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Highlights • Co-cultivation of microalgae with fungi performed well in wastewater remediation. • Co-cultivation assisted harvesting is a good way for biomass production and harvest. • Microalgal-fungal biomass might be a good feedstock for biodiesel production. Abstract Aiming at simplifying the harvesting procedure, reducing the production cost, and improving the quality of microalgae-based biodiesel, herein, a novel one-step method for oil-rich biomass production and harvesting was proposed by growing Chlorella sp. with Aspergillus sp. in molasses wastewater. Lipid content and fatty acid profile were measured to assess the suitability of microalgal-fungal biomass for biodiesel production. The results showed that the highest biomass yield (4.215 g/L) was obtained when the inoculation ratio of fungi and microalgae was 100. Activities of fungi positive impacted the decolorization of wastewater and the removal of suspended solids. Thus, co-cultivation system had better performance than mono-system of microalgae in the removal of nutrients in wastewater. Analysis of biomass compositions showed that compared with mono-system of microalgae, co-cultivation system produced biomass with higher lipid content (35.2%) and yield microbial cell oil with lower unsaturation degree, potentially increasing the quality of microbial-cell-lipid based biodiesel. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Batch-feeding modes of NH4HCO3 for absorption-microalgae hybrid process were optimized. • Influence of batch-feeding modes on NH3 escape was investigated. • Carbon conversion efficiency of hybrid process was intensified via batch-feeding modes optimization. • Value-added ingredients variation with batch-feeding modes was also evaluated. Abstract Ammonia-absorption-microalgae hybrid CO 2 capture process presented the potential advantages in cost-effective CO 2 capture and bioconversion. However, cultivation mode still needs to be intensified to reduce the negative influence of NH 3 escape and its inhibition on microalgae growth. In the current work, three batch feeding modes of ammonium (i.e. NH 4 HCO 3) for two Chlorella sp. (UTEX1602 and L38) were investigated. The experimental results indicated that initial NH 4 HCO 3 deficiency (mode A) was beneficial for microalgae growth compared to the cultivation modes of uniform feeding (mode B) and decreasing dosage (mode C). Chlorella L38 presented a higher growth rate than UTEX1602, and might be more suitable for absorption-microalgae hybrid CO 2 capture system. In detail, carbon utilization efficiency could achieve up to 76.8% in the absorption-microalgae hybrid process, which was two to three times higher than the conventional microalgae CO 2 fixation processes. NH 3 escape rate in absorption-microalgae hybrid process could be reduced to 24.2%, which was 18.8% lower than the conventional ammonia CO 2 absorption process. Moreover, nitrogen and carbon in NH 4 HCO 3 could be converted into biomass and value-added ingredients to realize resource recycling. [ABSTRACT FROM AUTHOR]

Abstract Microalgal biomass has recently been one of the most widely studied feedstocks for bio-hydrogen production, owing to its richness in fermentable components, e.g. polysaccharides and proteins, and high biomass productivity. In this study, biomass of microalga Chlorella sp. TISTR 8411 was converted to hydrogen through a sequential process consisting of an anaerobic solid-state fermentation (ASSF) followed by a dark fermentation. The microalga was grown photoautothrophically in 80-L rectangular glass tanks and then scaled-up to a 240-L open pond for the production of biomass. The highest biomass concentration attained was 4.45 g L−1. The biomass was harvested with over 90% flocculation efficiency at pH 11.5 and a biomass concentration of 2.6 g/L. The sequential process gave a total hydrogen yield (HY) of 16.2 mL/g-volatile-solid (VS), of which 11.6 mL/g-VS was from ASSF. The high HY obtained from the ASSF indicated that it was effective and could be integrated with a conventional hydrogen production process to improve energy recovery from biomass. Highlights • A sequential process for converting Chlorella sp. biomass to hydrogen was developed. • Cultivation of Chlorella sp. in a 240-L open pond gave 4.45 g-biomass/L. • PH 11.5 and a biomass concentration of 2.6 g/L are suitable harvesting conditions. • Anaerobic solid-state fermentation of Chlorella sp. gave a HY of 11.6 mL-H 2 /g-VS. • Dark fermentation of acid-thermal ASSF hydrolysate gave a HY of 4.6 mL-H 2 /g-VS. [ABSTRACT FROM AUTHOR]

The presence of heavy metals in aquaculture is a major concern due to possible toxicity effects to the organisms. Bioaccumulation with bacteria is an effective and economical way to remove heavy metals from the water. The objectives of this research were to measure the growth rate of probiotics (Bacillus sp. BpChIAY [BpChIAY] and Bacillus thruingiensis, [Bt]) under different concentrations of selected heavy metals, and to determine the ability of the probiotics to bioaccumulate selected metals. Bacterial strains were grown in nutrient broth with the addition of heavy metals (Cu, Cr, Cd, Zn, Ni) at 37oC to determine the growth under exposure to heavy metals. The bioaccumulation experiment was conducted by exposing the strains' pellets to heavy metals solutions. The concentrations of heavy metals were measured using Atomic Absorption Spectroscopy (AAS). The bacterial growth percentages when grown under 2 ppm Zn, Ni and Cd for BpChIAY were 128%, 103% and 67%, and for BT, the growth rates were 97.7%, 98.8% and 36.2%, respectively. The findings showed the order of the toxicity in the order from the most toxic: Cu>Cr>Cd>Zn>Ni. Both strains were able to bioaccumulate the heavy metals, and BpChIAY was a better metal absorber than BT at the rate of 0.0539 mg/g for Zn, 0.0781 mg/g for Ni and 0.0256 mg/g for Cd. [ABSTRACT FROM AUTHOR]

Highlights • Differently functionalized microplastics modulates the toxicity of TiO 2 NPs. • Neutral and positively charged microplastics inclined TiO 2 NPs toxicity. • Negatively charged microplastics decreased TiO 2 NPs toxicity. • Mixture toxicity was validated using mathematical modelling, Abbott. • Oxidative stress follows the trend: TiO 2 NPs+ Plain PS/NH 2 -PS > TiO 2 NPs+ COOH-PS. Abstract Increased utilization of titanium dioxide nanoparticles (TiO 2 NPs) for commercial as well as industrial purposes resulted in the accumulation of nanoparticles in the marine system. Microplastics being an emerging secondary pollutant in the marine ecosystem have an impact on the toxic effects of TiO 2 NPs which has not been evaluated up to date. So it is important to assess the toxic effects of both these pollutants on the marine environment. The present study examines the impact of differently functionalized microplastics on the toxic effects of P25 TiO 2 NPs to marine algae Chlorella sp. The tendency of nanoparticles to undergo aggregation in artificial seawater was observed with increase in time. The median effective concentration for TiO 2 NPs was found to be 81 μM which indicates higher toxic effects of NPs toward algae. In contrast, microplastics irrespective of their difference in functionalization had minimal toxic effect of about 15% at their higher concentration tested, 1000 mg L−1. Plain and aminated polystyrene microplastics enhanced the TiO 2 NPs toxicity which was further validated with oxidative stress determination studies like reactive oxygen species and lipid peroxidation assays. Negatively charged carboxylated polystyrene microplastics decreased the TiO 2 NPs toxicity with possible hetero-aggregation between TiO 2 NPs and microplastics in the system. The toxicity data obtained for the mixture was further corroborated with Abbott's mathematical model. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Biodegradability of florfenicol via two kinds Chlorella sp. was investigated. • Florfenicol could be removed by Chlorella L38 with removal ratio above 95%. • Chlorella L38 could grow with low inhibition rate under the high concentration of florfenicol. • Florfenicol biodegradation was the dominant pathway via microalgae purification. Abstract In this work, florfenicol removal via two kinds Chlorella sp. (UTEX1602 and L38) was investigated. The experimental results indicated that FF could be removed by biodegradation associated with microalgae growth. Compared to Chlorella sp. UTEX1602, L38 had a good self-adjustment capacity at the condition of high initial FF concentration. The biodegradation of FF followed the first order kinetic model with half-lives ranged from 3.53 to 7.63 days at different initial concentration. The removal efficiency of FF could achieve 97% when the FF concentration was set at 46 mg·L−1. While the FF concentration in the medium increased to 159 mg·L−1, more than 74% FF could still be purified via Chlorella sp. L38. Therefore, Chlorella sp. L38 could be promising alternative algae to be used for FF removal from different water sources. [ABSTRACT FROM AUTHOR]

