A Snapshot Picture of the Fungal Composition of Bee Bread in Four Locations in Bulgaria, Differing in Anthropogenic Influence

Abstract

Information about the fungal composition of bee bread, and the fermentation processes to which the fungi contribute significantly, is rather scarce or fragmentary. In this study, we performed an NGS-based metagenomics snapshot picture study of the fungal composition of bee bread in four locations in Bulgaria during the most active honeybee foraging period at the end of June 2020. The sampling locations were chosen to differ significantly in climatic conditions, landscape, and anthropogenic pressure, and the Illumina 2 × 250 paired-end reads platform was used for amplicon metagenomics study of the ITS2 region. We found that some of the already reported canonical beneficial core fungal species were present within the studied samples. However, some fungal genera such as Monilinia, Sclerotinia, Golovinomyces, Toxicocladosporium, Pseudopithomyces, Podosphaera and Septoriella were reported for the first time among the dominant genera for a honeybee related product. Anthropogenic pressure negatively influences the fungal composition of the bee bread in two different ways—urban/industrial pressure affects the presence of pathogenic species, while agricultural pressure is reflected in a decrease of the ratio of the beneficial fungi.

Extracts of Talaromyces purpureogenus Strains from Apis mellifera Bee Bread Inhibit the Growth of Paenibacillus spp. In Vitro

“…Seasonal factors may be relevant because we found the Talaromyces strains only in spring. Other studies exploring the composition of fungi in bee bread in Europe did not find any Talaromyces species, but samples were collected in the summer [ 29 , 84 ], when the absence of Talaromyces is consistent with our results. In worker bees, the prevalence of fungi was higher in fall and winter [ 32 ].…”

“…The presence of agricultural land (such as a canola field) within the foraging range increases the risk of fungicide residues in the food stores that influence the fungal community. The negative effect of agricultural pressure and fungicide contamination on the bee bread fungal community has been confirmed by sequence-based [ 29 ] and cultivation-based analysis [ 87 ]. Our results suggest that seasonal effects and agricultural pressure determine the presence of Talaromyces in bee bread.…”

“…In contrast, less attention has been paid to the composition and function of in-hive microbial communities that colonize the bee cuticle, hive surfaces, and food stores [ 28 ]. These consist of bacteria, yeast, and several genera of filamentous fungi that form the core mycobiome of pollen and bee bread, including Aspergillus , Cladosporium, Botrytis , Penicillium , Alternaria, Mucor, and Rhizopus [ 29 ]. Fungi are important for bee nutrition because they participate in pollen fermentation and its transformation into bee bread [ 30 ].…”

Bee Bread as a Promising Source of Bioactive Molecules and Functional Properties: An Up-To-Date Review

“…Furthermore, the richness of bee bread in microorganisms can give it the properties of a probiotic product [ 53 ]. A study conducted by Dimov et al [ 54 ] showed the following fungi composition in bee bread: Cladosporium, Penicillium, Alternaria, Monilinia, Sclerotinia, Ascosphaera, Toxicocladosporium, Botrytis, Pseudopithomyces, Camerosporium, Paraconiothyrium, Podosphaera, Golovinomyces, Paraphaeosphaeria, Periconia , and Septoriella . In addition, it was found that bee bread was rich in lactic acid bacteria, such as Apilactobacilluskunkeei , Lactiplantibacillus plantarum , Fructobacillusfructosus , Levilactobacillus brevis , Lactobacillus delbrueckii , Lactobacillus musae , Lactobacillus crustorum , and Lactobacillus delbrueckii [ 54 , 55 , 56 ].…”

“… [ 60 ] Cladosporium, Penicillium, Alternaria, Monilinia, Sclerotina, Ascosphaera, Toxicocladosporium, Botrytis, Pseudopithomyces, Camerosporium, Paraconiothyrium, Podosphaera, Golovinomyces, Paraphaeosphaeria, Periconia, and Septoriella NGS-sequencing Bulgaria Four samples (not identified). [ 54 ] Apilactobacilluskunkeei, Lactiplantibacillus plantarum, Fructobacillusfructosus, Levilactobacillus brevis, and Lactobacillus delbrueckii PCR-DGGE analysis RAPD-PCR analysis Italy Twelve samples (not identified) [ 55 ] Organic acids Oxalic acid UFLC-PDA Morocco One multifloral sample (Bupleurum spinosum, Anethum graveolens, Calendula officinalis, Anacyclus, Quercus ilex, Eucalyptus, Punica granatum, and Acacia) [ 20 ] Gluconic acid, Formic acid, Lactic acid, Acetic acid, Succinic acid, Propionic acid, Butyric acid HPLC-DAD Romania One sample (not determined) [ 21 ] Vitamins Vitamin A, Vitamin E, Thiamine, andRiboflavin HPLC Malaysia One sample (not determined) [ 30 ] Vitamin C Method AOAC 967.21 Malaysia Four multifloral samples ( Mi...…”