Growth Of Marine Microalgae Research Articles

Is hydrodynamic diameter the decisive factor? - Comparison of the toxic mechanism of nSiO2 and mPS on marine microalgae Heterosigma akashiwo

To investigate the toxic mechanism of SiO2 nanoparticles (nSiO2) and polystyrene microplastics (mPS) on microalgae Heterosigma akashiwo, growth inhibition tests were carried out. The growth and biological responses of the algae exposed to nSiO2 (0.5, 1, 1.5, 2, 5, 10 and 30 mg L−1) and mPS (1, 2, 5, 10, 30 and 75 mg L−1) were explored in f/2 media for 96 h. It was found that the hydrodynamic diameter of the particles seems to be one of the more important factors to influence the algae. nSiO2 and mPS with similar hydrodynamic diameters have the similar toxic mechanism on H. akashiwo, and the effects were dose- and time-dependent. High concentrations of micro-/nano-particles (MNPs) could inhibit the growth of algal cells, however, low concentrations of MNPs did not restrict or even promoted the growth of algae, known as “Hormesis” phenomenon. The 96 h-EC20 values of nSiO2 and mPS on H. akashiwo were 2.69 and 10.07 mg L−1, respectively, and chlorophyll fluorescence parameters indicated that the microalgal photosynthetic system were inhibited. The hydrophilic surface of nSiO2 increased the likelihood of nSiO2 binding to the hydrophilic functional group of microalgae, which may account for the slightly stronger toxic effect of nSiO2 than mPS. The algae continued to produce reactive oxygen species (ROS) under stress conditions. Total protein (TP) levels reduced, and superoxide dismutase (SOD) and catalase (CAT) levels increased to maintain ROS levels in the cells. The decrease in adenosine triphosphate (ATPase) indicated an impact on cellular energy metabolism. Cell membrane damage, cytoplasm and organelle efflux under stress were confirmed by scanning and transmission electron microscopy (SEM and TEM) images. This study contributes to the understanding of the size effect of MNPs on the growth of marine microalgae.

Effects of polystyrene microplastic on the growth and volatile halocarbons release of microalgae Phaeodactylum tricornutum

Volatile halocarbons (VHCs) are trace greenhouse gases that can damage the ozone layer. Trihalomethanes are one of the most common VHCs and play an important role in global climate change. Due to their steadily increasing abundance, microplastics pollutants have attracted growing concern from scientists. However, their impacts on the growth of marine microalgae and the release of VHCs remain unknown. The influence of polystyrene microplastic (PS, 0.1 μm) at different concentrations (25–200 mg/L) on the growth of P. tricornutum and their release of trihalomethanes were studied over 96 h. The results showed that PS can inhibit P. tricornutum growth. At 200 mg/L PS, cell growth, chlorophyll a concentration and photosynthetic efficiency of P. tricornutum were inhibited by 53.53%, 25.45% and 12.50%, respectively. PS concentrations of 25–50 mg/L promoted the release of the three trihalomethanes by P. tricornutum during the 96 h culture as a response to oxidative stress. However, 100–200 mg/L PS severely altered the physiological state of the P. tricornutum cells after 48 h, which reduced the release of trihalomethanes. Our study also demonstrated that the production and release of trihalomethanes served as a protective mechanism against oxidative stress and the toxic effects caused by PS.

Effects of nitric oxide on the growth of marine microalgae and carbonate chemistry parameters

Effects of nitric oxide on the growth of marine microalgae and carbonate chemistry parameters

Growth of Marine Microalgae in Landfill Leachate and Their Ability as Pollutants Removal.

