Biosynthesis methods employing microorganisms have emerged as an eco-friendly, clean, and viable alternative to chemical and physical processes. The present study reports the synthesis of copper oxide nanoparticles (CuONPs) using cell-free culture supernatant of marine Streptomyces sp. MHM38. For the optimized production of CuONPs, the influence of some parameters, such as the concentration of copper sulfate (CuSO4), reaction time, filtrate to substrate ratio, and pH, was studied. 5 mM of CuSO4 was optimal for nanoparticle (NP) production. Well-defined CuONP formation occurred after 60 min of incubation when an equal volume of filtrate (cell-free supernatant) to substrate (CuSO4 solution) was added. UV-visible spectroscopy analysis of CuONPs exhibited a peak at 550 nm, which corresponds to the surface plasmon resonance of CuONPs. Most of the particles were spherical and were 1.72–13.49 nm when measured using a transmission electron microscope. The antimicrobial activity of CuONPs was determined using a well diffusion method against Enterococcus faecalis ATCC 29212, Salmonella typhimurium ATCC 14028, Pseudomonas aeruginosa ATCC 9027, Escherichia coli ATCC 8939, fungi (Rhizoctonia solani, Fusarium solani, and Aspergillus niger), and yeast (Candida albicans ATCC 10237). The highest antimicrobial activities were recorded against Candida albicans ATCC 10237, whereas Salmonella typhimurium ATCC 14028 and Escherichia coli ATCC 8939 showed the less activity. The biochemical findings of the CuONP groups were significant ( p < 0.05 ) with diminished levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), lactate dehydrogenase (LDH), total and direct bilirubin, urea, and creatinine compared with the paracetamol group. Nonenzymatic and enzymatic antioxidants of the CuONP groups were significantly elevated ( p < 0.05 ) in SOD and GSH levels, and exceptionally low nitric oxide (NO) and malondialdehyde (MAD) levels were found for the paracetamol group. The histopathological examination of the CuONP groups assured the impact of improving CuONPs against paracetamol-induced liver damage.

Carotenoids, as phytonutrient pigments, are signified by their unique beneficial features that serve human health and the surrounding ecosystem. Haloalkaliphiles from soda lakes produce different natural bioactive molecules; however, their ability to produce carotenoids has been limited. Therefore, this study focused on the screening and isolation of carotenoid-producing haloalkaliphilic microbes. Out of 10 isolates, a powerful carotigenic bacterium was isolated, characterized phenotypically and identified on the molecular level as Virgibacillus halodenitrificans. By employing statistical approaches like Plackett–Burman design and central composite design, the influence of significant nutritional variables on carotenoids production was screened and optimized. Predictive modeling manifested that carotenoid yield was 36.42 mg/mL, a 2.12-fold enhancement compared to the basal conditions through inoculating 1.8% of bacterial biomass on optimized medium containing yeast extract (2 g/mL), peptone (10 g/mL) and NaCl (233.6 g/mL). The carotenoids content was confirmed by UV-Vis spectrum which detected a characteristic unique peak with left and right shoulders at 461 nm, 490 and 522 nm. However, FTIR and Raman spectroscopy showed the presence of several functional groups. Meanwhile, LC–MS confirmed that the examined carotenoids were composed of β-carotene, lutein and β-Apo-8′-carotenal mixture. As a bioactive agent, the carotenoids of V. halodenitrificans DASH showed characteristic antagonistic potency against a wide spectrum of Gram-positive and Gram-negative pathogens. Interestingly, a potent antifungal capacity was observed against Candida albicans, reflecting promising mycocidal efficacy against COVID-19 white fungal post-infections. Furthermore, carotenoids (20 μg/mL) inhibited the biofilm formation of P. aeruginosa and S. aureus by 54.01 ± 3.97% and 80.082 ± 0.895%, respectively. Our results proposed that haloalkaliphiles of Wadi El-Natrun lakes are promising sources of carotenoids that exhibited efficiency as safe, biocompatible and natural bioactive agents for environmental, medical and industrial applications.

Abstract The authors have withdrawn this preprint due to author disagreement.