A freshwater green microalgae Chlorella sp., UMACC344 was shown to produce high lipid content and has the potential to be used as feedstock for biofuel production. In this study, photosynthetic efficiency, biochemical profiles and non-targeted metabolic profiling were studied to compare between the nitrogen-replete and deplete conditions. Slowed growth, change in photosynthetic pigments and lowered photosynthetic efficiency were observed in response to nitrogen deprivation. Biochemical profiles of the cultures showed an increased level of carbohydrate, lipids and total fatty acids, while the total soluble protein content was lowered. A trend of fatty acid saturation was observed in the nitrogen-deplete culture with an increase in the level of saturated fatty acids especially C16:0 and C18:0, accompanied by a decrease in proportions of monounsaturated and polyunsaturated fatty acids. Fifty-nine metabolites, including amino acids, lipids, phytochemical compounds, vitamins and cofactors were significantly dysregulated and annotated in this study. Pathway mapping analysis revealed a rewiring of metabolic pathways in the cells, particularly purine, carotenoid, nicotinate and nicotinamide, and amino acid metabolisms. Within the treatment period of nitrogen deprivation, the key processes involved were reshuffling of nitrogen from proteins and photosynthetic machinery, together with carbon repartitioning in carbohydrates and lipids. [ABSTRACT FROM AUTHOR]

Nutrient starvation condition has already been exploited as a suitable strategy to induce more lipid production. In this study, nutrient limitation has been coupled with phytohormone or antioxidant supplementation to identify the potential of chemical stimulants to support growth and neutral lipid accumulation. Naphthalene acetic acid (NAA), and Ascorbic acid (AA), at concentrations of 5, 10, and 15 ppm were supplemented to N-limited level 1 (0.25 g NO 3 -N/L), N-limited level 2 (0.041 gNO 3 -N/L), and P-limited (0.01 gPO 4 -P/L) culture media of two Chlorella species to maximize biomass and lipid production. The results show that neutral lipid content increases 70 % when AA is added to the P-limited medium of Chlorella vulgaris IG-R-96 at 15 ppm. At N-limitation level 1 coupled with NAA and AA supplementations at 15 ppm, neutral lipid contents increase 107 % and 128 % in C. vulgaris IG-R-96, and 42 % and 60 % in Chlorella sorokiniana IG-W-96, respectively. When simultaneous N- and P-limitation is applied, neutral lipid content becomes almost double in C. vulgaris IG-R-96 at 10 ppm of NAA supplement. The effects of phytohormone and antioxidant on growth and neutral lipid accumulation is species-dependent and could be more effective when it is combined with nutrient limitation conditions. Stimulant supplementation is significantly effective for neutral lipid accumulation. [Display omitted] • Antioxidants and phytohormones improve lipid accumulation in nutrient-limited algal cultures. • In N-limited culture, the Ascorbic acid (AA), and naphthalene acetic acid (NAA) improve lipid content by 128 % and 107 %, respectively. • In P-limited medium, the AA improves lipid content of Chlorella vulgaris IG-R-96 by 70 %. • Simultaneous N- and P-limitation with NAA supplementation doubles lipid content. [ABSTRACT FROM AUTHOR]

Cadmium (Cd) is a metal that can negatively interfere with the metabolic systems of living beings. The objective of this work was to evaluate the capacity for cadmium removal in aqueous solutions by immobilized Chlorella sp. in calcium alginate beads. Beads without Chlorella sp. were used as a control. All the treatments were established in triplicate for 80 min, at four concentrations of cadmium (0, 20, 100 and 200 ppm), taking samples of aqueous solution every 10 min, to be read using atomic absorption equipment. The study determined that the treatment of alginate beads with immobilized Chlorella sp. removed 59.67% of cadmium at an initial concentration of 20 ppm, this being the best removal result.

Traditional markets play a major role in socio-economics and constitutes a significant aspect of Vietnamese culture. However, wastewater streams discharged from the markets are generally characterized by a lot of inorganic nutrients and organic substances originated from fresh food processing units. They could lead to serious water contamination if discharged without proper treatment. This study applied microalgae Chlorella sp. for eliminating inorganic nutrients (NO3−-N, NH4+-N and PO43−-P) and organic carbon (Chemical oxygen demand-COD) from wastewater of the Binh Dien market. The removal efficiencies reached for NH4+-N > 86%, for NO3−-N > 72%, and for PO43−-P > 69%, respectively, at algal density of 49 × 104 cell mL−1, and for COD > 96% at algal density of 35 × 104 cell mL−1 after five cultivating days. The effluence satisfied the Vietnamese standard, column B, of the National technical regulation on industrial wastewater (QCVN 40:2011/BTNMT). The results demonstrated that the culture system composed of green algal Chlorella sp. could be a potential candidate for the removal of nutrients and organic carbon by a wastewater treatment process from the Binh Dien market.

Background: This study was carried out to determine the oil fatty acids from two special species of microalgae; Spirulina sp.,Chlorella sp. and also Chaetoceros sp. collected from Bahmanshir River. Materials and Methods: Sampling of microalgae Chaetoceros sp. from Bahmanshir River was under taken using bottle samplers during spring season of 2013. Microalgae Spirulina sp. and Chlorella sp. were supplied from Shrimp Research Institute of Iran in Bushehr Province. Samples then were cultured under controlled laboratory conditions and mass culture for 100 liters was undertaken. Isolation of microalgae species from water of cultured media was carried out using filtration and centrifugation methods. The fatty acid compositions were determined by Gas – FID chromatography. Results: Results showed that regarding Saturated Fatty Acids (SFA) obtained from purified culture of Chaetoceros sp., Spirulina sp. and Chlorella sp. the maximum amount of total fatty acids were belonged to palmitic acids (C16:0) with 15.21%, 30.1% and 25.17% of total fatty acids respectively. Analysis of Mono Unsaturated Fatty Acids (MUFA) showed that in the Oleic acid was maximum amount of 34% in Spirulina sp. In addition the amount of MUFA in Chlorella sp. was 16.37% of total fatty acids. On the other hand the amount of palmeotic acid in purified culture of Chaetoceros sp. was 30.33% from total content of fatty acids. Analysis of Poly Unsaturated Fatty Acids (PUFA), Linoleic acid (C18:2) (Omega 6), revealed maximum percentage in Spirulina sp. with 18.8%. Results of Alpha linoleic acid (C18:3) (Omega3) analysis showed maximum amount of 9.66% in Chlorella sp. compared to other microalgae with lower omega 3 contents. Spirulina sp. contained maximum amount of Linoleic acid (C18:2) with 18.8% of total fatty acids. Therefore, Spirulina sp. can be considered as a rich source of omega 6 for the purpose of fatty acid extractions. The presence of PUFA in Chlorella sp. and Spirulina sp. was equivalent whereas the amount of Omega 3 in Chlorella sp. was higher than two other species. Conclusion: Results of this study revealed a diverse profile of fatty acids among many species of phytoplanktons and microalgae. There Chlorella sp. with a good candidate and a rich source of Omega 3 future applications. It is indicated that different species have totally different fatty acid profiles. Therefore, to acquire special products for a particular target, selection of specific species is essential.

