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Abstract Groundwater is an excellent alternative to freshwater for drinking, irrigation, and developing arid regions. Agricultural, commercial, industrial, residential, and municipal activities may affect groundwater quantity and quality. Therefore, we aimed to use advanced methods/techniques to monitor the piezometric levels and collect groundwater samples to test their physicochemical and biological characteristics. Our results using software programs showed two main types of groundwater: the most prevalent was the Na–Cl type, which accounts for 94% of the groundwater samples, whereas the Mg–Cl type was found in 6% of samples only. In general, the hydraulic gradient values, ranging from medium to low, could be attributed to the slow movement of groundwater. Salinity distribution in groundwater maps varied between 238 and 1350 mg L−1. Although lower salinity values were observed in northwestern wells, higher values were recorded in southern ones. The collected seventeen water samples exhibited brackish characteristics and were subjected to microbial growth monitoring. Sample WD12 had the lowest total bacterial count (TBC) of 4.8 ± 0.9 colony forming unit (CFU mg L−1), while WD14 had the highest TBC (7.5 ± 0.5 CFU mg L−1). None of the tested water samples, however, contained pathogenic microorganisms. In conclusion, the current simulation models for groundwater drawdown of the Quaternary aquifer system predict a considerable drawdown of water levels over the next 10, 20, and 30 years with the continuous development of the region.

This review delves into the mesmerizing technology of nano-agrochemicals, specifically pesticides and herbicides, and their potential to aid in the achievement of UN SDG 17, which aims to reduce hunger and poverty globally. The global market for conventional pesticides and herbicides is expected to reach USD 82.9 billion by 2027, growing 2.7% annually, with North America, Europe, and the Asia–Pacific region being the biggest markets. However, the extensive use of chemical pesticides has proven adverse effects on human health as well as the ecosystem. Therefore, the efficacy, mechanisms, and environmental impacts of conventional pesticides require sustainable alternatives for effective pest management. Undoubtedly, nano-agrochemicals have the potential to completely transform agriculture by increasing crop yields with reduced environmental contamination. The present review discusses the effectiveness and environmental impact of nanopesticides as promising strategies for sustainable agriculture. It provides a concise overview of green nano-agrochemical synthesis and agricultural applications, and the efficacy of nano-agrochemicals against pests including insects and weeds. Nano-agrochemical pesticides are investigated due to their unique size and exceptional performance advantages over conventional ones. Here, we have focused on the environmental risks and current state of nano-agrochemicals, emphasizing the need for further investigations. The review also draws the attention of agriculturists and stakeholders to the current trends of nanomaterial use in agriculture especially for reducing plant diseases and pests. A discussion of the pros and cons of nano-agrochemicals is paramount for their application in sustainable agriculture.

Abiotic stresses and climate changes cause severe loss of yield and quality of crops and reduce the production area worldwide. Flooding stress curtails soybean growth, yield, and quality and ultimately threatens the global food supply chain. Flooding tolerance is a multigenic trait. Tremendous research in molecular breeding explored the potential genomic regions governing flood tolerance in soybean. The most robust way to develop flooding tolerance in soybean is by using molecular methods, including quantitative trait loci (QTL) mapping, identification of transcriptomes, transcription factor analysis, CRISPR/Cas9, and to some extent, genome-wide association studies (GWAS), and multi-omics techniques. These powerful molecular tools have deepened our knowledge about the molecular mechanism of flooding stress tolerance. Besides all this, using conventional breeding methods (hybridization, introduction, and backcrossing) and other agronomic practices is also helpful in combating the rising flooding threats to the soybean crop. The current review aims to summarize recent advancements in breeding flood-tolerant soybean, mainly by using molecular and conventional tools and their prospects. This updated picture will be a treasure trove for future researchers to comprehend the foundation of flooding tolerance in soybean and cover the given research gaps to develop tolerant soybean cultivars able to sustain growth under extreme climatic changes.

