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Comparing Acute Effects of a Nano-TiO2 Pigment on Cosmopolitan Freshwater Phototrophic Microbes Using High-Throughput Screening.

Binh CT, Peterson CG, Tong T, Gray KA, Gaillard JF, Kelly JJ - PLoS ONE (2015)

Bottom Line: Production of titanium-dioxide nanomaterials (nano-TiO2) is increasing, leading to potential risks associated with unintended release of these materials into aquatic ecosystems.These results suggest that nanomaterial contamination has the potential to alter the distribution of phototrophic microbial taxa within freshwater ecosystems.The higher resistance of cyanobacteria could have significant implications as cyanobacteria represent a less nutritious food source for higher trophic levels and some cyanobacteria can produce toxins and contribute to harmful algal blooms.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, Loyola University Chicago, Chicago, Illinois, United States of America.

ABSTRACT
Production of titanium-dioxide nanomaterials (nano-TiO2) is increasing, leading to potential risks associated with unintended release of these materials into aquatic ecosystems. We investigated the acute effects of nano-TiO2 on metabolic activity and viability of algae and cyanobacteria using high-throughput screening. The responses of three diatoms (Surirella angusta, Cocconeis placentula, Achnanthidium lanceolatum), one green alga (Scenedesmus quadricauda), and three cyanobacteria (Microcystis aeruginosa, Gloeocapsa sp., Synechococcus cedrorum) to short-term exposure (15 to 60 min) to a common nano-TiO2 pigment (PW6; average crystallite size 81.5 nm) with simulated solar illumination were assessed. Five concentrations of nano-TiO2 (0.5, 2.5, 5, 10, and 25 mg L-1) were tested and a fluorescent reporter (fluorescein diacetate) was used to assess metabolic activity. Algae were sensitive to nano-TiO2, with all showing decreased metabolic activity after 30-min exposure to the lowest tested concentration. Microscopic observation of algae revealed increased abundance of dead cells with nano-TiO2 exposure. Cyanobacteria were less sensitive to nano-TiO2 than algae, with Gloeocapsa showing no significant decrease in activity with nano-TiO2 exposure and Synechococcus showing an increase in activity. These results suggest that nanomaterial contamination has the potential to alter the distribution of phototrophic microbial taxa within freshwater ecosystems. The higher resistance of cyanobacteria could have significant implications as cyanobacteria represent a less nutritious food source for higher trophic levels and some cyanobacteria can produce toxins and contribute to harmful algal blooms.

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Representative images from microscopic observations of algae after 30 min exposure to simulated sunlight without (A, C, E) and with 25 mg L-1 nano-TiO2 (B, D, F).Organisms pictured are Scenedesmus quadricauda (A & B), Surirella angusta (C & D) and Cocconeis placentula (E & F). Green arrows indicate examples of healthy cells; red arrows indicate examples of damaged cells; black arrows indicate examples of dead cells.
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pone.0125613.g002: Representative images from microscopic observations of algae after 30 min exposure to simulated sunlight without (A, C, E) and with 25 mg L-1 nano-TiO2 (B, D, F).Organisms pictured are Scenedesmus quadricauda (A & B), Surirella angusta (C & D) and Cocconeis placentula (E & F). Green arrows indicate examples of healthy cells; red arrows indicate examples of damaged cells; black arrows indicate examples of dead cells.

Mentions: Cell damage was readily apparent in microscopic observations of S. angusta, C. placentula and S. quadricauda cells that were exposed to nano-TiO2 with simulated solar illumination in the HTS assay (Fig 2). For example, healthy S. quadricauda cells were elliptical and contained abundant green chloroplasts (Fig 2A) whereas exposure to 25 mg L-1 nano-TiO2 for 30 min resulted in increased size of intracellular vacuoles causing an alteration of cell shape to spherical (Fig 2B). In addition, nano-TiO2 treatment resulted in a decrease in the abundance of chloroplasts within S. quadricauda cells due to leaking of cytoplasm out of the cells, rendering cells transparent (Fig 2B). Similarly, healthy S. angusta and C. placentula cells were pigmented (Fig 2C and 2E) and exposure to 25 mg L-1 nano-TiO2 for 30 min resulted in loss of cytoplasm and chloroplasts presumably due to cell wall damage, leaving empty siliceous frustules (Fig 2D and 2F). Healthy, damaged and dead A. lanceolatum cells could not be clearly discriminated under the microscope, so microscopic observation data are not reported for this algal species.