This study investigated the use of a high-pressure homogenization process for the production of high shear stress on Chlorella sp. cells in order to effectively degrade their cell walls. The high-pressure homogenization process was conducted by using various pressure conditions in the range of 68.94–275.78 MPa with different numbers of repeated cycles. The optimal high-pressure homogenization pretreatment conditions were found to be two cycles at a pressure of 206.84 MPa, which provided an extraction yield of 20.35% (w/w) total cellular lipids. In addition, based on the confocal microscopic images of Chlorella sp. cells stained by using nile red, the walls of Chlorella sp. cells were disrupted more effectively using this process when compared with the disruption achieved by conventional lipid-extraction processes. By using the by-product of Chlorella sp., 47.3% ethanol was obtained from Saccharomyces cerevisiae cultures. These results showed that the high-pressure homogenization process efficiently hydrolysed this marine resource for subsequent bioethanol production by using only water.

Introduction: Using bio-sorbents is regarded as one of the effective methods to remove heavy metals. Therefore, this study aimed to investigate Pb adsorption from contaminated water by Chaetoceros sp. and Chlorella sp. algae. Methods: This experimental study was conducted in a batch reactor. The amount of Pb adsorption by Chaetoceros sp. and Chlorella sp. algae was studied under such conditions as different adsorbent dosages (0.2, 0.5, 1.5 and 2 g/L), different pH (3, 4, 5, 6, 7, 8), different temperatures (20, 25, 30, 35, 40 °C), different contact times (30, 60, 90, 180, 360 minutes), different particle sizes (20, 40, 60, 100, 140 mesh) and different Pb concentrations(20, 40, 60 mg/L). Then adsorption isotherms and kinetic models of metal ions were determined based on Langmuir and Freundlich isotherms as well as first and second order kinetic models. Results: The efficiency of Pb removal by Chlorella sp. and Chaetoceros sp. algae was reported 78% and 60% respectively. The maximum adsorption was observed at optimal conditions including 25 °C, pH of 6, 180 minutes of contact time, particle size of 20 mesh, 1.5 gr/L of adsorbent and 20 mg/L concentration of Pb. Chlorella algae was observed to remove Pb more than Chaetoceros algae. Based on the study results, Pb absorption by Chlorella algae complies with Langmuir adsorption isotherm model, whereas Chaetoceros algae follows Freundlich model. The kinetic models of algae adsorption followed a second order equation. Conclusion: The study findings revealed that Chlorella algae can be effectively used in order to adsorb Pd from contaminated water due to its high efficiency of Pd adsorption.

Microalgae are powerful source for nutritionally valuable components as proteins, carbohydrates and especially unsaturated fatty acids. Microalgae may be employed in pharmaceutical, food, cosmetic, health industries, and biofuels. In this study for looking at high-level unsaturated fatty acids species, from 31 strains, by comparing growth curves, the best strain with a high growth rate and lipid content was selected by red Nile staining. It was determined by molecular identification that this strain belongs to the genus Chlorella sp. and is deposited into the Agricultural Biotechnology Research Institute of Iran Culture collection with culture collection number ABRIICC 30,041. Biomass analysis after growth optimization by response surface methodology showed that the selected strain had a specific growth rate of 0.216 ± 0.008 d -1 , biomass productivity of 142.58 ± 4.41 mg/Ld, and lipid content of 13.9 ± 0.26% with a high level of unsaturated fatty acids of 53.15%. It also included 51.3 ± 0.53% protein with a very high quality essential amino acids of 40.36%, the most lysine (8.77%) and arginine (13.31%) has been reported until now, and 26.9 ± 0.23% carbohydrates in photoautotroph condition. By MTT assay, there is no effect of cytotoxicity. This research introduces a potent native strain comparable with commercial strains that can be a hopeful source for food supplements and valuable bioactive ingredients in functional foods., (© 2023. The Author(s), under exclusive licence to Springer Nature B.V.)

This paper presents the data on growth performance of marine Chlorella sp. cultured in different cost-effective media including cow dung, cow urine, poultry litter, compost, NPK (nitrogen, phosphorus, and potassium), and UTR (Urea, TSP, and red potash). Growth curve of Chlorella sp. was determined at 5 mg of cow dung, poultry litter, compost, NPK, UTR and 5 µL of cow urine per 350 ml sea water (25 ppt) to identify the onset of stationary phase. Further four media among these were selected to continue the experiment at 8 mg and 11 mg of concentration. The higher cell densities were 4.21 × 10 6 and 4.18 × 10 6  cells/mL for NPK at 8 mg and 11 mg of concentration on 6th and 5th day, respectively. Cow dung with an 11 mg of concentration exhibited 2.67 × 10 6  cells/mL on the 3rd day, which is around 1.5 times greater than the highest growth in the same concentration of poultry litter. Chlorella sp. had a higher cell density in NPK media than in other media, however it was discarded since it is inorganic and costly. Due to the low cell density in cow urine media and the prolonged stationary phase in poultry litter media, the focus of the subsequent study was then placed on cow dung media. The data will contribute to the selection of locally available and cost-effective culture media by determining the stationary phases for specific microalgal species which will replace the costly and labor-intensive commercial media., (© 2023 The Author(s).)

In the context of global demand for carbon reduction, the formation of inorganic carbon (IC) in the wastewater from oil flooding becomes a potential threat. In this study, Chlorella sp. and Fusarium sp. were used to assemble a fungal-algal pellet to degrade polyacrylamide (PAM) and fix IC in synthetic oil-flooding wastewater. The results showed that the combination of Chlorella sp. and Fusarium sp. was more effective at degrading PAM and removing carbon than a monoculture. With PAM as the sole nitrogen source, the degradation of PAM by the consortium was enhanced up to 35.17 ± 0.86% and 21.63 ± 2.23% compared with the monocultures of fungi or microalgae, respectively. The degradation of the consortium was significantly enhanced by the addition of an external nitrogen source by up to 27.17 ± 2.27% and 22.86 ± 2.4% compared with the monoculture of fungi or microalgae, respectively. This may depend on the effect of synergy between the two species. For the removal of IC from the water, the removal efficiency of the consortium was higher than that of the microalgae by 38.5 ± 0.08%, which may be attributed to the ability of the fungi to aid in the adsorption of nutrients and its assimilation by the microalgae. Therefore, the Fusarium - Chlorella consortium can effectively degrade PAM, while simultaneously fixing carbon, which provides a feasible scheme for the treatment and carbon neutralization of the wastewater that contains PAM., Competing Interests: ZP was employed by The Architectural Design and Research Institute of HIT Co., Ltd.. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Zhang, Shangguan, Zhou, Peng and An.)