Heavy metals (HMs) toxicity is serious abiotic stress that is significantly reducing crop productivity and posing a serious threat to human health, soil and environmental quality. Therefore, it is urgently needed to find appropriate measures to mitigate the adverse impacts of HMs on soil, plants, humans and the environment. Biochar (BC) has emerged as an excellent soil amendment to minimize the adverse impacts of HMs and to improve soil fertility and environmental quality. Biochar application decreases HMs uptake and their translocation to plant parts by forming complexes and precipitation. Biochar also has improved soil pH, soil fertility and soil cation exchange capacity (CEC) and it also increases adsorption of HMs thus reduces their mobility and subsequent availability to plants. BC application also maintains membrane stability and improves uptake of nutrients, osmolytes accumulation, antioxidant activities, and gene expression, therefore, improves the plant performance under HMs stress. Biochar application also improves the photosynthetic performance by increasing the synthesis of photosynthetic pigments, stomata conductance and increasing the water uptake by plants. Besides this, BC also scavenges ROS by increasing the antioxidant activities, gene expression, and accumulation of proline in HMs contaminated soils. This review highlights the role of BC to mitigate the HMs toxicity in plants. We have discussed the role of BC in the modification of soil properties to induce tolerance against HMs toxicity. Moreover, we have discussed various mechanisms mediated by BC at the plant level to induce tolerance against HMs. Additionally, we also identified research gaps that must be fulfilled in future research studies.

Leaf rust caused by pathogen Puccinia has more potential to threaten the yield of wheat up to 10% as compared to the other two types of rust stem and yellow rust. The severity of the disease depends upon the developmental stage of the plant and susceptibility of the plant. The variability of wheat growing conditions favorable climatic patterns, and genomic polyploidy nature it becomes the most financial and nutritional crop. The Food and Agriculture organization (FAO) report on annual global supply and demand for wheat is ample for wheat production. The population development rate is increasing, which is estimated at 9 billion by 2025. To meet the demand for staple food the production of wheat is an important interest for its significance turn out Puccinia triticina causing brown rust disease in our country causes a huge amount of yield losses up to 50% (in severe cases) every year in all wheat-growing areas. Breeding of resistant varieties is the best and economic way to control this problem. Moreover, developing varieties is a continuous process because it can break the resistance of any variety by mutation. After screening 45 commercial varieties in 2019,2020 and 2021, only one variety was symptomless. After comparing varieties, showing resistance against urediniospores in the last three years only three varieties were similar showing resistant response against leaf rust. Moreover, after comparing environmental conditions favoring disease development in last three years it was observed that low temperature from 18 to 25 degree centigrade, humidity above 80% and high rainfall increases the incidence of disease development.

Abstract This study aimed to evaluate the efficiency of Enterobacter cloacae PS14 and Trichoderma asperellum T34 in the control of potato wilt, caused by Ralstonia solanacearum (Smith), under greenhouse and field conditions. In vitro, the endophyte E. cloacae PS14 caused the highest reduction of the pathogen growth among 7 screened bacteria. It produced an inhibition zone as 16.9 mm compared to a specific antibiotic (20.0 mm). E. cloacae PS14 was selected as an effective antagonistic bacterium to be compared to T. asperellum strain T34 for reduction of the disease as well as increasing the crop yield of potato plants. Both E. cloacae and T. asperellum reduced the disease severity up to 10.7–26.5%, respectively, under greenhouse and up to 26.6–36.6%, respectively, under field conditions. The results approved that both E. cloacae and T. asperellum increased the yield of the crop by 20.44–40.96%, respectively. Their mode of action was indicated by suppression of the pathogen as well as induction of plant systemic resistance. The induction of systemic resistance was confirmed by increasing the total phenol and salicylic acid contents as well as increasing the activities of peroxidase, lipoxygenase, and polyphenol oxidase in potato plants than the healthy or only infected plants. Production of siderophore, indole-3-acetic acid (0.577–0.884 μM), hydrogen cyanide (2.34–3.61 μg/ml), and salicylic acid (0.436–1.488 μg/ml) was confirmed by E. cloacae PS14 and T. asperellum T34, respectively, in vitro. The study recommends the new strain E. cloacae PS14, as new endophytic effective bacteria, in the control of R. solanacearum causing the potato wilt disease.

