BG-11 Medium Research Articles

Pilot-scale production of selenium-enriched Nostoc sphaeroides colonies and polysaccharides using two-phase cultivation strategy

Nostoc sphaeroides, originally discovered in selenium-rich fields, is a photosynthetic, nitrogen-fixing cyanobacterium that forms edible spherical macrocolonies. However, prolonged selenium supplementation negatively impacts colony quality in culture. To address this, a two-phase cultivation strategy was developed to spatiotemporally separate biomass accumulation from selenium enrichment, resulting in high-quality selenium-enriched N. sphaeroides colonies. The first phase focused on colony growth in nitrogen-free BG-110 medium, while the second phase emphasized selenium enrichment in selenium-supplemented, phosphorus-reduced, and nitrogen-containing BG-11 medium (“selenium enrichment medium”). Scale-up to 300 L confirmed the robustness of this process, achieving desired colony hardness of ∼3 newtons, selenium content of ∼350 μg/g, and yield of ∼0.5 g/L (dry weight). Additionally, polysaccharides containing ∼110 μg/g selenium were isolated from the colonies, exhibiting biochemical properties similar to selenium-free polysaccharides from control colonies. These results provide valuable insight into the potential of N. sphaeroides as a cell factory chassis for producing selenium bioproducts.

The Potential of Biocrust-Forming Cyanobacteria to Enhance Seedling Growth of Native Semi-arid Plants Through Seed Biopriming

AbstractIn drylands, extreme environmental conditions pose a challenge for restoration, especially on a large scale. Direct seeding is the most cost-effective approach to restore large areas, but it requires improvements to enhance seedling survival and establishment. For this purpose, biopriming seeds with cyanobacteria is promising due to their plant growth-promoting properties. We evaluated the effect of seed biopriming with native biocrust-forming cyanobacteria on seed germination and radicle length of four native plant species, two perennials (Macrochloa tenacissima and Thymus hyemalis) and two annuals (Plantago ovata and Stipa capensis), chosen for their ubiquity in Mediterranean drylands. Treatments included seed biopriming with cyanobacteria inoculants (biomass + exudate), seed priming only with the cyanobacterial exudate, and controls (BG11 culture medium and distilled water). Biopriming effect was assessed individually for four native biocrust-forming cyanobacteria species: Nostoc commune, Tolypothrix distorta, Trichocoleus desertorum, and Leptolyngbya frigida. Seed biopriming showed no effect on germination with similar rates among treatments (on average, 45 ± 12.6% for M. tenacissima, 38.8 ± 12.4% for T. hyemalis, 91.7 ± 9.8% for P. ovata and 77.6 ± 10.8% for S. capensis). However, biopriming significantly affected radicle length of annual plants. Radicles were significantly increased in P. ovata when treated with cyanobacterial exudates (15–30% increase over control), and in S. capensis when treated with cyanobacterial biomass + exudate (26–42% increase over control). These results indicate that the effect of seed biopriming is species specific, but selecting the appropriate plant species and biopriming treatment can enhance plant survival and establishment in drylands, making restoration efforts more successful.

Adaptation of Chlorella vulgaris immobilization on rice straw with liquid manure to create a sustainable feedstock for biogas production and potential feed applications

Rice straw (RS) is a widely available agricultural residue with significant potential for biogas production and feed applications; however, its poor digestibility and nutritional value limit its utilization. This study explores an innovative approach to enhance the digestibility and nutritional value of RS by cultivating Chlorella vulgaris through immobilization technology on RS, using liquid manure (LM) as an alternative to the traditional BG11 medium. The results showed an increase in chlorophyll a (Chl a) after 12 days for both the BG11 medium and LM-based treatments, from 0.13 to 0.34 and 0.24 mg Chl a/g product (DM), respectively. Additionally, the immobilized microalgal biomass increased to 284.18 and 170.14 mg algal biomass/g product (DM), respectively. Soaking under microaerobic conditions during cultivation led to the partial degradation of RS. This, combined with the formed microalgal biofilm, contributed to an improved digestibility of the dry matter, reaching 69.1% and 65.9% for the final products based on the BG11 medium and LM mediums, respectively, compared to 52.1% for the raw RS. Furthermore, the crude protein and lipids contents were significantly improved with the potential for applications in feed, reaching 21.4% and 4.1% for the BG11 medium-based product, while they were observed to be 12.8% and 3.0%, respectively, for the LM-based product. Additionally, carbon-to-nitrogen ratio was significantly reduced compared to the raw RS. The higher digestibility and improved nutritional value contributed to increased biogas production, reaching 129.3 and 118.7 mL/g (TS) for the products based on the traditional medium and LM medium, respectively, compared to 86.7 mL/g (TS) for the raw RS. The immobilization mechanism and biofilm development could be attributed to the roughness of the RS and extracellular polymer substances. This study demonstrates that integrating C. vulgaris cultivation on RS with LM as a nutrient source not only enhances the digestibility and nutritional value of RS but also offers a sustainable waste management solution with potential applications in biogas production and animal feed.

