Production, extraction and characterization of Chlorella vulgaris soluble polysaccharides and their applications in AgNPs biosynthesis and biostimulation of plant growth

Responses of Dunaliella sp. AL-1 to chromium and copper: Biochemical and physiological studies

Microalgae have gained recognition as versatile candidates for the remediation of heavy metals (HMs). This study investigated the biosorption potential of Dunaliella sp. AL1 for copper (Cu(II)) and hexavalent chromium (Cr(VI)) in aqueous solutions. The marine microalga Dunaliella sp. AL1 was exposed to half-sublethal concentrations of both metals in single and bimetallic systems, and responses in algal growth, oxidative stress, photosynthetic pigment production, and photosynthetic performance were evaluated. Cu and/or Cr exposure increased the generation of reactive oxygen species (ROS) in microalgae cells but did not impact algal growth. In terms of photosynthesis, there was a decrease in chlorophylls and carotenoids production in the microalgae culture treated with Cr, either alone or in combination with Cu. The study recorded promising metal removal efficiencies: 26.67%-20.11% for Cu and 94.99%-95.51% for Cr, in single and bimetallic systems, respectively. FTIR analysis revealed an affinity of Cu and Cr ions towards aliphatic/aldehyde C-H, N-H bending, and phosphate groups, suggesting the formation of complex bonds. Biochemical analysis of microalgae biomass collected after the removal of Cr alone or in combination with Cu showed a significant decrease in total carbohydrate content and soluble protein levels. Meanwhile, higher lipid accumulation was recorded and evidenced by BODIPY 505/515 staining. Fatty acid composition analysis by GC revealed a modulation in lipid composition, with a decrease in the ratio of unsaturated fatty acids (UFA) to saturated fatty acids (SFA), in response to Cu, Cr, and Cu-Cr exposure, indicating the suitability of the biomass for sustainable biofuel production.

Synthesis of polysaccharides by microalgae Chlorella sp

Microalgae are known to be the richest natural source of polysaccharides. The study aimed to evaluate the ability of microalgae from the Chlorella sp. genus to synthesize polysaccharides. Brody & Emerson max medium proved to be the most effective; the average cell content in the culture fluid at the beginning and at the end of cultivation for IPPAS Chlorella pyrenoidosa Chick was 1.23 ± 0.03 g/L and 1.71 ± 0.20 g/L, respectively. With a high average dry weight of IPPAS Chlorella pyrenoidosa Chick (4.45 ± 0.10 g/L), it produced the least amount of neutral sugars (0.75 ± 0.02 g/L) and uronic acids (0.14 ± 0.01 mg/L). The microalga IPPAS Chlorella vulgaris with the lowest average dry weight (1.18 ± 0.03 g/L) produced 0.80 ± 0.02 g/L of neutral sugars and 0.17 ± 0.01 mg/L of uronic acids. Microalgal polysaccharides have the potential to be used as a source for biologically active food additives, as they contain various types of polysaccharides that can be beneficial to human health.

A melanin-like polymer bearing phenylboronic units as a suitable bioplatform for living cell display technology

Surface display of functional groups with specific reactivity around living cells is an emerging, low cost and highly eco-compatible technology that serves multiple applications, ranging from basic biochemical studies to biomedicine, therapeutics and environmental sciences. Conversely to classical methods exploiting hazardous organic synthesis of precursors or monovalent functionalization via genetics, here we perform functional decoration of individual living microalgae using suitable biocoatings based on polydopamine, a melanin-like synthetic polymer. Here we demonstrate the one-pot synthesis of a functional polydopamine bearing phenylboronic units which can decorate the living cell surfaces via a direct ester formation between boronic units and surface glycoproteins. Furthermore, biosorption of fluorescent sugars on functionalized cell membranes is triggered, demonstrating that these organic coatings act as biocompatible soft shells, still functional and reactive after cell engineering.

Zinc oxide decorated plantain peel activated carbon for adsorption of cationic malachite green dye: Mechanistic, kinetics and thermodynamics modeling

Reports have shown that malachite green (MG) dye causes various hormonal disruptions and health hazards, hence, its removal from water has become a top priority. In this work, zinc oxide decorated plantain peels activated carbon (ZnO@PPAC) was developed via a hydrothermal approach. Physicochemical characterization of the ZnO@PPAC nanocomposite with a 205.2 m2/g surface area, porosity of 614.68 and dominance of acidic sites from Boehm study established the potency of ZnO@PPAC. Spectroscopic characterization of ZnO@PPAC vis-a-viz thermal gravimetric analyses (TGA), Fourier Transform Infrared Spectroscopy (FTIR), Powdered X-ray Diffraction (PXRD), Scanning Electron Microscopy and High Resolution - Transmission Electron Microscopy (HR-TEM) depict the thermal stability via phase transition, functional group, crystallinity with interspatial spacing, morphology and spherical and nano-rod-like shape of the ZnO@PPAC heterostructure with electron mapping respectively. Adsorption of malachite green dye onto ZnO@PPAC nanocomposite was influenced by different operational parameters. Equilibrium data across the three temperatures (303, 313, and 323 K) were most favorably described by Freundlich indicating the ZnO@PPAC heterogeneous nature. 77.517 mg/g monolayer capacity of ZnO@PPAC was superior to other adsorbents compared. Pore-diffusion predominated in the mechanism and kinetic data best fit the pseudo-second-order. Thermodynamics studies showed the feasible, endothermic, and spontaneous nature of the sequestration. The ZnO@PPAC was therefore shown to be a sustainable and efficient material for MG dye uptake and hereby endorsed for the treatment of industrial effluent.

Bioremediation potential of microalgae for sustainable soil treatment in India: A comprehensive review on heavy metal and pesticide contaminant removal

The escalating environmental concerns arising from soils contamination with heavy metals (HMs) and pesticides (PSTs) necessitate the development of sustainable and effective remediation strategies. These contaminants, known for their carcinogenic properties and toxicity even at small amounts, pose significant threats to both environmental ecology and human health. While various chemical and physical treatments are employed globally, their acceptance is often hindered by prolonged remediation times, high costs, and inefficacy in areas with exceptionally high pollutant concentrations. A promising emerging trend in addressing this issue is the utilization of microalgae for bioremediation. Bioremediation, particularly through microalgae, presents numerous benefits such as high efficiency, low cost, easy accessibility and an eco-friendly nature. This approach has gained widespread use in remediating HM and PST pollution, especially in large areas. This comprehensive review systematically explores the bioremediation potential of microalgae, shedding light on their application in mitigating soil pollutants. The paper summarizes the mechanisms by which microalgae remediate HMs and PSTs and considers various factors influencing the process, such as pH, temperature, pollutant concentration, co-existing pollutants, time of exposure, nutrient availability, and light intensity. Additionally, the review delves into the response and tolerance of various microalgae strains to these contaminants, along with their bioaccumulation capabilities. Challenges and future prospects in the microalgal bioremediation of pollutants are also discussed. Overall, the aim is to offer valuable insights to facilitate the future development of commercially viable and efficient microalgae-based solutions for pollutant bioremediation.

A sustainable green-approach for biofabrication of chitosan nanoparticles, optimization, characterization, its antifungal activity against phytopathogenic Fusarium culmorum and antitumor activity

Chitosan is a natural non-toxic, biocompatible, biodegradable, and mucoadhesive polymer. It also has a broad spectrum of applications such as agriculture, medical fields, cosmetics and food industries. In this investigation, chitosan nanoparticles were produced by an aqueous extract of Cympopogon citratus leaves as a reducing agent. According to the SEM and TEM micrographs, CNPs had a spherical shape, and size ranging from 8.08 to 12.01 nm. CNPs have a positively charged surface with a Zeta potential of + 26 mV. The crystalline feature of CNPs is determined by X-ray diffraction. There are many functional groups, including C꞊C, CH2-OH, C-O, C-S, N-H, CN, CH and OH were detected by FTIR analysis. As shown by the thermogravimetric study, CNPs have a high thermal stability. For the optimization of the green synthesis of CNPs, a Face centered central composite design (FCCCD) with 30 trials was used. The maximum yield of CNPs (13.99 mg CNPs/mL) was produced with chitosan concentration 1.5%, pH 4.5 at 40 °C, and incubation period of 30 min. The antifungal activity of CNPs was evaluated against phytopathogenic fungus; Fusarium culmorum. A 100% rate of mycelial growth inhibition was gained by the application of 20 mg CNPs/mL. The antitumor activity of the green synthesized CNPs was examined using 6 different cell lines, the viability of the cells reduced when the concentration of green synthesized CNPs increased, the IC50 dose of the green synthesized CNPs on the examined cell lines HePG-2, MCF-7, HCT-116, PC-3, Hela and WI-38 was 36.25 ± 2.3, 31.21 ± 2.2, 67.45 ± 3.5, 56.30 ± 3.3, 44.62 ± 2.6 and 74.90 ± 3.8; respectively.

