Fig. 4

Lys1 contributes to the suppression of Lactobacillus. A, B Quantification of midgut Lactobacillus (A) and hemolymph Lactobacillus (B) in larvae treated with dsLys1 or dsGFP. Midguts and hemolymph were collected from sixth-instar larvae at 72 h PE. C Depletion of Lys1 in the midgut at 48 and 72 h post-dsLys1 injection (hpi) validated by RT-qPCR. D Expression and purification of Lys1 mature peptide (Lys1). Lanes 1 and 2, crude protein extracts from bacteria (carrying the Lys1-pET32a plasmid) before (lane 1) and after (lane 2) IPTG induction. Lane 3, purified rLys1 protein. Lane 4, purified rLys1 cleaved by enterokinase. The two bands represent rTrx and Lys1. Lane 5, purified Lys1. E Representative MRS agar plates showing L. plantarum colonies after each treatment. L. plantarum were incubated with Lys1 or BSA at 25°C with agitation for 1 h, followed by spreading the mixture on MRS agar plates. F The number of L. plantarum colonies for each treatment was determined. Bacterial growth was exhibited as the ratio of viable colonies against BSA controls. Statistical differences were analyzed using Student’s t test (*p < 0.05)