Microalgae are microscopic photosynthetic organisms found in marine and freshwater environments. This organism is a eukaryotic group of polyphyletic and very diverse. This study investigated the biochemical composition and sub-chronic test of Chlorella Sp. and Spirulina Sp. isolated from Glagah coastal water (Yogyakarta, Indonesia) as a preclinical study to create potential nutritional supplement for human health. Microalgae culture was analyzed for biochemical composition using several methods: AAS for metal analysis (Pb, Cu, Fe, Mg, Zn, and Hg), GC-MS and UV spectrophotometer for fatty acid profiles analysis (lenolenic acid, eicosatrienoic acid, arachidonic acid, linoleic acid, oleic acid, eicosenoic acid, EPA, DHA, omega 6 and 9), Alkaloids, Steroids, Tanin and Saponin. The next step is to do a sub-chronic test of microalgae biomass using experimental animals. The result shows that Spirulina sp. and Chlorella sp. contain 16 and 10 different biochemical compounds respectively. Furthermore, organic nutritional properties in both of microalgae are relatively high with a rich biochemical profile of Fe and nutritious poly-unsaturated fats (such as linolenic acid, arachidonic acid, omega 6, and 9). Regarding sub-chronic toxicity test, it was clear that Spirulina and Chlorella did not affect the blood profile. These findings suggest that both of Glagah strain microalgae are considered to have great potential as a multi-nutritional human health supplement. [ABSTRACT FROM AUTHOR]

Shells were used to produce biomass materials through calcining due to their excellent mechanical properties. In this paper, the mussel shells were calcined by the vacuum tube furnace and muffle furnace at 600 °C, 700 °C and 800 °C respectively, and that prepared under optimum conditions was activated by K2CO3 in the hydrothermal method. The pore structure and morphology of the sample were characterized by specific surface area analyser (BET) and scanning electron microscopy (SEM). Then the Chlorella sp. was immobilized by mussel shell powder and chitosan, which was co-cultured for 60 days. The results showed that calcined shells at 700 °C in a vacuum tube furnace have an optimal specific surface area, up to 4.107 m2/g. K2CO3 hydrothermal modification method could effectively enlarge the pores of shell powder, from 4.107 nm up to 16.557 nm. The shell powder modified by chitosan had positive charges, which could attract the microalgae with negative charges, could live for up to 60 days. This article aims to use waste shells to immobilize microalgae, which is not only of great importance to the protection of the environment but also provides a novel way to immobilize microalgae. [ABSTRACT FROM AUTHOR]

The feasibility study on Chlorella sp. lipid extraction using an electrolysis treatment (ET) as pre-treatment was investigated. Stainless steel was used as the anode and cathode material. The ET method was conducted in a batch or continuous system with or without air aeration and recycling flow. The total lipid in Chlorella sp. AWET and AWET were not analysed due to small sample volume. Approximately same amount of lipids were attained from Chlorella sp. BWOET (7.97 ± 0.43% glipid/gdry wt) and BWET (7.95 ± 0.37% glipid/gdry wt) if treated at 5 V/cm and aerated at 16.7 μm3/s for 1800s. Whereas, if Chlorella sp. was treated at 13 V/cm and aerated at 16.7 μm3/s for 1800 s, the total lipid obtained in Chlorella sp. CWOET (8.18 ± 0.49% glipid/gdry wt) was 1.13-fold higher than CWET (7.22 ± 0.47% glipid/gdry wt). Meanwhile under semi-continuous system, similar pattern of result was achieved in Chlorella sp. DWOET (8.58 ± 0.49% glipid/gdry wt) with 1.11-fold higher than DWET (7.72 ± 0.54% glipid/gdry wt), if treated at 14 V/cm and recycled at 2.3 μm3/s for 3000s. This corresponded to lipid oxidation that might have occurred during the ET method. The fatty acid methyl ester (FAME) composition of Chlorella sp. DWOET and DWET contained predominantly methyl linolenate (C18:3) and methyl palmitate (C16:0). The concentrations of methyl palmitate attained in Chlorella sp. DWOET and DWET were 0.049 ± 0.005 g/m3 and 0.045 ± 0.005 g/m3, respectively. [ABSTRACT FROM AUTHOR]

Abstract - A study of a system for carbon dioxide reduction from biogas to increase the methane and accumulate oil in the form of lipid in the Chlorella vulgaris TISTR 8580 was proposed. The system coupled together with the CO2 reduction and oil production systems. Microalgae were cultivated in a photobioreactor bubble column with cell turbidity at 540 nm, where the specific growth and doubling time of the algae were calculated. Biogas was produced from the cow manure, which was injected directly into the C. vulgaris culture system with the different flow rates. The optimum biogas flow rate to affect the highest carbon dioxide fixation efficiency and methane content was tested. By applying the flow rate of 100 mL/min and a concentration of 1.9 x 107 cell/mL of C. vulgaris culture, which is shown that the maximum efficiency of CO2 reduction was 84.48%, while the methane in the biogas effluent increased to 89.40%. The highest biomass productivity, lipid production and content levels of 0.33 mg/L d-1, 4.74 mg/L d-1 and 14.35 % were achieved, respectively. These results show that the utilization of microalgae C. vulgaris is the effective alternative process for reducing the carbon dioxide content, while the biogas methane volumes are increased. The lipids accumulation in the microalgae C. vulgaris culture were 75.22% of unsaturated fatty acid. [ABSTRACT FROM AUTHOR]

Photobioreactor technology, especially bubble column configuration, employing microalgae cultivation (e.g., Chlorella sp.), is an ideal man-made environment to achieve sufficient microalgae biomass through its strictly operational control. Nutrients, typically N and P, are necessary elements in the cultivation process, which determine biomass yield and productivity. Specifically, N:P ratios have certain effects on microalgae's biomass growth. It is also attractive that microalgae can sequester CO 2 by using that carbon source for photosynthesis and, subsequently, reducing CO 2 emission. Therefore, this study aims to investigate the effect of N:P ratios on Chlorella sp.’s growth, and to study the dynamic of CO 2 fixation in the bubble column photobioreactor. According to our results, N:P ratio of 15:1 could produce the highest biomass yield (3568 ± 158 mg L −1 ). The maximum algae concentration was 105 × 10 6  cells mL −1 , receiving after 92 h. Chlorella sp. was also able to sequester CO 2 at 28 ± 1.2%, while the specific growth rate and carbon fixation rate were observed at 0.064 h −1 and 68.9 ± 1.91 mg L −1  h −1 , respectively. The types of carbon sources (e.g., organic and inorganic carbon) possessed potential impact on microalgae's cultivation. [ABSTRACT FROM AUTHOR]

This study aimed to assess the growth of Chlorella strains isolated from adverse environments at various concentrations of monoethanolamine (MEA), evaluating the CO 2 fixation and macromolecule production. For this purpose, the green algae Chlorella sp. and Chlorella fusca LEB 111 were tested against five concentrations of MEA: 50, 75, 100, 200 and 300 mg L −1 . The strain C. fusca LEB 111 exhibited higher tolerance to MEA as well as higher accumulation of dissolved inorganic carbon and efficiency of CO 2 utilization (approximately 37.0% w w −1 ) with the addition of 100 and 150 mg L −1 of MEA. In addition, the highest carbohydrate productivity and the highest lipid productivity were obtained with 50 and 100 mg L −1 of MEA, respectively. Thus, the absorbent increased the carbon concentration in the medium, and its use in culture can be exploited by C. fusca LEB 111 to produce higher macromolecule concentrations. [ABSTRACT FROM AUTHOR]

The aim of this study is to investigate the production of biodiesel from two kinds of microalgae Chlorella sp. and Spirulina platensis. Various items such as culture, lipid extraction and the production of biodiesel have been studied. The results showed that the rapid growth of Chlorella sp. from 0.2 to 0.5 gr per liter productivity biomass of cultivation is more suitable than Spirulina microalgae with slow growth of 0.1 to 0.3 gr per liter for the productivity biomass of culture. In comparison to 26.2% lipid content of microalgae Chlorella sp., Spirulina microalgae lipid content and the amount of 14.3 indicate a significant difference. Biodiesel output value was 28.2% by direct transesterification method. According to the results, it could be argued that microalgae Chlorella sp. features make the most suitable microalgae species for biodiesel production. These features include: rapid growth and high productivity, biomass and suitable lipid contents, environmentally easier cultivation rather than other species, suitable fatty acid profiles, having the most common fatty acids compounds (as C14:0, C16:0 and C18:0) in biodiesel. Extraction method had the best performance of extraction by the biomass Bligh and Dyer method. [ABSTRACT FROM AUTHOR]

