Effect of Bacterial Strains Isolated from Stored Shiitake (Lentinula edodes) on Mushroom Biodeterioration and Mycelial Growth

Abstract

Shiitake (Lentinula edodes) is a fungus that attracts the attention of consumers and researchers due to its flavour and bioactive compounds with biological activities. However, it swiftly loses quality because of its short shelf life. The present work evaluated the shelf life of cultivated shiitake carpophores with a weekly monitoring of the physico-chemical, microbiological, and sensory parameters under three different storage conditions. To establish the mycopathogenicity of fruitbody-inhabiting bacterial microbiota, 48 strains were isolated from shiitake throughout its storage time and subsequently inoculated on cap cuticles and slices. Additionally, an antibiogram of these bacterial strains against shiitake mycelium was performed. Shiitake had a total microbial load of 5 log cfu/g, composed mainly of Pseudomonas genus, followed by Enterobacteriaceae family, and moulds and yeasts. Among the 48 bacterial strains identified, 18 belonged to the Enterobacteriaceae family and 21 to the Pseudomonas genus. The biodeterioration capacity of the isolated strains increased throughout the conservation period, with slices being more damaged than cap cuticles. We observed a mycopathogenic behaviour of Burkholderia sp., Ewingella americana, Serratia sp., Microbacterium sp. and Rahnella sp. strains, although only the latter highly inhibited shiitake vegetative mycelium growth.

Microbiological Safety and Sensory Quality of Cultivated Mushrooms (Pleurotus eryngii, Pleurotus ostreatus and Lentinula edodes) at Retail Level and Post-Retail Storage

“…AMCs at retail level have been reported as follows: 7.7 to 8.4 log cfu/g for champignon, 5.0 to 5.3 log cfu/g for oyster, 4.9 to 6.9 log cfu/g for shiitake and 5.9 log cfu/g for king oyster [ 23 , 42 , 43 ]. AMCs at the harvest level ranged from 3.1 to 5.8 log cfu/g for champignon, 3.5 log cfu/g for oyster and 4.0 to 4.5 log cfu/g for shiitake [ 18 , 20 , 21 , 44 , 45 ]. Counts of LAB, yeasts and moulds were low (1.1, 2.2 and 2.9 log cfu/g, respectively, Table 2 ), which is in accordance with findings by Venturini et al [ 23 ].…”