EFFECT OF HIGH IRRADIANCE AND IRON ON VOLATILE ODOR COMPOUNDS IN THE CYANOBACTERIUM MICROCYSTIS-AERUGINOSA

The cyanobacterium, Microcystis aeruginosa was exposed to direct sunli ght for 3, 6 or 9 h in media containing either low or high concentrati ons of iron, in order to determine any effects on the composition of v olatile odour compounds (VOCs) released under photooxidative condition s. The most abundant VOCs detected included aliphatic hydrocarbons (C- 15-C-21), naphthalene and the terpenoid compounds, beta-cyclocitral, a nd beta-ionone. Exposure to sunlight and low iron concentrations resul ted in a decrease in beta-cyclocitral, beta-ionone, heptadecane and th e total VOCs concentration after 9 h with respect to the control cultu res. Six VOCs detected in the low iron cells were not detected in any of the high iron cells. However, those VOCs present in the high iron c ells, in general, occurred at higher concentrations than the equivalen t low iron cells after exposure to the sunlight conditions. Consequent ly, it was concluded that exposure to both high irradiance and high ir on concentrations influenced the VOCs composition in cyanobacteria and this was interpreted to represent a cellular change during the photoo xidation-promoting conditions. (C) 1998 Elsevier Science Ltd. All righ ts reserved.