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Cefradine is a broad-spectrum antibiotic employed in humans to resist bacterial infection. A large amount of cefradine was not fully utilized, which caused harm to aquatic life and ...aquatic environment. Herein, the toxicity, degradation and metabolic pathway of cefradine to the two microalgal species (Chlorella sp. L166 and Scenedesmus quadricauda) were investigated. The results showed that both microalgae showed excellent degradation performance for cefradine. Chlorella sp. L166 and Scenedesmus quadricauda exposed to 5 mg/L reached the highest removal rates, which were 97.27% and 98.50%, respectively. Although high concentration of cefradine inhibited the growth of both microalgal species, both microalgae showed the capacity to restore growth in high concentration of cefradine. In addition, hydrolysis and biodegradation were regarded as the main mechanisms of cefradine degradation on algae. Seven by-products of cefradine metabolism were identified by HPLC-MS and three metabolic pathways of cefradine in medium were revealed, including decarboxylation, demethylation, hydrolysis, side chain breaking and oxidation processes. These results provide a better understanding of the environmental risks of cefradine in wastewater and the efficient removal of cefradine in wastewater by microalgae.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ
Carbon dots are a new type of carbon-based material with some unique properties which are attractive for agricultural, biological, medical and nanotechnological applications. The widespread ...production of graphene for composite materials as well as the formation of carbon dots as by-products (industry, food heat treatment etc.) leading to inevitable environmental pollution. However, the environmental impact posed by them on living organisms is still insufficient investigated. We studied the effects of carbon dots synthesized in our laboratory via electrochemical (classified as graphene quantum dots), hydrothermal and microwave (classified as carbon nanodots) methods on the green microalga
Scenedesmus quadricauda
. The microalgae were exposed to different concentrations of carbon dots for 6 days. Our results showed that carbon dots did not induce oxidative stress and affect the photosynthetic activity of microalgae. However, carbon dots could decrease the growth rate of microalgae mainly due to reducing light, which occurred via the shading of microalgae by nanoparticles. The obtained results contribute to the understanding of the interaction of carbon dots and microalgae.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
•Uptake and toxicity of trivalent and hexavalent chromium in green alga was compared.•Viability, chlorophyll and mitochondrial proteins were more depleted by Cr(VI).•Cr(III) stimulated ROS and lipid ...peroxidation more than Cr(VI).•Reduction of Cr(VI) to Cr(III) and higher Cr content in high Cr(VI) dose was found.•pH affected Cr(VI) reduction and total Cr uptake.
Physiological responses of Scenedesmus quadricauda to Cr(VI) and Cr(III) excess were studied in buffer with circumneutral pH (6.5). Total Cr content was similar in low (1μM of both oxidation states) but higher in 10μM Cr(VI) treatment and high accumulation potential was detected (80–82% and 41–65% in 1 and 10μM treatments, respectively). Specific fluorescence indicator (6-((anthracen-9-yl) methyleneamino)-2H-chromen-2-one) confirmed partial reduction of Cr(VI) to Cr(III) under exposure conditions. Viability and chlorophyll autofluorescence were more depleted by Cr(VI) while Cr(III) stimulated increase in ROS and lipid peroxidation. Antioxidative enzyme activities showed significantly higher values in 10μM treatments of both Cr oxidation states. Depletion of mitochondrial proteins was not reflected in alteration of total soluble proteins indicating sensitivity of this organelle to Cr and TTC test showed no clear oxidation state-related effect. In this view, “Cr(VI) is not more toxic than Cr(III)” at least for some parameters. Subsequent study with the application of 10μM Cr(VI) confirmed that HEPES buffer is more suitable exposure solution for toxicological studied than water or inorganic salts (higher chlorophyll autofluorescence was observed) and pH 6.5 is more suitable than low or high pH (4.5 or 8.5) in terms of Cr uptake. Another known Cr(III) fluorescence indicator (naphthalimide–rhodamine) also confirmed partial reduction of Cr(VI) to Cr(III) at acidic pH but only traces were seen at alkaline pH.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Copper is an important metal for industry, and its toxic threshold in natural ecosystems has increased since the industrial revolution. As an essential nutrient, it is required in minute amounts, ...being toxic in slightly increased concentrations, causing great biochemical transformation in microalgae. This study aimed at investigating the physiology of Scenedesmus quadricauda, a cosmopolitan species, exposed to copper concentrations including those that trigger intracellular biochemical modifications. The Cu exposure concentrations tested ranged from 0.1 to 25 µM, thus including environmentally important levels. Microalgae cultures were kept under controlled environmental conditions and monitored daily for cell density, in vivo chlorophyll a, and photosynthetic quantum yield (ΦM). After 24 h growth, free Cu2+ ions were determined, and after 96 h, cellular Cu concentration, total carbohydrates, proteins, lipids, and cell volume were determined. The results showed that both free Cu2+ ions and cellular Cu increased with Cu increase in culture medium. Microalgae cell abundance and in vivo chlorophyll a were mostly affected at 2.5 µM Cu exposure (3.8 pg Cu cell−1) and above. Approximately 31% decrease of photosynthetic quantum yield was obtained at the highest Cu exposure concentration (25 µM; 25 pg Cu cell−1) in comparison with the control. However, at environmentally relevant copper concentrations (0.5 µM Cu; 0.4 pg Cu cell−1) cell volume increased in comparison with the control. Considering biomolecules accumulation per unit cell volume, the highest carbohydrates and proteins yield was obtained at 1.0 µM Cu (1.1 pg Cu cell−1), while for lipids higher Cu was necessary (2.5 µM Cu; 3.8 pg Cu cell−1). This study is a contribution to the understanding of the effects of environmentally significant copper concentrations in the physiology of S. quadricauda, as well as to biotechnological approach to increase biomolecule yield in microalgae production.
