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10. Calcium Alginate Core–Shell Liquid Beads Encapsulated with Microalgae for Wastewater Treatment.

Author

Tran, Du Tuan, Nguyen, Nhat‐Khuong, Yadav, Ajeet Singh, Chuang, Ann, Burford, Michele, Galogahi, Fariba Malekpour, Sreejith, Kamalalayam Rajan, and Nguyen, Nam‐Trung

Subjects
UPFLOW anaerobic sludge blanket reactors, CALCIUM alginate, WASTEWATER treatment, ALGINATES, CALCIUM ions, BEADS, MICROALGAE
Abstract

Liquid beads are core–shell particles with a liquid core and a solid shell. Calcium alginate liquid beads have been emerging as a promising platform for cell encapsulation. These beads have demonstrated their capability of encapsulating and culturing a wide range of human cells for tissue engineering. However, a significant research gap remains in the application of alginate liquid beads for encapsulating photosynthetic microorganisms. Herein, fast‐growing microalgae strain Chlorella vulgaris is encapsulated into calcium alginate liquid beads to facilitate the removal of nutrients from wastewater, minimizing the risk of eutrophication. Liquid bead‐microalgae systems are prepared, using different calcium ion concentrations as crosslinking ions. It has been thoroughly characterized for their morphologies, cell growth patterns, nutrient removal capabilities, and overall stability throughout the wastewater treatment process, with upflow anaerobic sludge blanket effluent as the wastewater model. The results indicate that the liquid bead‐microalgae system with the highest calcium ion concentration (5%) performs more efficiently, exhibiting a well‐formed crosslinking structure, leading to rapid cell growth with the highest cell density and the most effective removal of nutrients. The findings from this study provide valuable insights for future optimization and upscaling efforts in wastewater treatment systems based on calcium alginate liquid beads. [ABSTRACT FROM AUTHOR]

Published
2024
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14. Supplementary Methods, Tables and Figures from Phosphorus storage and utilization strategies of two bloom-forming freshwater cyanobacteria

Author

Xiao, Man, Burford, Michele A., Prentice, Matthew J., Galvanese, Elena F., Chuang, Ann, and Hamilton, David P.

Abstract

The inter-relationships between cellular phosphorus (P) storage, dissolved inorganic P (DIP) uptake affinity, alkaline phosphatase activity (APA) and dissolved inorganic nitrogen (DIN) concentrations were studied in two ubiquitous diazotrophic freshwater cyanobacteria, Raphidiopsis raciborskii (six strains) and Chrysosporum ovalisporum (two strains). DIP uptake kinetics were measured using rates of incorporation of the radio-isotope, 33P and APA as a proxy for DOP-ester utilization. The study showed that DIP uptake of individual strains followed Michaelis–Menten kinetics (modified in our study to incorporate cellular P quotas), but differed with DIN and P availability, and between growth stages. High-affinity DIP uptake and APA were activated below a P quota threshold of approximately 0.01 µg P µg−1 C across the species and strains. C. ovalisporum had significantly higher APA and P quotas (per unit C and cell) but lower uptake affinity than R. raciborskii. Demand for DIP by C. ovalisporum increased when N fixation occurred, but typically not for R. raciborskii. Our results indicate that cyanobacterial species and strains differ in their strategies to P limiting conditions, and highlight the interplay between N and P. Physiological adaptations like APA and diazotrophy of cyanobacteria adapting to low DIP and/or DIN conditions may occur simultaneously and drive species dominance in oligotrophic environments.

