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Isolation, identification and characterization of an electrogenic microalgae strain.

Wu Y, Guan K, Wang Z, Xu B, Zhao F - PLoS ONE (2013)

Bottom Line: One species showed direct electron transfer via membrane-associated proteins and indirect electron transfer via secreted oxygen.Dissolved oxygen concentration measurement showed gradients within the microalgae biofilm: 18.3 mg L(-1) in light decreasing to 4.29 mg L(-1) in the dark.This study diversified the exoelectrogen library and provided a potential model microalga to explore the associated mechanism of extracellular electron transfer.

View Article: PubMed Central - PubMed

Affiliation: Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, People's Republic of China.

ABSTRACT
Extracellular electron transfer involving microbes is important as it closely reflects the ability of cells to communicate with the environment. However, there are few reports on electron transfer mechanisms of pure microalgae and a lack of any model alga to study the transfer processes. In the present study, nine green microalgae species were isolated from wastewater and characterized in terms of their ability to transfer electrons between cells and an electrode. One species showed direct electron transfer via membrane-associated proteins and indirect electron transfer via secreted oxygen. The microalga was identified as Desmodesmus sp. based on phylogenetic analysis and electron microscopy. Electrochemical tests demonstrated that Desmodesmus sp. was able to act as a cathodic microorganism. Stable current densities of -0.24, 35.54 and 170 mA m(-2) were achieved at potentials of +0.2, -0.2 and -0.4 V, respectively, under illumination. Dissolved oxygen concentration measurement showed gradients within the microalgae biofilm: 18.3 mg L(-1) in light decreasing to 4.29 mg L(-1) in the dark. This study diversified the exoelectrogen library and provided a potential model microalga to explore the associated mechanism of extracellular electron transfer.

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Scanning electron micrographs of A8 cell.A: Magnification×2000; B: Magnification×11000. The strain A8 shows small dents observed at the poles (shown in thin arrow).
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pone-0073442-g003: Scanning electron micrographs of A8 cell.A: Magnification×2000; B: Magnification×11000. The strain A8 shows small dents observed at the poles (shown in thin arrow).

Mentions: For the isolated strain A8, the morphological characteristics included the presence of dents at the pole of the coenobia and ribs on the cell surface (Figure 3a and 3b), which are characteristic to Desmodesmus[22], [23]. The most striking feature of the cell wall ornamentation is the uninterrupted pattern of ribs and the absence of large warts, which are also in line with the diagnostic characters of Desmodesmus[24]; the presence of spines and the surface morphology of the cell wall are two important diagnostic characteristics to distinguish Scenedesmus and Desmodesmus species [23]. In cellular suspensions with moderate density, two-cell coenobia were the most frequent, but singular cell coenobia was rarely observed (Figure S2 and S3 in File S1).


Isolation, identification and characterization of an electrogenic microalgae strain.

Wu Y, Guan K, Wang Z, Xu B, Zhao F - PLoS ONE (2013)

Scanning electron micrographs of A8 cell.A: Magnification×2000; B: Magnification×11000. The strain A8 shows small dents observed at the poles (shown in thin arrow).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3760914&req=5

pone-0073442-g003: Scanning electron micrographs of A8 cell.A: Magnification×2000; B: Magnification×11000. The strain A8 shows small dents observed at the poles (shown in thin arrow).
Mentions: For the isolated strain A8, the morphological characteristics included the presence of dents at the pole of the coenobia and ribs on the cell surface (Figure 3a and 3b), which are characteristic to Desmodesmus[22], [23]. The most striking feature of the cell wall ornamentation is the uninterrupted pattern of ribs and the absence of large warts, which are also in line with the diagnostic characters of Desmodesmus[24]; the presence of spines and the surface morphology of the cell wall are two important diagnostic characteristics to distinguish Scenedesmus and Desmodesmus species [23]. In cellular suspensions with moderate density, two-cell coenobia were the most frequent, but singular cell coenobia was rarely observed (Figure S2 and S3 in File S1).

Bottom Line: One species showed direct electron transfer via membrane-associated proteins and indirect electron transfer via secreted oxygen.Dissolved oxygen concentration measurement showed gradients within the microalgae biofilm: 18.3 mg L(-1) in light decreasing to 4.29 mg L(-1) in the dark.This study diversified the exoelectrogen library and provided a potential model microalga to explore the associated mechanism of extracellular electron transfer.

View Article: PubMed Central - PubMed

Affiliation: Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, People's Republic of China.

ABSTRACT
Extracellular electron transfer involving microbes is important as it closely reflects the ability of cells to communicate with the environment. However, there are few reports on electron transfer mechanisms of pure microalgae and a lack of any model alga to study the transfer processes. In the present study, nine green microalgae species were isolated from wastewater and characterized in terms of their ability to transfer electrons between cells and an electrode. One species showed direct electron transfer via membrane-associated proteins and indirect electron transfer via secreted oxygen. The microalga was identified as Desmodesmus sp. based on phylogenetic analysis and electron microscopy. Electrochemical tests demonstrated that Desmodesmus sp. was able to act as a cathodic microorganism. Stable current densities of -0.24, 35.54 and 170 mA m(-2) were achieved at potentials of +0.2, -0.2 and -0.4 V, respectively, under illumination. Dissolved oxygen concentration measurement showed gradients within the microalgae biofilm: 18.3 mg L(-1) in light decreasing to 4.29 mg L(-1) in the dark. This study diversified the exoelectrogen library and provided a potential model microalga to explore the associated mechanism of extracellular electron transfer.

Show MeSH
Related in: MedlinePlus