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Search Results (226)

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Keywords = Scenedesmus

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11 pages, 1392 KiB  
Article
Microalgae Scenedesmus sp. as a Potential Inoculum in a CO2 Capture Device Against Changes in Environmental Temperature
by Yolanda Garrido, Joaquín Quesada-Medina, José David Sánchez, Ana Sánchez-Zurano, Eduardo Iniesta-López, Adrián Hernández-Fernández, Antonia Pérez de los Ríos and Francisco José Hernández-Fernández
Processes 2025, 13(8), 2479; https://doi.org/10.3390/pr13082479 - 6 Aug 2025
Abstract
This study investigates the viability of a native Scenedesmus sp. strain for use in a 50 L bubble column photobioreactor designed to reduce greenhouse gas emissions under simulated spring, extreme summer, and winter conditions. The experiments were conducted by placing the reactor in [...] Read more.
This study investigates the viability of a native Scenedesmus sp. strain for use in a 50 L bubble column photobioreactor designed to reduce greenhouse gas emissions under simulated spring, extreme summer, and winter conditions. The experiments were conducted by placing the reactor in a controlled climatic chamber, which allowed us to regulate the temperature, light intensity, and day–night cycles throughout the entire experiment. The results showed that under simulated spring conditions (a maximum temperature of 22 °C), the algal culture grew continuously for 61 days. Under extreme summer conditions (a maximum temperature of 39 °C), an initial drop in cell density was followed by recovery and continued growth over 75 days, although biomass production was 35% lower. Under winter conditions (a maximum temperature of 10 °C), the culture failed, indicating the need to prevent temperatures below 10 °C. In terms of biomass production, the culture densities achieved were 1.04 g L−1 and 0.68 g L−1 in the spring and summer trials, respectively. The Scenedesmus sp. strain demonstrated high carbon capture efficiency, tolerance to extreme heat, and sustained growth without the need for fresh medium or pH adjustments for over 60 days during spring and extreme summer conditions, confirming its potential for outdoor applications. Full article
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10 pages, 4976 KiB  
Article
Investigating the Effects of Hydraulic Shear on Scenedesmus quadricauda Growth at the Cell Scale Using an Algal-Cell Dynamic Continuous Observation Platform
by Yao Qu, Jiahuan Qian, Zhihua Lu, Ruihong Chen, Sheng Zhang, Jingyuan Cui, Chenyu Song, Haiping Zhang and Yafei Cui
Microorganisms 2025, 13(8), 1776; https://doi.org/10.3390/microorganisms13081776 - 30 Jul 2025
Viewed by 184
Abstract
Hydraulic shear has been widely accepted as one of the essential factors modulating phytoplankton growth. Previous experimental studies of algal growth have been conducted at the macroscopic level, and direct observation at the cell scale has been lacking. In this study, an algal-cell [...] Read more.
Hydraulic shear has been widely accepted as one of the essential factors modulating phytoplankton growth. Previous experimental studies of algal growth have been conducted at the macroscopic level, and direct observation at the cell scale has been lacking. In this study, an algal-cell dynamic continuous observation platform (ACDCOP) is proposed with a parallel-plate flow chamber (PPFC) to capture cellular growth images which are then used as input to a computer vision algorithm featuring a pre-trained backpropagation neural network to quantitatively evaluate the volumes and volumetric growth rates of individual cells. The platform was applied to investigate the growth of Scenedesmus quadricauda cells under different hydraulic shear stress conditions. The results indicated that the threshold shear stress for the development of Scenedesmus quadricauda cells was 270 µL min−1 (5.62 × 10−5 m2 s−3). Cellular growth was inhibited at very low and very high intensities of hydraulic shear. Among all the experimental groups, the longest growth period for a cell, from attachment to PPFC to cell division, was 5.7 days. Cells with larger initial volumes produced larger volumes at division. The proposed platform could provide a novel approach for algal research by enabling direct observation of algal growth at the cell scale, and could potentially be applied to investigate the impacts of various environmental stressors such as nutrient, temperature, and light on cellular growth in different algal species. Full article
(This article belongs to the Section Environmental Microbiology)
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16 pages, 1658 KiB  
Article
Environmentally Friendly Chelation for Enhanced Algal Biomass Deashing
by Agyare Asante, George Daramola, Ryan W. Davis and Sandeep Kumar
Phycology 2025, 5(3), 32; https://doi.org/10.3390/phycology5030032 - 23 Jul 2025
Viewed by 302
Abstract
High ash content in algal biomass limits its suitability for biofuel production by reducing combustion efficiency and increasing fouling. This study presents a green deashing strategy using nitrilotriacetic acid (NTA) and deionized (DI) water to purify Scenedesmus algae, which was selected for its [...] Read more.
