A Potential Fungal Probiotic Aureobasidium melanogenum CK-CsC for the Western Honey Bee, Apis mellifera

Abstract

Aureobasidium melanogenum has been used as an animal feed additive for improving thehealth of pets, however, it has not yet been applied in honey bees. Here, a fungal strain CK-CsC isolated from bee bread pollen, was identified as A. melanogenum. Following characterizing CK-CsC fermentation broth, the 4-days fermentation broth (SYM medium or bee pollen) of the CK-CsC was used to feed newly emerged adult honey bees in cages under laboratory-controlled conditions for analysis of survival, gene expression of nutrient and antibacterial peptide, and gut microbiota of honey bees. It was found that the CK–CsC fermentation broth (SYM medium or bee pollen) is nontoxic to honey bees, and can regularly increase nutrient gene expression of honey bees. However, significant mortality of bees was observed after bees were fed on the supernatant liquid of the fermentation broth. Notably, this mortality can be lowered by the simultaneous consumption of bee pollen. The honey bees that were fed bee pollen exhibited more γ-Proteobacteria, Bacteriodetes, and Actinobacteria in their gut flora than did the honey bees fed only crude supernatant liquid extract. These findings indicate that A. melanogenum CK–CsC has high potential as a bee probiotic when it was fermented with bee pollen.

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

“…The only location where Cladosporium is in second place is Kalina (15% of the OTUs counts), where the first place was occupied by members of the Toxicocladosporium genus (24% of the OTUs counts). This filamentous fungus has been reported previously to be one of the predominant genera within corbicular pollen and bee bread [9][10][11]13]. Its predominance within the core microbiota could be explained by its ability to secrete organic acids which preserve the collected pollen, by the secretion of extracellular enzymes which raise the nutritional value of the pollen [13], as well as by inhibiting pathogenic bacteria and fungi, for example, Ascoshpaera apis [10].…”

“…However, they are also members of the core bees-related genera. Spores of the genus have been found in pollen [11] and honey [46], but they have also been reported to have a beneficial effect on the development of worker bees [51], and also have a nutritional value [13].…”

“…Even though bee bread fungal microbiota is strongly influenced by seasonal and ecological factors, some "core" fungal genera have been identified within the pollen and bee bread-Cladosporium, Mucor, Alternaria, Botrytis, Penicillium, Aspergillus and Rhizopus [11,12]. Many of these have an ambiguous nature acting as probiotics [13] and/or shaping the bees' health and fitness [14] but also being producers of mycotoxins [15,16]. However, available data suggest that their positive influence overcomes the negative one, at least for the beehives [13,17,18].…”

“…Many of these have an ambiguous nature acting as probiotics [13] and/or shaping the bees' health and fitness [14] but also being producers of mycotoxins [15,16]. However, available data suggest that their positive influence overcomes the negative one, at least for the beehives [13,17,18].…”

“…available data suggest that their positive influence overcomes the negative one, at least for the beehives [13,17,18].…”