Degradation of Tyrosine in Bamboo Shoots (Phyllostachys pubescens) by Lactic Acid Bacteria

Abstract

Tyrosine degradable activity by lactic acid bacteria was examined using tyrosine as a substrate by stationary culture. The activity was assayed by measuring the decrease in tyrosine in the medium by photodiode array detection in HPLC. Seven strains of lactic acid bacteria which converted tyrosine into tyramine during cultivation were selected from 35 strains of type culture. High activity was observed in Enterococcus sp. and Lactococcus lactis subsp. cremoris, which degraded more than half of tyrosine added in a concentration of 1% (w/v) in three days of cultivation. In the reaction system using growing cells, Enterococcus faecalis IFO 3971 and Lactococcus lactis subsp. cremoris which showed the highest activity degraded tyrosine and solubilized white particles composed mainly of tyrosine in bamboo shoots cooked by hot water. After the reaction lactic acid and acetic acid content increased considerably whereas sugar content decreased.