High ash content in algal biomass limits its suitability for biofuel production by reducing combustion efficiency and increasing fouling. This study presents a green deashing strategy using nitrilotriacetic acid (NTA) and deionized (DI) water to purify Scenedesmus algae, which was selected for its high ash removal potential. The optimized sequential treatment (DI, NTA chelation, and DI+NTA treatment at 90–130 °C) achieved up to 83.07% ash removal, reducing ash content from 15.2% to 3.8%. Elevated temperatures enhanced the removal of calcium, magnesium, and potassium, while heavy metals like lead and copper were reduced below detection limits. CHN analysis confirmed minimal loss of organic content, preserving biochemical integrity. Unlike traditional acid leaching, this method is eco-friendly after three cycles. The approach offers a scalable, sustainable solution to improve algal biomass quality for thermochemical conversion and supports circular bioeconomy goals. Full article
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16 pages, 2838 KiB  
Article
Transcriptomic Response of Azospirillum brasilense Co-Cultured with Green Microalgae Chlorella sp. and Scenedesmus sp. During CO2 Biogas Fixation
by Carolina Garciglia-Mercado, Oskar A. Palacios, Claudia A. Contreras-Godínez, Jony Ramiro Torres-Velázquez and Francisco J. Choix
Processes 2025, 13(7), 2177; https://doi.org/10.3390/pr13072177 - 8 Jul 2025
Viewed by 695
Abstract
Microalgal–bacterial consortia are the environmentally sustainable biotechnological strategy to enhance the potential of microalgae. Understanding the regulatory mechanisms that enable bacteria to adapt to culture conditions of each bioprocess is crucial to ensure a successful synergic interaction. Thus, the present study evaluated the [...] Read more.
Microalgal–bacterial consortia are the environmentally sustainable biotechnological strategy to enhance the potential of microalgae. Understanding the regulatory mechanisms that enable bacteria to adapt to culture conditions of each bioprocess is crucial to ensure a successful synergic interaction. Thus, the present study evaluated the transcriptomic response of microalgal growth-promoting bacteria (MGPB) A. brasilense separately co-cultured with both green microalgae Scenedesmus sp. and Chlorella sorokiniana during CO2 fixation from biogas through a microarray-based approach. The transcriptome profiling revealed a total of 416 differentially expressed genes (DEGs) in A. brasilense: 228 (140 upregulated and 88 downregulated) interacting with Scenedesmus sp. and 188 (40 upregulated and 148 downregulated) associated with C. sorokiniana. These results support the modulation of signal molecules: indole-3-acetic acid (IAA), riboflavin, and biotin, during co-cultivation with both microalgae. The findings suggest that the metabolic A. brasilense adaptation was mainly favored during the mutualistic interaction with Scenedesmus sp. Finally, a valuable contribution is provided to the biotechnological potential of the microalga–Azospirillum consortium as an environmentally sustainable strategy to improve the bio-refinery capacity of these microalgae and biogas upgrading by valorizing CO2 of these gaseous effluent. Full article
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24 pages, 364 KiB  
Review
A Review on Innovative Strategies Towards Sustainable Drug Waste Management Through Algae-Based Systems
by Salvatore Avilia, Elio Pozzuoli, Manuela Iovinella, Claudia Ciniglia and Stefania Papa
Sci 2025, 7(3), 92; https://doi.org/10.3390/sci7030092 - 1 Jul 2025
Viewed by 508
Abstract
Drug removal from urban wastewater (UW) is a topic of growing interest. The new European Directive addresses this problem by introducing quaternary treatment by 2045, as part of the “Zero Pollution” plan from a One Health perspective. In this context, the role of [...] Read more.
