•Synthetic hormone analog NAA was tested to boost algal biomass and lipid accumulation.•NAA performed remarkable promoting effect on cell growth and lipid biosynthesis.•NAA modified proportions of ...fatty acids which were prone to high-quality biofuels.•NAA-treatment manipulated endogenous phytohormones metabolism.•Economic-estimation of NAA indicated possibility in developing lipid for biofuels.
This study attempted at maximizing biomass and lipid accumulation in Chlorella vulgaris by supplementation of natural abscisic acid (ABA) or synthetic 2,4-dichlorophenoxyacetic acid (2,4-D) and 1-naphthaleneacetic acid (NAA) hormone analogs. Amongst three tested additives, NAA-treatment performed remarkable promoting effect on cell growth and lipid biosynthesis. The favorable lipid productivity (418.6mg/L/d) of NAA-treated cells showed 1.48 and 2.24 times more than that of 2,4-D and ABA. NAA-treatment also positively modified the proportions of saturated (C16:0 and C18:0) and monounsaturated fatty acids (C18:1) which were prone to high-quality biofuels-making. Further, NAA-treatment manipulated endogenous phytohormones metabolism leading to the elevated levels of indole-3-acetic acid, jasmonic acid, and salicylic acid and such hormone accumulation might be indispensable for signal transduction in regulating cell growth and lipid biosynthesis in microalgae. In addition, the economic-feasibility and eco-friendly estimation of NAA additive indicated the higher possibilities in developing affordable and scalable microalgal lipids for biofuels.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Enantiomers of chiral pesticides usually display different toxic effects on non-target organisms in surrounding environment, but there are few studies on its enantioselective toxicity of ...paclobutrazol to aquatic organisms such as Chlorella vulgaris (C. vulgaris). In this study, the enantioselective bioaccumulation and toxicities, such as acute toxicity and oxidative stress, of the racemate, (2S, 3S)-enantiomer (S-enantiomer) and (2R, 3R)-enantiomer (R-enantiomer) of paclobutrazol to the C. vulgaris cells were investigated. The results showed that the algae cells were able to accumulate the paclobutrazol in a short time, while this bioaccumulation had no enantioselective distinction between the two enantiomers during biological metabolism. However, the racemate and two enantiomers of paclobutrazol significantly inhibited the growth of C. vulgaris, displayed different median lethal concentrations. The photosynthetic pigments, photosynthesis-related genes as well as antioxidation-related biomarkers in treated C. vulgaris were also investigated. In general, R-enantiomer was found to be more toxic to C. vulgaris cells than its racemate and S-enantiomer. Additionally, transmission electron microscopy (TEM) analysis showed the R-enantiomer caused more serious changes than S-enantiomer. Moreover, contents of two plant hormones (gibberellin, GA and indoleacetic acid, IAA) were determined in treated C. vulgaris. Higher paclobutrazol concentrations caused lower IAA contents significantly. Nevertheless, the two enantiomers showed no enantioselective effects on the biosynthesis of GA in C. vulgaris. Our results are helpful to understand the enantioselective effects of paclobutrazol enantiomers on non-target organisms, and useful for evaluating their environmental risks.
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•The acute toxicity of paclobutrazol to Chlorella vulgaris was enantioselective.•Paclobutrazol can enantioselectively enhance the antioxidant enzyme activities.•Paclobutrazol has enantioselective effects on photosynthesis of algae.•Morphology changes were found when algae exposed to paclobutrazol enantiomers.•No enantioselective bioaccumulation was occurred on paclobutrazol-treated algae.
Paclobutrazol enantiomers can enantioselectively inhibit the growth of Chlorella Vulgaris.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
► NiO nanoparticles have adverse effects on growth of algal cells. ► Living algae have the ability to accelerate the aggregation of NPs as well as to reduce NiO nanoparticles to zero valence nickel. ...► Green microalgae may be promising organisms for bioremediating nano-pollution.
