Diversity and functional potential of bacterial and fungal endophytes in traditional food wrapping leaves reveal implications for artisanal food safety and quality

Abstract

Plant leaves are widely utilised globally for the packaging and serving of traditionally prepared foods. The microbial communities associated with these wrapping leaves, particularly endophytes, are recognised to potentially influence food quality, safety, and preservation. Specifically, certain endophytes can enhance sensory attributes and nutritional value through fermentative processes, while the presence of harmful microorganisms may lead to spoilage and pose a risk of foodborne illness. This study utilised 16S rRNA, ITS metabarcoding and metagenomic functional analysis (PICRUSt2) to comprehensively investigate the composition and infer the putative functional potential of putative endophytic bacterial and fungal communities present in 53 samples of four different food wrapping leaves. The leaves examined included Thaumatococcus daniellii ( n = 10), Alstonia macrophylla ( n = 18), Theobroma species ( n = 14), and Megaphrynium macrostachyum ( n = 11). Distinct microbial community profiles were observed across the different leaf types. Highest bacterial species richness and community variability were detected in A. macrophylla samples, reflected by Principal Coordinates Analysis (PCoA) values (PCoA1 = 43.97%; PCoA2 = 10.68%). Conversely, M. macrostachyum exhibited the greatest fungal species richness and variability (PCoA1 = 20.08%; PCoA2 = 8.72%). Taxonomic analysis identified Proteobacteria as the dominant bacterial phylum and Stenotrophomonas as the dominant bacterial genus. Other notable bacterial taxa included the phyla Bacteroidota and Firmicutes, and genera such as Pseudomonas, Faecalibacterium , and Bacteroides . For fungal communities, Ascomycota was the dominant phylum. Additional fungal taxa included the phylum Basidiomycota and genera Cryptococcus, Candida, and Meyerozyma. A core microbiome analysis revealed that 42 bacterial (notably Stenotrophomonas and Chryseobacterium) and 7 fungal taxa (notably Pleosporaceae and Ascomycota) were shared across all examined wrapping leaves. The identified microbial communities (e.g., Lactobacillus and Geotrichum ) encompass taxa with potential beneficial roles, such as enhancing food fermentation and potentially contributing to human gut health upon consumption of the packaged food. However, the detection of potentially pathogenic and toxigenic bacterial taxa highlights a possible public health risk associated with the use of these leaves. Further investigation into the specific functionalities of these associated bacteria and fungi is essential to maximise their beneficial applications while simultaneously mitigating potential health risks posed by harmful strains.