Drug removal from urban wastewater (UW) is a topic of growing interest. The new European Directive addresses this problem by introducing quaternary treatment by 2045, as part of the “Zero Pollution” plan from a One Health perspective. In this context, the role of microalgae remains very promising in achieving clean and safe effluents, although its cost–benefit ratio needs to be carefully evaluated. The purpose of this review is to disclose the latest approaches to drug removal and energy recovery from UWs adopting different algae (Chlorella spp., Galdieria spp., and Scenedesmus spp.), to provide a detailed background for further research towards the development of new effective strategies on UW remediation while producing clean energy. We examined the most recent studies, considering most drugs found in wastewater, their management, as well as strategies used to recover energy while being mindful of a circular economy. There is growing interest in algae-based systems. The latest findings on algae–bacteria consortia show that it could be a better alternative to suspended biomass and represent a way to manage drug waste. This finding suggests that large-scale experiments should be conducted to confirm the potential benefits of such waste treatments. Full article
25 pages, 1107 KiB  
Review
Microalgae Cultivation in Wastewater: How Realistic Is This Approach for Value-Added Product Production?
by Rosangela Rodrigues Dias, Mariany Costa Deprá, Cristiano Ragagnin de Menezes, Leila Queiroz Zepka and Eduardo Jacob-Lopes
Processes 2025, 13(7), 2052; https://doi.org/10.3390/pr13072052 - 28 Jun 2025
Viewed by 710
Abstract
Microalgae cultivation in wastewater is a production approach that combines wastewater treatment with biomass generation for various applications. This strategy aligns with the concept of a circular bioeconomy, which aims to transform waste into valuable resources. However, although this is true, this synergy’s [...] Read more.
Microalgae cultivation in wastewater is a production approach that combines wastewater treatment with biomass generation for various applications. This strategy aligns with the concept of a circular bioeconomy, which aims to transform waste into valuable resources. However, although this is true, this synergy’s potential bumps into obstacles that still limit the consolidation of the commercial cultivation of microalgae using wastewater. This review analyzed how close or far we are from achieving the successful integration of commercial microalgae cultivation with wastewater treatment for the production of value-added products. The analysis of the scientific literature highlighted that certain strains, such as Chlorella, Arthrospira, and Scenedesmus, can remove up to 90% of nitrogen and phosphorus from effluents while maintaining productivities of up to 45 g/m2/day. The techno-economic analyses presented here indicate that production costs range between 1.98 and 9.69 EUR/kg, depending on the effluent composition and biomass productivity. From an environmental perspective, replacing synthetic media with wastewater can significantly reduce input use, but the environmental impacts associated with energy consumption remain a challenge. This paper also discusses the technological readiness level (TRL), which currently remains between levels 4 and 6, concentrated on demonstration and pilot scales. By gathering and critically analyzing the current literature, this work seeks to answer how realistic and sustainable this integration is today. Full article
(This article belongs to the Special Issue Research on Conversion and Utilization of Waste Biomass)
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20 pages, 888 KiB  
Article
The Cecal Distribution of Microalgal Pigments in Rats: Do Carotenoids and Chlorophylls Play a Pharmacobiotic Role?
by Tatiele Casagrande do Nascimento, Patrícia Acosta Caetano, Marcylene Vieira da Silveira, Luiz Eduardo Lobo, Uashington Da Silva Riste, Mariany Costa Deprá, Maria Rosa Chitolina Schetinger, Cristiano Ragagnin de Menezes, Roger Wagner, Eduardo Jacob-Lopes and Leila Queiroz Zepka
Foods 2025, 14(13), 2172; https://doi.org/10.3390/foods14132172 - 21 Jun 2025
Viewed by 369
Abstract
This study investigated the cecal distribution of lipophilic pigments (carotenoids and chlorophylls) from Scenedesmus obliquus and their effects on the activity of the intestinal microbiota in rats. Oleoresins containing different concentrations of microalgal pigments (from 0 to 600 µg·kg−1bw·d1 [...] Read more.