Leachate from landfill contains concentrated nutrients that may enter the terrestrial and aquatic environment, including nearby coastal areas. The nutrient contaminants eventually bring harm to marine organisms, including microalgae. This study was performed to investigate the growth of two green microalgal species, i.e. Chlorella sp. and Nannochloropsis sp. in diluted landfill leachate. Besides, the ability of nutrient removal by these microalgal was also explored from the changes of chemical oxygen demand (COD) and nutrients content. The initial and final concentrations of COD, NH3-N, and PO43− in the diluted leachate (5%, 10% and 15%) were measured and the growth patterns of these species were determined by counting the cell numbers for 12 days. Comparison of these microalgae showed that the growth rate of Nannochloropsis was significantly higher compared to Chlorella in all leachate concentrations. Leachate at 5% enhanced the growth of both microalgae, while leachates at 10% and 15% decreased their growth as early as at the beginning of the test. It is apparent that the less concentrated leachate discharged into seawater would not pose any toxicity to the environment and would not bear adverse effect to microalgae yet could promote their growth. This study also revealed that the microalgae could remediate leachate pollution by its ability of nutrient removal; thus, leading to the potential application in wastewater bioremediation, including industrial waste and palm oil mill effluent.

The Influence of Different Light Wavelengths on Growth, Enzymes Activity and Photosynthesis of the Marine Microalga Dunaliella parva W.Lerche 1937

Light is an important factor that influences the growth and photosynthetic efficiency of microalgae; however, little is known about how light intensity together with the wavelength affect the photosynthetic capacity and growth of marine microalgae. In the present study, the growth of the marine green microalga Dunaliella parva was studied and optimized under different light intensities (25 ~ 70 μmol m-2 s-1) and qualities (blue, green, and red) in comparison with white light at 40 μmol m-2 s-1 as a control. The growth was monitored by counting the cell number, pigment content, Chl a, Chl b, and carotenoids concentrations. The optimal growth and highest photosynthetic efficiency (Fv/Fm) were recorded at a light intensity of 40 μ mol m-2 s-1, white light, and 1.25 M NaCl (1.47 and 0.678×106 cell mL-1, respectively). The activity of antioxidant enzymes, including catalase and peroxidase, as well as ascorbate content, showed the highest values of 0.190 µM/min.mg Chl, 0.434 and 13.3 mg/g f.wt. respectively, under the green light, which confirmed the presence of environmental stresses.

Exposure-based ecotoxicity assessment of Co3O4 nanoparticles in marine microalgae.

The exposure-effect study was conducted to evaluate the effect of Co3O4 nanoparticles on Tetraselmis suecica. The growth suppressing effect has been observed during the interaction between nanoparticles and microalgae as indicated by 72 h EC50 (effective concentration of a chemical at which 50% of its effect is observed) value (45.13±3.95 mg/L) of Co3O4 nanoparticles for Tetraselmis suecica. Decline in chlorophyll a content also indicated the compromised photosynthetic ability and physiological state of microalgae. Further biochemical investigation such as increase in extracellular LDH (lactate dehydrogenase) level, ROS (reactive oxygen species), and levels of membrane lipid peroxidation in treated samples signifies the compromised cellular health and membrane disintegration caused by nanoparticles. Parallel to this, the cell entrapment, membrane damage, and attachment of nanoparticles on cell surface were also visualized by SEM-EDX (scanning electron microscope-energy dispersive X-ray) microscopy. The overall results of this study clearly indicated that Co3O4 nanoparticles might have toxic effects on growth of marine microalgae and other aquatic life forms as well. Hence, release of Co3O4 nanoparticles in aquatic ecosystem and resulting ecotoxic effect should be broadly addressed.

