Mahmoud Saleh Mahmoud Mohamed

Agricultural and agro-industrial wastes (e.g., potato peel waste) are causing severe environmental problems. The processes of pretreatment, saccharification, and fermentation are the major obstacles in bioethanol production from wastes and must be overcome by efficient novel techniques. The effect of exposing the fungi (yeast) Saccharomyces cerevisiae to laser source with the addition of graphitic carbon nitride nanosheets (g-C3N4) with different concentrations on bioethanol production was investigated through the implementation of a batch anaerobic system and using potato peel waste (PPW). Dichromate test was implemented as quantitative analysis for quantification of the bioethanol yield. The benefits of this test were the appearance of green color indicating the identification of ethanol (C2H5OH) by bare eye and the ease to calculate the bioethanol yield through UV–visible spectrophotometry. The control sample (0.0 ppm of g-C3N4) showed only a 4% yield of bioethanol; however, by adding 150 ppm to PPW medium, 22.61% of ethanol was produced. Besides, laser irradiations (blue and red) as influencing parameters were studied with and without the addition of g-C3N4 nanomaterials aiming to increase the bioethanol. It was determined that the laser irradiation can trigger the bioethanol production (in case of red: 13.13% and in case of blue: 16.14% yields, respectively) compared to the control sample (in absence of g-C3N4). However, by adding different concentrations of g-C3N4 nanomaterials from 5 to 150 ppm, the bioethanol yield was increased as follows: in case of red: 56.11% and, in case of blue: 56.77%, respectively. It was found that using fungi and exposing it to the blue laser diode source having a wavelength of 450 nm and a power of 250 mW for a duration of 30 min with the addition of 150 mg L−1 of g-C3N4 nanomaterials delivered the highest bioethanol yield from PPW. © 2021, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.

This study aimed to test and evaluate antibacterial and antifungal activities of secondary metabolites obtained from endophytic fungi isolated from the leaves of endemic plant Zygophyllum mandavillei. The fungus Cladosporium cladosporioides was the predominant isolated fungus with colonization and dominance frequencies percentage of 12.50 and 39.32 respectively. C. cladosporioides extract was found to have the best antimicrobial activity causing a zone of inhibition ranging from 20.7 to 25.7 mm against all tested bacterial and fungal phytopathogens. Gas Chromatography/Mass Spectrometry (GC/MS) analysis of the extract successfully identified six major compounds: Cladosporin, Isocladosporin, 5′- hydroxyasperentin, Di (2-ethylhexyl) phthalate, 1-acetyl-17-methoxyaspidospermidin-20-ol, and 3-phenylpropionic acid. Enhanced antimicrobial activity was recorded for 3-phenylpropionic acid with MIC value ranging from 3.90 to 15.62 μg/ml followed by 5′- hydroxyasperentin with MIC ranging from 7.81 to 62.5 μg/ml. The most effective compound, 3-phenylpropionic acid, was further characterized by Fourier transform infrared spectroscopy (FT-IR) in addition to nuclear magnetic resonance (NMR) and mass spectroscopy to elucidate the chemical structure. The cytotoxicity of 3-phenylpropionic acid revealed a lower level of cytotoxicity at the concentration range 0.01–10 µg/ml as indicated by the cell viability percentage which is ranging from 75.47–94.14%. These results suggested that 3-phenylpropionic acid may serve as a potential alternative approach for the management of plant phytopathogens.

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