This study investigated the cecal distribution of lipophilic pigments (carotenoids and chlorophylls) from Scenedesmus obliquus and their effects on the activity of the intestinal microbiota in rats. Oleoresins containing different concentrations of microalgal pigments (from 0 to 600 µg·kg−1bw·d1), previously characterized by chromatographic and spectrometric analyses, were administered for four weeks. At the end of the intervention, cecal content samples were collected and analyzed for their pigment composition, short-chain fatty acids (SCFAs), and probiotic microbiota. Nine pigments were identified in the cecal samples, with all-trans-zeaxanthin and pheophytin being the most abundant in all groups. Furthermore, 15-cis-lutein, all-trans-β-cryptoxanthin, and 9-cis-β-carotene—found exclusively in microalgal oleoresin—were detected only in animals receiving doses above 300 µg·kg−1bw.day−1, indicating a link with the SCFA modulation. These supplementations significantly increased the levels of acetate (300 and 450 µg·kg−1bw·d−1 −13% and 14%), butyrate (300 µg kg−1bw·d−1 −19%), and propionate (600 µg·kg−1bw·d−1 −16%). Notably, 300 µg·kg−1bw·d−1 significantly increased Bifidobacterium and Lactobacillus populations. Overall, the pigment supplementation positively influenced the gut microbiota composition and SCFA production in a dose-dependent manner, particularly at 300 µg·kg−1bw·d−1. These results support the potential application of microalgal pigments as functional food ingredients or supplements with gut health benefits. Full article
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18 pages, 5001 KiB  
Article
Repair Effects of Scenedesmus obliquus on Cucumber Seedlings Under Saline–Alkali Stress
by Zhao Liu, Yanlong Dong, Xiaoxia Jin, Yan Liu, Zhonghui Yue and Wei Li
Agronomy 2025, 15(6), 1468; https://doi.org/10.3390/agronomy15061468 - 16 Jun 2025
Viewed by 509
Abstract
In this study, cucumber seedlings were treated with Scenedesmus obliquus at different concentrations (0.25, 0.50, 0.75, 1 g·L−1) under saline–alkali stress (60 mM and 90 mM). The effects of Scenedesmus obliquus on the repair of cucumber seedlings under saline–alkali stress were [...] Read more.
In this study, cucumber seedlings were treated with Scenedesmus obliquus at different concentrations (0.25, 0.50, 0.75, 1 g·L−1) under saline–alkali stress (60 mM and 90 mM). The effects of Scenedesmus obliquus on the repair of cucumber seedlings under saline–alkali stress were explored from physiological and morphological perspectives by measuring growth physiological indices and observing microstructure. It provides a cytological basis for the development of microalgae biofertilizer. The results showed that the addition of Scenedesmus obliquus effectively alleviated the physiological and structural damage in cucumber seedlings caused by saline–alkali stress, with the best mitigation effect at 0.75 g·L−1. More specifically, the addition of Scenedesmus obliquus significantly improved seedling fresh weight and plant height under saline–alkali stress, increased stem vascular vessel diameter, thickened vessel walls, reduced structural damage, the structural recovery of mitochondria, nuclei, and other organelles in the phloem; The results showed that root xylem vessel distribution became more centralized, vessel diameter decreased, and wall thickness decreased, with other changes similar to those in the stem; The number and volume of mesophyll cells increased, chloroplast morphology recovered, and chlorophyll content rose, effectively alleviating the impact of saline–alkali stress on photosynthesis. MDA content decreased, mitigating oxidative damage caused by saline–alkali stress. Full article
(This article belongs to the Section Plant-Crop Biology and Biochemistry)
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19 pages, 2755 KiB  
Article
Real-Time Algal Monitoring Using Novel Machine Learning Approaches
by Seyit Uguz, Yavuz Selim Sahin, Pradeep Kumar, Xufei Yang and Gary Anderson
Big Data Cogn. Comput. 2025, 9(6), 153; https://doi.org/10.3390/bdcc9060153 - 9 Jun 2025
Cited by 2 | Viewed by 881
Abstract
Monitoring algal growth rates and estimating microalgae concentration in photobioreactor systems are critical for optimizing production efficiency. Traditional methods—such as microscopy, fluorescence, flow cytometry, spectroscopy, and macroscopic approaches—while accurate, are often costly, time-consuming, labor-intensive, and susceptible to contamination or production interference. To overcome [...] Read more.