This study was carried out using indoor controlled experiments to study the arsenic (As) uptake, biotransformation, and release behaviors of freshwater algae under growth stress. Three freshwater algae, Microcystis aeruginosa, Anabaena flosaquae, and Chlorella sp., were chosen. Two types of inhibitors, e.g., Cu2+ and isothiazolinone, were employed to inhibit the growth of the algae. The algae were cultivated to a logarithmic stage in growth media containing 0.1 mg/L P; then, 0.8 mg/L As in the form of arsenate (iAsV) was added, while both inhibitors were simultaneously added at dosages of 0.1 and 0.3 mg/L, with no addition of inhibitors in the control. After 2 days of exposure, the average growth rate (μ2d) was measured to represent the growth rates of the algae cells; the extra- and intracellular As concentrations in various forms, i.e., arsenate, arsenite (iAsIII), monomethyl arsenic (MMA), and dimethyl arsenic (DMA), were also measured. Without inhibitors, the average growth rate followed the order of M. aeruginosa, Chlorella sp., and A. flosaquae, with the growth rate of M. aeruginosa significantly higher than that of the other two algae. However, when Cu2+ was added as an external inhibitor, the order of the average growth rate for the three algae became partially reversed, suggesting differentiation of the algae in response to the inhibitor. This differentiation can be seen by the reduction in the average growth rate of M. aeruginosa, which was as high as 1730% at the 0.3-mg/L Cu2+ dosage when compared with the control, while for the other two algae, much fewer changes were seen. The great reduction in M. aeruginosa growth rate was accompanied by increases in extracellular iAsV and iAsIII and intracellular iAsV concentrations in the algae, indicating that As transformation is related to the growth of this algae. Much fewer or neglectable changes in growth were observed that were consistent with the few changes in the extra- and intracellular As speciation for the other two algae with Cu2+ inhibition and all the three algae with isothiazolinone inhibition, corroborating the above hypothesis again. All the algae tested in this study demonstrated great abilities for As transformation and release, as seen by the much higher rates of 86.11-99.98% and 81.11-99.89% for transformation and release when compared to the control, respectively. When inhibitors were added, the transformation and release values of only A. flosaquae decreased remarkably down to 72.37-86.79% and 64.67-85.24%, respectively, while no changes were seen for these values in the other two algae, indicating that growth stress did not affect the As transformation and release of the other algae. The biological productivity of As by the three algae followed the order of M. aeruginosa, Chlorella sp., and A. flosaquae, which was generally consistent with the As transformation and release in conditions with and without inhibitors, suggesting that the As behavior in the algae that was related to growth stress largely differed among algae species. [ABSTRACT FROM AUTHOR]

The investigation first time reports the efficacy of de-oiled algal biomass extract (DOABE) for mixotrophic cultivation of Chlorella sp. MCC27 to enhance biodiesel production in open tray systems and in BioXpert-V2 software connected photobioreactor (PBR). The cultivation systems with addition of DOABE (PBR systems + DOABE and open tray system + DOABE) as media were tested for quality and quantity of biodiesel. The presence of organic carbon and low nitrogen in DOABE caused >2 folds higher biomass productivity and >4 folds enhanced lipid productivity for the cells cultivated in PBR system + DOABE and open tray system + DOABE as compared to control (i.e. BBM). Biochemical analysis of cells from both the systems revealed the decrease in total carbohydrates and protein contents. The FAMEs analyses showed vehicular quality biodiesel. PBR system + DOABE showed edge over open tray system + DOABE in terms of biomass productivity and lipid content. The physical properties of biodiesel produced from Chlorella sp. MCC27 were more close to the fuel standards (ASTM D6751), when cells were cultivated in open tray system + DOABE than in PBR system + DOABE. Collectively, this study highlights the use of DOABE as a low cost feedstock for enhancing vehicular quality biodiesel production from microalgae. [ABSTRACT FROM AUTHOR]

The paper presents results of the study on efficient production of microalgae (Chlorella sp.) biomass. Culture was conducted on the basis of synthetic medium, in a laboratory storage tank photobioreactor with an active volume of 5 dm3, under forced aeration and mixing conditions. The culture control consisted in the spectrophotometric measurement of changes in the optical density of the culture medium as well as the determination of basic nutrients (total nitrogen and phosphorus) in the culture medium. In addition, Chemical Oxygen Demand (COD) and Total Organic Carbon (TOC) values were measured in biomass suspension. Within 35 days, algae absorbed about 230 g of nitrogen (over 30% by weight) and about 36 mg of phosphorus (over 90% by weight), and the OD686 exceeded 1.2. During this time, the COD value increased by over 80% and the total organic carbon content by over 20%. The high efficiency of algae biomass production has been achieved by limiting the possibility of bacterial infection and ensuring appropriate conditions, including aeration, circulation and availability of biogenic compounds. [ABSTRACT FROM AUTHOR]

A green microalga Chlorella sp. isolated from marine environment was investigated for its potential to pretreat saline antibiotic wastewater containing amoxicillin (AMX). Through Biolog EcoPlate assay, the Chlorella sp. showed its unique carbon source metabolic patterns under autotrophic condition. In addition, the microalga could effectively remove AMX (>99%) under initial AMX concentrations ranging from 10 to 150 mg/L through a treatability test. In the continuous AMX treatment using a lab-scale membrane photobioreactor (MPBR), a stable AMX removal efficiency of 85.6 ± 3.8% was observed. Moreover, with the aid of a subsequent bacterial treatment, the microalgal-bacterial process (the Chlorella sp. pretreatment followed by either intertidal wetland sediment or activated sludge) can achieve simultaneous AMX removal of >99% and total organic carbon (TOC) removal of ∼80%. In general, the microalgal pretreatment showed its great potential in effective removal of antibiotic residues, which could greatly enhance the overall treatment efficiency of saline antibiotic wastewater. [ABSTRACT FROM AUTHOR]

A complex of water-hyacinth derived pellets immobilized with Chlorella sp. was applied, for the first time, in the bioremediation of Cadmium (Cd). The Cd(II) removal efficiency of the complex was optimized by investigating several parameters, including the pellet materials, algal culture age, and light intensity. Results showed that the Cd(II) removal efficiency was positively related to the algal immobilization efficiency and the algal bioaccumulation capacity. Since higher surface hydrophilicity leads to higher immobilization efficiency, the water-hyacinth leaf biochar pellet (WLBp) was selected as the optimal carrier. A maximum Cd(II) removal efficiency of 92.45% was obtained by the complex of WLBp immobilized with algal cells in stationary growth phase and illuminated with a light intensity of 119 μmol m −2  s −1 . Recovery tests on both microalgal cells and the WLBp demonstrated that the algal cells and the biochar pellet can be economically recycled and reused. [ABSTRACT FROM AUTHOR]

