Effects of Culture Conditions on the Performance of Arthrospira platensis and Its Production of Exopolysaccharides

Investigation of self-regulation mechanisms of extracellular organic matters in reused medium on Spirulina platensis

Recirculating the cultivation medium of Spirulina platensis (S. platensis) enables efficient water and nutrient recycling, thereby reducing production costs. To figure out the inhibition components of the reused medium and cell oxidate response, this study delves into the metabolic regulation of the reused medium and its extracted organic matters (OMs) and extracellular polysaccharides (EPS) on S. platensis. The reused medium and the medium containing dissolved OMs and EPS significantly increased oxidative stress in S. platensis, reducing biomass production with inhibition rates ranging from 18.08 % to 26.59 %. Nevertheless, the incorporation of EPS from OMs augmented the synthesis of proteins, polyphenols, and chlorophyll in S. platensis, sustaining photosynthetic activity and a higher proportion of live cells. Future research should prioritize the characterization of OMs and EPS, mitigate the inhibitory effects of OMs extracted residue (molecular weight < 1000 Da), further optimize the recyclability of the reused medium, and enhance S. platensis's functional composition.

A novel bioactive and functional exopolysaccharide from the cyanobacterial strain Arthrospira maxima cultivated under salinity stress

Cyanobacterial exopolysaccharides (EPS) remain released by cyanobacteria in the surrounding environment with the main purpose of protection against harmful environmental conditions. Recently, they have received significant attention due to their unique structural characteristics, functional properties, and potential applications across various fields. The current study describes the evaluation of EPS production under salinity stress from Arthrospira maxima. The application of high salinity up to 40 g/L enhanced EPS production, which was collected and purified by alcohol precipitation followed by membrane dialysis and lyophilization. A yield of 60 mg/L was obtained. The Size exclusion chromatography gave for the purified EPS an apparent molecular weight of 2.1 × 105 Da. Monosaccharide composition showed that EPS is a heteropolymer, with mannose, xylose, and glucuronic acid identified as the predominant monosaccharides and derivatives. Nuclear magnetic resonance spectroscopy (13C and 1H) confirmed that EPS is a heteropolysaccharide, entirely in α- anomeric configuration, with glucuronic acid as a main monomer that is probably linked to mannose and xylose via α-glycosidic linkages. Bioactivity assessment of EPS revealed that it exhibits antibacterial activity against several strains, notably, Bacillus subtilis (MIC: 0.6 ± 0.05 mg/mL), Bacillus cereus (MIC: 1 ± 0.01 mg/mL), Escherichia coli (MIC: 0.8 ± 0.01 mg/mL) and Klebsiella pneumonia (MIC: 0.8 ± 0.01 mg/mL). Antioxidant activity was measured using the DPPH radical scavenging assay, yielding an IC₅₀ of 6.83 mg/mL. Besides, EPS was also found to exhibit an interesting emulsifying property with several oil types, indicating its potential as a versatile biopolymer for applications in various industrial sectors.

Microbial exopolysaccharides: Classification, biosynthetic pathway, industrial extraction and commercial production to unveil its bioprospection: A comprehensive review

Polysaccharides, found universally in all living-species, exhibit diverse biochemical structures and play crucial roles in microorganisms, animals, and plants to defend against pathogens, environmental stress and climate-changing. Microbial exopolysaccharides are essential for cell adhesion and stress resilience and using them has notable advantages over synthetic polysaccharides. Exopolysaccharides have versatile structures and physicochemical properties, used in food systems, therapeutics, cosmetics, agriculture, and polymer industries. Immense economic and infrastructural constraints hinder its widespread commercial use, necessitating a deeper understanding of metabolic-pathways amidst changing environmental climate that influences the biomass composition of EPS-producing wild-microbes. Green and sustainable extraction of EPS from microbes followed by commercial product development has still not been exploited comprehensively. Yield of EPS production vary from 0.1 to 3 g/g of cell weight, influenced by fermentation conditions. Economic barriers, including substrate and processing costs, limit commercial viability. Key biosynthetic pathways involve glycosyltransferases enzymes, whose regulatory network gaps and substrate specificity remain areas for optimization. Addressing these could enhance yields and lower production costs. Review illustrates various microbial-exopolysaccharides, influencing factors of production, and offer valuable insights on the bioplastic, biofuel, agri-bioproduct, and biomedicine. But their bioprospecting potential is yet to be exhaustively explored, along with their pros and cons nor documented comprehensively in scientific literature.