Citric acid is a commercially valuable organic acid widely used in food, pharmaceutical, and beverage industries. In this study, 260 yeast strains were isolated from soil, bread, juices, and fruits wastes and preliminarily screened using bromocresol green agar plates for their ability to produce organic acids. Overall, 251 yeast isolates showed positive results, with yellow halos surrounding the colonies. Citric acid production by 20 promising isolates was evaluated using both free and immobilized cell techniques. Results showed that citric acid production by immobilized cells (30–40 g/L) was greater than that of freely suspended cells (8–19 g/L). Of the 20 isolates, two (KKU-L42 and KKU-L53) were selected for further analysis based on their citric acid production levels. Immobilized KKU-L42 cells had a higher citric acid production rate (62.5%), while immobilized KKU-L53 cells showed an ∼52.2% increase in citric acid production compared with free cells. The two isolates were accurately identified by amplification and sequence analysis of the 26S rRNA gene D1/D2 domain, with GenBank-based sequence comparison confirming that isolates KKU-L42 and KKU-L53 were Candida tropicalis and Pichia kluyveri, respectively. Several factors, including fermentation period, pH, temperature, and carbon and nitrogen source, were optimized for enhanced production of citric acid by both isolates. Maximum production was achieved at fermentation period of 5 days at pH 5.0 with glucose as a carbon source by both isolates. The optimum incubation temperature for citric acid production by C. tropicalis was 32 °C, with NH4Cl the best nitrogen source, while maximum citric acid by P. kluyveri was observed at 27 °C with (NH4)2 SO4 as the nitrogen source. Citric acid production was maintained for about four repeated batches over a period of 20 days. Our results suggest that apple and banana wastes are potential sources of novel yeast strains; C. tropicalis and P. kluyveri which could be used for commercial citric acid production.

Mango hopper (Amritodus atkinsoni Lethierry) causes devastations in the early vegetative stage of the mango crop. The classical management of mango hopper is with systemic insecticides but their overuse has caused environmental pollution. Here, we have evaluated the entomopathogenic role of Clonostachys rosea through bioassay and optimized media for its large-scale culturing. The current study reveals the potentiality of C. rosea as entomopathogenic on A. atkinsoni. Initially, morphological and molecular characterization was used to validate local isolates’ identity as C. rosea. Further, we have evaluated the entomopathogenic role of C. rosea through a bioassay, where the highest mean mortality in A. atkinsoni was observed at a treatment concentration of 3 × 108 conidia/mL, with 96.67% mortality after 168 h of infection. This work also provides insight into the laboratory-based media standardization for C. rosea, resulting in oatmeal agar media and broth as the most suitable artificial media, and 20 °C temperature for its mass culture. Thus, C. rosea is a novo-entomopathogenic fungus on A. atkinsoni and has a high potency to be included in the management of mango hopper pests.

