PRJNA836348
Production of the terpenoid helvolic acid benefit Metarhizium robertsii to combat the Drosophila body surface microbiotas
The entomopathogenic fungus Metarhizium robertsii is able to produce the antibacterial nortriterpenoid helvolic acid. After the deletion of the core terpene cyclase gene MrHelA, the wild type and mutant strains were used to treat the males of Drosophila melanogaster W1118 line collected three days post eclosion. The flies were starved for two days by feeding with 5% glucose and then anesthetized on ice prior to being immersed in the spore suspensions in 0.05% Tween 20 for 30 sec. The flies only treated with 0.05% Tween 20 were used as mock controls. The treated insects were kept at a high moisture level for 16 h at 25 degree C. For each strain treatment, ten flies each were collected and vortexed in a centrifuge tube with 1 ml PBS buffer for 1 min. The washing buffers were collected and concentrated to 100 microliter by centrifugation. Every four concentrates were pulled together and concentrated to 100 microliter again as one biological repeat. There were eight independent repeats for each strain sample and mock control. DNA was extracted and amplified with the 16S V4 primers 515F and 806R. The products were used to generate the amplicon libraries for sequencing with the Illumina Miseq system.