Photo-triggered caffeic acid delivery via psyllium polysaccharide- gellan gum-based injectable bionanogel for epidermoid carcinoma treatment

Here, the simultaneous effect of chemo- and photothermal therapy against epidermoid carcinoma (EC) was investigated. A novel hydrogel, termed bionanogel (BNG), was designed using psyllium mucilage polysaccharide and bacterial gellan gum, incorporated with nanocomplex carrying caffeic acid (CA) and IR-820, and further characterized. The dual effect of BNG and 808 nm laser (BNG + L) on EC was investigated. Staining and scratch assays were performed to analyze their therapeutic effect on EC. In vivo evaluations of BNG + L in xenograft models were performed. Rapid transition, limited swelling, degradability and high tensile strength indicated BNG stability and sustained drug release. Irradiation with 808 nm laser light at 1.25 W /cm2 for 4 min resulted in a temperature increase of 53 °C and facilitated cell ablation. The in vitro studies showed that BNG + L suppressed cancer progression via a late apoptotic effect. The in vivo study showed that the slow release of CA from BNG + L significantly attenuated EC with low mitotic index and downregulation of proteins involved in cancer proliferation such as EGFR, AKT, PI3K, ERK, mTOR and HIF-1α. Thus, BNG could be a novel medium for targeted and controlled drug delivery for the treatment of epidermoid cancer when triggered by NIR light.

Photo-/thermo-responsive bioink for improved printability in extrusion-based bioprinting

Extrusion-based bioprinting has demonstrated significant potential for manufacturing constructs, particularly for 3D cell culture. However, there is a greatly limited number of bioink candidates exploited with extrusion-based bioprinting, as they meet the opposing requirements for printability with indispensable rheological features and for biochemical functionality with desirable microenvironment. In this study, a blend of silk fibroin (SF) and iota-carrageenan (CG) was chosen as a cell-friendly printable material. The SF/CG ink exhibited suitable viscosity and shear-thinning properties, coupled with the rapid sol-gel transition of CG. By employing photo-crosslinking of SF, the printability with Pr value close to 1 and structural integrity of the 3D constructs were significantly improved within a matter of seconds. The printed constructs demonstrated a Young's modulus of approximately 250 kPa, making them suitable for keratinocyte and myoblast cell culture. Furthermore, the high cell adhesiveness and viability (maximum >98%) of the loaded cells underscored the considerable potential of this 3D culture scaffold applied for skin and muscle tissues, which can be easily manipulated using an extrusion-based bioprinter.

Bionanofactory for green synthesis of collagen nanoparticles, characterization, optimization, in-vitro and in-vivo anticancer activities

Collagen nanoparticles (collagen-NPs) are promising biological polymer nanoparticles due to their exceptional biodegradability and biocompatibility. Collagen-NPs were bio-fabricated from pure marine collagen using the cell-free supernatant of a newly isolated strain, Streptomyces sp. strain NEAA-3. Streptomyces sp. strain NEAA-3 was identified as Streptomyces plicatus strain NEAA-3 based on its cultural, morphological, physiological properties and 16S rRNA sequence analysis. The sequence data has been deposited under accession number OR501412.1 in the GenBank database. The face-centered central composite design (FCCD) was used to improve collagen-NPs biosynthesis. The maximum yield of collagen-NPs was 9.33 mg/mL with a collagen concentration of 10 mg/mL, an initial pH of 7, an incubation time of 72 h, and a temperature of 35 °C. Using the desirability function approach, the collagen-NPs biosynthesis obtained after FCCD optimization (9.53 mg/mL) was 3.92 times more than the collagen-NPs biosynthesis obtained before optimization process (2.43 mg/mL). The TEM analysis of collagen-NPs revealed hollow sphere nanoscale particles with an average diameter of 33.15 ± 10.02 nm. FTIR spectra confirmed the functional groups of the collagen, collagen-NPs and the cell-free supernatant that are essential for the efficient capping of collagen-NPs. The biosynthesized collagen-NPs exhibited antioxidant activity and anticancer activity against HeP-G2, MCF-7 and HCT116 cell lines. Collagen-NPs assessed as an effective drug loading carrier with methotrexate (MTX), a chemotherapeutic agent. The TEM analysis revealed that the average size of MTX-loaded collagen-NPs was 35.4 ± 8.9 nm. The percentages of drug loading (DL%) and encapsulation efficiency (EE%) were respectively 22.67 and 45.81%.

Process optimization for gold nanoparticles biosynthesis by Streptomyces albogriseolus using artificial neural network, characterization and antitumor activities

Gold nanoparticles (GNPs) are highly promising in cancer therapy, wound healing, drug delivery, biosensing, and biomedical imaging. Furthermore, GNPs have anti-inflammatory, anti-angiogenic, antioxidants, anti-proliferative and anti-diabetic effects. The present study presents an eco-friendly approach for GNPs biosynthesis using the cell-free supernatant of Streptomyces albogriseolus as a reducing and stabilizing agent. The biosynthesized GNPs have a maximum absorption peak at 540 nm. The TEM images showed that GNPs ranged in size from 5.42 to 13.34 nm and had a spherical shape. GNPs have a negatively charged surface with a Zeta potential of - 24.8 mV. FTIR analysis identified several functional groups including C-H, -OH, C-N, amines and amide groups. The crystalline structure of GNPs was verified by X-ray diffraction and the well-defined and distinct diffraction rings observed by the selected area electron diffraction analysis. To optimize the biosynthesis of GNPs using the cell-free supernatant of S. albogriseolus, 30 experimental runs were conducted using central composite design (CCD). The artificial neural network (ANN) was employed to analyze, validate, and predict GNPs biosynthesis compared to CCD. The maximum experimental yield of GNPs (778.74 μg/mL) was obtained with a cell-free supernatant concentration of 70%, a HAuCl4 concentration of 800 μg/mL, an initial pH of 7, and a 96-h incubation time. The theoretically predicted yields of GNPs by CCD and ANN were 809.89 and 777.32 μg/mL, respectively, which indicates that ANN has stronger prediction potential compared to the CCD. The anticancer activity of GNPs was compared to that of doxorubicin (Dox) in vitro against the HeP-G2 human cancer cell line. The IC50 values of Dox and GNPs-based treatments were 7.26 ± 0.4 and 22.13 ± 1.3 µg/mL, respectively. Interestingly, treatments combining Dox and GNPs together showed an IC50 value of 3.52 ± 0.1 µg/mL, indicating that they targeted cancer cells more efficiently.

Green synthesis of silver nanoparticles using Phlebopus portentosus polysaccharide and their antioxidant, antidiabetic, anticancer, and antimicrobial activities

Silver nanoparticles (AgNPs) by green synthesis from fungi polysaccharides are attracting increasing attention owing to their distinctive features and special applications in numerous fields. In this study, a cost-effective and environmentally friendly biosynthesizing AgNPs method with no toxic chemicals involved from the fruiting body polysaccharide of Phlebopus portentosus (PPP) was established and optimized by single factor experiment and response surface methodology. The optimum synthesis conditions of polysaccharide-AgNPs (PPP-AgNPs) were identified to be the reaction time of 140 min, reaction temperature of 94 °C, and the PPP: AgNO3 ratio of 1:11.5. Formation of PPP-AgNPs was indicated by visual detection of colour change from yellowish to yellowish brown. PPP-AgNPs were characterized by different methods and further evaluated for biological activities. That the Ultraviolet-visible (UV-Vis.) spectroscopy displayed a sharp absorption peak at 420 nm confirmed the formation of AgNPs. Fourier transform infrared (FTIR) analysis detected the presence of various functional groups. The lattice indices of (111), (200), (220), and (331), which indicated a faced-centered-cubic of the Ag crystal structure of PPP-AgNPs, was confirmed by X-ray diffraction (XRD) and the particles were found to be spherical through high resolution transmission electron microscopy (HRTEM). Energy dispersive X-ray spectroscopy (EDS) determined the presence of silver in PPP-AgNPs. The percentage relative composition of elements was determined as silver (Ag) 82.5 % and oxygen (O) 17.5 % for PPP-AgNPs, and did not exhibit any nitrogen peaks. The specific surface area of PPP-AgNPs was calculated to be 0.5750 m2/g with an average pore size of 24.33 nm by BET analysis. The zeta potential was -4.32 mV, which confirmed the stability and an average particle size of 64.5 nm was calculated through dynamic light scattering (DLS). PPP-AgNPs exhibited significant free radical scavenging activity against DPPH with an IC50 value of 0.1082 mg/mL. The MIC values of PPP-AgNPs for E. coli, S. aureus, C. albicans, C. glabrata, and C. parapsilosis are 0.05 mg/mL. The IC50 value of the inhibition of PPP-AgNPs against α-glucosidase was 11.1 μg/mL, while the IC50 values of PPP-AgNPs against HepG2 and MDA-MB-231 cell lines were calculated to be 14.36 ± 0.43 μg/mL and 40.05 ± 2.71 μg/mL, respectively. According to the evaluation, it can be concluded that these green-synthesized and eco-friendly PPP-AgNPs are helpful to improve therapeutics because of significant antioxidant, antimicrobial, antidiabetic, and anticancer properties to provide new possibilities for clinic applications.

