Synthesis of silver and copper nanoparticle using Spirulina platensis and evaluation of their anticancer activity

The present research displays the green synthesis of stable silver nanoparticles (Ag-NPs) and copper oxide nanoparticles (CuO-NPs). The aqueous solution of Spirulina platensis (blue green algae) source was used as a reducing and capping agent and this study assessed the cytotoxicity of Ag- and CuO-NPs on three cancer cell cultures: A549 (lung cancer), HCT (human colon cancer), Hep2 (laryngeal carcinoma cancer) and normal cell (WISH). For NPs characterization, the UV/Vis spectroscopy was used where their formation and crystallinity were proven with λ max values for Ag- and CuO-NPs of 425 and 234 nm, respectively. According to X-ray diffraction and transmission electron microscopy (TEM), Ag-NPs were spherical in shape (size 2.23-14.68 nm) and CuO-NPs were small (size 3.75-12.4 nm). Zeta potential analysis showed the particles potential, which was recorded by -14.95 ± 4.31 mV for Ag-NPs and -21.63 ± 4.90 mV for CuO-NPs. After that, Ag- and CuO-NPs were assessed for anticancer properties against A549, HCT, Hep2 and WISH. IC50 of Ag-NPs recorded 15.67, 12.94, 3.8 and 10.44 µg/ml for WISH, A549, HCT and Hep2, respectively. IC50 for CuO-NPs was recorded as 32.64, 54.59, 3.98 and 20.56 µg/ml for WISH, A549, HCT and Hep2 cells, respectively. Safety limits for WISH and A549 were achieved 98.64% by 2.44 µg/ml and 83.43% by 4.88 µg/ml of Ag-NPs, and it was found to be 97.94% by 2.44 µg/ml against HCT, while that for Hep2 is 95.9% by 2.44 µg/ml. Concerning the anticancer effect of CuO-NPs, the safety limit was recorded as 88.70% by 2.44 and 98.48% by 4.88 µg/ml against WISH and A549, while HCT reached 89.92% by 2.44 µg/ml and Hep2 was 83.33% by 4.88 µg/ml. Green nanotechnology applications such as Ag-NPs and CuO-NPs have numerous benefits of ecofriendliness and compatibility for biomedical applications such as anticancer effects against cancer cells.

The Integrated Amendment of Sodic-Saline Soils Using Biochar and Plant Growth-Promoting Rhizobacteria Enhances Maize (Zea mays L.) Resilience to Water Salinity

The utilization of low-quality water or slightly saline water in sodic-saline soil is a major global conundrum that severely impacts agricultural productivity and sustainability, particularly in arid and semiarid regions with limited freshwater resources. Herein, we proposed an integrated amendment strategy for sodic-saline soil using biochar and/or plant growth-promoting rhizobacteria (PGPR; Azotobacter chroococcum SARS 10 and Pseudomonas koreensis MG209738) to alleviate the adverse impacts of saline water on the growth, physiology, and productivity of maize (Zea mays L.), as well as the soil properties and nutrient uptake during two successive seasons (2018 and 2019). Our field experiments revealed that the combined application of PGPR and biochar (PGPR + biochar) significantly improved the soil ecosystem and physicochemical properties and K+, Ca2+, and Mg2+ contents but reduced the soil exchangeable sodium percentage and Na+ content. Likewise, it significantly increased the activity of soil urease (158.14 ± 2.37 and 165.51 ± 3.05 mg NH4+ g-1 dry soil d-1) and dehydrogenase (117.89 ± 1.86 and 121.44 ± 1.00 mg TPF g-1 dry soil d-1) in 2018 and 2019, respectively, upon irrigation with saline water compared with non-treated control. PGPR + biochar supplementation mitigated the hazardous impacts of saline water on maize plants grown in sodic-saline soil better than biochar or PGPR individually (PGPR + biochar > biochar > PGPR). The highest values of leaf area index, total chlorophyll, carotenoids, total soluble sugar (TSS), relative water content, K+ and K+/Na+ of maize plants corresponded to PGPR + biochar treatment. These findings could be guidelines for cultivating not only maize but other cereal crops particularly in salt-affected soil and sodic-saline soil.

Interactive Impacts of Beneficial Microbes and Si-Zn Nanocomposite on Growth and Productivity of Soybean Subjected to Water Deficit under Salt-Affected Soil Conditions

Water stress or soil salinity is considered the major environmental factor affecting plant growth. When both challenges are present, the soil becomes infertile, limiting plant productivity. In this work a field experiment was conducted during the summer 2019 and 2020 seasons to evaluate whether plant growth-promoting microbes (PGPMs) and nanoparticles (Si-ZnNPs) have the potential to maintain soybean growth, productivity, and seed quality under different watering intervals (every 11 (IW0), 15 (IW1) and 19 (IW2) days) in salt-affected soil. The most extended watering intervals (IW1 and IW2) caused significant increases in Na+ content, and oxidative damage indicators (malondialdehyde (MDA) and electrolyte leakage (EL%)), which led to significant reductions in soybean relative water content (RWC), stomatal conductance, leaf K+, photosynthetic pigments, soluble protein. Subsequently reduced the vegetative growth (root length, nodules dry weight, and total leaves area) and seeds yield. However, there was an enhancement in the antioxidants defense system (enzymatic and non-enzymatic antioxidant). The individual application of PGPMs or Si-ZnNPs significantly improved leaf K+ content, photosynthetic pigments, RWC, stomatal conductance, total soluble sugars (TSS), CAT, POD, SOD, number of pods plant-1, and seed yield through decreasing the leaf Na+ content, MDA, and EL%. The combined application of PGPMs and Si-ZnNPs minimized the adverse impact of water stress and soil salinity by maximizing the root length, heavier nodules dry weight, leaves area, TSS and the activity of antioxidant enzymes, which resulted in higher soybean growth and productivity, which suggests their use under harsh growing conditions.