It has increasingly been recognized that defence of microalgae against predator grazing is a passive response to increase algal population density by excreting chemicals with a change in physical properties. As common biological pollutants in the cultivation of the microalgae, the community-based method was used to identify the ability of two microalgae, Chlorella sp. and Nannochloropsis oceanica, to defend against protozoan grazing. Mature protozoan samples with 14-day age were collected, using microscopy glass slides, in coastal waters of the Yellow Sea, northern China. For both microalgae, a gradient of concentrations was designed as 100 (control), 104, 105, 106 and 107 cell ml−1, respectively. Results showed that both test algal species represented strong defence effects on protozoan grazing, especially at high density levels. Species richness, abundance and taxonomic distinctness of the protozoan assemblages showed a sharp decrease at high concentration level (107 cell ml−1) of both algae. A significant variation in protozoan community structures was found to be driven by the gradient of the algal concentrations. The paired taxonomic distinctness indices of the protozoan communities showed an increasing trend of departure from the expected taxonomic pattern with increase of algal concentrations. Based on the results, we suggest that the community-based bioassay might be used as a feasible tool for identifying defence against protozoan grazing of microalgae. [ABSTRACT FROM AUTHOR]

A simple and rapid Chlorella sp. surface expressed alkaline phosphatase (AP-algae) biosensor modified with flower shaped ZnO nanoparticles for the determination of chlorpyrifos in an aqueous medium was developed. The detection principle was based on the inhibition of AP-algae in presence of chlorpyrifos. Enzyme would dephosphorylate the phosphate monoester of substrate 2-phospho- l -ascorbic acid to release l -ascorbic acid, which was monitored using voltammetric and ISFET techniques. The presence of pesticide would inhibit AP-algae enzyme activity and hence the current magnitude decreases. The decrease in current is quantitative in nature and used for determination of concentration of the pesticide. Flower shape ZnO nanoparticles not only provide surface for adsorption of AP-algae for better immobilization but also increases electron-transfer kinetics and sensitivity of the biosensor. The voltammetric and ISFET methods could measure chlorpyrifos in the linear concentration range from 10 −9 M to 10 −1 M and 10 −10 M to 10 −3 M, respectively, with nil interference from triazophos, malathion, acephate and some metal ions. Application aspects of the proposed biosensor were demonstrated using extracted soil samples and showed excellent reproducibility and reliability. [ABSTRACT FROM AUTHOR]

Contaminating organisms in mass cultivation present one of the major challenges that must be overcome for successful commercialization of algal biofuels. The present study identified a range of contaminating organisms in Chlorella cultures cultivated in outdoor raceway ponds at the Arizona Center for Algae Technology and Innovation (Mesa, AZ). Nineteen organisms or Operational Taxonomic Units (OTU) in the Chlorella culture were identified by a combination of microscopic observation and 18S rRNA denaturing gradient gel electrophoresis (DGGE). More detailed analyses identified these contaminating organisms as 2 fungi, 7 flagellates, 3 amoebae, 4 ciliates, 1 rotifer, and 2 large insects. Among them Poterioochromonas sp., a small flagellate, appeared to be one of the most harmful causing culture collapse. In order to control Poterioochromonas sp., various operational parameters and application strategies of ultrasonic treatment were investigated. During sixteen-day consecutive Chlorella cultivation in batch mode, the ultrasonication conditions of 6 L min −1 flow rate with the power of 495 W at 100% amplitude and a treatment frequency of once for 1 h every day, was proven to be the most effective in preventing Poterioochromonas outbreak in Chlorella culture with volume of 60 L. The above ultra-sonication method was also effective at destroying an unknown fungus, an amoeba ( Acanthocystis sp.), and ciliates (a member of the family Orchitophryidae). Our findings can serve as a technical foundation for the application of ultrasonication to control some of the contaminating microorganisms in mass cultivation of microalgae including Chlorella . [ABSTRACT FROM AUTHOR]

Brachionus plicatilis is used to feed fish and crustacean larvae in the aquaculture industry. It is well established that the type of microalgae may influence rotifer production. This experiment was conducted to determine the effect of five different locally available microalgae species at Fisheries Research Institute (FRI), Kampung Pulau Sayak, Kedah, Malaysia on the instantaneous growth rate (μ) of rotifer. Nannochloris sp., Tetraselmis sp., Isochrysis sp., Chlorella sp., and Nannochloropsis sp. were used as feed at different algae densities (0.1, 0.3, 0.7 and 1.5 × 106 cells/ml) and culture volumes (20, 70 and 210 ml). At algae densities ranging from 0.3 to 1.5 × 106 cells/ml, an average μ value of more than 0.90 per day were recorded for all algae species. However, at density of 0.1 × 106 cells/ml, only Tetraselmis sp. resulted in the significantly highest μ value compared with others (p < 0.05). In terms of volume, smaller culture volume of Tetraselmis sp. (20 ml) showed significantly higher μ compared with higher volume (70 and 210 ml cultures). [ABSTRACT FROM AUTHOR]

Suspensions of the model microalga Chlorella sp. TISTR 8990 were pretreated by ohmic heating to facilitate release of lipids from the cells in subsequent extraction and lipase-mediated transesterification to biodiesel. After ohmic pretreatment, the moist biomass was suspended in a system of water, hexane, methanol and immobilized lipase for extraction of lipids and simultaneous conversion to biodiesel. The ohmic pretreatment was optimized using an experimental design based on Taguchi method to provide treated biomass that maximized the biodiesel yield in subsequent extraction–transesterification operation. The experimental factors were the frequency of electric current (5–10 5  Hz), the processing temperature (50–70 °C), the algal biomass concentration in the slurry (algal fresh weight to water mass ratio of 1–3) and the incubation time (1–3 min). Extraction–transesterification of the pretreated biomass was carried out at 40 °C for 24 h using a reaction systems of a fixed composition (i.e. biomass, hexane, methanol, water and immobilized enzyme). Compared to control (i.e. untreated biomass), the ohmic pretreatment under optimal conditions (5 Hz current frequency, 70 °C, 1:2 mass ratio of biomass to water, incubation time of 2-min) increased the rate of subsequent transesterification by nearly 2-fold. [ABSTRACT FROM AUTHOR]

Two marine antimicrobial peptides (AMPs), PC-hepc from large yellow croaker ( Pseudosciaena crocea ) and scygonadin from mud crab ( Scylla serrata ), are potently active against specific bacteria and thus they could be used as substitutes for antibiotics in aquaculture. However, how to utilize the AMPs feasibly for marine cultured animals has been so far confused. In our study, a 510 bp of the Scy-hepc sequence was cloned into pMDC85 expression vector, which was then electroporated into Chlorella sp., and thus a transgenic Chlorella , in which the Scy-hepc gene was effectively expressed, was developed. The Scy-hepc fusion protein was successfully expressed in Chlorella sp. and it showed obvious bactericidal activity. In addition, the in vivo efficacy of the transgenic Chlorella was evaluated using Sparus macrocephalus and the hybrid Epinephelus fuscoguttatus (♀) × Epinephelus lanceolatus (♂). Results showed that the survival rate of S. macrocephalus fed with transgenic Chlorella (80 ± 10% after 72 h) was significantly higher than that of fish fed with the same dosage of wild-type Chlorella (33.33 ± 11.55% after 72 h). Similarly, results showed that the survival rate of the hybrid grouper fed with transgenic Chlorella (55 ± 5% after 36 h) was much higher than that of fish fed with the same dosage of wild-type Chlorella (25 ± 5% after 36 h). Therefore, in vitro and in vivo results indicated that the constructed transgenic Chlorella with the marine AMPs Scy-hepc could exert effective protection for fish against the Aeromonas hydrophila infection, providing an encouraging prospect for the expected use of transgenic Chlorella in aquaculture in future. [ABSTRACT FROM AUTHOR]