Microalgae's polysaccharides, are they potent antioxidants? Critical review

The scientific community continue to explore novel bioactive molecules by investigating natural origins; microalgae are photosynthetic organisms considered as a sustainable resource to use in many fields. They present a high diversity in species and richness in terms of attractive bio-compounds. The aim of this review is to (1) provide first an overview of current issues related to oxidative stress, and propose a natural metabolite derived from eukaryotic and prokaryotic microalgae; 'polysaccharides' as a powerful antioxidant agent, then, (2) organize the available data on the antioxidant potential of polysaccharides derived from the main microalgal groups (red microalgae, green microalgae, and cyanobacteria) and especially highlighted the key species of each group (Porphyridium sp., Chlorella sp., and Arthrospira sp., respectively), meanwhile, (3) we described the chemical composition of polysaccharides from each class, and (4) we cite briefly the most factors affecting the antioxidant activity of these molecules. Finally, we explored the major challenges and gaps found to require more investigation.

Polysaccharides from Spirulina platensis (PSP): promising biostimulants for the green synthesis of silver nanoparticles and their potential application in the treatment of cancer tumors

Photosynthetic cyanobacterial components are gaining great economic importance as prospective low-cost biostimulants for the green synthesis of metal nanoparticles with valuable medical and industrial applications. The current study comprises the biological synthesis of silver nanoparticles (Ag-NPs) using soluble polysaccharides isolated from Spirulina platensis (PSP) as reducing and capping agents. FTIR spectra showed major functional groups of PSP and biogenic silver nanoparticles including O-H, C-H (CH2), C-H (CH3), C=O, amide, and COO- groups. The UV/Vis spectroscopy scan analyses of the extracted PSP showed absorption spectra in the range of 200-400 nm, whereas the biogenic Ag-NPs showed a maximum spectrum at 285 nm. Transmission electron microscopy (TEM) analysis of the synthesized Ag-NPs showed spherical nanoparticles with mean size between 12 and 15.3 nm. The extracted PSP and Ag-NPs exhibited effective cytotoxic activity against Hep-G2 (human hepatocellular carcinoma). The IC50 for PSP and Ag-NPs were 65.4 and 24.5 µg/mL, respectively. Moreover, cell apoptosis assays for PSP and Ag-NPs against the growth of Hep-G2 cells revealed superior growth inhibitory effects of the green synthesized Ag-NPs that encouraged tracing the apoptotic signalling pathway. In conclusion, the current study demonstrated an unprecedented approach for the green synthesis of silver nanoparticles (NPs), using the polysaccharide of Spirulina platensis as reducing and capping agents, with superior anticancer activity against a hepatocellular carcinoma cell line.

Optimization and Physicochemical Characterization of Polysaccharide Purified from Sonneratia caseolaris Mangrove Leaves: a Potential Antioxidant and Antibiofilm Agent

The Box-Behnken design was applied to determine the optimal parameters of the extraction condition by using the response surface methodology (RSM) from the leaves of Sonneratia caseolaris L. The result indicates the best-optimized conditions used for the extraction of polysaccharides at 84.02 °C temperature, 3.12 h time, and 27.31 mL/g for the water-to-material ratio. The maximum experimental yield of 8.81 ± 0.09% was obtained which is in agreement with the predicted value of 8.79%. Thereafter, low molecular weight polysaccharide (SCLP) was separated after sequentially being purified through column chromatography with a relative molecular weight of 3.74 kDa. The physicochemical properties were evaluated by characterization techniques such as FT-IR spectra, NMR spectrum, and SEM analysis. RP-HPLC analysis confirmed that SCLP was a heteropolysaccharide, majorly comprising rhamnose (28.25%), and xylose (27.17%) residues, followed by mannose (18.90%), and galactose (17.17%), respectively. Thermal analysis (TGA-DSC) results showed that SCLP is a highly thermostable polymer with a degradation temperature of 361.63 °C. X-ray diffraction patterns and tertiary structure analyses indicate that SCLP had a semi-crystalline polymer having a triple-helical configuration. Moreover, SCLP displayed potential antibiofilm ability for all the tested pathogens while stronger activity against Klebsiella pneumoniae and Pseudomonas aeruginosa. In addition, SCLP has potential in vitro antioxidant activity on DPPH, ABTS radical, superoxide, and Fe2+ chelating. These findings indicate that the polysaccharide has potentially been used in functional food, cosmetics, and pharmacological industries.

Phycoremediation of heavy metals and production of biofuel from generated algal biomass: a review

Due to human activity and natural processes, heavy metal contamination frequently affects the earth's water resources. The pollution can be categorized as resistant and persistent since it poses a significant risk to terrestrial and marine biological systems and human health. Because of this, several appeals and demands have been made worldwide to try and clean up these contaminants. Through bioremediation, algal cells are frequently employed to adsorb and eliminate heavy metals from the environment. Bioremediation is seen as a desirable strategy with few adverse effects and low cost. Activities and procedures for bioremediation involving algal cells depend on various environmental factors, including salinity, pH, temperature, the concentration of heavy metals, the amount of alga biomass, and food availability. Additionally, the effectiveness of removing heavy metals from the environment by assessing how environmental circumstances affect algal activities. The main issues discussed are (1) heavy metal pollution of water bodies, the role of algal cells in heavy metal removal, the methods by which algae cells take up and store heavy metals, and the process of turning the algae biomass produced into biofuel. (2) To overcome the environmental factors and improve heavy metals bioremediation, many strategies are applied, such as immobilizing the cells, consortium culture, and using dry mass rather than living cells. (3) The processes for converting produced algal biomass into biofuels like biodiesel and biomethanol. The present study discusses the life cycle assessment and the limitations of biofuel products from algae biomass.

Growth patterns of Pseudomonas aeruginosa in milk fortified with chitosan and selenium nanoparticles during refrigerated storage

Pseudomonas spp are considered a common milk-associated psychotropic bacteria, leading to milk deterioration during storage; therefore, our study aimed to study the distribution of Pseudomonas aeruginosa in raw milk and its associated products then studying the growth behavior of P. aeruginosa in milk after employing chitosan nanoparticles (CsNPs 50, 25, and 15 mg/100ml) and selenium nanoparticles (SeNPs 0.5, 0.3 and 0.1 mg/100ml) as a trial to control the bacterial growth in milk during five days of cooling storage. Our study relies on the ion gelation method and green synthesis for the conversion of chitosan and selenium to nanosized particles respectively, we subsequently confirmed their shape using SEM and TEM. We employing Pseudomonas selective agar medium for monitoring the bacterial growth along the cooling storage. Our findings reported that high prevalence of Pseudomonas spp count in raw milk and kareish cheese and high incidence percent of P. aeruginosa in ice cream and yogurt respectively. Both synthesized nanoparticles exhibited antibacterial activity in a dose-dependent manner. Moreover, CsNPs50 could inhibit the P. aeruginosa survival growth to a mean average of 2.62 ± 1.18 log10cfu/ml in the fifth day of milk cooling storage; also, it was noted that the hexagonal particles SeNPs0.5 could inhibit 2.49 ± 11 log10cfu/ml in comparison to the control P. aeruginosa milk group exhibited growth survival rate 7.24 ± 2.57 log10cfu/ml under the same conditions. In conclusion, we suggest employing chitosan and selenium nanoparticles to improve milk safety and recommend future studies for the fate of nanoparticles in milk.

