Algal carbohydrates: Sources, biosynthetic pathway, production, and applications

Enhanced carbon capture and utilization in transgenic Chlorella sorokiniana harboring pyridoxal kinase under dynamic carbon dioxide levels

Microalgae are crucial in carbon capture, utilization, and storage due to the efficient CO2 assimilation through photosynthesis and potential for high-value biochemical production. However, limited research has explored genetic strain to enhance carbon capture under dynamic CO2 conditions. This research aimed to optimize carbon capture in Chlorella sorokiniana by introducing pyridoxal kinase (pdxY) and cultivation in fluctuating CO2 concentrations. The sequential optimization successfully led to 34% increase in growth with improved carbon capture efficiency to 88.5%. Transgenic strains 2023PY and BSLPY demonstrated superior performance under high (2%) and low (0.04%) CO2, respectively. Addition of Tris base to the medium stabilized pH at favorable level, which is crucial for optimum growth. Scale-up cultivation in 2-L photobioreactor achieved net-zero carbon emissions across all strains. These findings highlight the potential of genetic engineering and process optimization in advancing microalgal carbon capture, along with the production of protein, starch, and lipid for sustainable applications.

Advancements in the Extraction, Characterization, and Bioactive Potential of Laminaran: A Review

Laminaran, a bioactive β-glucan derived from brown algae, has garnered significant attention due to its diverse pharmacological properties, including antioxidant, immunomodulatory, and mucosal protective effects. Despite promising research highlighting its potential applications in functional foods, nutraceuticals, and pharmaceuticals, the commercial utilization of laminaran remains limited, primarily due to challenges in extraction efficiency, structural complexity, and a lack of standardized methodologies. This review critically examines recent advancements in the extraction, purification, structural characterization, and biological evaluation of laminaran. Both conventional and emerging extraction methods-including ultrasound-assisted extraction, microwave-assisted extraction, and enzymatic techniques-are evaluated for their efficiency, scalability, and sustainability. Analytical tools, such as high-performance liquid chromatography, nuclear magnetic resonance, and mass spectrometry, are discussed for their roles in elucidating key structural features, such as molecular weight, degree of polymerization, and glycosidic linkage patterns, which are closely tied to laminaran's biological activity. Innovative extraction technologies have improved yield and purity, while structural insights have deepened the understanding of structure-function relationships. Interdisciplinary collaboration will be critical to advance laminaran from a marine-derived polysaccharide to a commercially viable bioactive compound for health, nutrition, and biomaterial applications.

Marine algal polysaccharides for drug delivery applications: A review

In recent decades, there has been a growing interest in the use of polysaccharides that exhibit biological activity for a wide range of innovative applications. This is due to their nontoxicity, biodegradability, biocompatibility, and therapeutic properties. The diverse properties of polysaccharides derived from marine algae make them a promising strategy for the construction of drug delivery systems (DDSs). Marine algal polysaccharides can be utilized in regenerative medicine and gene delivery to facilitate the controlled release of therapeutic substances, which is a critical stage in the fight against severe diseases. Algal polysaccharide-based nanoparticles, microspheres, hydrogels, patches, and films are among the numerous controllable and sustained anti-inflammatory and anticancer DDSs that can be used due to the biological activities of these algal polymers. This review paper summarizes the advantages and applications of marine algal polysaccharides in DDSs (such as nanoparticles, microspheres, hydrogels, patches and films) as well as recent advances in drug delivery technologies, thereby providing valuable information for future research on drug delivery-based algal polysaccharides.

High Ca2+ concentrations enhance Microcystis colony formation through upregulating polysaccharide-, energy metabolism-, and transmembrane transport-related pathways

Colony formation plays a critical role in Microcystis blooms. Previous studies have demonstrated that high Ca2+ concentrations can bring about the rapid aggregation of Microcystis aeruginosa, leading to the formation of colonies with morphologies resembling those observed in the wild over extended periods. However, the mechanisms through which high Ca2+ levels enhance colony formation remain inadequately understood. This study investigated the impact of Ca2+ concentrations on M. aeruginosa colony formation and elucidated the underlying mechanisms. The results indicated that high Ca2+ concentrations (≥50 mg/L) significantly enhanced colony formation, with an increase in colony size observed as Ca2+ concentrations rose within the range of 1-400 mg/L. In addition, the cell surface hydrophobicity and zeta potential increased with Ca2+ concentrations, primarily due to the augmented secretion of extracellular polymeric substances (EPS) and compression of the double electric layer. This decreased interaction energy among Microcystis cells and facilitated colony formation. The energy barrier decreased from 2684.35 KT to 123.64 KT as the Ca2+ concentration rose from 10 mg/L to 400 mg/L, indicating a significantly greater propensity for aggregation in the 400 mg/L Ca2+ group compared to the control. Additionally, this study found that high Ca2+ concentrations upregulated extracellular polysaccharide-, transmembrane transport-, and energy metabolism-related pathways while downregulating photosynthesis-related pathways. This enhanced polysaccharide content in EPS and ultimately promoted colony formation. These findings provide new insights into the role of elevated Ca2+ concentrations in Microcystis colony formation, contributing to the advancements in the knowledge of cyanobacterial bloom mechanisms.

Improvement of Adsorption Capacity by Refined Encapsulating Method of Activated Carbon into the Hollow-Type Spherical Bacterial Cellulose Gels for Oral Absorbent

To reduce the risk of adsorption of granular activated carbon (AC) in the gastrointestinal tract, we successfully prepared a hollow-type spherical bacterial cellulose gel encapsulated with AC (ACEG) and evaluated its pH tolerance and adsorption capacity. The bacterial cellulose gel membrane of ACEG features a three-dimensional mesh structure of cellulose fibers, allowing the selective permeation of substances based on their size. In this study, the preparation method of ACEGs was investigated, and the indole saturation adsorption capacity of the obtained gel was measured. We modified the gel culture nucleus gel from calcium alginate gel to agar gel, facilitating the encapsulation of previously challenging particles. The new preparation method used sodium hydroxide solution for sterilization and dissolution to remove the debris of Komagataeibacter xylinus, which was feared to remain in the bacterial cellulose membrane. This treatment was also confirmed to have no effect on the adsorption capacity of the AC powder. Therefore, this new preparation method is expected not only to improve the performance of ACEGs but also to be applied to a wide range of adsorbent-encapsulated hollow-type bacterial cellulose gels.