Anoxia and anaerobic respiration are involved in “spawn-burning” syndrome for edible mushroom Pleurotus eryngii grown at high temperatures

•Edible mushroom planted with bags developed the symptoms of spawn-burning at high growth temperatures.•High growth temperatures alone was not a direct factor resulting in spawn-burning symptoms of P. eryngii.•Increased anaerobic respiration of mycelia due to anoxia in mushroom bags was involved in spawn-burning.•The anaerobic respiration metabolites showed significant inhibition to mycelial growth.

“Spawn-burning” syndrome has become one of the most serious problem for edible mushroom cultivation in mushroom bags at high growth temperatures in China. The symptoms of spawn-burning are that the mushroom mycelia ceases growth, dies, and becomes contaminated with mould and bacteria. This article used Pleurotus eryngii as material to study the cause of spawn-burning syndrome. Spawn-burning of P. eryngii occurred at 34 °C, which was far lower than maximum growth temperature of 38 °C or the lethal temperature of 41 °C. Aerobic respiration increased at high growth temperature. At 34 °C, there was increased oxygen consumption by aerobic respiration and decreased dissolved oxygen content in the mushroom bags resulting in anoxia. Anaerobic respiration increased with higher anaerobic respiratory enzyme activities for alcohol dehydrogenase (ADH), pyruvate decarboxylase (PDC), and lactate dehydrogenase (LDH), increased. The anaerobic respiration metabolites of ethanol, acetaldehyde and lactate accumulated, which have an inhibitory effect on mushroom mycelia growth. In conclusion, inadequate oxygen supply in the bags to the mycelia was correlated to spawn-burning at high growth temperature. On this basis, methods to increase oxygen supply for mushroom bags will need to be developed to control spawn-burning for edible mushroom production.