Cryogenic X-ray photoelectron spectroscopy determines surface composition of algal cells and gives insights into their spontaneous sedimentation

• The flotation properties of two green microalgal species isolated from Northern Sweden, Chlorella vulgaris 13-1 and Coelastrella sp. 3-4, were investigated. C. vulgaris 13-1 is a flotating alga that remains suspended in solution during culturing, while Coelastrella sp. 3-4 is readily sedimenting in the stationary growth phase. We were the first to use cryogenic X-ray photoelectron spectroscopy (Cryo-XPS) to gain information on the chemical composition of the algal cell surface and added to these data results obtained from diffuse reflectance - Fourier Transform infrared spectroscopy (DR-FTIR) and classical chemical extractions of carbohydrates, lipids and proteins. Based on the Cryo-XPS data the surface of the sedimenting Coelastrella sp. 3-4 strain is rich in proteins and lipids, while the cell surface of non-flocculating C. vulgaris 13-1 is predominated by carbohydrates, but is poor in lipids. The Zeta-potential of both strains was equally negative. Cell size and the amount of carbohydrates on the algal cell surface, but not the negative surface charge, therefore indicate colloidal stability of microalgae in solutions and can be applied to predict flotation properties of green microalgae.

Ämnesord

NATURVETENSKAP  -- Kemi -- Annan kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences -- Other Chemistry Topics (hsv//eng)

NATURVETENSKAP  -- Kemi -- Fysikalisk kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences -- Physical Chemistry (hsv//eng)

NATURVETENSKAP  -- Kemi -- Materialkemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences -- Materials Chemistry (hsv//eng)

NATURVETENSKAP  -- Biologi -- Biofysik (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences -- Biophysics (hsv//eng)

TEKNIK OCH TEKNOLOGIER  -- Annan teknik -- Livsmedelsteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Other Engineering and Technologies -- Food Engineering (hsv//eng)

Nyckelord

Microalgae

Flotation properties

Electrophoretic mobility

Cryo-XPS

DR-FTIR

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