Growth criteria of two common cyanobacteria isolated from Egyptian flooded soil, as influenced by some pesticides

Abstract

Higher rates of the two organophosphorus Insecticides (dimethoate and dursban) induced severe drop in the dry weight gain of Nostoc muscorum and Anabaena oryzae. The fungicide karathane seemed to be inhibitory to the growth of Anabaena whereas all levels of the fungicide, except the two higher stimulated the growth of Nostoc. Trifluralin at all levels inhibited the growth of both organisms. However the magnitude of inhibition was always more pronounced in Anabaena. The lowest concentrations of dursban and dimethoate favored chlorophyll a synthesis in the cells of both cyanobacteria. Contrary to chlorophyll, total carotenoid accumulation was significantly suppressed. Moderate and higher doses of karathane and trifluralin increased chlorophyll a biosynthesis in Nostoc and to lesser extent in Anabaena, a phenomenon that was accompanied by significant increase in total carotenoid content. Glucose uptake by both organisms from media was accelerated following adminestration of all pesticides, an effect that was intensified with further increase in concentrations. Dimethoate and dursban favored the total carbohydrate accumulation in the cells of both organisms, whereas karathane and trifluralin accentuated the process, more prominently in Nostoc.