Revealing the Bacterial Quorum-Sensing Effect on the Biofilm Formation of Diatom Cylindrotheca sp. Using Multimodal Imaging

Diatoms contribute to carbon fixation in the oceans by photosynthesis and always form biofouling organized by extracellular polymeric substances (EPS) in the marine environment. Bacteria-produced quorum-sensing signal molecules N-acyl homoserine lactones (AHLs) were found to play an important role in the development of Cylindrotheca sp. in previous studies, but the EPS composition change was unclear. This study used the technology of alcian blue staining and scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM), and time-of-flight secondary ion mass spectrometry (ToF-SIMS) to directly observe the biofilm formation process. The results showed that AHLs promote the growth rates of diatoms and the EPS secretion of biofilm components. AHLs facilitated the diatom-biofilm formation by a forming process dependent on the length of carbon chains. AHLs increased the biofilm thickness and the fluorescence intensity and then altered the three-dimensional (3D) structures of the diatom-biofilm. In addition, the enhanced EPS content in the diatom-biofilm testified that AHLs aided biofilm formation. This study provides a collection of new experimental evidence of the interaction between bacteria and microalgae in fouling biofilms.

Green fabrication of chitosan nanoparticles using Lavendula angustifolia, optimization, characterization and in‑vitro antibiofilm activity

Chitosan nanoparticles (CNPs) are promising polymeric nanoparticles with exceptional physicochemical, antimicrobial and biological characteristics. The CNPs are preferred for a wide range of applications in the food industry, cosmetics, agriculture, medical, and pharmaceutical fields due to their biocompatibility, biodegradability, eco-friendliness, and non-toxicity. In the current study, a biologically based approach was used to biofabricate CNPs using an aqueous extract of Lavendula angustifolia leaves as a reducing agent. The TEM images show that the CNPs were spherical in shape and ranged in size from 7.24 to 9.77 nm. FTIR analysis revealed the presence of several functional groups, including C-H, C-O, CONH₂, NH₂, C-OH and C-O-C. The crystalline nature of CNPs is demonstrated by X-ray diffraction. The thermogravimetric analysis revealed that CNPs are thermally stable. The CNPs' surface is positively charged and has a Zeta potential of 10 mV. For optimising CNPs biofabrication, a face-centered central composite design (FCCCD) with 50 experiments was used. The artificial intelligence-based approach was used to analyse, validate, and predict CNPs biofabrication. The optimal conditions for maximum CNPs biofabrication were theoretically determined using the desirability function and experimentally verified. The optimal conditions that maximize CNPs biofabrication (10.11 mg/mL) were determined to be chitosan concentration 0.5%, leaves extract 75%, and initial pH 4.24. The antibiofilm activity of CNPs was evaluated in‑vitro. The results show that 1500 μg/mL of CNPs suppressed P. aeruginosa, S. aureus and C. albicans biofilm formation by 91.83 ± 1.71%, 55.47 ± 2.12% and 66.4 ± 1.76%; respectively. The promising results of the current study in biofilm inhibition by necrotizing biofilm architecture, reducing its significant constituents and inhibiting microbial cell proliferation encourage their use as natural biosafe and biocompatible anti-adherent coating in antibiofouling membranes, medical bandage/tissues and food packaging materials.

Accessing the biotechnological potential of a novel isolated microalga from a semi-arid region of Brazil

The use of microalgae as a source of food and pharmaceutical ingredients has garnered growing interest in recent years. Despite the rapid growth of the nutraceutical market, knowledge about the potential of bioactive molecules from microalgae remains insufficient. The present study aimed to investigate the biotechnological potential of the green microalga Desmodesmus armatus isolated from a semi-arid region of Brazil. The algal biomass was characterized in terms of gross biochemical composition, exopolysaccharide content, enzymatic inhibition capacity, and antioxidant, antibacterial, and hemolytic activities from solvents of different polarities (water, ethanol, acetone, and hexane). D armatus biomass had 40% of crude protein content, 25.94% of lipids, and 25.03% of carbohydrates. The prebiotic potential of exopolysaccharides from D armatus was demonstrated, which stimulated the growth of Lacticaseibacillus rhamnosus and Lactiplantibacillus plantarum bacteria strains. Moreover, the enzyme inhibition capacity for the proteases chymotrypsin (34.78%-45.8%) and pepsin (16.64%-27.27%), in addition to α-amylase (24.79%) and lipase (31.05%) was confirmed. The antioxidant potential varied between the different extracts, with 2,2-diphenyl-1-picrylhydrazyl sequestration values varying between 17.51% and 63.12%, and those of the 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) method between 6.82% and 22.89%. In the antibacterial activity test, only the ethanolic extract showed inhibition against Listeria sp. (at minimum inhibitory concentration [MIC] = 256 µg mL-1). This fraction also presented the highest significant levels of hemolysis (31.88%-52.45%). In summary, the data presented in the study suggest the presence of biocompounds with biotechnological and nutraceutical potential in the D armatus biomass. Future studies may evaluate the inclusion of this biomass in foods in order to increase their biological value.

Carboxymethylated Rhizoma alismatis Polysaccharides Regulate Calcium Oxalate Crystals Growth and Reduce the Regulated Crystals' Cytotoxicity

OBJECTIVE

This study explored the effects of polysaccharides (RAPD) extracted from the traditional anti-stone Chinese medicine Rhizoma alismatis and their carboxymethylated derivatives (RAPs) on the crystal phase, morphology, and size of calcium oxalate (CaOx). It also determined the damaging ability of the regulated crystals on human renal tubular epithelial cells (HK-2).

METHODS

RAPD carboxymethylation with a carboxyl group (-COOH) content of 3.57% was carried out by the chloroacetic acid solvent method. The effects of -COOH content in RAPs and RAP concentration on the regulation of CaOx crystal growth were studied by controlling the variables. Cell experiments were conducted to explore the differences in the cytotoxicity of RAP-regulated crystals.

RESULTS

The -COOH contents of RAPD, RAP1, RAP2, and RAP3 were 3.57%, 7.79%, 10.84%, and 15.33%, respectively. RAPs can inhibit the growth of calcium oxalate monohydrate (COM) and induce the formation of calcium oxalate dihydrate (COD). When the -COOH content in RAPs was high, their ability to induce COD formation was enhanced. In the crystals induced by RAPs, a high COD content can lower the damage to cells. In particular, the cytotoxicity of the crystals induced by RAP3 was the lowest. When the concentration of RAP3 increased, the cytotoxicity gradually increased due to the reduced size of the formed COD crystals. An interaction was observed between RAPs and crystals, and the number of RAPs adsorbed in the crystals was positively correlated with the -COOH content in RAPs.

CONCLUSIONS

RAPs can reduce the damage of CaOx to HK-2 cells by regulating the crystallization of CaOx crystals and effectively reducing the risk of kidney stone formation. RAPs, especially RAP3 with a high carboxyl group content, has the potential to be developed as a novel green anti-stone drug.

Regulatory mechanism of high-concentration CO2 on polysaccharide accumulation in Tetradesmus obliquus cultured in sludge extract

Microalgae such as Tetradesmus obliquus have great potential in immobilizing high-concentration CO₂ and removing highly toxic organic matters, which could be produced from coal chemical industry and coal chemical wastewater biological treatment process. In this study, Tetradesmus obliquus was cultured in sludge extract and high-concentration CO₂ was added. The maximum cell density and dry weight were respectively (111.46 ± 4.87) × 10⁶ cell/mL and 3.365 ± 0.168 g/L under 30% CO₂. Tetradesmus obliquus accumulated the most polysaccharides (629.60 ± 31.48 mg/L) on the 30th day under 30% CO₂. The results of proteomic showed that the upregulation of A0A2Z4THB7 and A0A383VAT1 promoted polysaccharide accumulation. Polysaccharide was mainly formed at the stable phase instead of the log-growth phase due to the abiotic stress caused by high TOC at the log-growth phase. Collectively, this study revealed the regulatory mechanism of high-concentration CO₂ on the toxicity removal and accumulation of polysaccharides in Tetradesmus obliquus.