•Free Cu2+ ions and cellular Cu increased with Cu increase in culture medium.•Cell volume of Scenedesmus quadricauda increased with increasing Cu concentrations.•The highest carbohydrates and proteins yield was obtained at 1.1 pg Cu cell−1, while for lipids higher Cu was necessary 3.8 pg Cu cell−1.•This study is a contribution to the understanding of the effects of environmentally significant copper concentrations in the physiology of S. quadricauda, as well as a biotechnological approach to increase biomolecule yield in microalgae production.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
The relationship between different species of phytoplankton and
Anopheles gambiae
mosquito larvae was studied in order to improve malaria control.
Anopheles gambiae
larval habitat was surveyed by ...sampling phytoplankton at 51 sites. The deleterious effect of
Scenedesmus quadricauda
on third instar larvae was evaluated in the laboratory. 27 phytoplankton species were encountered in the field survey.
Anopheles gambiae
larvae had a positive association with high densities of
Spirogyra
(Pearson chi-square = 25.56, P < 0.0001) and a negative association with high densities of green algae (
Spirogyra, Elakotothrix
,
Coelastrum
,
Ankystrodesmus
,
Chlorella
,
Kirchneriella
,
Selanastrum
, and
Scenedesmus
) and cyanobacteria (
Oscillatoria
, and
Nostoc
). Laboratory bioassays revealed that
S. quadricauda
is indigestible and toxic to
An. gambiae
larvae that ingest it. The larval mortality was 100% when larvae ingested only
S. quadricauda
and 85.6% if larvae were exposed to a mixture of
S. quadricauda
and cat food. The findings of this study indicate that phytoplankton management with
S. quadricauda
or other green algae offers a possible way to eliminate
An. gambiae
production. Complementary studies are needed to investigate the deleterious effect of these algae on
An. gambiae
under semi-natural and natural conditions.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The potential use of the immobilized fresh water algae (in Ca-alginate) of Scenedesmus quadricauda to remove Cu(II), Zn(II) and Ni(II) ions from aqueous solutions was evaluated using Ca-alginate ...beads as a control system. Ca-alginate beads containing immobilized algae were incubated for the uniform growth at 22 °C for 5 days. Adsorption of Cu(II), Zn(II) and Ni(II) ions on the immobilized algae showed highest values at around pH 5.0. Adsorption of Cu(II), Zn(II) and Ni(II) ions on the immobilized algae increased as the initial concentration of metal ions increased in the medium. The maximum adsorption capacities of the immobilized algal biosorbents for Cu(II), Zn(II) and Ni(II) were 75.6, 55.2 and 30.4 mg/g (or 1.15,0.933 and 0.465 mmol/g) biosorbent, respectively. When the heavy metal ions were in competition, the amounts of adsorbed metal ions were found to be 0.84 mol/g for Cu(II), 0.59 mol/g for Ni(II) and 0.08 mol/g for Zn(II), the immobilised algal biomass was significantly selective for Cu(II) ions. The adsorption-equilibrium was also represented with Langmuir, Freundlich and Dubinin-Radushkevich adsorption isotherms. The adsorption of Cu(II), Zn(II) and Ni(II) ions on the immobilized algae followed second-order kinetic.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The use of microalgae in a number of sectors, including biodiesel, feed and food production, is proving to be of great interest. An evaluation was made of the possible biostimulant effects on ...Chlorella vulgaris and Scenedesmus quadricauda of humic-like substances (HLs) extracted from agro-industrial wastes. These included digestate from the waste of an agro-livestock farm (D-HL), oil extraction residues from rape (B-HL, Brassica napus L.) and tomato residues (T-HL). The microalgal growth medium (BG11) was supplemented with HLs to evaluate their effect on biomass yield as well as carbohydrate, chlorophylls a and b, lipid and fatty acid contents. Our results showed that the HLs used in the test are effective biostimulants of C. vulgaris and S. quadricauda. The biostimulant effect seems to depend on the type of extract used for cultivating the microalgae, the concentration and the species treated. Among the extracts applied to the growth medium, D-HL and T-HL seem to have a significant effect on microalgal biomass and lipid production. Although B-HL showed no significant effect on the biomass and lipid content of C. vulgaris and S. quadricauda, its presence in the growth medium increased the saturated:unsaturated fatty acid ratio (SFA/UFA) and stimulated the sugar metabolism of the microalgae by increasing their carbohydrate and chlorophyll content.
