Background: Escherichia coli, Enterobacter spp., Klebsiella pneumoniae and Enterococcus spp., common gut bacteria in giant pandas, include opportunistic pathogens. The giant panda is an endangered species, classified as vulnerable by the World Wildlife Foundation. Continuous monitoring for the emergence of antimicrobial resistance (AMR) among bacterial isolates from giant pandas is vital not only for their protection but also for public health. Results: A total of 166 E. coli, 68 Enterobacter spp., 116 K. pneumoniae and 117 Enterococcus spp. isolates were collected from fecal samples of 166 giant pandas. In the antimicrobial susceptibility tests, 144 E. coli isolates, 66 Enterobacter spp. isolates, 110 K. pneumoniae isolates and 43 Enterococcus spp. isolates were resistant to at least one antimicrobial. The resistant isolates carried antimicrobial resistance genes (ARGs), including sul3, bla_TEM, bla_SHV and tetA. The differences in the prevalence of the bla types implied that the genetic basis for β-lactam resistance among the E. coli, Enterobacter spp. and K. pneumoniae isolates was different. The strain K. pneumoniae K85 that was resistant to sixteen antimicrobials was selected for whole genome sequencing. The genome contained Col440I, IncFIB_K and IncFII_K plasmids and altogether 258 ARGs were predicted in the genome; 179 of the predicted ARGs were efflux pump genes. The genetic environment of the β-lactamase genes bla_CTX-M-3 and bla_TEM-1 in the K. pneumoniae K85 genome was relatively similar to those in other sequenced K. pneumoniae genomes. In comparing the giant panda age groups, the differences in the resistance rates among E. coli, K. pneumoniae and Enterobacter spp. isolates suggested that the infections in giant pandas of different age should be treated differently. Conclusions: Antimicrobial resistance was prevalent in the bacterial isolates from the giant pandas, implying that the gut bacteria may pose serious health risks for captive giant pandas. The resistance genes in the genome of K. pneumoniae K85 were associated with insertion sequences and integron-integrase genes, implying a potential for the further spread of the antimicrobial resistance.

Lentinula edodes (Berk.) Pegler, also known as Shiitake, is one of the most popular edible mushroom species containing high contents of polysaccharides, proteins and unique aroma, widely cultivated in China, Japan and Korea. A series of studies has been carried out on the extraction and active effect of the L. edodes polysaccharides, but the molecular mechanisms involved in the protein expression profiles during the whole life cycle are relatively unclear. This study employed an iTRAQ-MS/MS proteomic approach, combined with real-time quantitative PCR (qRT-PCR) and enzyme activity assays, to systematically analyze the protein expression profiles and their relationship with lignocellulose degradation in L. edodes across four key developmental stages: mycelia (SF), brown film formation (BF), primordia (YF), and fruiting bodies (MF). A total of 2043 proteins were identified, with 1188 being differentially expressed proteins (DEPs). Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses revealed that metabolic processes, carbohydrate metabolism, and related pathways were significantly active during development. The study specifically focused on carbohydrate-active enzymes (CAZymes), identifying 197 CAZyme proteins classified into 78 families. Key families such as glycoside hydrolases (GHs) and carbohydrate esterases (CEs) played crucial roles in lignocellulose degradation. The enzymatic activities of major lignin-degrading enzymes (laccase, manganese peroxidase, and lignin peroxidase) were dynamically regulated across the developmental stages. qRT-PCR results largely corroborated the proteomic data, confirming the reliability of the protein expression profiles. This study provides a comprehensive, stage-resolved proteomic landscape of lignocellulose degradation during L. edodes development, revealing species-specific temporal dynamics, offering a valuable basis for understanding its growth and development, with implications for edible fungus cultivation and biomass conversion applications.