Biofilmed-PGPR: Next-Generation Bioinoculant for Plant Growth Promotion in Rice under Changing Climate

The exopolysaccharide matrix of the diazotrophic cyanobacteria was used to integrate the phosphorus (P) and potassium (K) solubilizing bacteria for enhanced survival of the plant growth-promoting bacteria and, ultimately, survival of bacteria in the rhizosphere for better plant growth. A new biofilm-based formulation comprising the diazotrophic cyanobacteria Anabaena AMP2, phosphorus-solubilizing Bacillus megaterium var. phosphaticum PB1, and potassium-solubilizing Rhizobium pusense KRBKKM1 was tested for efficacy in rice. The growth medium with half-strength BG-11 medium supplemented with 3% glucose showed best for biofilm formation under in vitro conditions. Analysis of the methanolic extract of the cyanobacterial-bacterial biofilm (CBB) showed antioxidants, such as 2-methoxy phenol and pentadecane, which are proven to improve plant-microbe interactions and plant growth promotional activity, respectively. Treatment of rice seeds with CBB extract at 10 mL or 20 mL/100 g showed significant enhancement in germination percentage and seedling length. Therefore, a pot culture experiment with the CBB formulations was carried out, and different growth and yield parameters were recorded. Principal component analysis showed that the plant growth, yield, soil dehydrogenase activity, and soil chlorophyll content were positively correlated with rice plants amended with vermiculite-based CBB at 2 kg/hm2 followed by a spray with aqueous CBB formulation at 5 mL/L on 15 and 30 d after the rice transplanting (T6) grown with a 25% reduced level of NPK chemical fertilizers than the recommended dose. Further, Pearson correlation analysis showed that yield was positively correlated with soil dehydrogenase (r = 0.92**) and soil chlorophyll content (r = 0.96**). We concluded that CBB could be used as a novel biofilm-based bio-inoculant to increase rice productivity and crop fitness as a component in integrated nutrient management and sustainable organic farming strategies with reduced chemical fertilizers.

Comparative study of the synthesis of polyhydroxyalkanoates by cyanobacteria Spirulina platensis and green microalga Chlorella vulgaris

The article presents the results of the study of the growth and synthesis of degradable polyhydroxyalkanoates (PHA) of cyanobacteria Spirulina platensis (Nordst) Geitl. and green microalga Chlorella vulgaris (Beijer), in the cultures of which the production of “green” plastics was studied, including in relation to the dynamics of the fatty acid composition of lipids associated with the formation of PHA. The reorganization of constructive metabolism during the development of both cultures and the dynamics of accumulation of lipids and PHA in cells against the background of a decrease in protein were studied. On a modified BG-11 medium, with a decrease in the NaNO3 concentration to 0.5 g/L and the addition of sodium acetate (3/0 g/L), the yields of polymers for C. vulgaris and S. platensis reached 20.0 and 16.2 %, respectively. The composition and properties of the polymer, which is a homopolymer of 3-hydroxybutyric acid (P(3HB)), were studied using GC, FTIR spectroscopy, HPLC, and DTA. The average molecular weight of P(3HB) samples was determined to be 416–467 kDa; crystallinity was 54–56 % with a gap between the melting point and thermal degradation temperature of 109–114 °C.