Meta-Analysis of Abiotic Conditions Affecting Exopolysaccharide Production in Cyanobacteria

Background: cyanobacterial exopolysaccharides (EPSs) exhibit diverse biological and physicochemical properties, making them valuable for applications in environmental remediation, soil improvement, wastewater treatment, and bioenergy production. Results: the production of cyanobacterial EPSs is significantly influenced by various factors, including abiotic factors and strains. Recent research has focused on optimizing EPS production by regulating key abiotic factors such as light, temperature, pH, and nutritional conditions. This review systematically compiles and analyzes published data on the effects of abiotic factors on cyanobacterial EPS biosynthesis, with a focus on genus-specific responses. Using meta-analysis techniques, we provide a comprehensive overview of the key factors influencing EPS production. Light and nutrient conditions are the most significant factors affecting EPS production, with high light intensities and optimal nutrient conditions enhancing EPS synthesis. Optimal temperature ranges and pH levels are essential for maximizing EPS production, and cyanobacteria exhibit genus-specific responses to variations in these factors. The addition of specific nutrients, such as NaCl, trace metals (e.g., Mg, Zn, Cu), and elevated CO2 levels, significantly impacts EPS production. Conclusions: the response to these factors varies among different cyanobacterial genera, highlighting the need for genus-specific optimization strategies. This review provides a theoretical basis for optimizing EPS production across diverse cyanobacterial genera and for understanding multi-factor interactions and practical applications in future research.

Types, synthesis pathways, purification, characterization, and agroecological physiological functions of microbial exopolysaccharides: A review

Exopolysaccharides (EPS), originating from various microbes, are essential bioproducts with widespread applications including packaging, biomedicine, wastewater treatment, cosmetics, agriculture, and food industries. Particularly, in the field of sustainable agriculture, microbial EPS have positive effects on plant growth and have gained considerable interest among agriculturists. However, few studies have elucidated the mechanisms of action of EPS in soil-microbe-plant interactions in agroecosystems. This review focuses on the sources and types of EPS, biosynthetic processes, factors affecting EPS yield, extraction and purification methods employed to produce microbial EPS, and structural characterization methods for EPS. Moreover, the agroecological physiological functions of microbial EPS with respect to promoting soil health (e.g., improving soil structure and fertility and repairing contaminated soil) and plant growth (e.g., plant growth and physiological metabolism under normal and stress conditions, such as salt, drought, heavy metals, and extreme temperatures) are critically highlighted. Furthermore, existing challenges and prospects for agricultural applications are discussed. This review demonstrates that the application of microbial EPS in agriculture provides a new type of green material for agricultural producers to improve soil quality, increase agricultural productivity, and provide new ideas for sustainable agricultural development.

Comprehensive Review of the Latest Investigations of the Health-Enhancing Effects of Selected Properties of Arthrospira and Spirulina Microalgae on Skin