Monitoring algal growth rates and estimating microalgae concentration in photobioreactor systems are critical for optimizing production efficiency. Traditional methods—such as microscopy, fluorescence, flow cytometry, spectroscopy, and macroscopic approaches—while accurate, are often costly, time-consuming, labor-intensive, and susceptible to contamination or production interference. To overcome these limitations, this study proposes an automated, real-time, and cost-effective solution by integrating machine learning with image-based analysis. We evaluated the performance of Decision Trees (DTS), Random Forests (RF), Gradient Boosting Machines (GBM), and K-Nearest Neighbors (k-NN) algorithms using RGB color histograms extracted from images of Scenedesmus dimorphus cultures. Ground truth data were obtained via manual cell enumeration under a microscope and dry biomass measurements. Among the models tested, DTS achieved the highest accuracy for cell count prediction (R2 = 0.77), while RF demonstrated superior performance for dry biomass estimation (R2 = 0.66). Compared to conventional methods, the proposed ML-based approach offers a low-cost, non-invasive, and scalable alternative that significantly reduces manual effort and response time. These findings highlight the potential of machine learning–driven imaging systems for continuous, real-time monitoring in industrial-scale microalgae cultivation. Full article
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18 pages, 2566 KiB  
Article
Potential of Natural Sheep Casings Waste as a Sole Nitrogen Source for the Marine Microalga Scenedesmus rubescens MDP19 Growth and Lipid Production
by Sanaa Ouzakar, Nadia Skali Senhaji, Francesca Rigano, Cinzia Cafarella, Francesco Cacciola, Luigi Mondello and Jamal Abrini
Recycling 2025, 10(3), 109; https://doi.org/10.3390/recycling10030109 - 1 Jun 2025
Viewed by 1039
Abstract
The meat industry is one of the main sources of organic waste in the food processing sector. Due to their high content of biodegradable organic matter, these wastes represent a potentially valuable resource for the development of recycling and valorization processes, particularly with [...] Read more.
The meat industry is one of the main sources of organic waste in the food processing sector. Due to their high content of biodegradable organic matter, these wastes represent a potentially valuable resource for the development of recycling and valorization processes, particularly with regard to the circular economy and environmental sustainability. The present study aimed at assessing the potential of natural sheep casings waste (NSCW) as a source of nitrogen for promoting the growth and lipid production of Scenedesmus rubescens MDP19, a marine microalga isolated from the Mediterranean coastline of northern Morocco. For this purpose, we evaluated the effects of different NSCW concentrations (0.25–5 g L−1) on the microalga growth, its ability to utilize organic waste components (proteins, amino acids, and carbohydrates) as nutrients, and its efficiency in eliminating nitrogen and phosphorus. Lipid and pigment contents were determined using colorimetric methods, and their composition was analyzed by high-performance liquid chromatography coupled with atmospheric pressure chemical ionization mass spectrometry (HPLC-APCI-MS/MS). The results showed that S. rubescens MDP19 achieved the highest biomass production of 1.737 g L−1 at an NSCW concentration of 5 g L−1. This strain removed 33.70–47.63% of protein, 71.84–87.62% of amino acids, 41.9–92.97% of carbohydrates, 59.72–99.30% of nitrogen, and 80.74–99.10% of phosphorus. Furthermore, S. rubescens MDP19 showed a significantly enhanced lipid content (68.11%) at an NSCW concentration of 0.5 g L−1. At this concentration, the lipid composition of S. rubescens MDP19 was particularly complex, including monounsaturated and polyunsaturated fatty acids, digalactosyldiacylglycerols, sulfoquinovosyldiacylglycerols, phosphatidylglycerols, and acylglycerols. The pigment profile includes neoxanthin, canthaxanthin, lutein, chlorophyll a, geranylgeranyl chlorophyll a, chlorophyllide b, hydrochlorophyllide b, and pheophytin a. These results indicate that natural sheep casings waste represents a promising source of nitrogen, reducing the need for nutrient supplementation in microalgae production. This approach not only offers a sustainable and economical alternative for optimizing microalgae cultivation but also contributes to the valorization of organic waste, thus supporting more ecological and responsible practices. Full article
(This article belongs to the Topic The Role of Microorganisms in Waste Treatment)
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17 pages, 2741 KiB  
Review
Polyamine-Mediated Growth Regulation in Microalgae: Integrating Redox Balance and Amino Acids Pathway into Metabolic Engineering
by Leandro Luis Lavandosque and Flavia Vischi Winck
SynBio 2025, 3(2), 8; https://doi.org/10.3390/synbio3020008 - 28 May 2025
Viewed by 945
Abstract
Polyamines play a pivotal role in regulating the growth and metabolic adaptation of microalgae, yet their integrative regulatory roles remain underexplored. This review advances a comprehensive perspective of microalgae growth, integrating polyamine dynamics, amino acid metabolism, and redox balance. Polyamines (putrescine, spermidine, and [...] Read more.
