Microbial L-asparaginase (ASNase) is an important anticancer agent that is used extensively worldwide. In this study, 40 bacterial isolates were obtained from the Red Sea of Saudi Arabia and screened for ASNase production using a qualitative rapid plate assay, 28 of which were producing large L-asparagine hydrolysis zones. The ASNase production of the immobilized bacterial cells was more favorable than that of freely suspended cells. A promising isolate, KKU-KH14, was identified by 16S rRNA gene sequencing as Bacillus licheniformis. Maximal ASNase production was achieved using an incubation period of 72 h, with an optimum of pH 6.5, an incubation temperature of 37 °C, an agitation rate 250 rpm, and with glucose and (NH₄)₂SO₄ used as the carbon and nitrogen sources, respectively. The glutaminase activity was not detected in the ASNase preparations. The purified ASNase showed a final specific activity of 36.08 U/mg, and the molecular weight was found to be 37 kDa by SDS-PAGE analysis. The maximum activity and stability of the purified enzyme occurred at pH values of 7.5 and 8.5, respectively, with maximum activity at 37 °C and complete thermal stability at 70 °C for 1 h. The K_m and V_max values of the purified enzyme were 0.049995 M and of 45.45 μmol/ml/min, respectively. The anticancer activity of the purified ASNase showed significant toxic activity toward HepG-2 cells (IC₅₀ 11.66 µg/mL), which was greater than that observed against MCF-7 (IC₅₀ 14.55 µg/mL) and HCT-116 cells (IC₅₀ 17.02 µg/mL). The results demonstrated that the Red Sea is a promising biological reservoir, as shown by the isolation of B. licheniformis, which produces a glutaminase free ASNase and may be a potential candidate for further pharmaceutical use as an anticancer drug.

The bioconversion of cellulosic wastes into high-value bio-products by saccharification and fermentation processes is an important step that can reduce the environmental pollution caused by agricultural wastes. In this study, enzymatic saccharification of treated and untreated date palm cellulosic wastes by the cellulases from Geobacillus stearothermophilus was optimized. The alkaline pre-treatment of the date palm wastes was found to be effective in increasing the saccharification percentage. The maximum rate of saccharification was found at a substrate concentration of 4% and enzyme concentration of 30 FPU/g of substrate. The optimum pH and temperature for the bioconversions were 5.0 and 50°C, respectively, after 24h of incubation, with a yield of 31.56mg/mL of glucose at a saccharification degree of 71.03%. The saccharification was increased to 94.88% by removal of the hydrolysate after 24h by using a two-step hydrolysis. Significant lactic acid production (27.8mg/mL) was obtained by separate saccharification and fermentation after 72h of incubation. The results indicate that production of fermentable sugar and lactic acid is feasible and may reduce environmental pollution by using date palm wastes as a cheap substrate.

The synthesis of bioplastic from marine microbes has a great attendance in the realm of biotechnological applications for sustainable eco-management. This study aims to isolate novel strains of poly-β-hydroxybutyrate (PHB)-producing bacteria from the mangrove rhizosphere, Red Sea, Saudi Arabia, and to characterize the extracted polymer. The efficient marine bacterial isolates were identified by the phylogenetic analysis of the 16S rRNA genes as Tamlana crocina, Bacillus aquimaris, Erythrobacter aquimaris, and Halomonas halophila. The optimization of PHB accumulation by E. aquimaris was achieved at 120 h, pH 8.0, 35 °C, and 2% NaCl, using glucose and peptone as the best carbon and nitrogen sources at a C:N ratio of 9.2:1. The characterization of the extracted biopolymer by Fourier-transform infrared spectroscopy (FTIR), Nuclear magnetic resonance (NMR), and Gas chromatography-mass spectrometry (GC-MS) proves the presence of hydroxyl, methyl, methylene, methine, and ester carbonyl groups, as well as derivative products of butanoic acid, that confirmed the structure of the polymer as PHB. This is the first report on E. aquimaris as a PHB producer, which promoted the hypothesis that marine rhizospheric bacteria were a new area of research for the production of biopolymers of commercial value.