Adverse effects of manufactured nickel oxide nanoparticles on the microalgae
Chlorella
vulgaris were determined by algal growth-inhibition test and morphological observation via transmission electron microscopy (TEM). Results showed that the NiO nanoparticles had severe impacts on the algae, with 72
h EC
50 values of 32.28
mg NiO
L
−1. Under the stress of NiO nanoparticles,
C. vulgaris cells showed plasmolysis, cytomembrane breakage and thylakoids disorder. NiO nanoparticles aggregated and deposited in algal culture media. The presence of algal cells accelerated aggregation of nanoparticles. Moreover, about 0.14% ionic Ni was released when NiO NPs were added into seawater. The attachment of aggregates to algal cell surface and the presence of released ionic Ni were likely responsible for the toxic effects. Interestingly, some NiO nanoparticles were reduced to zero valence nickel as determined by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analysis. The maximum ratios of nickel reduction was achieved at 72
h of exposure, in accordance with the time-course of changes in soluble protein content of treated
C. vulgaris, implying that some proteins of algae are involved in the process. Our results indicate that the toxicity and bioavailability of NiO nanoparticles to marine algae are reduced by aggregation and reduction of NiO. Thus, marine algae have the potential for usage in nano-pollution bio-remediation in aquatic system.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Many pharmaceuticals have negative effects on biota when released into the environment. For example, recent work has shown that the commonly prescribed antidiabetic drug, metformin ...(N,N-dimethylbiguanide), has endocrine disrupting effects on fish. However, effects of metformin on aquatic primary producers are poorly known. We exposed cultured isolates of a freshwater chlorophyte, Chlorella vulgaris, to a range of metformin concentrations (0-767.9 mg L-1) to test the hypothesis that exposure negatively affects photosynthesis and growth. A cessation of growth, increase in non-photochemical quenching (NPQ, NPQmax), and reduced electron transport rate (ETR) were observed 24 h after exposure to a metformin concentration of 767.8 mg L-1 (4.6 mM). By 48 h, photosynthetic efficiency of photosystem II (Fv/Fm), α, the initial slope of the ETR-irradiance curve, and Ek (minimum irradiance required to saturate photosynthesis) were reduced. At a lower concentration (76.8 mg L-1), negative effects on photosynthesis (increase in NPQ, decrease in ETR) were delayed, occurring between 72 and 96 h. No negative effects on photosynthesis were observed at an exposure concentration of 1.5 mg L-1. It is likely that metformin impairs photosynthesis either through downstream effects from inhibition of complex I of the electron transport chain or via activation of the enzyme, SnRK1 (sucrose non-fermenting-related kinase 1), which acts as a cellular energy regulator in plants and algae and is an ortholog of the mammalian target of metformin, AMPK (5' adenosine monophosphate-activated protein kinase).
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Microalgae are fast-growing photosynthetic organisms which have the potential to be exploited as an alternative source of liquid fuels to meet growing global energy demand. The cultivation of ...microalgae, however, still needs to be improved in order to reduce the cost of the biomass produced. Among the major costs encountered for algal cultivation are the costs for nutrients such as CO₂, nitrogen and phosphorous. In this work, therefore, different microalgal strains were cultivated using as nutrient sources three different anaerobic digestates deriving from municipal wastewater, sewage sludge or agro-waste treatment plants. In particular, anaerobic digestates deriving from agro-waste or sewage sludge treatment induced a more than 300% increase in lipid production per volume in
cultures grown in a closed photobioreactor, and a strong increase in carotenoid accumulation in different microalgae species. Conversely, a digestate originating from a pilot scale anaerobic upflow sludge blanket (UASB) was used to increase biomass production when added to an artificial nutrient-supplemented medium. The results herein demonstrate the possibility of improving biomass accumulation or lipid production using different anaerobic digestates.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
There is a pressing need to develop efficient and sustainable approaches to harvesting microalgae for biofuel production and water treatment. CO sub( 2)-switchable crystalline nanocellulose (CNC) ...modified with 1-(3-aminopropyl)imidazole (APIm) is proposed as a reversible coagulant for harvesting microalgae. Compared to native CNC, the positively charged APIm-modified CNC, which dispersed well in carbonated water, showed appreciable electrostatic interaction with negatively charged Chlorella vulgaris upon CO sub( 2)-treatment. The gelation between the modified CNC, triggered by subsequent air sparging, can also enmesh adjacent microalgae and/or microalgae-modified CNC aggregates, thereby further enhancing harvesting efficiencies. Moreover, the surface charges and dispersion/gelation of APIm-modified CNC could be reversibly adjusted by alternatively sparging CO sub( 2)/air. This CO sub( 2)-switchability would make the reusability of redispersed CNC for further harvesting possible. After harvesting, the supernatant following sedimentation can be reused for microalgal cultivation without detrimental effects on cell growth. The use of this approach for harvesting microalgae presents an advantage to other current methods available because all materials involved, including the cellulose, CO sub( 2), and air, are natural and biocompatible without adverse effects on the downstream processing for biofuel production.
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IJS, KILJ, NUK, PNG, UL, UM
•A MFC was constructed with C. vulgaris for promoting food waste treatment.•Optimal initial density of C. vulgaris in cathode chamber of MFC was 150mgL−1.•Biomass productivity and total lipid content ...of C. vulgaris were promoted by MFC.•Inoculated in MFC, C. vulgaris presented the higher biodiesel quality.
