This study involved the generation of microbiota-free and mono-colonized honeybees to investigate the effects of different gut symbionts on Nosema ceranae infection. Honeybees were collected from an experimental apiary and kept in an incubator at 35°C with 50% humidity. The bees were fed sterile sucrose syrup and pollen, and their gut bacteria were isolated and grown on agar plates. The bees were then mono-colonized with different gut symbionts, including S. alvi M0351, B. choladohabitans W8113, and G. apicola B14384H2.
The bees were challenged with N. ceranae spores and the effects of the different gut symbionts on the infection were investigated. The results showed that the gut symbionts had different effects on the infection, with some reducing the number of N. ceranae spores in the gut. The study also involved the use of dsRNA to knockdown specific genes in N. ceranae and the use of engineered S. alvi to deliver the dsRNA to the bees. The results showed that the engineered S. alvi was able to colonize the bees and reduce the number of N. ceranae spores in the gut.