Molecular dynamics of seed priming at the crossroads between basic and applied research

The potential of seed priming is still not fully exploited. Our limited knowledge of the molecular dynamics of seed pre-germinative metabolism is the main hindrance to more effective new-generation techniques. Climate change and other recent global crises are disrupting food security. To cope with the current demand for increased food, feed, and biofuel production, while preserving sustainability, continuous technological innovation should be provided to the agri-food sector. Seed priming, a pre-sowing technique used to increase seed vigor, has become a valuable tool due to its potential to enhance germination and stress resilience under changing environments. Successful priming protocols result from the ability to properly act on the seed pre-germinative metabolism and stimulate events that are crucial for seed quality. However, the technique still requires constant optimization, and researchers are committed to addressing some key open questions to overcome such drawbacks. In this review, an update of the current scientific and technical knowledge related to seed priming is provided. The rehydration-dehydration cycle associated with priming treatments can be described in terms of metabolic pathways that are triggered, modulated, or turned off, depending on the seed physiological stage. Understanding the ways seed priming affects, either positively or negatively, such metabolic pathways and impacts gene expression and protein/metabolite accumulation/depletion represents an essential step toward the identification of novel seed quality hallmarks. The need to expand the basic knowledge on the molecular mechanisms ruling the seed response to priming is underlined along with the strong potential of applied research on primed seeds as a source of seed quality hallmarks. This route will hasten the implementation of seed priming techniques needed to support sustainable agriculture systems.

Artificial intelligence-based optimization for chitosan nanoparticles biosynthesis, characterization and in‑vitro assessment of its anti-biofilm potentiality

Chitosan nanoparticles (CNPs) are promising biopolymeric nanoparticles with excellent physicochemical, antimicrobial, and biological properties. CNPs have a wide range of applications due to their unique characteristics, including plant growth promotion and protection, drug delivery, antimicrobials, and encapsulation. The current study describes an alternative, biologically-based strategy for CNPs biosynthesis using Olea europaea leaves extract. Face centered central composite design (FCCCD), with 50 experiments was used for optimization of CNPs biosynthesis. The artificial neural network (ANN) was employed for analyzing, validating, and predicting CNPs biosynthesis using Olea europaea leaves extract. Using the desirability function, the optimum conditions for maximum CNPs biosynthesis were determined theoretically and verified experimentally. The highest experimental yield of CNPs (21.15 mg CNPs/mL) was obtained using chitosan solution of 1%, leaves extract solution of 100%, initial pH 4.47, and incubation time of 60 min at 53.83°C. The SEM and TEM images revealed that CNPs had a spherical form and varied in size between 6.91 and 11.14 nm. X-ray diffraction demonstrates the crystalline nature of CNPs. The surface of the CNPs is positively charged, having a Zeta potential of 33.1 mV. FTIR analysis revealed various functional groups including C-H, C-O, CONH2, NH2, C-OH and C-O-C. The thermogravimetric investigation indicated that CNPs are thermally stable. The CNPs were able to suppress biofilm formation by P. aeruginosa, S. aureus and C. albicans at concentrations ranging from 10 to 1500 µg/mL in a dose-dependent manner. Inhibition of biofilm formation was associated with suppression of metabolic activity, protein/exopolysaccharide moieties, and hydrophobicity of biofilm encased cells (r ˃ 0.9, P = 0.00). Due to their small size, in the range of 6.91 to 11.14 nm, CNPs produced using Olea europaea leaves extract are promising for applications in the medical and pharmaceutical industries, in addition to their potential application in controlling multidrug-resistant microorganisms, especially those associated with post COVID-19 pneumonia in immunosuppressed patients.

Improved effects of combined application of nitrogen-fixing bacteria Azotobacter beijerinckii and microalgae Chlorella pyrenoidosa on wheat growth and saline-alkali soil quality

Soil salinization seriously affects crop yield and soil productivity. The application of bacteria and microalgae has been considered as a promising strategy to alleviate soil salinization. However, the effect of bacteria-microalgae symbiosis on saline-alkali land is still unclear. This study evaluated the effects of Azotobacter beijerinckii, Chlorella pyrenoidosa, and their combined application on the wheat growth and saline-alkali soil improvement. The results showed that, among all the treatments, A. beijerinckii + live C. pyrenoidosa combined inoculation group (BA) had the best effect on increasing wheat plant biomass, improving salt tolerance, and improving soil fertility. The dry weight of wheat plant in the BA group increased by 66.7%, 17.4%, and 35.0%, respectively, compared with the control group (CK), A. beijerinckii inoculation group (B), and live C. pyrenoidosa inoculation group (A). The total nitrogen content of wheat plant in the BA group increased by 69.5%, 76.7%, and 71.1%, compared with the CK, B, and A group. The proline content of wheat plant in the BA group was 100% higher than that in the CK group. The N/P ratio and K/Na ratio of wheat plant increased by 157% and 12.9% in the BA group compared with the CK group, respectively, which was more conducive to alleviating nitrogen limitation and salt stress. The A. beijerinckii + live C. pyrenoidosa inoculation treatment better reduced soil pH and improved the availability of phosphorus in soil. This study illustrated the comprehensive application prospects of bacteria-microalgae interactions on wheat growth promotion and soil improvement in saline-alkali land, and provided a new effective strategy for improving saline-alkali soil quality and increasing crop productivity.

Biosynthesis and Antimicrobial Evaluation of Zinc Oxide Nanoparticles Using Chlorella vulgaris Biomass against Multidrug-Resistant Pathogens

The rampant increase in antibiotic resistance has created a global barrier to the treatment of multidrug-resistant infections. Biogenic synthesis of nanomaterials is a novel approach to producing nanostructures with biological resources. Algae are known to be clean, nontoxic, cost-beneficial, and environmentally acceptable. Chlorella vulgaris is a popular microalga for its broad applications in food, supplements, pharmaceuticals, and cosmetics. In this study, we used Chlorella vulgaris biomass lyophilized powder as our green resource for the biosynthesis ZnONPs. Chlorella vulgaris culture was harvested at the end of the logarithmic phase, and the biomass was lyophilized. ZnONPs were synthesized using lyophilized biomass and 20 mM zinc acetate dihydrate at a temperature of 70 °C and continuous stirring in a water bath overnight. At the end of the reaction, UV-Vis absorption of colloidal suspension proved the synthesis of ZnONPs. The physicochemical characteristics of nanoparticles were analyzed using FTIR, DLS, TEM, and XRD. Based on FTIR spectra. The antibacterial activity of green synthesized nanostructures was evaluated against methicillin-resistant staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE). The synthesized ZnONPs have oxygen-containing groups on the surface that show the synthesized nanoparticles' stabilization. The Zeta potential was -27.4 mV, and the mean particle size was measured as 33.4 nanometers. Biogenic ZnONPs produced in this method have a notable size distribution and excellent surface energy, which can have vast applications like antimicrobial potential in pharmaceuticals as topical forms. Additionally, in order to evaluate the antimicrobial activity of ZnO nanoparticles, we used MRSA and VRE strains and the results showed the anti-MRSA activity at 400 and 625 μg mL^-1, respectively. Thus, these biogenic ZnO nanoparticles revealed a substantial antibacterial effect against multidrug-resistant pathogens, associated with several serious systemic infections, and have the potential as an antimicrobial agent for further study.

Modulation of the metabolite content of the unicellular rhodophyte Porphyridium purpureum using a 2-stage cultivation approach and chemical stressors

There have been growing interests in microalgal biotechnology for the biorefining of bioactive compounds such as carotenoid pigments, ω-3 fatty acids, antioxidants or antimicrobials for sectoral applications in the pharmacology, nutraceutical and cosmetic fields. This study focused on the unicellular marine rhodophyte Porphyridium purpureum CCAP 1380/1 A, which was cultivated via a two-stage batch growth mode for 10 days using hydrogen peroxide (H₂O₂), the phytohormone methyl jasmonate (MJ) and three plant extracts (Passiflora incarnata, Panax ginseng and Valeriana officinalis). The microalgal biomass was then analysed for its protein, phycoerythtin, carbohydrate and pigment composition together with its pigment content and antioxidant activity. Of note, MJ increased the protein and phycoerythtin content (up to 225 µg BSA eq./mg DW and 15 mg/ml, respectively) while both the MJ and H₂O₂ treatments increased carotenoid pigment yields (β-carotene and zeaxanthin, up to 5 and 4 mg/g, respectively). Carbohydrates were enhanced ∼10 fold by the Valeriana officinalis treatment (up 192 μg starch eq./mg). Overall, neutral lipids and antioxidants were mostly negatively affected by the plant extracts. The greatest antioxidant activity registered was obtained with the H₂O₂ treatment (15 μmol Trolox eq./g DW with TEAC assay). P. purpureum contains multiple valuable compounds of commercial interest. These results indicate that they can be favorably modulated using specific cultivation regimes and chemical enhancers, thereby facilitating the exploitation of the biomass by applying a suitable co-refinery pipeline.