Chia (Salvia hispanica L.) is a specialty crop capable of providing healthy food and metabolites. The goal of our study was to explore the possibility of expanding seed yield, oil production, and metabolites of chia in response to amino acid, barthenosteriode, and algae extract treatments used as bio-stimulants. The experiment was conducted in the field in a randomized complete block design with three repeats. The treatments were (1) control (spray only with water), (2) amino acids with nutrients (2 mL/L vs. 4 mL/L), (3) brassinolide (5 mL/L vs. 10 mL/L), and algae extract (2 mL/L vs. 4 mL/L). The growth and yield measurements of chia, such as chlorophyll, carotenoids, amino acids, indoles, phenols, macro- and micronutrients, carbohydrates, total oil, and fatty acids were analyzed. The chia plants sprayed with growth stimulant materials showed increases in most studied characteristics, particularly algae extract at 4 mL/L, followed by algae extract at 2 mL/L during the first and second seasons. Meanwhile, amino acids at 4 mL/L led to the third-highest increases in most cases. Conversely, all bio-stimulant treatments decreased total phenols in leaves (mg/100 g f.w.), especially seaweed at 4 mL/L, compared to high levels in the control during both seasons. Control plants showed the lowest levels of the measurements mentioned previously when scored by barthenosteriode at 5 mL/L during the first and second seasons. GLC for fixed oil in chia showed the recognition of four biocomponents. i.e., oleic, linoleic, palmitic, and α-α linolenic acids. The main biocomponent was α-α linolenic acid and reach (49.7 to 57.9%). The application of seaweed at 4 mL/L could be exploited to improve growth, seed crop, fixed oil production, chemicals and bio-constituents, especially the fixed oil composition of chia (Salvia hispanica L.) plant.

Abstract Rhizobacteria have been reported as bioagents of bacterial diseases and plant growth promoters. The present in vitro study and greenhouse experiment aimed to evaluate the efficiency of Bacillus subtilis, B. amyloliquefaciens, Pseudomonas fluorescens, and P. aeruginosa for the control of bacterial wilt caused by Clavibacter michiganensis subsp. michiganensis and promoting the growth of tomato plants. Effect of formulated and cell suspensions on disease reduction and the pathogen colonization frequency in plants were assessed. The tested bacterial species were able to inhibit the growth of the causal pathogen in vitro. Under greenhouse conditions, the highest reduction in disease severity was detected in tomato plants treated with formulated B. amyloliquefaciens (74.4%), followed by P. aeruginosa (66.7%), while the lowest reduction occurred in tomato seedlings treated with cell suspensions of P. fluorescens (40%) and B. subtilis (53.3%). The four bacterial species produced siderophores, hydrogen cyanide and indole acetic acid in different concentrations. The study confirmed that the use of the four bacterial species as suspensions or formulations could be applied as future eco-friendly alternatives to the synthetic fungicides for controlling the bacterial wilt of tomato caused by C. michiganensis subsp. michiganensis.

The development of new, safe, and effective methods of managing fungal pathogens is required. This study was conducted to perform an initial in vitro assessment of the antifungal activity of water-based plant extracts from three plants which are invasive in Egypt: Prosopis juliflora, Ipomoea carnea, and Leucaena leucocephala. These extracts were tested against three pathogenic fungi species that cause high crop losses in Egypt: Fusarium solani, Alternaria solani, and Colletotrichum circinans. Three extract concentrations, 10%, 20%, and 30%, were tested using a completely randomized design, with three replicates per treatment. Antifungal activity was determined based on the effects of plant extracts on fungal radial growth inhibition, average daily growth of fungi, spore formation, spore germination, and total biomass. Inhibition of the growth of fungal strains increased with increasing plant extract concentration, with the highest inhibitory rate at the 30% extract concentration. In addition, spore density, spore germination, and total biomass decreased significantly with increasing extract concentration. The three fungal pathogens differed in their inhibition and their response to these plant extracts. Prosopis juliflora had the highest inhibitory effect on the three fungal pathogens, compared to the extracts from the other two invasive plants. The results of this feasibility study indicate that P. juliflora extracts have high antifungal activity and follow-up in vivo assays should be conducted to determine their efficacy in the safe and sustainable management of these and other fungal pathogens.

