L-PHENYLALANINE AMMONIA-LYASE ACTIVITIES IN CELL-SUSPENSION CULTURES OF EUCALYPTUS-POLYBRACTEA .1. EFFECTS OF INOCULUM DENSITIES AND CONDITIONED MEDIUM ON L-PHENYLALANINE AMMONIA-LYASE ACTIVITIES

The activities of L-phenylalanine ammonia-lyase (EC 4.3.1.5; PAL) in c ell suspension cultures of Eucalyptus polybractea R. T. Baker were mea sured using high-performance liquid chromatography (HPLC) by monitorin g the production of trans-cinnamic acid. The effects of the variations of inoculum sizes on PAL activities and cell growth were investigated . High-density cultures had a short-term lag phase of cell growth and little PAL activity, whereas low-density cultures resulted in the supp ression of cell growth and a remarkable increase in PAL activity. In c ell cultures on conditioned medium prepared by mixing fresh medium wit h the filtrates of medium cultured for four days, the growth of the ce lls inoculated at a low-density was facilitated, and PAL activity was depressed.