Auricularia cornea, an edible mushroom, is one of the most widely cultivated species of the Auricularia in China (Ma et al., 2023). In July 2024, transparent blisters were discovered on the edge of Auricularia cornea's fruiting bodies in a growing farm in Liuzhou, Guangxi province, China. As this symptomatology has not been found in any previous reports in China, it was designated as "Blisters Disease" based on the characteristic transparent blister-like symptoms. A sterile syringe was utilized to aspirate the contents from the interior of the diseased tissue for laboratory analysis. The contents were diluted (100-fold dilution) and plated onto a potato dextrose agar (PDA) medium, followed by incubation at 28 ℃ for 48 hours. Single colonies were separated after two rounds of purification, and these colonies appeared yellowish-white, raised, smooth, and circular. The cells were gram-negative and short rods. The 16S rDNA gene was amplified using the universal primers 27F and 1492R (Lane 1991). PCR was conducted in a 20 μL reaction mixture, and a 1403 bp was obtained. The 16S sequence was submitted to Genbank as PV241794. The 16S sequences were compared using BLAST in NCBI, and the sequence showed 99.64% similarity to the Acetobacter indonesiensis strain LMG 1583 (AJ419841.1). A phylogenetic tree was generated via the neighbor-joining algorithm in MEGA. The strain was identified as Acetobacter sp. XJ-2024 based on its morphology, 16S rDNA sequences, and phylogenetic analysis. Young fruiting bodies of A. cornea were induced to serve as a host material for pathogenicity testing. The prepared bacterial suspensions (10⁸ CFU/mL) were directly sprayed onto the surface of three bags of fruiting bodies; an additional three bags were treated with sterile deionized water to act as a negative control. All treated fruiting bodies were then incubated at 28 ℃ with 85% to 90% relative humidity. The A. cornea treated with bacterial suspension displayed symptoms identical to those observed in the farm, whereas the control group remained symptom-free. Initially, the condition manifested as small, localized transparent vesicles protruding from both the upper and lower surfaces of the tender edges of A. cornea. These early-stage vesicles contained a yellowish-white, turbid fluid. As the disease progressed, the vesicles gradually enlarged and spread across the entire fruiting bodies, eventually coalescing into extensive blistered regions that compromised the fungal tissue's structural integrity. To fulfill Koch's postulates, the bacteria were re-isolated from the symptomatic fruiting bodies following artificial inoculation. The re-isolated colonies exhibited morphological characteristics identical to those originally isolated from the field samples (yellowish-white, raised, smooth, and circular), and were confirmed as gram-negative short rods. Subsequent 16S rDNA sequencing and phylogenetic analysis identified the re-isolated strain as Acetobacter sp., consistent with the original isolate. To our knowledge, this study represents the first report of blister disease in A. cornea and identifies Acetobacter sp. as its causative agent, marking a novel discovery in edible fungal pathology. This finding expands our understanding of edible fungal pathology and highlights the importance of continued surveillance and research into emerging diseases in cultivated edible fungi.
Nie et al. (Sun,) studied this question.