Wheat is the most extensively cultivated crop and occupies a central place in human nutrition providing 20% of the daily food calories. This study was conducted to find both T and ψ effects on wheat germination and the cardinal Ts value; a lab experiment was accomplished using HTT models. Cultivars were germinated under different accelerated aging periods (AAP, 0, 24, 48, and 72 h) at each of the following constant Ts of 15, 20, 25, 30, and 35 °C at each of the ψs of 0, −0.05, −0.1, −0.15, and −0.2 MPa. GR, GP, and other germination parameters (GI, GRI, CVG, SVI-I, SVI-II, GE, and MGT) were significantly determined by solute potential, temperature, and reciprocal action in both cultivars (p ≤ 0.01). Depending on the confidence interval of the model co-efficiently between cultivars, there was no significant difference. Hence, the average of cardinal Ts was 15, 20, and 35 °C for the Tb, To, and Tc, respectively, in the control condition (0 MPa). Hydro-time values declined when Ts was raised to To in cultivars, then remained constant at Ts ≥ To (2.4 MPah−1 in Pirsabak 15 and 0.96 MPah−1 in Shahkar). The slope of the relationship between ψb(50) and TTsupra with temperature when Ts is raised above To and reaches 0 at Tc. In conclusion, the assessed parameter values in this study can easily be used in simulation models of wheat germination to quantitatively characterize the physiological status of wheat seed populations at different Ts and ψs.

Effective biosafe management strategies are used to decrease world crop damage produced by plant-parasitic nematodes. This study evaluated the efficiency of hydroxyapatite nanoparticles (n-HAP) and mycorrhizal fungi to control the Meloidogyne incognita infecting tomato plants. Application of n-HAP significantly increased the juveniles’ mortality (195.67%) and egg hatching inhibition percentage (80.71%) compared to the untreated control, in vitro. Mycorrhizal and/or n-HAP treatments increased the plant growth parameters (root and shoot length, dry weight, and leaf area) and reduced the negative consequence of nematode infection. This may be due to indirect mechanisms through increasing plant nutrient uptake efficiency and increasing the internal plant resistance against nematode infection. In dual-treated plants, phosphorus, nitrogen, and calcium content recorded the highest value in the nematode-infected plants. Whereas the dual inoculation significantly increased mineral contents in tomato plants compared with control, this may induce the strength of the cell wall of the epidermal layer and cortex and consequently increase the plant resistance against nematode infection. Our results revealed that the application of the plant resistance-stimulants enhanced the plant growth parameters and internal nutrient content and reduced the nematode’s criteria. Consequently, the internal plant resistance against nematode infection was induced.

Fusarium wilt caused by Fusarium oxysporum f. sp. lycopersici (FOL) in tomatoes is globally recognized as one of the most significant tomato diseases, both in fields and in greenhouses. Macroalgae contain a diversity of bioactive complexes. This research was carried out to assess the value of the extracts from three macroalgae (Sargassum dentifolium belongs to Phaeophyta, Gracilaria compressa belongs to Rhodophyta, and Ulva lactuca belongs to Chlorophyta) against wilt disease in tomato plants. The fungal pathogen was isolated from diseased tomato plants growing in several parts of Saudi Arabia. Isolates of the pathogen were identified by morphological and molecular methods. Three organic solvents, in addition to water, were used for extraction to assess the effect of reducing FOL hyphal growth on potato dextrose agar (PDA). Radial reductions in pathogen hyphal growth were seen with all of the solvent and water extracts, but the three macroalgae methanol extracts that were tested showed the greatest reduction in pathogen hyphal growth. The total phenol content of the S. dentifolium extract was higher than that of the other two macroalgae. The phenolic compounds showed variability in all of the extracts that were identified and calculated by high-performance liquid chromatography (HPLC). Phloroglucinol (7.34 mg/g dry weight), vanillic acid (7.28 mg/g dry weight), and gallic acid (6.89 mg/g dry weight) were the phenolic compounds with the highest concentrations in the S. dentifolium, G. compressa, and U. lactuca extracts, respectively. The mycelium of FOL treated with a crude macroalgae extract of tested at 100 µg/mL was examined with a scanning electron microscope. The results showed an obvious difference between the extract-treated and untreated hyphae. The extract-treated hyphae collapsed and bruised, as well as; empty and dead. In the greenhouse experiment, S. dentifolium powder was used to evaluate its effect on disease decline. It led to a decrease in disease severity of 40.8%. The highest total yield (560.8 g) was obtained from the plants treated with S. dentifolium powder. We recommend the use of macroalgae extracts to combat fungal phytopathogens. Because chemical fungicides are extremely toxic to humans and the environment, macroalgae extracts are a good alternative that can be widely and safely used in the field.