Food waste contains large amount of organic matter that may be troublesome for handing, storage and transportation. A microbial fuel cell (MFC) was successfully constructed with different inoculum densities of Chlorella vulgaris for promoting food waste treatment. Maximum COD removal efficiency was registered with 44% and 25gCODL−1d−1 of substrate degradation rate when inoculated with the optimal initial density (150mgL−1) of C. vulgaris, which were 2.9 times and 3.1 times higher than that of the abiotic cathode. With the optimum inoculum density of C. vulgaris, the highest open circuit voltage, working voltage and power density of MFC were 260mV, 170mV and 19151mWm−3, respectively. Besides the high biodiesel quality, promoted by MFC stimulation the biomass productivity and highest total lipid content of C. vulgaris were 207mgL−1d−1 and 31%, which were roughly 2.7 times and 1.2 times higher than the control group.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
•LEDs are suitable light source of microalgal cultivations.•Blue light LED illumination led to significantly increased cell size.•Red light LED illumination led to small-sized cell with active ...divisions.•Innovative process with wavelength shift increased biomass and FAME.
LEDs light offer several advantages over the conventional lamps, thereby being considered as the optimal light sources for microalgal cultivation. In this study, various light-emitting diodes (LEDs) especially red and blue color with different light wavelengths were employed to explore the effects of light source on phototrophic cultivation of Chlorella vulgaris. Blue light illumination led to significantly increased cell size, whereas red light resulted in small-sized cell with active divisions. Based on the discovery of the effect of light wavelengths on microalgal biology, we then applied appropriate wavelength at different growth stages; blue light was illuminated first and then shifted to red light. By doing so, biomass and lipid productivity of C. vulgaris could be significantly increased, compared to that in the control. These results will shed light on a novel approach using LED light for microalgal biotechnology.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Sulfadiazine (SD), sulfamerazine (SM1), and sulfamethazine (SM2) are widely used and disorderly discharged into surface water, causing contamination of lakes and rivers. However, microalgae are ...regard as a potential resource to alleviate and degrade antibiotic pollution. The physiological changes of Chlorella vulgaris in the presence of three sulfonamides (SAs) with varying numbers of -CH
groups and its SA-removal efficiency were investigated following a 7-day exposure experiment. Our results showed that the growth inhibitory effect of SD (7.9-22.6%), SM1 (7.2-45.9%), and SM2 (10.3-44%) resulted in increased proteins and decreased soluble sugars. Oxidative stress caused an increase in superoxide dismutase and glutathione reductase levels but decreased catalase level. The antioxidant responses were insufficient to cope-up with reactive oxygen species (hydrogen peroxide and superoxide anion) levels and prevent oxidative damage (malondialdehyde level). The ultrastructure and DNA of SA-treated algal cells were affected, as evident from the considerable changes in the cell wall, chloroplast, and mitochondrion, and DNA migration. C. vulgaris-mediated was able to remove up to 29% of SD, 16% of SM1, and 15% of SM2. Our results suggest that certain concentrations of specific antibiotics may induce algal growth, and algal-mediated biodegradation process can accelerate the removal of antibiotic contamination.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
•Algae C. humicola and C. vulgaris can tolerate NaCl to a concentration of 100 mM.•C. humicola exhibited high tolerance responses, biomass, lipid and proline content.•Increased cell size under NaCl ...treatment linked with high metabolites accumulation.•SEM-EDS spectra addresses altered essential minerals in algae under NaCl stress.
In the present study, microalgae Chlorococcum humicola and Chlorella vulgaris were grown in different concentrations of NaCl (25–1000 mM) to elucidate its impact on morphology, lipid synthesis, minerals status and antioxidative responses. Scanning Electron microscopy showed distorted cell morphology and increased cell size by 33.52% (C. humicola) and 27.79% (C. vulgaris) at 100 mM NaCl. Energy Dispersive Spectroscopy data revealed reduction in mineral contents (C, S, Fe, Mg, Si, Mn and Zn) by 14–54% in both algae. Further, C. humicola was found to have high lipid content than C. vulgaris under NaCl regime. The activities of superoxide dismutase, catalase and glutathione reductase were increased by 2.5–5 folds in both algae as compared to control. The increased level of ascorbate, cysteine and proline in both algae indicated tolerance against salinity. Thus, C. humicola and C. vulgaris may exhibit dual benefits viz., high lipid production and reclamation of sodic soil.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
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