The study investigated silver nanoparticles (AgNPs) synthesized extracellularly using an actinomycete isolated from sediment of the Suez Gulf, Red Sea, Egypt. Screening for biosynthesis of AgNPs revealed that among the forty one actinomycetes tested, only two exhibited the ability to synthesize AgNPs with antibacterial activity. The most potent isolate was selected and identified as Streptomyces rochei MHM13 (accession number KR108310) on the basis of morphological and physiological properties, together with 16S rRNA sequence. The biosynthesized AgNPs significantly inhibited the growth of medically important pathogenic bacteria (Vibrio fluvialis, Pseudomonas aeruginosa, Salmonella typhimurium, Vibrio damsela, Escherichia coli, Bacillus subtilis, Staphylococcus aureus, Bacillus cereus). The biosynthesized AgNPs were achieved by addition of silver nitrate (1mM) to the culture supernatant and monitored by colour change after incubation then characterized by UV–Visible spectrophotometer, X-ray, Fourier transform-infrared spectroscopy and scanning electron microscopy. The obtained AgNPs are spherical in shape with a particle size of 22–85nm. Plackett–Burman design was employed for optimization of the culture conditions for the production of AgNPs by S. rochei. Synergetic effect of AgNPs with six different antibiotics was evaluated. The microbiologically synthesized silver nanoparticles acted as an anti-biofouling agent. Moreover, silver nanoparticles exhibited a significant degree of anticancer activity against five different tumour cell lines

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 ( ) 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 ( ) 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.

A total of 17 actinomycetes were isolated and screened against five bacterial pathogens. Forty-one per cent of the isolates were active against the tested pathogens. The most potent isolate was identified as Streptomyces parvus by using a 16S rRNA sequence analysis. S. parvus produced active compound(s) against a number of Gram negative and Gram positive bacteria. The obtained inhibition zones were 14, 19, 20 and 20 mm against Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Aeromonas hydrophila, respectively. Moreover, the anticancer activity of S. parvus was tested against four different cell lines: human liver cancer cell line, mouse lymphoma cell line, breast cancer cell line and human colon cancer cell line. The inhibition activities were 53%, 56%, 57% and 42%, respectively. To achieve a maximum production of the bioactive compound, Plackett–Burman design was applied. The productivity increased up to 1.3-fold, when S. parvus was grown in optimized medium composed of: 10 g L⁻¹ starch, 1.5 g L⁻¹ KNO₃, 0.75 g L⁻¹ K₂HPO₄, 0.75 g L⁻¹ MgSO₄∙7H₂O, 0.015 g L⁻¹ FeSO₄, 2 mL (10³ colony-forming units mL⁻¹) inoculum size with pH 8 for 7 d of incubation. The main constitutes of S. parvus crude extract were determined by gas–liquid chromatography mass spectrometry. They were found to be ethane, 1,1-diethoxy; di-n-octyl phthalate; ethanol, 2,2-diethoxy; 9,12-octadecadienoic acid; methyl ester (E,E) and benzoic acid.

The implementation of actinomycetes for the biosynthesis of metal nanoparticles as a nature-friendly, safe and hopeful way is welcome due to its non-toxicity and naturalness. Out of nine actinomycetes isolates was isolated from sediment of the Suez Gulf, Egypt, only one isolate (M8) showed ability for biosynthesis of gold nanoparticles using extracellular supernatant. Isolate (M8) was selected and identified as Streptomyces griseus on the basis of cultural, morphological, and physiological properties, additionally 16S rRNA sequence. The gold nanoparticleswere confirmed using by Visible UV spectrophotometer, Fourier Transform Infrared (FTIR) Spectroscopy and Transmission Electron Microscopy (TEM). Au-Nps ranged from 19 to 28 nm in size and hexagonal in shape. Au-NPs synthesized by Streptomyces griseus isolate (M8) showed displayed a significant antimicrobial activity against gram positive bacteria Enterococcus faecalis 29212 (10 mm), gram negative bacteria Escherichia coli 19404, Pseudomonas aeruginosa 9027, Salmonella typhimurium 14028, Vibriofluvialis, and Vibrio damsel (10, 20, 28, 25 and 18 mm respectively), and yeast Candidaalbicans (18 mm) in well diffusion method. Moreover, gold nanoparticles exhibited a significant degree of anticancer activity against two different cancer cell lines Colon carcinoma cells (HCT-116) using 61.9 ug/well and breast carcinoma cells (MCF-7) using 46.6 ug/well.

Amylase producing actinobacteria were isolated and characterized from terrestrial environment. There are a limited number of reports investigating the marine environment; hence, in the present study, four marine enzymes were tested for their amylase production ability. On starch agar plates, the Streptomyces rochei strain showed a higher hydrolytic zone (24 mm) than the other isolates. Growth under optimized culture conditions using Plackett‐Burman’s experimental design led to a 1.7, 9.8, 7.7, and 3.12‐fold increase for the isolates S. griseorubens, S. rochei, S. parvus, and Streptomyces sp., respectively, in the specific activity measurement. When applying the Box‐Behnken design on S. rochei using the most significant parameters (starch, K₂HPO₄, pH, and temperature), there was a 12.22‐fold increase in the specific activity measurement 7.37 U/mg. The α‐amylase was partially purified, and its molecular weight was determined using sodium dodecyl sulfate‐polyacrylamide gel electrophoresis. α‐Amylase was particularly active at pH 6 and 65°C. The purified enzyme was most active at 65°C and pH 6, thermal stability of 70°C for 40 min, and salt concentration of 1 M with Km and Vmax of 6.58 mg/ml and 21.93 μmol/ml/min, respectively. The α‐amylase was improved by adding Cu⁺², Zn⁺², and Fe⁺² (152.21%, 207.24%, and 111.89%). Increased production of α‐amylase enzyme by S. rochei KR108310 leads to production of significant industrial products.

Flowers are rich sources of bioactive antimicrobial, antioxidant, and anticancer components. This study aimed to determine the constituents of the ethanol extract of Malvaviscus arboreus red flower (ERF) by GC-MS analysis and HPLC identification of phenolic compounds and flavonoids, in addition to the ¹HNMR fingerprint. The antimicrobial, antioxidant, and cytotoxic activities of the ERF were investigated. The GC-MS analysis revealed twenty-one components, while HPLC analysis revealed the presence of phenolic and flavonoid compounds. The ERF showed antifungal and antibacterial activity. The highest antibacterial activity was found against Vibrio damsela where a time-kill assay revealed a decline in the amount of viable V. damsela. For fungi, the highest activity was observed against Aspergillus terreus. Using the SRB test on HepG2, the anti-proliferative efficacy of the ERF was evaluated. Cell cycle analysis was utilized to determine autophagic cell death. The ERF prevented the proliferation of the HepG2 cell line with an IC₅₀ of 67.182 µg/µL. The extract primarily promoted apoptosis in HepG2 cells by accumulating hypodiploid cells in the sub-G0/G1 phase, increased caspase 3/7 activity, and caused considerable autophagic cell death in apoptosis-deficient cells. Finally, the observed elevation of cancer cell death indicated that ERF had substantial anticancer potential against HepG2 cells.