Red palm weevil (RPW) is a dangerous pest that infects the date palm tree and makes tunnels in the tree’s trunk. RPW infection is followed by secondary invaders of microorganisms that cause degradation of the trunk tissues leading to toppling the crown and death of the tree in a short time. This study showed that Fusarium oxysporum Schlecht. was the common fungal species isolated from the root and trunk tissues of the date trees infested with RPW, which recorded 100% of frequency. Pathogenicity of 4 isolates of F. oxysporum was confirmed on date palm seeds and seedlings. The results confirmed that all isolates involved in rot of the germinated seeds (40–100% incidence), root rot, and death of palm seedlings (20–100%) under artificial infection as well as degradation of date palm petioles. Application of 20 L/palm of systemic fungicide (Topsin) at 1% as foliar and soil drench of date palm for successive three times successfully reduced development of the deterioration and suppressed the growth of F. oxysporum. Interestingly this fungicide did not suppress the growth of Trichoderma viride Pers. So, our results recommend this fungicide to suppress the pathological and degradable activities of F. oxysporum during the integrated pest management of RPW on date palm trees.

The ecosystem is considerably affected due to the extensive use of chemical pesticides and fertilizers. As an alternative strategy, this study aimed to assess the biocontrol potential of the bioagents arbuscular mycorrhizal fungi and plant growth-promoting Trichoderma harzianum MZ025966 against tomato root-knot nematodes (Meloidogyne javanica). T. harzianum showed a great potentiality to produce indole acetic acid (IAA) (12.11 ± 2.12 μg/mL) and exhibited a noticeable activity of ammonification. Furthermore, T. harzianum revealed protease and lipase enzymatic activity of 28.36 ± 2.82 U/mL and 12.30 ± 0.31 U/mL, respectively, which may illustrate the control mechanism of nematode eggs and juveniles. As in mycorrhizal and/or T. harzianum inoculated tomato plants, the penetration rates of nematodes, as well as the number of juveniles, females, egg mass, and galls were significantly reduced. The lowest number of juveniles was observed in the case of either single mycorrhizal inoculation (45%) or in combination with T. harzianum (55%). The enzymatic activity of glutathione peroxidase and catalase was enhanced in tomato plants inoculated with the bioagents to overcome the negative impact of nematode parasitism. Our results proved that the application of biocontrol agents not only reduced the nematode population and penetration rate but also improved the plant growth, increased the nutritional elemental content and stimulated the plant’s systematic resistance.

The soil-borne pathogens Rhizoctonia solani and Sclerotium rolfsii have emerged as major pathogens of radish (Raphanus sativus) worldwide. The induction of soil suppressive of radish root rot disease was evaluated in soil repeatedly inoculated with R. solani, nonpathogenic binucleate Rhizoctonia sp. AG-A W1 (BNR) and S. rolfsii. The repeated inoculations of soil with R. solani and BNR significantly suppressed the disease severity of R. solani and S. rolfsii compared to the control. In contrast, the repeated inoculation of soil with S. rolfsii significantly suppressed only the pathogen, S. rolfsii. The community structure was examined using PCR-DGGE (polymerase chain reaction denaturing gradient gel electrophoresis) method. The bands of Trichoderma sp. were observed in the first, second and third inoculations of the soil with BNR. Similarly, bands of Trichoderma sp. were observed in the second and third inoculations of the soil with S. rolfsii and R. solani. Compared to the control, disease severity was significantly reduced in the soil repeatedly inoculated with S. rolfsii and R. solani . In conclusion, Trichoderma species were accumulated in specific patterns depending on the applied fungal inoculum in the suppressive soil.