Abstract Biosynthesis methods, employing microorganisms, have emerged as an eco-friendly, clean and viable alternative to chemical and physical methods. The present study reports the biosynthesis of copper oxide nanoparticles (CuONPs) using cell-free culture supernatant of marine Streptomyces sp. MHM38. For the optimized production of copper oxide nanoparticles, the influence of some parameters such as concentration of copper sulphate, reaction time, filtrate to substrate ratio and pH were studied. 5mM CuSO4 was optimal for NP production. Well-defined CuONP formation occurred after 60 min incubation when equal volume of filtrate (cell-free supernatant) to substrate (CuSO4 solution) was added. NPs remained stable in aqueous solution with increasing time at pH 8. CuONPs were characterized by UV-vis spectroscopy, X-ray diffraction (XRD) and finally the nature of the nanoparticles was identified by elemental analysis (EDX). Uv-vis spectroscopy of CuONPs exhibited peak at 550 nm which corresponds to the Surface Plasmon Resonance of CuONPs. Most of the particles are spherical in shape and size ranges from 1.06 – 6.5 nm analyzed using Transmission Electron Microscope (TEM). Antimicrobial activity of CuONPs was performed by well diffusion method against Enterococcus faecalis ATCC 29212, Salmonella typhimurium ATCC 14028, Pseudomonas aeruginosa ATCC 9027, Escherichia coli ATCC 8939), fungi (Rhizoctonia solani, Fusarium solani, Aspergillus niger) and yeast (Candida albicans ATCC 10237) .The highest antimicrobial activities recorded were against Candida albicans ATCC 10237, were as Salmonella typhimurium ATCC 14028 and Escherichia coli ATCC 8939 showed the lesser activity. The preventive efficacy of CuONPs was evaluated against the oxidative stress induced by paracetamol (PAC) in albino rats. The biochemical findings of CuONPs groups appeared a significant (p˂0.05) diminish in the levels of ALT, AST, ALP, LDH, total and direct bilirubin, Urea, and Creatinine as compared to paracetamol group. Non-enzymatic and enzymatic antioxidants of CuONPs groups were significantly elevated (p˂0.05) in SOD and GSH levels and significantly low NO and MAD levels compared to the paracetamol group. Also, the histopathological examination of the CuONPs groups assured that the impact of improving CuONPs against paracetamol-induced liver damage.

Background: Because of the ability of their bioactive metabolites production, many researchers were attracted to investigate and isolating marine actinomycetes from unique location with a unique environment. Information on antimicrobial activity and antifouling agents by Streptomyces sp. from the Ras Garib area, Gulf of Suez, Egypt is limited. One of the metabolites produced by the actinomycetes was biosurfactant. This paper describes the possibility of marine actinomycetes isolates for the production of biosurfactants, In addition to the possibility of using it as antimicrobial and antifouling agents.Results: Marine actinobacterial isolates RG3 and RG8 had emulsification indexes of 76 and 68%, respectively. The two marine actinobacterial isolates were identified using 16srDNA as Streptomyces althioticus RG3 and Streptomyces californicus RG8, and submitted in the database of genetic information with accession number MW661230 and MW661234, respectively. Biosurfactants were stable at 10% NaCl, in case of Streptomyces althioticus RG3 and stable at 10%–15% NaCl in the case of Streptomyces californicus RG8. A temperature of 35℃ was suitable for the stability of biosurfactants produced by both strains. Both strains produced the most biosurfactant when exposed to alkaline conditions. We characterized the biosurfactants produced by both strains including features such as the chemical composition of the biosurfactants and FTIR analysis. The antimicrobial activity of biosurfactants extract evaluated using a well diffusion method against Vibrio alginolyticus MK170250, Escherichia coli ATCC 8739, Pseudomonas aeruginosa ATCC 4027, and Staphylococcus aureus ATTC 25923. Streptomyces althioticus RG3 biosurfactants have been shown to have better antimicrobial activity than Streptomyces californicus RG8, indicating that they may be used in pharmaceutical industries and in the manufacture of antifouling products.Conclusions: Streptomyces althioticus RG3 and Streptomyces californicus RG8, isolated from Ras Garib, Gulf of Suez, Egypt, were able to develop very stable biosurfactants under stress conditions, which could be useful in a variety of industries such as pharmaceuticals and antifouling manufacturing.