Adsorptive recovery of arsenic (III) ions from aqueous solutions using dried Chlamydomonas sp

The present study aimed to descry the effectiveness of dried microalga Chlamydomonas sp. for disposing of arsenic from aqueous solution. The study included examining the impact of some factors on algae's adsorption capacity (optimization study), such as initial concentrations of heavy metal, biosorbent doses, pH and contact time. All trials have been performed at constant temperature 25 °C and shaking speed of 300 rpm. The optimization studying indicated the pH 4, contact time at 60 min, temperature 25 °C and biomass concentration of 0.6 g/l were the best optimum conditions for the bioremediation activity with maximum removal percentage 95.2% and biosorption capacity 53.8 mg/g. Attesting of biosorption by applying FTIR (Fourier transfigure infrared), XRD (X-ray diffraction), SEM-EDX (Scanning Electron Microscope - Energy Dispersive X-ray), DLS (Dynamic light scarring) and ZP (Zeta Potential) was conducted. Also, Kinetics, isotherm equilibrium and thermodynamics were carried out to explain the plausible maximum biosorption capacity and biosorption rate of biosorbent q maximum.

The Therapeutic Potential of Algal Nanoparticles: A Brief Review

Recently, the green synthesis of metallic nanoparticles (NPs) has received tremendous attention as a simple approach. The green pathway of biogenic synthesis of metallic NPs through microbes may provide a sustainable and environmentally friendly protocol. Green technology is the most innovative technology for various biological activities and lacks toxic effects. Reports have shown the algae-mediated synthesis of metal NPs. Algae are widely used for biosynthesis as they grow fast; they produce biomass on average ten times that of plants and are easily utilized experimentally. In the future, the production of metal NPs by different microalgae and their biological activity can be explored in diverse areas such as catalysis, medical diagnosis, and anti-biofilm applications.

Investigation of the chemical composition and physicochemical properties of Chlorella vulgaris biomass treated with pulsed discharges technology for potential use in the food industry

The use of chlorella as a dietary supplement has great prospects. Nevertheless, the processing of chlorella is associated with certain difficulties that limit its use on an industrial scale. Problems with the processing are primarily related to the thick and strong cell wall of chlorella (50-100 nm), which is poorly digested by most vertebrate species due to its complex multilayer structure. Our experiments have shown that discharge pulse treatment contributes to the destruction of the strong cell wall of chlorella. The results of atomic force microscopy and the determination of the antioxidant activity of the suspension confirm this. A study of the chemical composition of dried chlorella biomass showed a content of 56.8% protein and 12.6% fat, which causes a high nutritional value of chlorella. The study of the physicochemical properties of the prepared chlorella preparation showed pronounced hydrophilicity of proteins. Observation of gels with different contents of chlorella preparation, formed during heating and subsequent cooling and stored for seven days at +8 °C, showed that the gels do not emit a synergistic liquid. Total gels based on the chlorella preparation are characterized by high stability. Based on the results obtained, we concluded that the preparation based on disintegrated chlorella has a high potential for functional and technological application in food technologies

Application of RSM for Bioremoval of Methylene Blue Dye from Industrial Wastewater onto Sustainable Walnut Shell (Juglans regia) Biomass

Dyes are a significant group of organic contaminants known to negatively affect both humans and aquatic environments. In the textile industry, interest in agricultural-based adsorbents has increased, particularly around adsorption. In this study, methylene blue was eliminated from an aqueous solution using a walnut (Juglans regia) shell. These materials are widely available and inexpensive, and its cost can be a major factor in wastewater treatment batch experiments. Response surface methodology (RSM) is based on a face-centred central composite design, used to identify the independent variable. With the use of RSM, the biomass of J. regia shells was assessed for its capacity to absorb dyes from aqueous solutions, including methylene blue. Maximum methylene blue dye removal percentages (97.70%) were obtained with a 30 mg/L concentration of methylene blue dye, 1.5 gm of biomass, an initial pH of 6, and a contact duration of 60 min at 25 °C. Additionally, particles were absorbed onto the J. regia shell’s surface throughout the biosorption process, according to scan electron microscopy. Functional groups were discovered in the Fourier Transform Infrared Spectroscopy spectra, which are crucial for binding during the biosorption of methylene blue. It has been demonstrated that J. regia shell biomass performs well as a biosorbent in the removal of methylene blue from wastewater effluents. It is also a promising, biodegradable, environmentally friendly, economical, and cost-effective biosorbent.

Antioxidant, Immunomodulatory and Potential Anticancer Capacity of Polysaccharides (Glucans) from Euglena gracilis G.A. Klebs

The present study was carried out to determine the bioactivity of polysaccharides extracted from Euglena gracilis (EgPs). These were characterized by FT-IR and GC-MS. Cytotoxicity analyses (MTT) were performed on healthy human gingival fibroblast cell lines (HGF-1), obtaining an IC₅₀ of 228.66 µg mL^-1, and cell lines with anticancer activity for colon cancer (HCT-116), breast cancer (MCF-7), human leukemia (U-937, HL-60) and lung cancer (NCl-H460), showing that EgPs have anticancer activity, mainly in HTC-116 cells (IC₅₀ = 26.1 µg mL^-1). The immunological assay determined the immunomodulatory capacity of polysaccharides for the production of proinflammatory cytokines IL-6 and TNF-α in murine macrophages (RAW 264.7) and TNF-α in human monocytes (THP-1). It was observed that the EgPs had a stimulating capacity in the synthesis of these interleukins. The antioxidant capacity of polysaccharides and their biomass were analyzed using the ABTS method (18.30 ± 0.14% and (5.40 ± 0.56%, respectively, and the DPPH method for biomass (17.79 ± 0.57%). We quantitatively profiled HGF-1 proteins by liquid chromatography-tandem mass spectrometry analysis, coupled with 2-plex tandem mass tag labelling, in normal cells. In total, 1346 proteins were identified and quantified with high confidence, of which five were considered to be overexpressed. The data is available through ProteomeXchange, under identifier PXD029076.

Soluble Extracellular Polymeric Substances Produced by Parachlorella kessleri and Chlorella vulgaris: Biochemical Characterization and Assessment of Their Cadmium and Lead Sorption Abilities

In the present study, the potential of lead and cadmium removal by the extracellular polymeric substances (EPS) produced from Parachlorella kessleri and Chlorella vulgaris were investigated. Carbohydrates were the dominant components of EPS from both analyzed species. The contents of reducing sugars, uronic acids, and amino acids were higher in EPS synthesized by C. vulgaris than in EPS from P. kessleri. The analysis of the monosaccharide composition showed the presence of rhamnose, mannose and galactose in the EPS obtained from both species. The ICP-OES (inductively coupled plasma optical emission spectrometry) analyses demonstrated that C. vulgaris EPS showed higher sorption capacity in comparison to P. kessleri EPS. The sorption capacity of C. vulgaris EPS increased with the increase in the amount of metal ions. P. kessleri EPS had a maximum sorption capacity in the presence of 100 mg/L of metal ions. The FTIR analysis demonstrated that the carboxyl, hydroxyl, and carbonyl groups of EPS play a key role in the interactions with metal ions. The present study showed C. vulgaris EPS can be used as a biosorbent in bioremediation processes due to its biochemical composition, the presence of significant amounts of negatively charged uronic acids, and higher sorption capacity.