Recently, there have been urgent economic and scientific demands to decrease the use of chemical fungicides during the treatment of phytopathogens, due to their human health and environmental impacts. This study explored the biocontrol efficacy of novel and eco-friendly preen (uropygial) oil and endophytic Bacillus safensis in managing postharvest Botrytis grey mold in strawberry fruit. The preen oil (25 μL/mL) showed high antifungal activity against B. cinerea Str5 in terms of the reduction in the fungal radial growth (41.3%) and the fungal colony-forming units (28.6%) compared to the control. A new strain of Bacillus safensis B3 had a good potential to produce chitinase enzymes (3.69 ± 0.31 U/mL), hydrolytic lipase (10.65 ± 0.51 U/mL), and protease enzymes (13.28 ± 0.65 U/mL), which are responsible for the hydrolysis of the B. cinerea Str5 cell wall and, consequently, restrict fungal growth. The in vivo experiment on strawberry fruit showed that preen (uropygial) oil reduced the disease severity by 87.25%, while the endophytic bacteria B. safensis B3 reduced it by 86.52%. This study reports the efficiency of individually applied bioagents in the control of phytopathogenic fungi for the first time and, consequently, encourages their application as a new and innovative strategy for prospective agricultural technology and food safety.

This research evaluated the efficacy of essential oils in the management of cucumber powdery mildew. Essential oils of lemongrass, lemon, thyme, peppermint, abundance blend, purification blend, and thieves blend were tested in vitro and under greenhouse conditions in two separate experiments. The effects of essential oils were tested against powdery mildew disease at concentrations of 1.0–2.5 mL/L, and the consequent impact of the oils on plant growth was evaluated. Powdery mildew fungus, Podosphaera xanthii, was identified using sequencing of the ITS region. The essential oils significantly reduced disease incidence up to 77.3% compared with the positive control (p < 0.5). Moreover, the essential oils increased the plant length (up to 187 cm), leaf area (up to 27.5 cm2), fresh weight (up to 123 g), dry weight (up to 22.5 g), number of flowers (16.3), and metabolite content compared with the positive control (p < 0.5). Cell membrane injury decreased significantly in the oil-treated pants (p < 0.5), indicating the protective effect of essential oils. This study recommends the application of essential oils in an appropriate dose (2.5 mL/L) to protect cucumber plants against powdery mildew. Overdose of the oils (more than 2.5 mL/L) should be avoided due to adverse effects.

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.

L-glutaminase is an important anticancer agent that is used extensively worldwide by depriving cancer cells of L-glutamine. The marine bacterium, Halomonas meridian was isolated from the Red Sea and selected as the more active L-glutaminase-producing bacteria. L-glutaminase fermentation was optimized at 36 h, pH 8.0, 37 °C, and 3.0% NaCl, using glucose at 1.5% and soybean meal at 2%. The purified enzyme showed a specific activity of 36.08 U/mg, and the molecular weight was found to be 57 kDa by the SDS-PAGE analysis. The enzyme was highly active at pH 8.0 and 37 °C. The kinetics’ parameters of Km and Vmax were 12.2 × 10−6 M and 121.95 μmol/mL/min, respectively, which reflects a higher affinity for its substrate. The anticancer efficiency of the enzyme showed significant toxic activity toward colorectal adenocarcinoma cells; LS 174 T (IC50 7.0 μg/mL) and HCT 116 (IC50 13.2 μg/mL). A higher incidence of cell death was observed with early apoptosis in HCT 116 than in LS 174 T, whereas late apoptosis was observed in LS 174 T more than in HCT 116. Also, the L-glutaminase induction nuclear fragmentation in HCT 116 was more than that in the LS 174T cells. This is the first report on Halomonas meridiana as an L-glutaminase producer that is used as an anti-colorectal cancer agent.

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.