Effect of biodegradable chelating ligands on Fe uptake in and growth of marine microalgae

Iron (Fe) is an important nutrient for phytoplankton. The low solubility of Fe in oxic waters can be a growth-limiting factor for phytoplankton. Synthetic aminopolycarboxylates (APCs) such as ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA) are widely used as Fe complexing agents for microalgae culture. However, the presence of these non-ready biodegradable APCS in aquatic systems may have serious environmental consequences. In the present study, the effects of biodegradable chelating ligands (hydroxyiminodisuccinic acid (HIDS), methylglycinediacetic acid (MGDA), and iminodisuccinate (IDS)) on Fe uptake in and growth of three coastal microalgae (Heterosigma akashiwo, Prymnesium parvum, and Skeletonema marinoi-dohrnii complex) were investigated, and the results were compared with those of non-ready biodegradable APCs (EDTA, ethylenediamine tetra-methylene phosphonic acid (EDTMP), and DTPA). The biodegradable chelating ligands did not have significant growth inhibition effect on the phytoplankton. Although the growth of the algae (except S. marinoi-dohrnii complex) was not affected substantially by 1.5 and 7.5 μM of DTPA, growth inhibition occurred by 7.5 μM of EDTMP and 150 μM of EDTA, DTPA, and EDTMP. The effect of chelating ligands on microalgal growth was likely to be associated with the intracellular Fe uptake influenced by the chelating ligands. On average, intracellular Fe concentrations for biodegradable chelating ligands were substantially higher than those for non-ready biodegradable APCs. Except H. akashiwo, the ratio of intra/extracellular Fe concentrations was highest for MGDA followed by IDS and HIDS. The results indicate that biodegradable chelating ligands are more efficient than non-ready biodegradable APCs in intracellular Fe uptake and algal growth.

Investigation of phyco-remediation of road salt run-off with marine microalgae Nannochloropsis gaditana

ABSTRACTPhyco-remediation is an environmental-friendly method, which involves the application of beneficial microalgae to treat wastewater-containing pollutants for a diverse range of conditions. Several industrial processes generate hyper saline wastewater, which is a significant challenge for conventional wastewater treatment, and the disposal of saline waters also has a negative impact on the environment. Road salt run-off is one such saline wastewater stream not currently treated and one that contributes significantly to negatively impacting receiving bodies of water. In this study, Nannochloropsis microalgae were able to assimilate >95% of the nitrates within 8 days in road salt concentrations ranging from 2.6% to 4.4% under phototrophic cultivation mode. Biomass yields of 1–2 g/l of culture were obtained with the maximum lipid of 22% (g/g) biomass in the road salt media. The crude road salt media provided all the essential micronutrients needed for algal cultivation. The fatty acid composition analysis of the obtained lipid composed of C16 and C18 over 45% of FAME are suitable for biofuel. This study has established that the use of road salt containing nitrate and phosphate nutrients will support the growth of marine micro algae for remediation of a waste water system that are the concern at winter-prevalent regions.

The Effect of Temperature and Salinity on the Growth of Skeletonema costatum and Chlorella capsulata in vitro

Salinity and temperature are two of the major factors controlling the growth rate of microalgae. In this study, the effect of salinity and temperature on the growth of marine microalgae; Chlorella capsulata and Skeletonema costatum were investigated to optimize the microalgal biomass production. These species were cultured at different salinities (20, 25 and 30 ‰) and temperatures (20, 25 and 30°C). Skeletonema costatum and Chlorella capsulata had significantly higher (p<0.05) growth rate when cultured at salinities of 30 and 25 ‰, respectively. In terms of temperature, the highest (p<0.05) growth rate was observed in Skeletonema costatum and Chlorella capsulata cultivated at temperatures of 30 and 25°C, respectively. This study indicated that Skeletonema costatum was suitable to marine condition, whereas Chlorella capsulata showed optimum growth at lower salinity and temperature. In addition, can be concluded, Chlorella capsulata and Skeletonema costatum can be considered as suitable species for large outdoor micro algal cultivation.International Journal of Life Sciences 10 (1) : 2016; 40-44

Evidence for the mutual effects of dimethylsulfoniopropionate and nitric oxide during the growth of marine microalgae