Sweet sorghum as alternative carbon sources for Chlorella sp. valued-added compounds production: A mechanistic insight using transcriptomics

Substituting agricultural by-products for glucose as a carbon source is an effective strategy for reducing the cultivation cost of Chlorella sp. However, the response mechanism of Chlorella sp. to variations in carbon sources remains unclear, and the potential of microalgal biomass for food development warrants further exploration. This study used hydrolysate of sweet sorghum stem juice (HSJ) for the mixotrophic cultivation of Chlorella sp. And transcriptomic analysis was performed to investigate the physiological and metabolic mechanisms as well as the biosynthesis of value-added compounds (e.g., pigments and proteins) of Chlorella sp. in response to changes in carbon sources. The HSJ + NM group (HSJ supplemented with nitrogen and minerals) significantly increased total chlorophyll, carotenoids, lutein, and protein levels by 18.02 %, 13.34 %, 35.95 %, and 20.36 %, respectively, compared to the control (adjusted BG-11 medium supplemented with 10 g/L glucose). Notably, transcript levels of genes for multiple key enzymes involved in glycolysis/gluconeogenesis, TCA cycle, oxidative phosphorylation pathway, and photosynthesis pathways were significantly up-regulated. The activity of these pathways promoted the pigments and proteins synthesis in Chlorella sp. Encouragingly, the cost of cultivating Chlorella sp. with HSJ + NM (0.495 USD/kg) was 43.35 % of glucose (1.142 USD/kg). Further, by fermenting Chlorella sp. cultures with Saccharomyces cerevisiae and further homogenizing and blending the fermentation broth, we developed a nutritious and palatable Chlorella sp. fermented beverage, addressing the common issue of algal odor in such products. This study provides theoretical and practical foundations for the mixotrophic cultivation of microalgae and the application of microalgal biomass in food innovation.

Individual and combined effects of ionophore antibiotics monensin and lasalocid on growth, oxidative stress and antioxidant responses of Microcystis aeruginosa

ABSTRACT To assess the impact of monensin, lasalocid, and a 1:1 (w/w) mixture of monensin and lasalocid on the formation of Microcystis aeruginosa-based harmful algal blooms (HABs), laboratory experiments were conducted [temperature 20 ± 1°C, illumination PAR 30 ± 4 μmol/m2 ·s (12-h light/dark cycle), growth medium BG-11] at concentrations of 100, 200, 500, 1,000, and 2,000 μg/L. Measurements included optical density, cell protein, chlorophyll ‘a’ (Chl. a) content, oxidative stress, catalase activity (CAT), and guaiacol peroxidase activity (GPX). Monensin treatment showed a dose-dependent positive effect on M. aeruginosa growth at concentrations ≤500 μg/L and a gradual dose-dependent growth inhibition at concentrations of 1,000 and 2,000 μg/L. The results indicated that monensin has a significant positive effect on the formation of HABs by M. aeruginosa. Lasalocid treatment showed a growth reduction of M. aeruginosa at concentrations ≤500 μg/L and a growth increase at higher concentrations (1,000 and 2,000 μg/L). The 1:1 (w/w) mixture test showed an intermediate response, as indicated by the individual treatments signifying the potential interactive effects of these antibiotics on M. aeruginosa. Furthermore, alterations in Chl. ‘a’, oxidative stress, CAT, and GPX measurements provided evidence of the impact of these antibiotics on the existence of M. aeruginosa.

Unraveling the residual sludge-mediated waste transformation and physiological regulation mechanism of Tetradesmus obliquus

The accumulation of residual sludge as process waste from water treatment engineering needs to be addressed urgently. Tetradesmus obliquus is an important algal species in the field of wastewater treatment. In this study, T. obliquus was cultured in different sludge extract to determine its ability to utilize wastes from the liquid phase and convert them into biomass, and to analyze the response of the microalgae to toxic stress using proteomics. The results showed that the sludge extract medium was superior to the BG11 medium in accumulating biomass, with dry weights, proteins and polysaccharides at least 1.09, 1.12 and 1.28 times higher than those of BG11 medium. In toxic group, T. obliquus reduced TOC from an initial 426.8±20.0 mg/L to 180.4±8.5 mg/L with a simultaneous 48.4 % reduction in toxicity. Toxic sludge extract produced greater damage to the photosystem of T. obliquus compared to the blank, significantly inhibiting the expression of two photosystem II core proteins, A0A383VSL5 (0.290 down) and A0A383V2Z3 (0.308 down), on day 5. However, these impairments were reversible, and at day 20, the expression of A0A383VSL5 was not inhibited, the inhibitory effect of A0A383V2Z3 (0.575 down) was attenuated. These results fill a gap on the treatment of various types of residual sludge by T. obliquus and provide promising strategies for microalgae treatment of residual sludge, whether non-toxic or toxic.