Wheat leaf rust is one of the world’s most widespread rusts. The progress of the disease was monitored using two treatments: chitosan nanoparticles and salicylic acid (SA), as well as three application methods; spraying before or after the inoculation by 24 h, and spraying both before and after the inoculation by 24 h. Urediniospore germination was significantly different between the two treatments. Wheat plants tested for latent and incubation periods, pustule size and receptivity and infection type showed significantly reduced leaf rust when compared to untreated plants. Pucciniatriticina urediniospores showed abnormalities, collapse, lysis, and shrinkage as a result of chitosan nanoparticles treatment. The enzymes, peroxidase and catalase, were increased in the activities. In both treatments, superoxide (O₂⁻) and hydrogen peroxide (H₂O₂), were apparent as purple and brown discolorations. Chitosan nanoparticles and SA treatments resulted in much more discoloration and quantitative measurements than untreated plants. In anatomical examinations, chitosan nanoparticles enhanced thickness of blade (µ), thickness of mesophyll tissue, thickness of the lower and upper epidermis and bundle length and width in the midrib compared to the control. In the control treatment’s top epidermis, several sori and a large number of urediniospores were found. Most anatomical characters of flag leaves in control plants were reduced by biotic stress with P. triticina. Transcription levels of PR1-PR5 and PR10 genes were activated in chitosan nanoparticles treated plants at 0, 1 and 2 days after inoculation. In light of the data, we suggest that the prospective use of chitosan nanoparticles might be an eco-friendly strategy to improve growth and control of leaf rust disease.

This study aimed to synthesize silver nanoparticles (AgNPs) by pomegranate and orange peel extracts using a low concentration of AgNO₃ solution to controlearly blight of tomato caused by Alternaria solani. The pathogen was isolated from infected tomato plants growing in different areas of Saudi Arabia. The isolates of this pathogen were morphologically and molecularly identified. Extracts from peels of pomegranate and orange fruits effectively developed a simple, quick, eco-friendly and economical method through a synthesis of AgNPs as antifungal agents against A. solani. Phenolic content in the pomegranate peel extract was greater than orange peel extract. Phenolic compounds showed a variation of both peel extracts as identified and quantified by High-Performance Liquid Chromatography. The phenolic composition displayed variability as the pomegranate peel extract exhibited an exorbitant amount of Quercitrin (23.62 mg/g DW), while orange peel extract recorded a high amount of Chlorogenic acid (5.92 mg/g DW). Biosynthesized AgNPs were characterized using UV- visible spectroscopy which recorded an average wavelength of 437 nm and 450 nm for pomegranate and orange peels, respectively. Fourier-transform infrared spectroscopy exhibited 32x73.24, 2223.71, 2047.29 and 1972.46 cm⁻¹, and 3260.70, 1634.62, 1376.62 and 1243.76 cm⁻¹ for pomegranate and orange peels, respectively. Transmission electron microscopy showed spherical shape of nanoparticles. Zetasizer analysis presented negative charge values; −16.9 and −19.5 mV with average particle sizes 8 and 14 nm fin case of pomegranate and orange peels, respectively. In vitro, antifungal assay was done to estimate the possibility of biosynthesized AgNPs and crude extracts of fruit peels to reduce the mycelial growth of A. solani. AgNPs displayed more fungal mycelial inhibition than crude extracts of two peels and AgNO₃. We recommend the use of AgNPs synthesized from fruit peels for controlling fungal plant pathogens and may be applied broadly and safely in place by using the chemical fungicides, which display high toxicity for humans.

Polyhydroxybutyrates (PHBs) are macromolecules synthesized by bacteria. Because of their fast degradability under natural environmental conditions, PHBs were selected as alternatives for the production of biodegradable plastics. Sixteen PHB-accumulating strains were selected and compared for their ability to accumulate PHB granules inside their cells. Isolate AS-02 was isolated from cattle manure and identified as Bacillus wiedmannii AS-02 OK576278 by means of 16S rRNA analysis. It was found to be the best producer. The optimum pH, temperature, and incubation period for the best PHB production by the isolate were 7, 35 °C, and 72 h respectively. PHB production was the best with peptone and glucose as nitrogen and carbon sources at a C/N ratio of (2:1). The strain was able to accumulate 423, 390, 249, 158, and 144 mg/L PHB when pretreated orange, mango, banana, onion peels, and rice straw were used as carbon sources, respectively. The extracted polymer was characterized by Fourier transform infrared (FTIR), nuclear magnetic resonance (NMR), and GC-MS spectroscopy, which confirmed the structure of the polymer as PHB. The isolate B. wiedmannii AS-02 OK576278 can be considered an excellent candidate for industrial production of PHB from agricultural wastes.