Minimizing the Adversely Impacts of Water Deficit and Soil Salinity on Maize Growth and Productivity in Response to the Application of Plant Growth-Promoting Rhizobacteria and Silica Nanoparticles

The development of new approaches for sustaining soil quality, leaf health, and maize productivity are imperative in light of water deficit and soil salinity. Plant growth-promoting rhizobacteria (PGPR) and silica nanoparticles (SiNP) are expected to improve soil chemistry leading to improved plant performance and productivity. In this field experiment, water deficit is imposed by three irrigation intervals—12 (I1), 15 (I2), and 18 (I3) days. Plants are also treated with foliar and soil applications (control, PGPR, SiNP, and PGPR + SiNP) to assess soil enzymatic activity, soil physicochemical properties, plant physiological traits, biochemical analysis, nutrient uptake, and productivity of maize (Zea mays L.) plants grown under salt-affected soil during the 2019 and 2020 seasons. With longer irrigation intervals, soil application of PGPR relieves the deleterious impacts of water shortage and improves yield-related traits and maize productivity. This is attributed to the improvement in soil enzymatic activity (dehydrogenase and alkaline phosphatase) and soil physicochemical characteristics, which enhances the plants’ health and growth under longer irrigation intervals (i.e., I2 and I3). Foliar spraying of SiNP shows an improvement in the physiological traits in maize plants grown under water shortage. This is mainly owing to the decline in oxidative stress by improving the enzymatic activity (CAT, SOD, and POD) and ion balance (K+/Na+), resulting in higher photosynthetic rate, relative water content, photosynthetic pigments, and stomatal conductance, alongside reduced proline content, electrolyte leakage, lipid peroxidase, and sodium content under salt-affected soil. The co-treatment of SiNP with PGPR confirms greater improvement in yield-related traits, maize productivity, as well as nutrient uptake (N, P, and K). Accordingly, their combination is a good strategy for relieving the detrimental impacts of water shortage and soil salinity on maize production.

Short-term changes in phytoplankton assemblages and their potential for heavy metal bioaccumulation – a laboratory study

This study focused on phytoplankton changes in polluted waters of Lake Manzala and the assessment of heavy metal bioaccumulation capacity during the 15-day laboratory experiment. Phytoplankton samples were analyzed every day and the concentration of zinc, iron and lead in water, in phytoplankton and in filtrate – every fifth day of the experiment. Significantly higher phytoplankton abundance was recorded in water from the El-Boom station (basin I) compared to the New Bahr El-Baqar drain (basin II), followed by distinct differences in its composition and chlorophyll content. However, the most abundant species were the same in both basins, i.e. Chroococcus minor, Microcystis aeruginosa, Actinoptychus octonarius, Aulacoseira granulata, Pantocsekiella ocellata, Kirchneriella obesa and Nephrocytium limneticum. Water in basin I was more polluted with heavy metals compared to basin II. Basin I was characterized by the dominance of cyanobacteria and high relative abundance of chlorophytes compared to basin II, where either cyanobacteria and/or diatoms dominated in the phytoplankton. In the former basin, the highest uptake factors (UFs) were recorded for iron and zinc and the lowest UF for lead. In basin II, the highest UF was determined for zinc, but relatively high UFs were recorded also for iron and lead. The presented results suggest that phytoplankton can contribute to natural biosorbents of heavy metals in Egyptian lakes.

The relationship between phytoplankton and fish in nutrient-rich shallow Lake Qarun, Egypt

The present study focused on the determination of the baseline data and correlations between biological and physicochemical variables, including the assessment of trophic conditions in Lake Qarun. The concentrations of nutrients were high, with the maxima usually in the east subarea (total nitrogen 6.40 mg dm-3, mineral nitrogen 2.34 mg dm-3, orthophosphates 0.22 mg dm-3). A total of 134 phytoplankton species were recorded. Bacillariophyceae and Dinophyceae co-dominated spatially and seasonally in phytoplankton assemblages. The highest phytoplankton density (935 × 104 cells dm-3) and chlorophyll a content (69.3 μg dm-3) were recorded in the east subarea of the lake, whereas the largest total and dominant fish (Mugil cephalus and Solea spp.) were in the west. Tilapia zillii and Engraulis encrasicolus were most abundant in the east and in the middle part, respectively. When phytoplankton density decreased from the east toward the west subarea, the Secchi disk depth increased. The TLI-based assessment indicated hypereutrophic waters at most sites of Lake Qarun. Statistically significant positive or negative correlations were found between the dominant fish species: T. zillii and Solea spp., and the phytoplankton density, Dinophyceae density, concentrations of TP, chlorophyll a, ammonium, nitrite and nitrate. Such correlations may be helpful to better understand how to enhance the sustainable fish production.