Polyamines play a pivotal role in regulating the growth and metabolic adaptation of microalgae, yet their integrative regulatory roles remain underexplored. This review advances a comprehensive perspective of microalgae growth, integrating polyamine dynamics, amino acid metabolism, and redox balance. Polyamines (putrescine, spermidine, and spermine) biology in microalgae, particularly Chlamydomonas reinhardtii, is reviewed, exploring their critical function in modulating cell cycle progression, enzymatic activity, and stress responses through nucleic acid stabilization, protein synthesis regulation, and post-translational modifications. This review explores how the exogenous supplementation of polyamines modifies their intracellular dynamics, affecting growth phases and metabolic transitions, highlighting the complex regulation of internal pools of these molecules. Comparative analyses with Chlorella ohadii and Scenedesmus obliquus indicated species-specific responses to polyamine fluctuations, linking putrescine and spermine levels to important tunable metabolic shifts and fast growth phenotypes in phototrophic conditions. The integration of multi-omic approaches and computational modeling has already provided novel insights into polyamine-mediated growth regulation, highlighting their potential in optimizing microalgae biomass production for biotechnological applications. In addition, genomic-based modeling approaches have revealed target genes and cellular compartments as bottlenecks for the enhancement of microalgae growth, including mitochondria and transporters. System-based analyses have evidenced the overlap of the polyamines biosynthetic pathway with amino acids (especially arginine) metabolism and Nitric Oxide (NO) generation. Further association of the H2O2 production with polyamines metabolism reveals novel insights into microalgae growth, combining the role of the H2O2/NO rate regulation with the appropriate balance of the mitochondria and chloroplast functionality. System-level analysis of cell growth metabolism would, therefore, be beneficial to the understanding of the regulatory networks governing this phenotype, fostering metabolic engineering strategies to enhance growth, stress resilience, and lipid accumulation in microalgae. This review consolidates current knowledge and proposes future research directions to unravel the complex interplay of polyamines in microalgal physiology, opening new paths for the optimization of biomass production and biotechnological applications. Full article
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16 pages, 4066 KiB  
Article
Synthesis and Characterization of MAPTAC-Modified Cationic Corn Starch: An Integrated DFT-Based Experimental and Theoretical Approach for Wastewater Treatment Applications
by Joaquín Alejandro Hernández Fernández and Jose Alfonso Prieto Palomo
J. Compos. Sci. 2025, 9(5), 240; https://doi.org/10.3390/jcs9050240 - 14 May 2025
Viewed by 503
Abstract
Phosphorus contamination in water bodies is a major contributor to eutrophication, leading to algal overgrowth, oxygen depletion, and ecological imbalance. Conventional treatment methods, including chemical precipitation and synthetic adsorbents, are often limited by high operational costs, low biodegradability, and secondary pollutant generation. In [...] Read more.
