ACCUMULATION OF COBALT BY MYCELIAL CULTURES OF LENTINULA EDODES (BERK.) PEGLER

摘要

The aim of our previous study was to optimize the growth conditions of submerged mycelial cultures of L. edodes in order to obtain a new dietary supplement enriched in vitamin B_(12). We designed a biotechnological process in which cobalamin precursors were added to the culture medium. At the optimal Co(II) concentration in the cultivation medium the amount of cobalamin in submerged cultivated mycelia was ten thousand-fold higher than that recorded for fruiting bodies. The target of the present research was to control the cobalt content in mycelia cultivated in cobalt-enriched media and to investigate the kinetics of cobalt accumulation by submerged cultivated mycelial cultures. Experimental L. edodes strain was cultivated under submerged conditions in a 10-L fermenter in medium enriched in 40 μg/ml Co(II). Mycelial test-samples were harvested each day and washed either with 0.9% solution of NaCl, or with 3 mmol/L solution of EDTA. In the mycelia washed with the solution of NaCl was determined the total cobalt content. After washing of harvested mycelium with solution of EDTA, which forms stable complex compounds with ions of the heavy metal there was determined only the intracellular cobalt. The cobalt content in harvested mycelia was determined by AAS method. The time-course of the total and intracellular cobalt in mycelial dry weight indicated, that the most effective accumulation of this element occurred at the beginning of the trophophase (Log phase of growth), between the second and fourth day of cultivation. The difference between amount of total cobalt and intracellular cobalt decreased after 6 days of the cultivation.