Ozone-induced Fatty Acid and Viability Changes in Chlorella

Abstract

Ozone-treated cells of the photosynthetic green alga ChloreUa sorokiniana var. pacificensis exhibit an exponential decline in viability, as measured by their ability to form colonies on agar plates. Postexposure conditions appear to have little, if any, effect on this rate of decline. Except in young (early exponential phase) cells, culture age did not affect this rate. The decline in cell viability was correlated with the production of malondialdehyde, arising from the oxidative breakdown of an ozonide of unsaturated fatty acid material. The loss of fatty acids is substantiated by gas-liquid chromatography. A loss of 5 X 10`5 moles of fatty acid per cell corresponds to 75% nonviable cells after 50 minutes of ozone exposure.

Effects of in vitro treatment with ozone on the physical and chemical properties of membranes

“…1971, Frederick and Heath 1974. Decreased levels of polyansaturated fatty acids and of sterols following exposure of plant tissue to ozone have also been noted (Frederick andHeath 1974, Trevathan et al 1979), and protection against ozone is afforded by antioxidants (Rich 1964). Studies with liposomes have demonstrated that lipid peroxidation causes leakiness (Goldstein andWeissman 1977, Hicks andGebicki 1978) and increases lipid microviscosity (Dobretsov et al 1977).…”

“…For example,, malondialdehyde, a product of lipid peroxidation, accumulates after ozone treatment (Tomiinson atid Rich 1970, Muddera/. 1971, Frederick and Heath 1974. Decreased levels of polyansaturated fatty acids and of sterols following exposure of plant tissue to ozone have also been noted (Frederick andHeath 1974, Trevathan et al 1979), and protection against ozone is afforded by antioxidants (Rich 1964).…”

Fatty acids of ozone‐exposed Scots pine and poplar trees and of damaged field‐grown Norway spruce trees

“…In contrast, at higher ozone concentrations, model membranes of egg lecithin reacted with ozone by producing malondialdehyde (MUDD et al 1971). Furthermore, a decline of viability and a loss of fatty acids were observed in Chlorella cells (FREDERICK and HEATH 1975). These findings support the view that low doses of ozone react with proteins, while lipids are affected only at higher ozone concentrations (TINGEY and TAYLOR 1982).…”

Ozone-induced Loss of Intracellular Potassium Ion from Chlorella sorokiniana

“…3). Furthermore, while cells lose their viability (ability to grow on an agar plate) upon ozone exposure, this viability loss occurs only after a short lag period (5 to 10 min) (10). In addition, the K+ efflux of cells exposed to 03 at 15 C does not return to its pre-exposure rate.…”