Phosphorus contamination in water bodies is a major contributor to eutrophication, leading to algal overgrowth, oxygen depletion, and ecological imbalance. Conventional treatment methods, including chemical precipitation and synthetic adsorbents, are often limited by high operational costs, low biodegradability, and secondary pollutant generation. In this study, a cationic starch was synthesized through free radical graft polymerization of 3-methacrylamoylaminopropyl trimethyl ammonium chloride (MAPTAC) onto corn starch. The modified polymer exhibited a high degree of substitution (DS = 1.24), indicating successful functionalization with quaternary ammonium groups. Theoretical calculations using zDensity Functional Theory (DFT) at the B3LYP/6-311+G(d,p) level revealed a decrease in chemical hardness (from 0.10442 eV to 0.04386 eV) and a lower ionization potential (from 0.24911 eV to 0.15611 eV) in the modified starch, indicating enhanced electronic reactivity. HOMO-LUMO analysis and molecular electrostatic potential (MEP) maps confirmed increased electron-accepting capacity and the formation of new electrophilic sites. Experimentally, the cationic starch showed stable zeta potential values averaging +15.3 mV across pH 5.0–10.0, outperforming aluminum sulfate (Alum), which reversed its charge above pH 7.5. In coagulation-flocculation trials, the modified starch achieved 87% total suspended solids (TSS) removal at a low coagulant-to-biomass ratio of 0.0601 (w/w) using Scenedesmus obliquus, and 78% TSS removal in real wastewater at a 1.5:1 ratio. Additionally, it removed 30% of total phosphorus (TP) under environmentally benign conditions, comparable to Alum but with lower chemical input. The integration of computational and experimental approaches demonstrates that MAPTAC-modified starch is an efficient, eco-friendly, and low-cost alternative for nutrient and solids removal in wastewater treatment. Full article
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10 pages, 3721 KiB  
Article
Influence of Algal Strain on Permeate Flux Rate in Crossflow Microfiltration
by Mostafa Khademi and Chandra Theegala
Phycology 2025, 5(2), 18; https://doi.org/10.3390/phycology5020018 - 7 May 2025
Viewed by 692
Abstract
The separation of microalgae from a culture medium is a major cost and energy hurdle for the efficient production of algal biomass. Crossflow microfiltration has been found to be promising for the algal cell concentration process. Three algal strains with different cell sizes [...] Read more.
The separation of microalgae from a culture medium is a major cost and energy hurdle for the efficient production of algal biomass. Crossflow microfiltration has been found to be promising for the algal cell concentration process. Three algal strains with different cell sizes and morphology, namely Chlorella vulgaris, Nannochloris sp., and Scenedesmus sp., were studied. Analysis of the culture suspensions showed very different particle size distributions for the selected strains due to cell clustering. For a given membrane under the same operational conditions to achieve an equal volumetric reduction factor, Nannochloris sp., with the biggest particles and smallest cells, demonstrated the highest permeation flux, and in the same order of the particle sizes, it was followed by Chlorella vu. and Scenedesmus sp. For all the selected algal species, the highest dewatering rate (176–303 L/m2·h) was obtained by means of the membrane with the smallest pore size of 0.05 µm. Full article
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13 pages, 4386 KiB  
Article
Qualitative Assessment of Microalgae–Bacteria Biofilm Development on K5 Carriers: Photoheterotrophic Growth in Wastewater
by Henrique Sousa, Kerry A. Kinney, Cátia A. Sousa and Manuel Simões
Microorganisms 2025, 13(5), 1060; https://doi.org/10.3390/microorganisms13051060 - 2 May 2025
Viewed by 536
Abstract
Wastewater (WW) treatment using biofilms harboring bacteria and microalgae is considered a promising polishing solution to improve current treatment technologies present in wastewater treatment plants (WWTPs), but their interaction in a sessile community remains to be understood. In this work, multi-species biofilms of [...] Read more.