Study of the Physicochemical and Biological Properties of the Lipid Complex of Marine Microalgae Isolated from the Coastal Areas of the Eastern Water Area of the Baltic Sea

The Baltic Sea algae species composition includes marine euryhaline, freshwater euryhaline, and true brackish water forms. This study aimed to isolate a lipid–pigment complex from microalgae of the Baltic Sea (Kaliningrad region) and investigate its antimicrobial activity against Gram-positive and Gram-negative bacteria. Microalgae were sampled using a box-shaped bottom sampler. Sequencing was used for identification. Spectroscopy and chromatography with mass spectroscopy were used to study the properties of microalgae. Antibiotic activity was determined by the disc diffusion test. Lipids were extracted using the Folch method. Analysis of the results demonstrated the presence of antimicrobial activity of the lipid–pigment complex of microalgae against E. coli (the zone diameter was 17.0 ± 0.47 mm and 17.0 ± 0.21 mm in Chlorella vulgaris and Arthrospira platensis, respectively) and Bacillus pumilus (maximum inhibition diameter 16.0 ± 0.27 mm in C. vulgaris and 16.0 ± 0.22 mm in A. platensis). The cytotoxic and antioxidant activities of the lipid complexes of microalgae C. vulgaris and A. platensis were established and their physicochemical properties and fatty acid composition were studied. The results demonstrated that the lipid–pigment complex under experimental conditions was the most effective against P. pentosaceus among Gram-positive bacteria. Antimicrobial activity is directly related to the concentration of the lipid–pigment complex. The presence of antibacterial activity in microalgae lipid–pigment complexes opens the door to the development of alternative natural preparations for the prevention of microbial contamination of feed. Because of their biological activity, Baltic Sea microalgae can be used as an alternative to banned antibiotics in a variety of fields, including agriculture, medicine, cosmetology, and food preservation.

Identification of Metabolites with Antibacterial Activities by Analyzing the FTIR Spectra of Microalgae

Biologically active substances from microalgae can exhibit antioxidant, immunostimulating, antibacterial, antiviral, antitumor, antihypertensive, regenerative, and neuroprotective effects. Lipid complexes of microalgae Chlorella vulgaris and Arthrospira platensis exhibit antibacterial activity and inhibit the growth of the Gram-positive strain Bacillus subtilis; the maximum zone of inhibition is 0.7 ± 0.03 cm at all concentrations. The carbohydrate-containing complex of C. vulgaris exhibits antibacterial activity, inhibits the growth of the Gram-positive strain B. subtilis, Bacillus pumilus; the maximum zone of inhibition is 3.5 ± 0.17 cm at all concentrations considered. The carbohydrate complex of A. platensis has antimicrobial activity against the Gram-negative strain of Escherichia coli at all concentrations, and the zone of inhibition is 2.0–3.0 cm. The presence of mythelenic, carbonyl groups, ester bonds between fatty acids and glycerol in lipid molecules, the stretching vibration of the phosphate group PO₂, neutral lipids, glyco- and phospholipids, and unsaturated fatty acids, such as γ-linolenic, was revealed using FTIR spectra. Spectral peaks characteristic of saccharides were found, and there were cellulose and starch absorption bands, pyranose rings, and phenolic compounds. Both algae in this study had phenolic and alcohol components, which had high antibacterial activity. Microalgae can be used as biologically active food additives and/or as an alternative to antibiotic feed in animal husbandry due to their antibacterial properties.

Extracellular Metabolites of Heterotrophic Auxenochlorella protothecoides: A New Source of Bio-Stimulants for Higher Plants

The biodiversity of microalgal species is enormous, and their versatile metabolism produces a wide diversity of compounds that can be used in food, healthcare, and other applications. Microalgae are also a potential source of bio-stimulants that enhance nutrition efficiency, abiotic stress tolerance, and/or crop quality traits. In this study, the extracellular metabolites of Auxenochlorella protothecoides (EAp) were prepared using three different culture strategies, and their effects on plant growth were examined. Furthermore, the composition of EAp was analyzed by GC-MS. The elongation of lateral roots and the cold-tolerance of Arabidopsis thaliana and Nicotiana benthamiana were promoted by EAp. Moreover, EAp from high-cell-density fermentation stimulated the growth of the leafy vegetables Brassica rapa and Lactuca sativa at dilutions as high as 500- and 1000-fold. Three major groups of compounds were identified by GC-MS, including organic acids or organic acid esters, phenols, and saccharides. Some of these compounds have known plant–stimulating effects, while the rest requires further investigation in the future. Our study demonstrates that EAp is a potential bio-stimulant, while also providing an environmentally friendly and economical microalgae fermentation process.

Microalgae as feedstock for bioactive polysaccharides

Due to the increase in industrial demand for new biosourced molecules (notably bioactive exopolysaccharides (EPS)), microalgae are gaining popularity because of their nutraceutical potential and benefits health. Such health effects are delivered by specific secondary metabolites, e.g., pigments, exopolysaccharides, polyunsaturated fatty acids, proteins, and glycolipids. These are suitable for the subsequent uses in cosmetic, nutraceutical, pharmaceutical, biofuels, biological waste treatment, animal feed and food fields. In this regard, a special focus has been given in this review to describe the various methods used for extraction and purification of polysaccharides. The second part of the review provides an up-to-date and comprehensive summary of parameters affecting the microalgae growth and insights to maximize the metabolic output by understanding the intricacies of algal development and polysaccharides production. In the ultimate part, the health and nutraceutical claims associated with marine algal bioactive polysaccharides, explaining their noticeable potential for biotechnological applications, are summarized and comprehensively discussed.

NF-κB and AMPK-Nrf2 pathways support the protective effect of polysaccharides from Polygonatum cyrtonema Hua in lipopolysaccharide-induced acute lung injury

ETHNOPHARMACOLOGICAL RELEVANCE

The raw and honey-processed P. cyrtonema recorded in ancient classics of Chinese medicine as having the effect of moisturizing the lungs and relieving coughs, and it has also been proved to have therapeutic effects on lung diseases in modern research. Polysaccharides are the main components with biological activities in raw and honey-processed P. cyrtonema, but there is no research for their lung-protective effect.

AIM OF STUDY

This study aimed to investigate the protective effect and the possible mechanism of polysaccharides from raw and honey-processed P. cyrtonema in LPS-induced acute lung injury in mice.

MATERIALS AND METHODS

Polysaccharides, PCP and HPCP, were respectively separated and extracted from raw and honey-processed P. cyrtonema, and the molecular weight, monosaccharide composition and other basic chemical characteristics were analyzed by HPGCP, HPLC, FI-IR, and NMR. The model of ALI mice was established by intratracheal instillation of LPS. Moreover, the protective effects of PCP and HPCP for ALI mice were evaluated by detecting the wet-to-dry ratio and histopathology in the lungs, the content of inflammatory factors TNF-α, IL-6, IL-1β in BLAF, and the content of MPO and SOD in lung tissue. In addition, the lung-protective mechanism of PCP and HPCP was explored by detecting the levels of some proteins and mRNA related to inflammation and oxidative stress pathways.

RESULTS

PCP and HPCP with molecular weights of 8.842 × 10³ and 5.521 × 10³Da were mainly composed of three monosaccharides. Moreover, it is found that fructose and galactose were mainly β-D, and glucose was α-D. Both PCP and HPCP could significantly improve lung injury, reduce the level of inflammatory factors in BALF and the level of MPO in lung tissue, and increase the level of SOD. In addition, PCR and WB indicated that PCP and HPCP at least inhibited pulmonary inflammation through the NF-κB pathway, and reduced the occurrence of pulmonary oxidative stress through the AMPK-Nrf2 pathway.

CONCLUSIONS

Polysaccharides from raw and honey-processed P. cyrtonema had a protective effect in LPS-induced lung injury in mice. This effect may be related to the antioxidant and anti-inflammatory activities of PCP and HPCP in the lungs through the NF-κB pathway and AMPK-Nrf2 pathway. And HPCP seems to perform more than PCP.

Structural analysis and in vitro antitumor effect of polysaccharides from Pholiota adiposa

Pholiota adiposa is an edible chestnut mushroom with many health benefits, such as antioxidant and anticancer activity. In this paper, polysaccharides were extracted from Pholidota adiposa using an acid extraction process. The crude polysaccharide was purified using DEAE-cellulose chromatography, and two polysaccharide fractions of SPAP2-1 and SPAP2-2 were obtained. The structure was characterized using UV, GPC, GC, FT-IR, methylation, and NMR analysis. Monosaccharide component analysis indicated that SPAP2-1 (19 kDa) and SPAP2-2 (20 kDa) contained mannose, glucose, and galactose with different molecular ratios. Their antitumor effects were investigated using the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl tetrazolium (MTT) assay, Annexin V-fluorescein isothiocyanate (FITC), propidium iodide (PI) staining, and flow cytometry. By analyzing the changes in the cells, SPAP2-1 caused damage and changed the proliferation rate of HeLa cells. SPAP2-1 showed strong interference to the cell cycle of HeLa cells and induced cell apoptosis. Overall, these results suggested that polysaccharides from Pholiota adiposa, especially SPAP2-1, may have the potential to be used as a tumor cell inhibitor, which needs further study.