The Impact of pH and Growth Phases on Photosynthetic Pigments and Carotene of Coelastrella saipanensis N. Hanagata (Scenedsmacese, Shaerophleales)

The present study aimed to investigate the effects of level pH and the growth phases of Coelastrella saipanensis on Chlorophyll a,b, total, and Carotene. The algae were cultured in BG11 media and grown at different pH levels. We measured chlorophyll a, b, total chlorophyll, growth phases, and carotene concentrations. The results showed that at pH 8.5, the measurements of photosynthetic pigments-chlorophyll a, Chlorophyll b, and the total chlorophyll (0.183, 0.268, and 0.433 mg L-1, respectively). The highest values of chlorophyll a (0.185 mg L-1), and b (0.339 mg L-1), and the total chlorophyll (0.492 mg L-1) were recorded in the stationary phase. In addition, the study found that at pH 8.5 and the beginning of the stationary phase, the highest levels of chlorophyll a, b, and total chlorophyll were 0.216, 0.398, and 0.603 mg L-1, respectively, in correlation with pH-cell harvesting phase interaction. Similarly, carotene concentrations were increased as photosynthetic pigments and recorded the highest values (2.533 mg L-1) at pH 8.5, and 3.275 mg L-1 at the stationary phase. Therefore, the algal C. saipanensis is a vital source of carotene to support nutrition and health It is used as an antioxidant.

Different organic carbon sources affect microalgal growth and extracellular polymeric substances synthesis to trigger biomass flocculation process

The addition of organic carbon sources into the culture medium represents an effective strategy for microalgae cultivation. However, its influence on the subsequent flocculation process remains poorly understood. In this study, four representative organic carbon sources were supplemented to microalgal cultures with the aim of evaluating their potential to enhance biomass accumulation, optimize fatty acid composition and improve phototolerance. The results demonstrated that the addition of ethanol, sodium acetate, glucose and fructose to the cultures resulted in extracellular protein contents of 90.9, 125.7, 67.5 and 46.0 mg/g, respectively, compared to 36.8 mg/g observed in the control culture with pure BG-11 medium. The addition of organic carbon sources led to alterations in protein content and the composition ratio of charged groups within the extracellular polymeric substances of microalgae, which in turn influenced the flocculation process. This study provides valuable insights into the selection of appropriate organic carbon sources for promoting microalgal growth and clarifies the flocculation mechanisms under various carbon utilization strategies.

Isolation and Molecular Characterisation of Chlorogonium sp. from Industrial Wastewater

Microalgae are photosynthetic, unicellular microorganisms also known as phytoplankton. They are small plant-like entities. In this research, the sample were collected from cement factory in a sterilised 20L container wrapped with foil paper and were transported down to Federal University, Wukari where it was kept in refrigerator at biochemistry laboratory. Blue-Green media (BG-11) was prepared. Wastewater containing Microalgae obtained from cement wastewater pond were cultivated in BG-11 medium to determine the growth of the organism. BG-11 medium contained macronutrients, trace metals and some vitamins which aid the growth of the organism. The wastewater sample containing with suspected microalgae was inoculated (inoculum ratio = 25%) and incubated under atmospheric CO2 at room temperature (30±2°C) in our laboratory for two to three weeks during the incubation period. In order to purify the isolates, the upper growth layer was first decanted into a freshly produced medium and then plated on BG-11 media that had been solidified with 1% agar-agar. For several of the cultures, growth on the agar plates continued for around three weeks. Following repeated sub-culturing, the emerging greenish colonies were re-emerged into a sterile BG-11 agar medium. In isolation of organism from the industrial cement waste water, the isolate was identified by morphological and molecular identification by extracting the DNA, run the electrophoretic analysis and PCR using primers for 18S rRNA eukaryotic microalgal and then run the sequence analysis. The results of this study obtained, indicated that, the electrophoretic result show the band has 1800-2000base pair and the organism isolated from the industrial cement waste water were chlorogonium sp. with a percent similarity of 78.65% and accession number of OR886595 based on data Gene Bank blast results.