Comparing Acute Effects of a Nano-TiO2 Pigment on Cosmopolitan Freshwater Phototrophic Microbes Using High-Throughput Screening.

Binh CT, Peterson CG, Tong T, Gray KA, Gaillard JF, Kelly JJ - PLoS ONE (2015)

Representative images from microscopic observations of algae after 30 min exposure to simulated sunlight without (A, C, E) and with 25 mg L-1 nano-TiO2 (B, D, F).Organisms pictured are Scenedesmus quadricauda (A & B), Surirella angusta (C & D) and Cocconeis placentula (E & F). Green arrows indicate examples of healthy cells; red arrows indicate examples of damaged cells; black arrows indicate examples of dead cells.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4414569&req=5

pone.0125613.g002: Representative images from microscopic observations of algae after 30 min exposure to simulated sunlight without (A, C, E) and with 25 mg L-1 nano-TiO2 (B, D, F).Organisms pictured are Scenedesmus quadricauda (A & B), Surirella angusta (C & D) and Cocconeis placentula (E & F). Green arrows indicate examples of healthy cells; red arrows indicate examples of damaged cells; black arrows indicate examples of dead cells.
Mentions: Cell damage was readily apparent in microscopic observations of S. angusta, C. placentula and S. quadricauda cells that were exposed to nano-TiO2 with simulated solar illumination in the HTS assay (Fig 2). For example, healthy S. quadricauda cells were elliptical and contained abundant green chloroplasts (Fig 2A) whereas exposure to 25 mg L-1 nano-TiO2 for 30 min resulted in increased size of intracellular vacuoles causing an alteration of cell shape to spherical (Fig 2B). In addition, nano-TiO2 treatment resulted in a decrease in the abundance of chloroplasts within S. quadricauda cells due to leaking of cytoplasm out of the cells, rendering cells transparent (Fig 2B). Similarly, healthy S. angusta and C. placentula cells were pigmented (Fig 2C and 2E) and exposure to 25 mg L-1 nano-TiO2 for 30 min resulted in loss of cytoplasm and chloroplasts presumably due to cell wall damage, leaving empty siliceous frustules (Fig 2D and 2F). Healthy, damaged and dead A. lanceolatum cells could not be clearly discriminated under the microscope, so microscopic observation data are not reported for this algal species.

Bottom Line: Production of titanium-dioxide nanomaterials (nano-TiO2) is increasing, leading to potential risks associated with unintended release of these materials into aquatic ecosystems.These results suggest that nanomaterial contamination has the potential to alter the distribution of phototrophic microbial taxa within freshwater ecosystems.The higher resistance of cyanobacteria could have significant implications as cyanobacteria represent a less nutritious food source for higher trophic levels and some cyanobacteria can produce toxins and contribute to harmful algal blooms.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, Loyola University Chicago, Chicago, Illinois, United States of America.

ABSTRACT
Production of titanium-dioxide nanomaterials (nano-TiO2) is increasing, leading to potential risks associated with unintended release of these materials into aquatic ecosystems. We investigated the acute effects of nano-TiO2 on metabolic activity and viability of algae and cyanobacteria using high-throughput screening. The responses of three diatoms (Surirella angusta, Cocconeis placentula, Achnanthidium lanceolatum), one green alga (Scenedesmus quadricauda), and three cyanobacteria (Microcystis aeruginosa, Gloeocapsa sp., Synechococcus cedrorum) to short-term exposure (15 to 60 min) to a common nano-TiO2 pigment (PW6; average crystallite size 81.5 nm) with simulated solar illumination were assessed. Five concentrations of nano-TiO2 (0.5, 2.5, 5, 10, and 25 mg L-1) were tested and a fluorescent reporter (fluorescein diacetate) was used to assess metabolic activity. Algae were sensitive to nano-TiO2, with all showing decreased metabolic activity after 30-min exposure to the lowest tested concentration. Microscopic observation of algae revealed increased abundance of dead cells with nano-TiO2 exposure. Cyanobacteria were less sensitive to nano-TiO2 than algae, with Gloeocapsa showing no significant decrease in activity with nano-TiO2 exposure and Synechococcus showing an increase in activity. These results suggest that nanomaterial contamination has the potential to alter the distribution of phototrophic microbial taxa within freshwater ecosystems. The higher resistance of cyanobacteria could have significant implications as cyanobacteria represent a less nutritious food source for higher trophic levels and some cyanobacteria can produce toxins and contribute to harmful algal blooms.

Show MeSH
Related in: MedlinePlus