Gutierrez-Merino, J. | Search bioRxiv

bioRxiv2021

Beehives possess their own distinct microbiomes

Honey bees use plant material to manufacture their own food. These insect pollinators visit flowers repeatedly to collect nectar and pollen, which are shared with other hive bees to produce honey and beebread. While producing these products, beehives accumulate a tremendous amount of microbes, including bacteria that derive from plants and different parts of the honey bees body. In this study, we conducted 16S rDNA metataxonomic analysis on honey and beebread samples that were collected from 15 beehives in the southeast of England in order to quantify the bacteria associated with beehives. The results highlighted that honeybee products carry a significant variety of bacterial groups that comprise bee commensals, environmental bacteria and pathogens of plants and animals. Remarkably, this bacterial diversity differs amongst the beehives, suggesting a defined fingerprint that is affected, not only by the nectar and pollen gathered from local plants, but also from other environmental sources. In summary, our results show that every hive possesses their own distinct microbiome, and that honeybee products are valuable indicators of the bacteria present in the beehives and their surrounding environment.

microbiology↗

bioRxiv2019

Beneficial bacteria activate type-I interferon production via the cytosolic sensors STING and MAVS

Type-I interferon (IFN-I) cytokines are produced by innate immune cells in response to microbial infections, cancer and autoimmune diseases. These cytokines trigger protective responses in neighbouring cells through the activation of IFN-I stimulated genes. One of the most predominant pathways associated with IFN-I production is mediated by the cytosolic sensors STING and MAVS, intracellular adaptors that become activated in the presence of microbial nucleic acids in the cytoplasm, leading to IFN-I production via TANK-binding kinase (TBK)-1 and IFN regulatory factors. However, the role of these sensors in responses induced by beneficial microbes has been relatively unexplored. Here we have screened 12 representative strains of lactic acid bacteria (LAB), a group of beneficial microbes found in fermented food and probiotic formulations worldwide, for their ability to trigger IFN-I responses. Two isolates (Lactobacillus plantarum and Pediococcus pentosaceus) induced an IFN-I production that was significantly higher that the rest, both in macrophage cell lines and human primary macrophages. This response correlated with stronger interaction with macrophages and was susceptible to phagocytosis inhibitors, suggesting bacterial internalisation. Accordingly, macrophages deficient for STING and, to a lesser extent, MAVS failed to respond to the two LAB, showing reduced TBK-1 phosphorylation and IFN-I activation. Furthermore, LAB-induced IFN-I was biologically active and resulted in expression of interferon stimulated genes, which was also STING- and MAVS-dependent. Our findings demonstrate a major role for STING in the production of IFN-I by beneficial bacteria and the existence of bacteria-specific immune signatures, which can be exploited to modulate protective responses in the host.

immunology↗