Effect of cephalexin on chlorophyll and carotenoid content of Chlorella pyrenoidosa-2378 and its biodegradation in BG-11 medium

Cephalexin (CFX), a β-lactam antibiotic which is identified for the treatment of different disease infections, has been reported as a micropollutant in wastewater released from sewage, hospital, or pharmaceutical industries. Chlorella pyrenoidosa-2378, a green microalgal strain, is recognized for its degradation ability against wastewater pollutants and the potential of the biomass it produces. In this present study, the cultivation process of Chlorella pyrenoidosa-2378 strain with CFX concentration of 50 mg/L, 100 mg/L, 150 mg/L, and 200 mg/L added to its culture medium labeled as test I, test II, test III, and test IV, respectively, is the process being observed for evaluation of its degradation ability and as sustainable approach for antibiotic degradation. chlorophyll a in test IV, chlorophyll b in test III, and carotenoid content in test I were observed to be higher in amount than control by 0.775 mg/L, .069 mg/L, and 0.356 mg/L, respectively. Using the HPLC method, the total removal efficiency was observed to be 79.09%, 86.26%, 89.62%, and 88.03% against 50, 100, 150, and 200 mg/L concentrations of CFX, respectively. The observations that C. pyrenoidosa-2378 remained stable while being used as an alternative bioremediation method, provide an alibi for its novelty and potentiality to be used commercially for biomass production and at industrial scale for degradation.Graphical

Characterization of UV-absorbing Mycosporine-like Amino Acids in Freshwater Cyanobacterium Nostoc calcicola

Mycosporine-like amino acids (MAAs) are gaining attention for their UV photoprotective properties and potential applications in biomedical fields, cosmetics, and toiletries. In this study, Nostoc calcicola a genus of cyanobacteria distributed in freshwater were tested for MAA production. This organism was provided by the Freshwater Algae Culture Collection of the Institute of Hydrobiology, the Chinese Academy of Sciences. It was isolated and cultured in the laboratory, in 500 ml glass flasks containing 300 ml of liquid medium BG11 treated on UV-B light 0.1 Wm–2. At different time, cultures were exposed to UV-B light at intensity 0.1 W. m-1 to determine the Maximum PSII photochemical (Fv/Fm). MAAs were extracted using 100% HPLC grade methanol and separated through high-performance liquid chromatography and liquid chromatography/mass spectrometry. Based on liquid chromatography/mass spectrometry analysis, one MAA compound was identified as porphyra. Thus, UV-B treatment of Nostoc calcicola significantly enhanced the production of UV-absorbing mycosporine-like amino acids (MAAs). The content of porphyra could reach up to 8.5 mg/g dry weight in Nostoc calcicola under UV-B treatments for 2 days. The present cyanobacteria could be used for biotechnology research and the UV-absorbing compound porphyra may be of great value in the development of novel sunscreens.

Use of mining effluents for the production of algal-based colorants

In this research, a mining effluent was used to produce microalgal and cyanobacterial biomass to obtain red (carotenoids) and blue pigments (phycocyanin). Two strains were isolated from a hydrothermal source in Norte de Santander and grown in mining wastewater mixed with 50% BG-11 medium for the Osci_UFPS01 cyanobacterium and 50% with Bold Basal medium for the Chlo_UFPS01 microalgae. A carbon, nitrogen, and phosphorus experiment design was developed, and subsequent response surface analysis (RSM) was used to determine the optimal operating conditions for the formation of the products of interest. A notable decrease in pigment production was observed compared to that in the controls without mining wastewater. Overall, 45% of phycocyanin (C PC) per unit dry weight (DW) and 1,129% (w/w) of carotenoids were obtained in the cultures with a mining wastewater mixture in the final optimization processes.

