POSTHARVEST DECAY OF THE CULTIVATED MUSHROOM PLEUROTUS ERYNGII CAUSED BY LACTOCOCCUS LACTIS subsp LACTIS

Pleurotus eryngii is one of the most commercially-grown mushrooms in the world. In this study, the pathogen causing postharvest water-soaked and sunken lesions on the stipes and decay of P. eryngii in Jiangsu (China) was isolated and identified as Lactococcus lactis subsp. lactis based on phenotypic characteristics and the nucleotide sequences of 16S rRNA and gyrB gene. Disease incidence rates were 45.0 +/- 8.0% after mushroom storing for 5 days at 20 degrees C in summer, 35.5 +/- 6.3% in autumn, 20.5 +/- 3.5% in spring, and only 7.5 +/- 2.5% in winter. Disease development was closely related to the ambient temperature at which the harvested mushrooms were kept. Thus, cold storage was an effectively method to control the disorder, for the pathogen's growth was strongly inhibited when mushrooms were grown at a temperature below 10 degrees C and postharvest storage was at 5 degrees C. L. lactis subsp. lactis greatly inhibited the mycelial growth of P. eryngii, and it had obvious extracellular protease activity. To our knowledge, this is the first report that L. lactis subsp. lactis is the causal agent of postharvest decay of P. eryngii.