460 melanin indicated a significant antiviral efficacy (77% inhibition) of Herpes simplex virus (HSV1). The melanin pigment showed antioxidant activities with IC50 of 42 ± 0.021 and 17 ± 0.02 µg/mL against DPPH and NO, respectively. Melanin had cytotoxic action against human breast cancer and skin cancer cell lines (Mcf7and A431) as well as exerting a low percentage of cell death against normal skin cell lines (Hfb4). Melanin was effective in wound management of human skin cells by 63.04 ± 1.83% compared with control (68.67 ± 1.10%). The novelty in the study is attributed to the possibility of using gamma rays as a safe method in small economic doses to stimulate melanin production from the fungi that have been isolated. In summary, melanin produced from fungi has significant biological activities that encourage its usage as a supportive medical route.

Mycosynthesis of silver nanoparticles using marine fungi and their antimicrobial activity against pathogenic microorganisms.

OBJECTIVES: At the present time, there is a persistent need to get rid of environmental contaminants by eco-friendly, sustainable, and economical technologies. Uncontrolled disposal practices of domestic and industrial solid and liquid wastes led to water pollution which has negative impacts on public health, environment, and socio-economic development. Several water-borne diseases are spreading man to man by microorganisms such as pathogenic bacteria. For the protection of water bodies, all wastewater from various sources should be managed and remediated properly. Myco-remediation is a form of bioremediation in which fungi are used to get rid of contaminants. Fungi are attractive agents for the biosynthesis of nanoparticles especially silver nanoparticles (AgNPs) which are considered one of the most widely utilized nanoparticles because of their unique characteristics such as antibacterial, antiviral, antifungal, and anti-inflammatory properties. METHODS: This study uses silver nitrate and supernatants of four marine fungi; Penicillium simplicissimum, Aspergillus terreus, Aspergillus japonicus, and Aspergillus oryzae for extracellular biosynthesis of silver nanoparticles and to evaluate its activity against different pathogenic microorganisms. These nanoparticles may subsequently be applied for the treatment or nano-bioremediation of microbial contaminants in water bodies and improve water quality. RESULTS: Silver nanoparticles were synthesized and the results revealed that spherical and well-dispersed nanoparticles of different sizes were formed with sizes ranging between 3.8 and 23 nm. Characterization results approved the existence of stable nanocrystalline elemental silver. Antibacterial activity results revealed that AgNPs can be used as a powerful antimicrobial agent for several pathogenic bacteria, yeast, and fungi. Among the biosynthesized NPs mediated by the four marine fungi, AgNPs mediated by A. japonicus (5 mM) had the highest antibacterial activity, while AgNPs mediated by Penicillium simplicissmum (8 mM) had the highest antifungal activity. CONCLUSION: Marine fungi can biosynthesize stable AgNPs that exhibit potent antimicrobial activity against a variety of pathogens.

Effect of silver nanoparticles on tropane alkaloid production of transgenic hairy root cultures of Hyoscyamus muticus L. and their antimicrobial activity.

The utilization of nanotechnology and biotechnology for enhancing the synthesis of plant bioactive chemicals is becoming increasingly common. The hairy root culture technique can be used to increase secondary metabolites such as tropane alkaloids. Agrobacterium was used to induce hairy roots from various explants of Hyoscyamus muticus. The effect of nano-silver particles (AgNPs) at concentrations of 0, 25, 50, 100, and 200 mg/L on tropane alkaloids synthesis, particularly hyoscyamine and scopolamine, was studied in transgenic hairy root cultures. Different types of explants obtained from 10-day-old seedlings of H. muticus were inoculated with two strains of Agrobacterium rhizogenes (15,834 and A4). The antimicrobial activity of an ethanolic extract of AgNPs-induced hairy root cultures of H. muticus was tested. The frequency of hairy roots was higher in hypocotyl, root, leaf, and stem explants treated with A. rhizogenes strain A4 compared to those treated with strain 15,834. In transgenic hairy root cultures, AgNPs application at a concentration of 100 mg/L resulted in the highest total tropane alkaloid production, which exhibited broad-spectrum antimicrobial activity. The study demonstrated the potential of nano-silver as an elicitor for promoting the production of target alkaloids in Hyoscyamus muticus hairy root cultures, which exhibit high biological activity.

Novel biosynthesis of tellurium nanoparticles and investigation of their activity against common pathogenic bacteria.

Objectives: Tellurium has received substantial attention for its remarkable properties. This study performed in vitro and in vivo testing of the antibacterial action of tellurium nanoparticles biosynthesized in actinomycetes against methicillin-resistant Staphylococcus aureus (MRSA), a common blood bacterial pathogen. Methods: Nine actinomycete isolates were tested for their potential to reduce potassium tellurite (K2TeO3) and form tellurium nanoparticles (TeNPs). The most efficient actinomycete isolate in producing Tellerium nanoparticles was identified through molecular protocols. The generated TeNPs were characterized using UV, TEM, EDX, XRD and FTIR. The bacterial species implicated in bloodstream infections were detected at El Hussein Hospital. Bacterial identification and antibiotic susceptibility testing were performed using Vitek 2. An animal infection model was used to test the efficacy of the produced TeNPs against the most commonly isolated methicillin-resistant S. aureus using survival assays, colony counting, cytokine assessment and biochemical testing. Results: The most efficient actinomycete isolate was identified as Streptomyces graminisoli and given the accession number (OL773539). The mean particle size of the produced TeNPs was 21.4 nm, and rods and rosette forms were observed. Methicillin-resistant S. aureus (MRSA) was the main bacterium (60%) causing blood stream infections, and was followed by Escherichia coli (25%) and Klebsiella pneumoniae (15%). The produced TeNPs were tested against MRSA, the bacterium most frequently isolated from blood, and showed a promising action inhibition zone of 24 ± 0.7 mm and an MIC of 50 µg/ml. An animal infection model indicated the promise of TeNPs alone or in combination with standard drugs to combat MRSA in a rat intravenous infection model. Conclusion: TeNPs combined with vancomycin have successive impact to combat bacteremia for further verification of results.

Identification of Novel Bioactive Compound Derived from Rheum officinalis against Campylobacter jejuni NCTC11168.

Gastric diseases are increasing with the infection of Campylobacter jejuni. Late stages of infection lead to peptic ulcer and gastric carcinoma. C. jejuni infects people within different stages of their life, especially childhood, causing severe diarrhea; it infects around two-thirds of the world population. Due to bacterial resistance against standard antibiotic, a new strategy is needed to impede Campylobacter infections. Plants provide highly varied structures with antimicrobial use which are unlikely to be synthesized in laboratories. A special feature of higher plants is their ability to produce a great number of organic chemicals of high structural diversity, the so-called secondary metabolites. Twenty plants were screened to detect their antibacterial activities. Screening results showed that Rheum officinalis was the most efficient against C. jejuni. Fractionation pattern was obtained by column chromatography, while the purity test was done by thin-layer chromatography (TLC). The chemical composition of bioactive compound was characterized using GC-MS, nuclear magnetic resonance, and infrared analysis. Minimal inhibitory concentration (MIC) of the purified compound was 31.25 µg/ml. Cytotoxicity assay on Vero cells was evaluated to be 497 µg/ml. Furthermore, the purified bioactive compound activated human lymphocytes in vitro. The data presented here show that Rheum officinalis could potentially be used in modern applications aimed at the treatment or prevention of foodborne diseases.