Dimethylsulfoniopropionate (DMSP) and nitric oxide (NO) in marine microalgae are considered as two important compounds involved in a variety of physiological functions. We examined the NO responses and the growth of Isochrysis galbana Parke and Gymnodinium sp. when supplemented with different concentrations of DMSP solutions in the cultures. Production of DMSP and dimethylsulfide (DMS) in Amphidinium carterae and Emiliania Huxleyi was investigated after the addition of NO donor sodium nitroprusside (SNP) and NO solution to algal media. The release peaks of NO were observed in cell suspensions of I. galbana Parke and Gymnodinium sp. immediately after the injection of DMSP solutions. The growth of these two microalgae was found to be significantly promoted or inhibited caused by exogenous DMSP. There was a decrease of DMSP concentrations in algal cultures within 24 h, accompanied with an increase in DMS, due to the effect of NO. The results provided direct evidence to confirm that there exist mutual effects of DMSP and NO during the growth of marine microalgae, which is speculated to be related to their roles as signaling molecules in planktonic communities.

Effect of Different Light Wavelength on the Growth of Marine Microalgae

Tetraselmis sp. and Nannochloropsis sp. are common marine microalgae used as substrates for production of biodiesel which is the third generation alternative energy. Recently, wavelength of light is believed to influence the growth of marine microalgae. In this investigation, two different types of light wavelength; red and blue which can influence the production of microalgae were investigated. The marine microalgae growths were observed in terms of biomass which was then measured using the UV-vis spectrophotometer. The results showed that both Tetraselmis sp. and Nannochloropsis sp. grow better in the blue light compared to the red light indicated by the higher absorbance readings.

Effect of Salinity and Temperature on the Growth of Diatoms and Green Algae

Salinity and temperature are two of the major factors controlling the growth rate of microalgae. In this study, the effect of salinity and temperature on the growth of marine microalgae; an unidentified Chlorella sp. and Chaetoceros calcitrans were investigated to optimize the microalgal biomass production. These species were cultured at different salinities (20, 25 and 30‰) and temperatures (20, 25 and 30°C). C. calcitrans and Chlorella sp. had significantly higher (p<0.05) growth rate when cultured at salinities of 30 and 25‰, respectively. In terms of temperature, the highest (p<0.05) growth rate was observed in C. calcitrans and Chlorella sp. cultivated at temperatures of 30 and 25°C, respectively. This study indicated that C. calcitrans was suitable to marine condition, whereas Chlorella sp. showed optimum growth at lower salinity and temperature.

Investigation Into the Suitability of Inland Ground Saline Water for the Growth of Marine Microalgae for Industrial Purposes

An increasing shortage of crude oil has necessitated into alternative energy sources. In Australia, inappropriate agricultural practices have left large areas of agricultural land subject to secondary salinisation from rising water tables. Opportunities have arisen from groundwater interception schemes for the aquacultural production of marine microalgae far inland from coastal areas where a shortage of suitable sites and strict environmental regulations makes the production of large volumes of microalgae unrealistic. Four small-scale laboratory experiments were undertaken to determine the potential growth of the two species of marine microalgae, Isochrysis galbana Parke and Tetraselmis suecica Stein, in inland saline ground water sourced from a ground water monitoring bore in rural Victoria. The results showed that at the termination of the experiments the differences between experimental units and control treatments of I. galbana and T. suecica with and without algal growth nutrient were not significantly different.

Complexation of iron by microbial siderophores and effects of iron chelates on the growth of marine microalgae causing red tides