Arthospira platensis and Spirulina platensis microalgae are a rich source of pro-health metabolites (% d.m.): proteins (50.0-71.3/46.0-63.0), carbohydrates (16.0-20.0/12.0-17.0), fats (0.9-14.2/6.4-14.3), polyphenolic compounds and phenols (7.3-33.2/7.8-44.5 and 4.2/0.3 mg GAE/g), and flavonoids (1.9/0.2 QUE/g) used in pharmaceutical and cosmetic formulations. This review summarises the research on the chemical profile, therapeutic effects in dermatological problems, application of Arthrospira and Spirulina microalgae, and contraindications to their use. The pro-health properties of these microalgae were analysed based on the relevant literature from 2019 to 2024. The antiviral mechanism of microalgal activity involves the inhibition of viral replication and enhancement of immunity. The anti-acne activity is attributed to alkaloids, alkanes, phenols, alkenes, phycocyanins, phthalates, tannins, carboxylic and phthalic acids, saponins, and steroids. The antibacterial activity generally depends on the components and structure of the bacterial cell wall. Their healing effect results from the inhibition of inflammatory and apoptotic processes, reduction of pro-inflammatory cytokines, stimulation of angiogenesis, and proliferation of fibroblasts and keratinocytes. The photoprotective action is regulated by amino acids, phlorotannins, carotenoids, mycosporins, and polyphenols inhibiting the production of tyrosinase, pro-inflammatory cytokines, and free oxygen radicals in fibroblasts and the stimulation of collagen production. Microalgae are promising molecular ingredients in innovative formulations of parapharmaceuticals and cosmetics used in the prophylaxis and therapy of dermatological problems. This review shows the application of spirulina-based commercial skin-care products as well as the safety and contraindications of spirulina use. Furthermore, the main directions for future studies of the pro-health suitability of microalgae exerting multidirectional effects on human skin are presented.

Challenges and opportunities in bioprocessing of gellan gum: A review

Gellan gum (GG) - the microbial exopolysaccharide is increasingly being adopted into drug development, tissue engineering, and food and pharmaceutical products. In spite of the commercial importance and expanding application horizon of GG, little attention has been directed toward the exploration of novel microbial cultures, development of advanced screening protocols, strain engineering, and robust upstream or downstream processes. This comprehensive review not only attempts to summarize the existing knowledge pool on GG bioprocess but also critically assesses their inherent challenges. The process optimization design augmented with advanced machine learning modeling tools, widely adopted in other microbial bioprocesses, should be extended to GG. The unification of mechanistic insight into data-driven modeling would help to formulate optimal feeding and process control strategies.

Engineering strategies and applications of cyanobacterial exopolysaccharides: A review on past achievements and recent perspectives

Cyanobacteria are ideally suited for developing sustainable biological products but are underdeveloped due to a lack of genetic tools. Exopolysaccharide (EPS) is one of the essential bioproducts with widespread industrial applications. Despite their unique structural characteristics associated with distinct biological and physicochemical aspects, EPS from cyanobacteria has been underexplored. However, it is expected to accelerate in the near future due to the utilization of low-cost cyanobacterial platforms and readily available information on the structural data and specific features of these biopolymers. In recent years, cyanobacterial EPSs have attracted growing scientific attention due to their simple renewability, rheological characteristics, massive production, and potential uses in several biotechnology domains. This review focuses on the most recent research on potential new EPS producers and their distinct compositions responsible for novel biological activities. Additionally, nutritional and process parameters discovered recently for enhancing EPS production and engineering strategies applied currently to control the biosynthetic pathway for enhanced EPS production are critically highlighted. The process intensification of previously developed EPS extraction and purification processes from cyanobacterial biomass is also extensively explained. Furthermore, the newly reported biotechnological applications of cyanobacterial exopolysaccharides are also discussed.

Optimization of an Alternative Culture Medium for Phycocyanin Production from Arthrospira platensis under Laboratory Conditions

Arthrospira platensis, known as spirulina, is a cyanobacterium with multiple nutritional benefits, as it contains substantial amounts of proteins, fatty acids, and pigments. However, the production of this microalga has faced significant challenges, primarily related to the cost and composition of the required culture medium for its optimal growth. This study focused on optimizing two nitrogen sources (urea and potassium nitrate) to maximize the growth of A. platensis and the production of phycocyanin, a photosynthetic pigment of significant commercial value. Optimization was performed using the response surface methodology (RSM) with a central composite design (CCD). Analysis of variance (ANOVA) was employed to validate the model, which revealed that the different concentrations of urea were statistically significant (p < 0.05) for biomass and phycocyanin production. However, potassium nitrate (KNO3) showed no significant influence (p > 0.05) on the response variables. The RSM analysis indicated that the optimal concentrations of KNO3 and urea to maximize the response variables were 3.5 g L-1 and 0.098 g L-1, respectively. This study offers valuable perspectives for the efficient production of A. platensis while reducing production costs for its cultivation on a larger scale.

