Uncovering Antimicrobial Peptide from Zophobas atratus Using Transcriptome Analysis

Zophobas atratus which is also referred as giant meal worm, belongs to the largest darkling beetle family. The rich protein and fat content in the giant meal worm made it as excellent protein source in pet feed and thus instigated the commercial rearing. Insect antimicrobial peptides (AMPs) have therapeutic potential with wide range of activity against bacteria, fungus, parasites, and viruses. However, there is a lack of study of AMPs from Zophobas atratus . We have immunized the giant meal worm with Escherichia coli, Staphylococcus aureus, Candida albicans and total RNA was isolated and sequenced. De novo transcriptome assembly and functional annotations was done. The AMPs were predicted using in silico pipeline from transcriptome data. A total of 355,771,565 raw reads with 26.6 gigabytes was obtained. After trimming and low-quality sequences removal, 328,196,384 (92.2%) total clean reads was obtained. A total of 47,635 unigenes were assembled with the average length of 1109 bp. AMP pipeline predicted a total of 752 peptides of which 177 were novel AMPs all of which are non-allergens. Based on the α-helix secondary structure requirement for higher efficiency 14 peptides were synthesized and tested in vitro to determine the minimum inhibitory concentrations. Eventually, the peptides Za 7, Za 15, Za 22 were selected as the prime candidates for the development of antimicrobial agents and none of them showed hemolytic activity up to 100 μg/mL. Our data provides an insight in Zophobas atratus transcriptome derived AMPs and understanding its antimicrobial activity.