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BFBNIB, DOBA, GIS, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Allelopathy by hydrophytes can be utilized to control algal blooms. This study was conducted to investigate the allelopathic effect (inhibition) of
Scenedesmus quadricauda
on
Microcystis flos-aquae
. ...When
M. flos-aquae
was co-cultured with
S. quadricauda
, the secretion of high-MW biopolymer by
M. flos-aquae
was inhibited by
S. quadricauda
. We further identified the allelochemicals and found that 4-tert-butylpyrocatechol (TBC) was the main active ingredient that could inhibit the growth of
M. flos-aquae
. When the dose of TBC was larger than 0.2 mg/L, almost all of the
M. flos-aquae
died. Additionally, TBC was found to suppress the growth of
M. flos-aquae
by disturbing the synthesis and secretion of proteins and polysaccharides and harming the chlorophyll to affect the light harvesting of algal cells. Therefore, TBC has the potential for use as a potential and promising algaecide to restrain the biomass of
M. flos-aquae
.
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CEKLJ, DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NUK, OBVAL, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Anaerobic digestion (AD) is one of the most efficient processes for treating agri-food waste in order to obtain renewable energy. Olive mill solid waste (OMSW) is the main residue from the two-phase ...olive oil manufacturing process; it has a high organic content and high C/N ratio, which hinders its AD, giving low methane yield. In the present study, a microalga,
Scenedesmus quadricauda
, was used as co-substrate for the AD of OMSW to compensate for its nitrogen deficiency. The robustness and the high growth rate of
S. quadricauda
make this microalga a potential source of nitrogen to co-digest with carbon-rich substrates. Different co-digestion mixtures of OMSW-microalgae and the single substrates were tested. For all co-digestion mixtures, the alkalinity value at the end of the experiment remained below 4889 ± 245 mg CaCO
3
L
−1
and pH in the range of 7.50–7.67 indicating stability and good process performance. Results showed the highest methane yield (461 mL CH
4
STP g
−1
VS added) for the co-digestion mixture 75% OMSW-25%
S. quadricauda
(C/N = 25.3), which was 104 and 23% higher than that obtained from the single microalga (C/N = 5.6) and OMSW (C/N = 31.9), respectively. No ammonia inhibition was detected despite the high protein content of the microalgae. The transference function model allowed for adequately fitting the experimental results of methane production with time in the anaerobic experiments. The highest maximum methane production rate,
R
m
, among the different co-digestion mixtures assayed was obtained for the mixture 75% OMSW-25%
S. quadricauda
with a value of 89 mL CH
4
g
−1
VS day
−1
.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
In the present study, complex patterns of algal response to chromium (K
2
Cr
2
O
7
, Cr) and cadmium (CdSO
4
, Cd) toxicity were examined. Chlorophyll and starch content, photosynthetic activity and ...respiration rate, fatty acid content and composition, cell density (growth rate), malondialdehyde content (oxidative stress), ferric reducing antioxidant power and phenolic content (antioxidant activity) were measured in the model green algae species
Scenedesmus quadricauda
and
Chlorella sorokiniana
during exposure to 20 or 50 μM of Cr or Cd. Cell response to Cd showed similar patterns in both algae, whereas Cr effects differed, especially regarding the antioxidant activity
.
Malondialdehyde content, starch content, and respiration rate were the parameters most affected by both metals in both species. Only respiration rate increased dramatically under all treatments studied. In general, the Cd or Cr poisoning induced the transition of cell metabolism from “assimilatory” mode with active photosynthesis to “catabolic” mode characterized by elevated respiration and increased content of starch, a substrate for respiration.
Chlorella sorokiniana
cells showed a prominent response to Cr indicating suitability for bioassay of Cr contamination in the aquatic environment. A method for comprehensive screening of algal species on their heavy metal tolerance is proposed.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
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