An interventional clinical trial investigating the effects of Spirulina platensis on dental fluorosis and antioxidant system in lambs reared in endemic areas

This study aimed to evaluate the protective effect of Spirulina platensis primary against dental fluorosis and secondary against oxidative stress in lambs reared in endemic fluorosis areas. Forty-eight lambs aged 5 months were divided into four equal groups (each one including 6 males and 6 females). Groups I and II served as controls belonging respectively to fluorosis-free (Settat) and endemic fluorosis (El Fokra) areas, while the other two Groups III and IV (belonging to El Fokra) received respectively a fixed daily intake of 250 and 500 mg/kg bodyweight (BW) of Spirulina platensis. The experiment was carried out for 13 months until the adult incisors appeared for all animals. According to the Dean's Fluorosis Index (DFI), 500 mg/kg BW/day of Spirulina platensis (Group IV) protected against dental fluorosis. Moreover, in both male and female lambs, this dose significantly (p < 0.0001) reduced the plasmatic levels of fluoride, proteins, GSH, and MDA compared to the Group II. Furthermore, enzymatic activities of catalase and SOD increased significantly (p < 0.0001) in male and female lambs of the Group IV as compared to Group II. In conclusion, our findings support the potential use of Spirulina platensis as a valuable solution for addressing fluorosis in sheep, warranting further clinical trials.

Techno-economic assessment of co-production of edible bioplastic and food supplements from Spirulina

Large amount of plastic wastes harming the environment have raised concerns worldwide on finding alternatives to non-biodegradable plastics. Microalgae has been found as a potential source for bioplastic production, besides its more common application in the pharmaceutical and nutraceutical industry. In this study, the objective was to techno-economically evaluate the large-scale co-production of Spirulina powder as food supplements and edible bioplastic for food packaging. The scale of production was large enough to satisfy 1% of local (Thailand) plastic demand (i.e., approx. 1200 MT y-1), and 1% of the global Spirulina demand (approx. 1000 MT y-1) as food supplements. Results showed that the co-production of the Spirulina powder and bioplastic revealed an attractive venture with a payback time (PBT) as low as 2.6 y and ROI as high as 38.5%. This was because the revenues generated were as high as US$ 55.6 million y-1, despite high capital (US$ 55.7 million) and operating (US$ 34.9 million y-1) costs. Sensitivity analysis showed differences in the profitability based on variations of major parameters in the study, where the split ratio of biomass used for food supplement versus bioplastic production and the bioplastic's selling price were found to be the most sensitive.

Preparation and Characterization of Intracellular and Exopolysaccharides during Cycle Cultivation of Spirulina platensis

The dried cell weight (DCW) of Spirulina platensis gradually decreased from 1.52 g/L to 1.18 g/L after five cultivation cycles. Intracellular polysaccharide (IPS) and exopolysaccharide (EPS) content both increased with increased cycle number and duration. IPS content was higher than EPS content. Maximum IPS yield (60.61 mg/g) using thermal high-pressure homogenization was achieved after three homogenization cycles at 60 MPa and an S/I ratio of 1:30. IPS showed a more fibrous, porous, and looser structure, and had a higher glucose content and Mw (272.85 kDa) compared with EPS, which may be indicative of IPS's higher viscosity and water holding capacity. Although both carbohydrates were acidic, EPS had stronger acidity and thermal stability than IPS; this was accompanied by differences in monosaccharide. IPS exhibited the highest DPPH (EC₅₀ = 1.77 mg/mL) and ABTS (EC₅₀ = 0.12 mg/mL) radical scavenging capacity, in line with IPS's higher total phenol content, while simultaneously showing the lowest HO^• scavenging and ferrous ion chelating capacities; thus characterizing IPS as a superior antioxidant and EPS as a stronger metal ion chelator.