# Optimization and Stability Assessment of Monochamus alternatus Antimicrobial Peptide MaltAtt-1 in Komagataella phaffii GS115 for the Control of Pine Wood Nematode

## TL;DR

This study explores the production and stability of an antimicrobial peptide from a beetle to control a harmful nematode in pine trees.

## Contribution

The study establishes a eukaryotic expression system for MaltAtt-1 and evaluates its stability and nematocidal potential.

## Key findings

- MaltAtt-1 is a hydrophilic, stable protein with α-helices, β-folds, and irregular curls.
- Optimal fermentation conditions for MaltAtt-1 include 72 h induction time, 30 °C, pH 7.6, 2.0% methanol, and 1% initial glycerol.
- MaltAtt-1 showed 71.94% corrected mortality of B. xylophilus at 300 mg·L−1 in 3 hours.

## Abstract

MaltAtt-1 is an antimicrobial peptide isolated from Monochamus alternatus with nematocidal activity against pine wood nematode. In this study, a eukaryotic expression system based on Komagataella phaffii GS115 was established, and its secretory expression of MaltAtt-1 was realized. The basic properties and secondary and tertiary structures of the antimicrobial peptide MaltAtt-1 were identified by bioinformatics analysis. MaltAtt-1 is a hydrophilic stable protein, mainly composed of an α-helix (Hh), β-folds (Ee), and irregular curls (Cc). The optimal fermentation conditions for MaltAtt-1 were determined by a single-factor test and the Box–Behnken response surface method, including an induction time of 72 h, induction temperature of 30 °C, culture medium of pH 7.6, methanol volume fraction of 2.0%, and an initial glycerol concentration of 1%. The stability of MaltAtt-1 indicated its resistant to UV irradiation and repeated freezing and thawing, but the antibacterial activity decreased significantly under the influence of high temperature and a strong acid and base, and it decreased significantly to 1.1 cm and 0.83 cm at pH 2.0 and pH 10.0, respectively. The corrected mortality of B. xylophilus achieved 71.94% in 3 h at a concentration of 300 mg·L−1 MaltAtt-1 exposure. The results provide a theoretical basis for the antimicrobial peptide MaltAtt-1 to become a new green and efficient nematicide.