Digitalised prediction of blue pigment content from Spirulina platensis: Next-generation microalgae bio-molecule detection

The motive of this study is to predict the concentration of C-phycocyanin (CPC) from Spirulina platensis by adapting several colour models along with machine learning (ML) and deep learning (DL) techniques. Initially, three different culture mediums such as Zarrouk, BG-11, and AF6 were compared, and the BG-11 medium was chosen due to its overall best biomass growth, least amount of chemical usage, and CPC production. The performance of the convolutional neural network (CNN) without the input parameters of ‘Abs’ and ‘Day’ results in a higher R2 of 0.7269 as compared to both support vector machine (SVM) and artificial neural network (ANN) with R2 of 0.2725 and 0.2552, respectively. The absence of regularisation techniques has caused the scenario of model overfitting, showing results of R2Train = 0.9891 and R2Val = 0.5170 (without image augmentation) and R2Train = 0.9710 and R2Val = 0.5521 (including 20 % dropout but without image augmentation). Meanwhile, both SVM and ANN models were observed to show significantly high accuracy when including extra parameters of ‘Abs’ and ‘Day’ as compared to the CNN model with R2 of 0.9903 and 0.9827, respectively. We aim to establish a high precision and real-time assessment of microalgae biomolecule intelligent system that requires low cost, less time consumption, and is widely applicable, addressing the challenges associated with conventional microalgae quantification and identification.

THE INVESTIGATION OF ELEMENTS AFFECTING CERTAIN MICROALG'S DEVELOPMENT AND POSSIBLE ANTIBACTERIAL PROPERTIES

During the previous few decades, the pursuit has experienced an increase for novel marine-derived molecules with potential use in the pharmaceutical, human or animal nutrition, cosmetics, and bioenergy industries. The current study aimed at obtaining the optimum growth rate of some microalgal isolates and finding their antibacterial activity. The microalgae were purified in BG11 medium and the biomass extracted using ethanol, acetone, diethyl ether and methanol was then examined for antimicrobial activity by disc diffusion and minimum inhibitory concentration methods.The optimum growth rate obtained at pH 8, temperature 26-28 ℃, and 2000 lux for all algal isolates. All microalgae extracts showed antimicrobial activity against tested bacteria with different solvents. The higher antibacterial activity obtained with ethanol extracts while water extract showed low antibacterial activity. Chlorella sp. and Spyrogyra sp. showed higher antibacterial rather than other isolates. Overall, these results imply that microalgae extracts, particularly those from Spirogyra sp. and Chlorella sp., may be sources of antibacterial chemicals. To identify and describe the precise bioactive substances in charge of the reported inhibitory effects, additional study is required. Further research into the mechanisms of action, safety, and possible uses of these microalgae extracts in bacterial infection management would be advantageous

Antifungal activity of Neowestiellopsis persica against Rhizoctonia solani in root and crown of Faba bean cultivated under modified BG-110 medium composition

Rhizoctonia solani, a fungal pathogen, affects the quality and yield of Faba bean crops and hinders plant export. Chemical fungicides effectively control fungal pathogens, but their long-term use harms the environment, soil properties, and human health. Cyanobacteria, a promising source of natural bioactive compounds, have shown efficacy against the fungal colony growth of various plant pathogens, highlighting the need for sustainable practices. As a result, this study examined the biological control of the Rhizoctonia solani disease that affects the Faba bean's root and crown. Disease assessments were then done in five groups: (1) healthy control; (2) control infected with Rhizoctonia solani and not treated with cyanobacterial extract; (3) plant infected with Rhizoctonia solani and treated with cyanobacterial extract suspension of 0.02, (4) 0.04, and (5) 0.08 g/L phosphate during 20 and 34 days. The results of the antioxidant activity by the 2,2-Diphenyl-1-picrylhydrazyl (DPPH) assay showed that with increasing phosphate concentration, the activity increased significantly. The results of enzymatic activity indicated that time did not significantly impact the enzymatic activity of glutathione peroxidase (GPx), catalase (CAT), and guaiacol peroxidase (GPX), with the highest and lowest activity being related to codes 2 and control, respectively. However, time had a significant effect on superoxidase dismutase (SOD) activity, with the highest activity reported on day 35. Moreover, the results showed that increasing the concentration of the extract significantly decreased cell viability in hepatoblastoma (HepG-2) cell lines. The cyanobacterial extract treatment caused over 66 % damage to plants infected with Rhizoctonia solani. The overall results indicated that Neowestiellopsis persica, grown under higher phosphate concentrations, can be used as an effective antifungal biocontrol against Rhizoctonia solani in Faba bean roots and crowns.