The local algae species,Chlorella vulgarisandScenedesmus regularis,from a highly saline water body of Kapulukaya Reservoir were isolated to analyze their carotenoid composition and content using HPLC method. The gradient solvent system of methanol–acetonitrile–water (84:14:2, v/v/v) and methylene chloride (100%), used to resolve a range of carotenoids from the saponified cells, proved an acceptable separation as inferred from the retention factor (k) ranging between 0.75 and 7.76 and the separation factor (α) values greater than 1. Resolution peaks assigned to carotenoids, 21 forC. vulgarisextracts and 22 forS. regularisextracts, were reached within the duration time of 45 min. Main carotenoids identified either tentatively or positively were all-trans-lutein, 9- or 9′-cis-lutein, 13- or 13′-cis-lutein,cis-lutein, All-trans-α-carotene, 9- or 9′-cis-α-carotene, All-trans-β-carotene, 9- or 9′-cis-β-carotene in the species except for all-trans-β-cryptoxanthin found only inS. regularis. Auroxanthin, neochrome, neoxanthin, andcis-neoxanthin were identified as epoxy-containing compounds. Quantitatively,C. vulgariswas distinguished to have greater amount of lutein andcis-isomers (2.74 mg/g), 77.89% whileS. regulariswas predominated by β-carotene andcisisomers as major component, being 80.72% (5.76 mg/g) in total carotenoids (TC). In terms of total carotenoids, the species were considered to be efficient sources for further practical applications. [ABSTRACT FROM AUTHOR]

This study explores the challenges facing microalgae biofuel production, specifically low lipid content and difficulties with algal cell harvesting. The purpose of the research is to investigate the effect of seawater content and nanoparticle concentration on freshwater microalgae growth and biofuel production. The principal results of the study show that increasing the proportion of seawater and nanoparticles enhances the lipid content and cell diameter of microalgae, while excessive concentrations of nanoparticles and low seawater content lead to reduced microalgae growth. Furthermore, an optimal cell diameter was identified at a nanoparticle concentration of 150 mg/L. The study also reveals that increasing seawater content can decrease zeta potential and increase chlorophyll a content due to the concentration of dissolved organic matter. Increasing the seawater content from 0% to 25% decreased zeta potential by 1% owing to the instability and aggregation of the cells. Chlorophyll a for the 0% seawater was 0.55 which is increased to 1.32 only due to the increase in the seawater content. This significant increase is due to the concentration of dissolved organic matter in seawater. Additionally, the presence of seawater positively affects microalgae metabolic activity and biochar yield. The findings of this study offer valuable insights into the potential for optimizing microalgae biofuel production. The use of seawater and nanoparticles has shown promise in enhancing microalgae growth and biofuel yield, and the results of this study underscore the scientific value of exploring the role of seawater and nanoparticles in microalgae biofuel production. Further research in this area has the potential to significantly contribute to the development of sustainable energy solutions. • Increasing the proportion of seawater and nanoparticles enhances the lipid content and cell diameter of microalgae. • Excessive concentrations of nanoparticles and low seawater content lead to reduced microalgae growth. • An optimal cell diameter was identified at a nanoparticle concentration of 150 mg/L. • The presence of seawater positively affects microalgae metabolic activity and biochar yield. [ABSTRACT FROM AUTHOR]

The high potential Chlorella sp. was obtained after the UV mutation which produces higher biomass and lipid content than the wild type. The lipid content and biomass were increased from 34 to 48 % dry cell weight and 1.42 to 1.97 g/L respectively. Further, hydrogen peroxide (H 2 O 2) treatment increased both biomass and lipid content in mutant, whereas wild type did not show any considerable change in both biomass and lipid content. A 3-fold increase in total lipid yield was observed after the H 2 O 2 treatment in mutant when compared to the untreated wild type. H 2 O 2 treatment also altered the fatty acid composition of lipids resulting in enhanced eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) content. Overall results indicate that the strain improvement of Chlorella sp. by UV mutagenesis and oxidative stress by H 2 O 2 treatment enhances the biomass and lipid content with high amounts of omega-3 fatty acids. Furthermore, the H 2 O 2 treated mutant cells showed upregulation of the important genes involved in the fatty acid synthesis pathway. [Display omitted] • UV mutagenesis increased both biomass and lipid content in Chlorella sp. • Total lipid yield increased 3-fold after H 2 O 2 treatment in mutant. • H 2 O 2 treatment enhanced the eicosapentaenoic and docosahexaenoic content. • H 2 O 2 treatment upregulated the omega-3 fatty acid desaturase in mutant. [ABSTRACT FROM AUTHOR]

Nghiên cứu được thực hiện nhằm tìm ra điều kiện dinh dưỡng và hàm lượng glucose sử dụng thích hợp cho sự phát triển của tảo Chlorella sp. Nghiên cứu gồm hai thí nghiệm được tiến hành trong phòng với nhiệt độ 26-28°C, tảo được nuôi trong bình thủy tinh 8 lít với mật độ ban đầu 2×106 tế bào/mL ở độ mặn 25‰ và môi trường nuôi cấy là Walne. Thí nghiệm 1 được tiến hành gồm 3 nghiệm thức với 3 lần lặp lại trong điều kiện: quang dưỡng, quang dị dưỡng và dị dưỡng, trong đó nguồn carbon hữu cơ cung cấp trong điều kiện quang dị dưỡng và dị dưỡng là glucose với hàm lượng 10g/L. Ở thí nghiệm 2, tảo Chlorella sp. được nuôi trong điều kiện quang dị dưỡng với hàm lượng glucose khác nhau: 5g/l, 10g/L và 15g/L. Kết quả thí nghiệm 1 cho thấy tảo Chlorella sp. phát triển tốt nhất ở nghiệm thức quang dị dưỡng, mật độ cao nhất 106,53±0,69×106 tế bào/mL, khác biệt có ý nghĩa thống kê với các nghiệm thức còn lại. Ở thí nghiệm 2, tảo Chlorella sp. ở nghiệm thức glucose 10g/L đạt mật độ 99,66±1,77×106 tế bào/mL, cao hơn có ý nghĩa so với các nghiệm thức còn lại.

Pengendalian emisi gas CO2 sangat dibutuhkan untuk mengurangi efek Gas Rumah Kaca (GRK). Penerapan Carbon Capture Storage (CCS) dapat menjaga stabilitas CO­2 dan mencegah pelepasan CO2 ke atmosfer dalam upaya mitigasi global. Salah satu bentuk teknologi CCS yaitu menggunakan kultur mikroalga dalam fotobioreaktor. Optimalisasi fotobioreaktor dengan menggunakan mikroalga air laut jenis Chlorella sp. Pengoperasian alat dilakukan secara step running dengan variasi acak sesuai matriks Design-Expert. Performa terbaik fotobioreaktor dilihat berdasarkan tingkat penyerapan gas CO2 dan produktivitas mikroalga tertinggi. Kondisi optimum hasil percobaan didapatkan dengan variasi kecepatan aliran fluida 23 cm/detik dan laju alir injeksi gas CO2 0,61 ml/detik. Produktivitas mikroalga yang didapatkan sebesar 0,405 gram/liter. Sedangkan kondisi optimum berdasarkan Design-Expert didapatkan dengan variasi kecepatan aliran fluida 25,82 cm/detik dan laju alir injeksi CO2 0,61 ml/detik. Produktivitas mikroalga yang didapatkan sebesar 0,427 gram/liter. Gas CO2 yang terserap tiap gram mikroalga sebesar 0,638 gram.

Descreve-se um caso de infecção disseminada por Chlorella sp. em um ovino, na região semiárida da Paraíba, Brasil. O animal apresentou emagrecimento e aumento de volume abdominal há um mês. Na necropsia, foram observados nódulos esverdeados em fígado, pulmões, intestino e linfonodos. Histologicamente, os nódulos correspondiam a piogranulomas com miríades de algas intralesionais. Provavelmente, a infecção tenha ocorrido em consequência do consumo de água estagnada ou capim que tinha sido cortado em uma área irrigada, que são condições frequentes no período da seca na região semiárida.