Wastewater (WW) treatment using biofilms harboring bacteria and microalgae is considered a promising polishing solution to improve current treatment technologies present in wastewater treatment plants (WWTPs), but their interaction in a sessile community remains to be understood. In this work, multi-species biofilms of Chlorella vulgaris, Chlorella sorokiniana, or Scenedesmus obliquus were selected as representative microalgae species of interest for WW bioremediation, and Rhodococcus fascians, Acinetobacter calcoaceticus, or Leucobacter sp. were selected as the bacteria for co-cultivation in a synthetic WW since they are normally found in WW treatment processes. The attached consortia were developed in specific carriers (K5 carriers) for 168 h, and their biofilm formation ability was evaluated in a profilometer and via scanning electron microscopy (SEM) imaging. From the selected microorganisms, C. sorokiniana was the microalga that adapted best to co-cultivation with R. fascians and A. calcoaceticus, developing a thicker biofilm in these two consortia (3.44 ± 0.5 and 4.51 ± 0.8 µm, respectively) in comparison to the respective axenic cultures (2.55 ± 0.7 µm). In contrast, Leucobacter sp. did not promote biofilm growth in association with C. vulgaris and C. sorokiniana, while S. obliquus was not disturbed by the presence of this bacterium. Some bacterial clusters were observed through SEM, especially in A. calcoaceticus cultures in the presence of microalgae. In some combinations (especially when C. vulgaris was co-cultivated with bacteria), the presence of bacteria was able to increase the number of microalga cells adhered to the K5 carrier. This study shows that biofilm development was distinctly dependent on the co-cultivated species, where synergy in biofilm formation was highly dependent on the microalgae and bacteria species. Moreover, profilometry appears to be a promising method for biofilm analyses. Full article
(This article belongs to the Special Issue Function and Responses of Algae to Wastewater Treatment)
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14 pages, 813 KiB  
Article
Assessment of Potential Toxic Effects of Fungicide Fludioxonil on Human Cells and Aquatic Microorganisms
by Maria Antonopoulou, Anna Tzamaria, Sotiris Papas, Ioanna Efthimiou and Dimitris Vlastos
Toxics 2025, 13(5), 358; https://doi.org/10.3390/toxics13050358 - 30 Apr 2025
Viewed by 589
Abstract
Fludioxonil is a widely used fungicide that is frequently used to combat fungal plant diseases. Consequently, excessive concentrations of fludioxonil may enter and accumulate over time in aquatic systems, harming (micro) organisms in several ways. Thus, it is of great importance to evaluate [...] Read more.
Fludioxonil is a widely used fungicide that is frequently used to combat fungal plant diseases. Consequently, excessive concentrations of fludioxonil may enter and accumulate over time in aquatic systems, harming (micro) organisms in several ways. Thus, it is of great importance to evaluate the potential toxic effects of fludioxonil using bioassays. In the present study, various in vitro assays were used to assess the possible effects of fludioxonil in human cells and aquatic microorganisms. For the investigation of the toxic effects of fludioxonil on freshwater microalgae, Scenedesmus rubescens and Dunaliella tertiolecta were exposed to various environmentally relevant concentrations of the fungicide for a period of 96 h. Fludioxonil at 50–200 μg L−1 significantly limited the growth of both microalgae, especially in the first 24 h of the exposure, where inhibitions up to 82.34% were calculated. The toxicity of fludioxonil was further evaluated via the Microtox test, and the studied fungicide was found to be less toxic for the bacteria Aliivibrio fischeri. Regarding human cells, the fludioxonil’s toxic and cyto-genotoxic effects were assessed using the Trypan blue exclusion test and the Cytokinesis Block MicroNucleus (CBMN) assay. Cell viability in all fludioxonil-treated concentrations was similar to control values according to the results of the Trypan blue exclusion test. However, the CBMN assay was used and revealed that fludioxonil had genotoxic potential in higher concentrations and exerted cytotoxic activity against human lymphocytes. Specifically, only the highest dose of fludioxonil, i.e., 10 μg mL−1, exerted genotoxic effects against human lymphocytes, whereas treatment with 0.5, 1, and 5 μg mL−1 did not lead to statistically significant induction of micronuclei (MN) frequencies compared with the control culture. However, fludioxonil-mediated cytotoxicity was statistically significant, which was demonstrated by the decreased CBPI (cytokinesis block proliferation index) values in all cases except for the lowest dose, i.e., 0.5 μg mL−1. Full article
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