FACTORS INFLUENCING GROWTH AND TOXIN PRODUCTION BY CULTURES OF THE FRESH-WATER CYANOBACTERIUM LYNGBYA-WOLLEI FARLOW-EX-GOMONT

Collections of Lyngbya wollei were taken from Guntersville Reservoir, Alabama, over a period of three years. Healthy filaments were isolated and transferred to agar plates of Z-8 and LM6E media. Unialgal isolat es were cultured for the study of growth and paralytic shellfish poiso n (PSP) production. Filaments were extracted and the toxins were detec ted using high performance liquid chromatography (HPLC) with post colu mn oxidation followed by fluorescence detection. HPLC profiles show th at laboratory cultures of L. wollei produced decarbamoyl gonyautoxin 2 and 3, plus several other PSP like toxins whose structures are under investigation. At 26 degrees C and a light intensity of 11 or 22 mu mo l m(-2) s(-1) optimum production of both biomass and toxins occurred. A decrease or increase in temperature or light flux caused a reduction in dry weight or toxicity. Compared to control levels, lower PO4-P an d NO3-N and higher calcium levels gave rise to higher biomass and toxi city. Lower calcium, calcium- or PO4-P deficient medium and high NO3-N or PO4-P caused a large decrease in dry weight and toxicity.