Search

Abstract In order to investigate the stimulating effect of TiO2 nanoparticles on the growth rate and the increase of some metabolites in the microalgae Spirulina platensis, the anatase and rutile forms of the TiO2 nanoparticle were compared to the bulk form, in the presence or absence of citrate, on the microalga. The highest chlorophyll, carotenoid, phycocyanin (PC), allophycocyanin (APC), and phycoerythrin (PE) were observed on 3rd day. The highest PC and APC/PE were obtained by rutile and anatase, respectively. Rutile NPs could stimulate the increase of dry biomass and maximum specific growth rate (µm) better than anatase and even the bulk form. Carbohydrate production was stimulated by bulk and rutile. Low concentrations of nanoparticles often had a better effect in increasing PC, APC, and PE pigments. The addition of citrate without TiO2 stimulated the production of astheaxanthin, lipid, protein, and ROS. The simultaneous treatment by citrate-TiO2 was able to reduce the negative effect of nanoparticles on dry weight, but totally, its effect was dependent on the form of TiO2 and stress time. Antioxidant activity was stimulated by the bulk form and caused a decrease in Malondialdehyde (MDA), but an increase in MDA was observed by nanoparticles. The highest ROS was observed in the treatment with rutile (with citrate) on the 3rd day. In general, the stimulating effect of TiO2 on the improvement of indices or its negative effects on S.platensis microalga depended on the form and concentration of TiO2, the presence or absence of citrate, and the duration of treatments. IntroductionThe titanium element, in some cases, improves plant metabolic processes (Gohari et al., 2022; Carvajal and Alcaraz 1998). TiO2 nanoparticles in different forms have many applications in industry, and it is possible to find their way into aquatic ecosystems (Yang et al., 2015). The two forms of anatase and rutile have different surfaces, structural, and toxicity properties (Parrino et al., 2021). Some studies have shown that anatase has more cytotoxicity and photocatalytic activity than the rutile form (Clément et al., 2013). Of course, some sources mention TiO2 with low toxicity (Parrino et al., 2021). However, the effects of TiO2 nanoparticles depend on the type of organism under investigation, nanoparticle concentration, physicochemical and morphological characteristics such as its size and crystal structure. S. platensis, a spiral filamentous blue-green microalgae, has attracted the attention of researchers due to its numerous economic applications, including as a fertilizer and enhancer in agriculture, and has valuable minerals, vitamins, and nutritional compounds (Godlewska et al., 2019; Deng and Chow, 2010). Citric acid is required for various biological processes (Mudunkotuwa and Grassian, 2010). The citrate-nanometal complex can facilitate the entry of NPs along with citrate into the cell (Rupasinghe, 2011); hence the citrate form of nanometals has been recommended for the growth of plants (Chandrika et al., 2021). Some studies on plants have also shown that citrate reduces the adverse effects of nanoparticles (Tirani et al., 2018). Citrate can be adsorbed on the oxides of nanoparticles through Van der Waals bonds and prevent particles from aggregation (Park and Shumaker-Parry 2014; Rupasinghe 2011; Mudunkotuwa and Grassian, 2010).The aim of researchThe goal of this research was a comparative evaluation of the possible stimulating or adverse effects of bulk forms and nanoparticles of TiO2 (anatase and rutile), with or without citrate (in concentrations of 12.5, 25, 50, 100 and 200 mg. L-1) on the growth, biomass and intracellular compounds of microalgae S. platensis in 5 days. Materials and Methods Zarrouk nutrient medium was used for the growth of microalgae. Anatase nanoparticles 10-25 nm (Purity 99.9%, Specific surface area, SSA 200-240 m2 g-1), rutile nanoparticles 30 nm, (Purity 99.9%, SSA 35-60 m2 g-1) and bulk sample (diameter

In order to investigate the stimulating effect of TiO2 nanoparticles on the growth rate and the increase of some metabolites in the microalgae Spirulina platensis, the anatase and rutile forms of the TiO2 nanoparticle were compared to the bulk form, in the presence or absence of citrate, on the microalga. The highest chlorophyll, carotenoid, phycocyanin (PC), allophycocyanin (APC), and phycoerythrin (PE) were observed on 3rd day. The highest PC and APC/PE were obtained by rutile and anatase, respectively. Rutile NPs could stimulate the increase of dry biomass and maximum specific growth rate (μm) better than anatase and even the bulk form. Carbohydrate production was stimulated by bulk and rutile. Low concentrations of nanoparticles often had a better effect in increasing PC, APC, and PE pigments. The addition of citrate without TiO2 stimulated the production of astheaxanthin, lipid, protein, and ROS. The simultaneous treatment by citrate-TiO2 was able to reduce the negative effect of nanoparticles on dry weight, but totally, its effect was dependent on the form of TiO2 and stress time. Antioxidant activity was stimulated by the bulk form and caused a decrease in Malondialdehyde (MDA), but an increase in MDA was observed by nanoparticles. The highest ROS was observed in the treatment with rutile (with citrate) on the 3rd day. In general, the stimulating effect of TiO2 on the improvement of indices or its negative effects on S.platensis microalga depended on the form and concentration of TiO2, the presence or absence of citrate, and the duration of treatments. [ABSTRACT FROM AUTHOR]

Introduction: Bergamot (Citrus bergamia) belongs to the Rutaceae family. The purpose of this study was to identify the phytochemical compounds and antioxidant activity of Bergamot essential oil as well as investigating the effect of its antimicrobial activity on some pathogenic strains causing infection using in vitro. Materials & Methods: In this experimental study, phytochemical compounds of Bergamot essential oil were identified using gas chromatography–mass spectrometry. Antioxidant potential was evaluated by radical scavenging capacity assay (IC50). The antimicrobial effect of Bergamot essential oil was tested through Kirby-Bauer, agar diffusion (well), broth microdilution susceptibility assay, and pour plate (minimum bactericidal concentration) methods. Findings: Phytochemical analysis of the essential oil confirmed the presence of 19 constituents in Bergamot. The main constituents were Limonene (31.58%) and Linalool (21.47%). The Antioxidant activity (IC50) of Bergamot essential oil was equal to 212μg/ml. The minimum inhibitory concentration of Bergamot essential oil for Pseudomonas aeruginosa, Escherichia coli, Staphylococcus epidermidis and Streptococcus pyogenes was 4, 8, 2 and 2 mg/ml, respectively. The minimum bactericidal concentration for bacteria was 8, 8, 4 and 4 mg/ml, respectively. Discussion & Conclusions: This study revealed the considerable inhibitory effects of Bergamot essential oil on the pathogenic strain causing infection, including Gram-positive bacteria (Staphylococcus epidermidis and Streptococcus pyogenes). Although more research is needed in this field, Bergamot essential oil can be used as a new antimicrobial agent in the pharmaceutical and food industries.