We evaluate the effects of nutrient limitation on cellular composition of polar lipid classes/species in Chlorella sp. using modern polar lipidomic profiling methods (liquid chromatography⁻tandem mass spectrometry; LC-MS/MS). Total polar lipid concentration was highest in nutrient-replete (HN) cultures with a significant reduction in monogalactosyldiacylglycerol (MGDG), phosphatidylglycerol (PG), phosphatidylcholine (PC), and phosphatidylethanolamine (PE) class concentrations for nutrient-deplete (LN) cultures. Moreover, reductions in the abundance of MGDG relative to total polar lipids versus an increase in the relative abundance of digalactosyldiacylglycerol (DGDG) were recorded in LN cultures. In HN cultures, polar lipid species composition remained relatively constant throughout culture with high degrees of unsaturation associated with acyl moieties. Conversely, in LN cultures lipid species composition shifted towards greater saturation of acyl moieties. Multivariate analyses revealed that changes in the abundance of a number of species contributed to the dissimilarity between LN and HN cultures but with dominant effects from certain species, e.g., reduction in MGDG 34:7 (18:3/16:4). Results demonstrate that Chlorella sp. significantly alters its polar lipidome in response to nutrient limitation, and this is discussed in terms of physiological significance and polar lipids production for applied microalgal production systems.

The influence of N-replenishment on cell growth, chlorophyll content, nitrogen uptake, and accumulation of starch and lipid was studied in Chlorella sp. N-starved algal cells were fully recovered within 2 days after N-replenishment. Stored starch in N-deficient culture was degraded immediately during recovery process. However, lipid response had a period of delay when suffered from long starvation. During the recovery process, neutral lipid was reduced accompanied by an increase in membrane lipid. It was speculated that starch served as a source of carbon and energy catabolized to support quick recovery of the culture, while lipid preferred to play a structural role that specific fatty acid species were released from storage lipid and as building blocks for quick synthesis of membrane lipid. In light of rapid growth recovery and no net degradation in total fatty acids, a semi-continuous cultivation process might be a potential way to enhance lipid productivity. [ABSTRACT FROM AUTHOR]

We have previously shown that a combined system involving solvent absorption, membrane desorption and microalgal cultivation can provide an effective approach to carbon dioxide capture and utilisation (Energy Environ. Sci., 2016, 9, 1074). In this article, we evaluate aqueous solutions of monoethanolamine (MEA) and potassium glycinate (PG) for membrane desorption of CO 2 , and compare these with our previous work using potassium carbonate (K 2 CO 3 ). Enhanced growth of Chlorella sp. was observed with 20 wt% PG at 0.5 CO 2 loading (moles of CO 2 absorbed per mol solvent) relative to a baseline control in which carbon dioxide was only available from atmospheric diffusion. Similar growth rates to the control were observed for PG at 0.2 loading. For MEA, algal growth was accelerated at 0.5 loading but was inhibited at 0.2 loading. This was related to the volatile MEA crossing the membrane and poisoning the algae. Considering the kinetics of CO 2 absorption into the solvent, the improvement of microalgal growth and the system stability in case of solvent leakage, amino acids such as PG are the ideal solvent for this application. [ABSTRACT FROM AUTHOR]

Laboratory tests, by following standardized Organization for Economic Co-operation and Development (OECD) protocols, were run for evaluating the acute effects of iron magnetic microparticles (MPs), recently proposed for lake restoration, on Chlorella sp. (algal growth) and on the rotifer B . calyciflorus (mortality). In addition, the MPs potential indirect effects on rotifer egg bank were assessed by performing hatching rate test with B . calyciflorus cysts in contact with dissolved iron (Tot-Fe dis ). In the algal growth test, no inhibition occurred at the two lowest MPs concentrations (0.01 and 0.05 g l −1 ) which would correspond, considering the adsorption efficiency ratio (Phosphorus: MPs), to P concentrations lower than 0.94 mg P l −1 , much higher than typical concentrations found in natural waters. For higher MPs dose (EC 50 for Chlorella sp. was 0.15 g l −1 ), no nutrient limitations but high turbidity and Tot-Fe dis values cause negative effects on algal growth. For the case of B . calyciflorus , LC 50 was 1.63 g MPs l −1 (corresponding to 30.7 mg P l −1 ). When analyzing Tot-Fe dis effect, the hatching rate of B . calyciflorus cysts was 100% for all treatments. To sum up our results for B . calyciflorus acute and chronic toxicity tests, it is extremely unlikely the mortality of adult organisms in contact with MPs as well as an affectation of the rotifer egg bank. In conclusion, it is expected that MPs addition in a real whole-lake application cause minor lethal and sublethal effects on both Chlorella sp. and B . calyciflorus . [ABSTRACT FROM AUTHOR]

In this work, a novel harvesting strategy using ferrofluids coupled with flocculation as a magnetic directional harvesting system was developed, providing a fast and easy way to effectively collect microalgae with no further modifications made to the ferrofluids. With a ferrofluid dosage of 25 mg L −1 , a high harvesting efficiency of 95–100% was achieved within 1 min. In addition, we successfully performed a wastewater recycling strategy coupled with a microalgal ferrofluid-harvesting dynamic flow-through system to harvest biomass of Chlorella sp. MTF-7 which could achieve over 80% of the maximum level after three repeated recycling cultivations. This work demonstrated the use of an integrated microalgal ferrofluid-harvesting dynamic flow-through system to develop a simple and effective strategy to enhance microalgal harvesting efficiency, along with wastewater recycling, in a marine microalgal Chlorella sp. MTF-7. [ABSTRACT FROM AUTHOR]

The feasibility of the bioremediation of cadmium (Cd) using microalgal-biochar immobilized complex (MBIC) was investigated. Major operating parameters (e.g., pH, biosorbent dosage, initial Cd(II) concentration and microalgal-biochar ratio) were varied to compare the treatability of viable algae ( Chlorella sp.), biochar and MBIC. The biosorption isotherms obtained by using algae or biochar were found to have satisfactory Langmuir predictions, while the best fitting adsorption isotherm model for MBIC was the Sips model. The maximum Cd(II) adsorption capacity of MBIC with a Chlorella sp.: biochar ratio of 2:3 (217.41 mg g −1 ) was higher than that of Chlorella sp. (169.92 mg g −1 ) or biochar (95.82 mg g −1 ) alone. The pseudo-second-order model fitted the biosorption process of MBIC well ( R 2 > 0.999). Moreover, zeta potential, SEM and FTIR studies revealed that electrostatic attraction, ion exchange and surface complexation were the main mechanisms responsible for Cd removal when using MBIC. [ABSTRACT FROM AUTHOR]

The present study investigates the effect of single step transesterification method for the improvement of biodiesel yield using algal biomass. Different photobioreactor configurations were studied to find out the most suitable reactor for biomass production. Suitable conditions for HCl catalyzed transesterification were determined for the improvement of biodiesel production. Maximum lipid conversion (95%) was observed under catalyst concentration, algal biomass/methanol ratio, reaction temperature, reaction time and biomass drying duration of 4 M, 1:5, 65 °C, 7 h and 90 min, respectively. Single step transesterification showed significant improvement in lipid conversion as compared to conventional two steps transesterification. The kinetics and thermodynamics of the reaction was also determined. The results could help in development of sustainable technology with improved biodiesel quality. [ABSTRACT FROM AUTHOR]

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