SUMMARYThe growth rates of 13 species of abundant red tide algae in media with different iron species complexed with microbial siderophores (Ferrichrome and Ferrioxamine) and Fe‐Catechol were investigated. Our study demonstrated that the Fe‐chelates (at molar ratios = 1:1) were bioavailable to some red tide species. In Fe‐Catechol medium, growth was observed for the raphidophyte Heterosigma akashiwo, the dinoflagellates Heterocapsa circularisquama and Heterocapsa triquetra, the diatom Ditylum brightwellii, the cryptophyte Rhodomonas ovalis, the chlorophyte Oltmannsiellopsis viridis, and the haptophyte Cricosphaera roscoffensis. In Ferrioxamine medium, we found the growth of the dinoflagellate Karenia mikimotoi, the diatom Ditylum brightwellii, and the cryptophyte Rhodomonas ovalis. But, the existence of higher ligand concentrations (molar ratios ≥ 1:10) decreased the growth rates of most red tide species that were examined. Furthermore, all red tide species examined were not able to grow in Ferrichrome medium. In particular, the Chattonella species examined did not grow in the presence of Fe‐chelates. These results suggest that bioavailability of iron depends not only on ligand species, but also on the concentration of the ligands; moreover, microbial siderophores may play an important role in controlling the uptake of iron complexed with organic materials that exist in coastal water and the formation of red tides in coastal areas.

Identification and quantification of indole-3-acetic acid in the kelp Laminaria japonica Areschoug and its effect on growth of marine microalgae

A method was established for the identification and quantification of indole-3-acetic acid (IAA) in extracts of the kelp Laminaria japonica. An IAA content of 90–95 μg kg−1 fresh weight in kelp extract was determined by high performance liquid chromatography (HPLC). IAA identification was based on a combination of co-chromatography and comparative chromatography with a standard, analysis of UV spectra, and atmospheric pressure electrospray mass spectrometry (APESI-MS). IAA was isolated by silica gel chromatography and HPLC. The effect on the growth of four marine microalgae of the pure IAA isolated from kelp extract was investigated. Exogenously added IAA from kelp enhanced the growth of Chlorella sp., Dunaliella salina and Porphyridium cruentum, but not that of Chaetoceros muelleri. IAA from kelp significantly inhibited the accumulation of soluble cellular proteins in Chlorella sp. and P. cruentum, and had a very significant effect on chlorophyll biosynthesis in Chlorella sp. However, there was no obvious effect of IAA on the regulation of biosynthesis of cellular polysaccharides in these four marine microalgae.

Effects of macroalgae Ulva pertusa (Chlorophyta) and Gracilaria lemaneiformis (Rhodophyta) on growth of four species of bloom-forming dinoflagellates

The effects of fresh thalli and culture medium filtrates from two species of marine macroalgae, Ulva pertusa Kjellm (Chlorophyta) and Gracilaria lemaneiformis (Bory) Dawson (Rhodophyta), on growth of marine microalgae were investigated in co-culture under controlled laboratory conditions. A selection of microalgal species were used, all being identified as bloom-forming dinoflagellates: Prorocentrum donghaiense Lu sp., Alexandrium tamarense (Lebour) Balech, Amphidinium carterae Hulburt and Scrippsiella trochoide (Stein) Loeblich III. Results showed that the fresh thalli of either U. pertusa or G. lemaneiformis significantly inhibited the microalgal growth, or caused mortality at the end of the experiment. However, the overall effects of the macroalgal culture filtrates on the growth of the dinoflagellates were species-specific (inhibitory, stimulatory or none) for different microalgal species. Results indicated an allelopathic effect of macroalga on the co-cultured dinoflagellate. We then took P. donghaiense as an example to further assess this hypothesis. The present study was carried out under controlled conditions, thereby excluded the fluctuation in light and temperature. Nutrient assays showed that nitrate and phosphate were almost exhausted in G. lemaneiformis co-culture, but remained at enough high levels in U. pertusa co-culture, which were well above the nutrient limitation for the microalgal growth, when all cells of P. donghaiense were killed in the co-culture. Daily f/2 medium enrichment greatly alleviated the growth inhibition on P. donghaiense in G. lemaneiformis co-culture, but could not eliminate it. Other environmental factors, such as carbonate limitation, bacterial presence and the change of pH were also not necessary for the results. We thus concluded that allelopathy was the most possible reason leading to the negative effect of U. pertusa on P. donghaiense, and the combined roles of allelopathy and nutrient competition were essential for the effect of G. lemaneiformis on P. donghaiense.