Microbiome Seminar: Irene Newton, PhD, Indiana U. | Evolution of a Protective Symbiont In Honey Bee
Evolution of a Protective Symbiont In Honey Bees by Professor Irene Newton, PhD Microbes, through their metabolic capabilities, confer upon their hosts extended functions and phenotypes. An example of this is the use of protective bacterial symbionts by insects. Many microbes specifically associate with arthropod hosts and protect brood or food from fungal fouling. We have discovered that the honey bee microbe, Bombella apis, is an antifungal symbiont. The European honey bee (A. mellifera) is used extensively to produce hive products and for crop pollination, but pervasive concerns about colony health and population decline have sparked an interest in the microbial communities that are associated with these important insects. B. apis is a recently described bacterial species that is found in important and defined niches within the honey bee hive – namely nurse hypopharyngeal glands, royal jelly, and queen digestive tracts. B. apis is unique in its ability to thrive in the presence of royal jelly, a substance that inhibits the growth of other microbes, and, interestingly, this microbe dominates the microbiome of honey bee queens. Using extensive sampling and sequencing, we identified changes in the Bombella genome in its transition to association with the honey bee. Using cocultures, fungal challenge of in vitro reared honey bees, we show that B. apis inhibits fungal growth and protects bees from fungal pathogens. In addition, we show that B. apis does this through the secretion of an antifungal metabolite, likely a polyketide, based on comparative genomics. Because this symbiont is present in key hive environments we show that Bombella apis is protective, and its production of an antifungal metabolite protects key hive resources from fungal fouling.
Evolution of a Protective Symbiont In Honey Bees by Professor Irene Newton, PhD Microbes, through their metabolic capabilities, confer upon their hosts extended functions and phenotypes. An example of this is the use of protective bacterial symbionts by insects. Many microbes specifically associate with arthropod hosts and protect brood or food from fungal fouling. We have discovered that the honey bee microbe, Bombella apis, is an antifungal symbiont. The European honey bee (A. mellifera) is used extensively to produce hive products and for crop pollination, but pervasive concerns about colony health and population decline have sparked an interest in the microbial communities that are associated with these important insects. B. apis is a recently described bacterial species that is found in important and defined niches within the honey bee hive – namely nurse hypopharyngeal glands, royal jelly, and queen digestive tracts. B. apis is unique in its ability to thrive in the presence of royal jelly, a substance that inhibits the growth of other microbes, and, interestingly, this microbe dominates the microbiome of honey bee queens. Using extensive sampling and sequencing, we identified changes in the Bombella genome in its transition to association with the honey bee. Using cocultures, fungal challenge of in vitro reared honey bees, we show that B. apis inhibits fungal growth and protects bees from fungal pathogens. In addition, we show that B. apis does this through the secretion of an antifungal metabolite, likely a polyketide, based on comparative genomics. Because this symbiont is present in key hive environments we show that Bombella apis is protective, and its production of an antifungal metabolite protects key hive resources from fungal fouling.