Recent biotechnological developments in reshaping the microalgal genome: A signal for green recovery in biorefinery practices

The use of renewable energy sources as a substitute for nonrenewable fossil fuels is urgently required. Algae biorefinery platform provides an excellent alternate to overcome future energy problems. However, to let this viable biomass be competent with existing feedstocks, it is necessary to exploit genetic manipulation and improvement in upstream and downstream platforms for optimal bio-product recovery. Furthermore, the techno-economic strategies further maximize metabolites production for biofuel, biohydrogen, and other industrial applications. The experimental methodologies in algal photobioreactor promote high biomass production, enriched in lipid and starch content in limited environmental conditions. This review presents an optimization framework combining genetic manipulation methods to simulate microalgal growth dynamics, understand the complexity of algal biorefinery to scale up, and identify green strategies for techno-economic feasibility of algae for biomass conversion. Overall, the algal biorefinery opens up new possibilities for the valorization of algae biomass and the synthesis of various novel products.

Gallic acid-coated silver nanoparticles as perspective drug nanocarriers: bioanalytical study

The ability of silver nanoparticles (AgNPs) to be used as drug nanocarriers has helped rapidly to invent novel strategies to treat diseases, such as cancer. The nanoparticles may offer a valuable tool to novel pH-sensitive drug delivery systems in the present scenario because of their undergoing mechanisms associated with the regulated dissolution, aggregation, and generation of oxygen radicals as well. These processes could be monitored by electrochemical (bio)sensors that are less money and time-consuming compared to other analytical approaches, however, with comparable analytical performance. In this paper, synthesized and microscopically characterized gallic acid-coated AgNPs (GA-AgNPs) are investigated using spectral and electrochemical methods. To investigate the Ag⁺ release, a 21-day ageing experiment is performed spectrophotometrically, finding that the peak maximum of GA-AgNPs spectra diminished by 24.5%. The highest Ag⁺ content was electrochemically determined in the supernatant solution after centrifugation (6.97 μmol·L^-1), while no significant concentration of silver ions in solution after redispersion was observed (1.26 μmol·L^-1). The interaction experiment indicates a stabilization of GA-AgNPs in the presence of long-chain dsDNA as well as a mutual electrostatic interaction with DNA sugar-phosphate backbone. This interaction mechanism is confirmed by FTIR analysis, showing a shift (1049 to 1061 cm^-1 and 913 to 964 cm^-1) specific to DNA phosphate bands. Finally, doxorubicin-loaded GA-AgNPs are monitored for the specific drug release in the physiological and more reactive weakly acidic microenvironment. Hereby, electrochemical (bio)sensing of GA-AgNPs undergoing mechanisms shows a huge potential to be used for monitoring of drug delivery systems at cancer therapy.

Characterization, antioxidant and anticoagulant properties of exopolysaccharide from marine microalgae

The sulfated exopolysaccharide extracted from marine microalgae attracted considerable attention from both the nutraceutical and pharmaceutical industries. In the present study biomass of five marine microalgae were screened to find strains with high capacity for the production of sulfated exopolysaccharides. The anticoagulant and antioxidant activities of extracted sulfated polysaccharides were evaluated using activated partial thromboplastin time (aPTT), prothrombin time (PT), DPPH and ABTS assays, respectively. The sulfated polysaccharides extracted from Picochlorum sp. showed a strong DPPH scavenging effect with 85% antioxidant activity. The sulfated polysaccharides of Chlorella sorokiniana, Chlorella sp. (L₂) and Chlorella sp. (D₁) scavenged more than 90% of the ABTS radicals. However, the sulfated polysaccharide extracted from Chlorella sorokiniana, and Chlorella sp. (N4) showed anticoagulant properties. The dual anticoagulant-antioxidant activities in Chlorella sorokiniana could be explained by the combination of various factors including sulfate content and their binding site, monosaccharide residue and glycoside bond which are involved in the polysaccharide’s bioactivity.

Sulfated exopolysaccharides (sPS) were extracted from marine green microalgae by the heated acid extraction method.

sPS with the higher sulfate/sugar ratio presented potent ABTS radical scavenging activity.

Some of the sPS revealed anticoagulant effects in activated partial thromboplastin time (aPTT) and prothrombin time (PT) assays.

Potential of three local marine microalgae from Tunisian coasts for cadmium, lead and chromium removals

Metal elements are widely used in various industrial activities and are considered as common water source contaminants. Thus, the development of cost-effective, simple design and efficient processes for trace metal elements removal from contaminated water sources is of great interest. The effects of cadmium, lead and chromium on growth, biomolecules accumulation and metabolic responses of Amphora coffaeiformis, Navicula salinicola and Dunaliella salina isolated from Tunisian coasts were tested. The bioremediation capacities of the three microalgae strains and the mechanisms involved in ions metal removal were also investigated. N. salinicola and D. salina seem to be better tolerating to Cr, while A. coffaeiformis and N. salinicola showed high resistance to Pb. The expression profile analyses by qRT-PCR of the antioxidant defense-related genes revealed that Cd, Pb and Cr treatments induce the up-regulation of catalase and superoxide dismutase coding genes for A. coffaeiformis and D. salina. Regarding N. salinicola, the catalase coding gene seems to be overexpressed after Cd, Pb and Cr exposure while only Cd and Cr induce superoxide dismutase gene overexpression. Moreover, the phytochelatin synthase (a metal chelator synthesis-related gene) was up-regulated in N. salinicola, A. coffaeiformis and D. salina after Cr exposure and also in A. coffaeiformis and D. salina after Cd exposure. While Pb treatments induce overexpression of phytochelatin synthase coding gene only for D. salina. Studied strains showed promising metal removal efficiencies for both Pb and Cr ions metals reached 95% for D. salina. Ion metal removal mechanisms study revealed that intracellular bioaccumulation process is used by D. salina for Cr up-taking. However, both intracellular and extracellular removal mechanisms are involved for Pb and Cr removal using A. coffaeiformis, N. salinicola and for Pb removal using D. salina. FTIR analysis demonstrated that several functional groups as carboxyl, hydroxyl, amino, phosphate and sulfate may participate in the bioadsorption process.

Bioactivity and Plant Growth Stimulation Studies using Mangifera indica L. Gum

The potential of plant gum as a bioactive agent and plant growth enhancer has not been exploited well and plant gums are suitable for such purposes as they are non-toxic and biodegradable. Therefore, the aim of this study was to verify the potential of Mangifera indica (MI) gum as a bioactive agent and plant growth enhancer. Plant gum was collected from the bark of MI and polysaccharides were extracted, purified and characterized with ultraviolet-visible (UV-Vis) spectroscopic, Fourier-transform infrared spectroscopy and gas chromatography (GC) analyses. Crude and purified polysaccharides were tested for their antibacterial and antioxidant activity. The crude gum was subjected to plant growth stimulation study like germination percentage, shoot length, root length and wet weight of chilli (Capsicum frutescens). The effect of MI gum on soil porosity and water holding capacity (WHC) was also tested. UV-Vis and GC analyses of gum polysaccharide showed the presence of several types of monosaccharides in MI gum. The plant gum did not show any antibacterial activity against Escherichia coli, Pseudomonas sp., Bacillus sp. and Staphylococcus aureus, but was found to exhibit low antioxidant activity. The gum was found to enhance the seed germination and seedling growth in-vitro and in-vivo.

Integrated microalgal biorefinery for the production and application of biostimulants in circular bioeconomy

Adverse detrimental impacts of environmental pollution over the health regimen of people has driven a shift in lifestyle towards cleaner and natural resources, especially in the aspects of food production and consumption. Microalgae are considered a rich source of high value metabolites to be utilized as plant growth biostimulants. These organisms however, are underrated compared to other microbial counterparts, due to inappropriate knowledge on the technical, enviro-economical constrains leading to low market credibility. Thus, to avert these issues, the present review comprehensively discusses the biostimulatory potential of microalgae interactively combined with circular bio-economy perspectives. The biochemical content and intracellular action mechanism of microalgal biostimulants were described. Furthermore, detailed country-wise market trends along with the description of the existing regulatory policies are included. Enviro-techno-economic challenges are discussed, and the consensus need for shift to biorefinery and circular bio-economy concept are emphasized to achieve sustainable impacts during the commercialization of microalgal biostimulants.