Published
2023
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15. Recent insights into physiological responses to nutrients by the cylindrospermopsin producing cyanobacterium, Cylindrospermopsis raciborskii

Author

Burford, Michele, Willis, Anusuya, Chuang, Ann, Man, Xiao, and Orr, Phil

Abstract

The harmful cyanobacterium Cylindrospermopsis raciborskiiis a widespread species increasingly being recorded in freshwater systems around the world. Studies have demonstrated some key attributes of this species which may explain its global dominance. It has a high level of flexibility with respect to light and nutrients, being capable of growth under low and variable light conditions. However, it is the strategy with respect to nutrient utilization that has received more attention. Unlike many bloom forming species, the dominance of this species is not simply linked to higher nutrient loads. In fact it appears that it is more competitive when phosphorus and nitrogen availability is low and/or variable. An important component of this flexibility appears to be the result of within-population strain variability in responses to nutrients, as well as key physiological adaptations. Strain variability also appears to have an effect on the population-level cell quota of toxins, specifically cylindrospermopsins (CYNs). Field studies in Australia showed that populations had the highest proportion of toxic strains when dissolved inorganic phosphorus was added, resulting in stoichiometrically balanced nitrogen and phosphorus within the cells. These strategies are part of an arsenal of responses to environmental conditions, making it a challenging species to manage. However, our ability to improve bloom prediction will rely on a more detailed understanding of the complex physiology and ecology of this species.

Published
2024
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29. Phosphorus storage and utilization strategies of two bloom-forming freshwater cyanobacteria.

Author

Xiao M, Burford MA, Prentice MJ, Galvanese EF, Chuang A, and Hamilton DP

Subjects
Fresh Water, Kinetics, Nitrogen Fixation, Phosphorus, Cyanobacteria
Abstract

The inter-relationships between cellular phosphorus (P) storage, dissolved inorganic P (DIP) uptake affinity, alkaline phosphatase activity (APA) and dissolved inorganic nitrogen (DIN) concentrations were studied in two ubiquitous diazotrophic freshwater cyanobacteria, Raphidiopsis raciborskii (six strains) and Chrysosporum ovalisporum (two strains). DIP uptake kinetics were measured using rates of incorporation of the radio-isotope, 33 P and APA as a proxy for DOP-ester utilization. The study showed that DIP uptake of individual strains followed Michaelis-Menten kinetics (modified in our study to incorporate cellular P quotas), but differed with DIN and P availability, and between growth stages. High-affinity DIP uptake and APA were activated below a P quota threshold of approximately 0.01 µg P µg -1 C across the species and strains. C. ovalisporum had significantly higher APA and P quotas (per unit C and cell) but lower uptake affinity than R. raciborskii . Demand for DIP by C. ovalisporum increased when N fixation occurred, but typically not for R. raciborskii . Our results indicate that cyanobacterial species and strains differ in their strategies to P limiting conditions, and highlight the interplay between N and P. Physiological adaptations like APA and diazotrophy of cyanobacteria adapting to low DIP and/or DIN conditions may occur simultaneously and drive species dominance in oligotrophic environments.

Published
2023
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30. How to effectively manage myopia.

Author

Chuang AY

Abstract

Myopia has become epidemic in the world. Without effective control, the progression may lead to excessive myopia with severe complications affecting vision and ocular alignment. The genetic factors and environmental factors of myopia are closely interrelated to each other. Asian ethnicity and parental myopia, among other genetic factors, influence the refractive outcome dramatically when environmental risk factors such as hours of near work and reading distance are analyzed. Outdoor activities are protective measures that retard myopia progression. Total time under the sun and not the specific outdoor activities are contributing factors. Current effective treatments for myopia include atropine of high, moderate, and low doses, relative peripheral myopia-inducing devices, and bifocal spectacles including prism bifocal spectacle lenses. Although atropine is considered highly effective in randomized controlled trials, it is not well tolerated in a clinical setting, especially in high dosage. Since the severity of rebound effect of atropine after cessation of usage and the side effects are directly related to the concentration of the medication, it is recommended that low-dose atropine is used in the initial attempt. Higher concentration for better control can be considered when compliance is observed. Devices that induce relative peripheral myopia such as orthokeratology are moderately effective interventions that are well accepted by children who wish to be spectacle free. Bifocal spectacles generally have low effect in myopia control. Prism bifocal spectacle lenses may have a special niche in myopia retardation for patients with low lags of accommodation., Competing Interests: The authors have no conflicts of interest to declare.

Published
2017
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