Enhancing immobilized Chlorella vulgaris growth with novel buoyant barium alginate bubble beads

Microalgae immobilization in alginate beads shows promise for biomass production and water pollution control. However, carrier instability and mass transfer limitations are challenges. This study introduces buoyant barium alginate bubble beads (BABB), which offer exceptional stability and enhance Chlorella vulgaris growth. In just 12 days, compared to traditional calcium alginate beads, BABB achieved a 20 % biomass increase while minimizing cell leakage and simplifying harvesting. BABB optimization involved co-immobilization with BG-11 medium, enrichment of CO2 in internal bubbles, and the integration of Fe nanoparticles (FeNPs). In the open raceway pond reactor, these optimizations resulted in a 39 % increase in biomass over 7 days compared to the unoptimized setup in closed flasks. Furthermore, enhancements in pigment and organic matter production were observed, along with improved removal of ammonia nitrogen and phosphate. These results highlight the overall advantages of BABB for microalgae immobilization, offering a scientific foundation for their effective utilization.

Characterization and potentiality of plant-derived silver nanoparticles for enhancement of biomass and hydrogen production in Chlorella sp. under nitrogen deprived condition

Energy is a crucial entity for the development and it has various alternative forms of energy sources. Recently, the synthesis of nanoparticles using benign biocatalyst has attracted increased attention. In this study, silver nanoparticles were synthesized and characterized using Azadirachta indica plant-derived phytochemical as the reducing agent. Biomass of the microalga Chlorella sp. cultivated in BG11 medium increased after exposure to low concentrations of up to 0.48 mg L−1 AgNPs. In addition, algal cells treated with 0.24 mg L−1 AgNPs and cultivated in BG110 medium which contained no nitrogen source showed the highest hydrogen yield of 10.8 mmol L−1, whereas the untreated cells under the same conditions showed very low hydrogen yield of 0.003 mmol L−1. The enhanced hydrogen production observed in the treated cells was consistent with an increase in hydrogenase activity. Treatment of BG110 grown cells with low concentration of green synthesized AgNPs at 0.24 mg L−1 enhanced hydrogenase activity with a 5-fold increase of enzyme activity compared to untreated BG110 grown cells. In addition, to improve photolytic water splitting efficiency for hydrogen production, cells treated with AgNPs at 0.24 mg L−1 showed highest oxygen evolution signifying improvement in photosynthesis. The silver nanoparticles synthesized using phytochemicals derived from plant enhanced both microalgal biomass and hydrogen production with an added advantage of CO2 reduction which could be achieved due to an increase in biomass. Hence, treating microalgae with nanoparticles provided a promising strategy to reduce the atmospheric carbon dioxide as well as increasing production of hydrogen as clean energy.

Exploring freshwater microalgal strains for Omega-3 polyunsaturated fatty acids and carotenoids from the Ganges River in India

Microalgae, increasingly recognized as a cost-effective reservoir of natural compounds. Their extensive application in nutraceuticals, and pharmaceuticals industry are making them mercantile worthy. This study delves into the realm of bioprospecting freshwater microalgae with focus on extracting high-value products, specifically omega-3 polyunsaturated fatty acids and carotenoids. Freshwater-derived microalgal strains were isolated from Ganges River and refined, and grown in BG-11 culture medium. Microscopic examination was used to screen these microalgae based on morphology. Subsequently, the biochemical properties of the selected microalgal strains were investigated. Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), two crucial omega-3 polyunsaturated fatty acids, were identified in significant quantities in Chlorella variabilis (3.6±1.32%; 2.7±0.13%) and Monoraphidium contortum (2.2±0.36%; 3.2±0.2%). Moreover, the investigation also focused on carotenoids; lutein and astaxanthin. The findings indicated a high concentration of lutein in Chlorella variabilis (4.5 mg g−1), while Monoraphidium contortum exhibited abundant levels of astaxanthin (5.9 mg g−1). These research findings demonstrate the promising capacity of the isolated microalgal strains to yield valuable bioactive compounds.