# Bioactive peptides from Chlamydomonas reinhardtii protein hydrolysate: Identification, antimicrobial activity, and mechanism of action

## TL;DR

This study identifies antimicrobial peptides from algae that can inhibit Salmonella, offering a natural food preservation solution.

## Contribution

The first evidence of antimicrobial peptides from Chlamydomonas reinhardtii hydrolysates with experimental and computational validation.

## Key findings

- TC3–10 fraction strongly inhibits Salmonella with membrane disruption and enzyme activity reduction.
- Peptide EWRPF shows high binding affinity to Salmonella enzymes via molecular docking.
- C. reinhardtii-derived peptides are promising natural bio-preservatives.

## Abstract

Algal-derived peptides are gaining attention as potential natural bio-preservatives. This study aimed to identify antimicrobial peptides from Chlamydomonas reinhardtii protein hydrolysates against Salmonella. Protein hydrolysates were prepared, fractionated, and screened for antimicrobial activity, and the optimal fraction TC3–10 was selected for mechanisms elucidation, peptides identification and in silico analysis. Results showed that TC3–10 displayed the continuously strong inhibitory effect at the concentraction at 0.25–1 mg/mL of 40.24 ± 6.94 %-46.36 ± 3.86 %, primarily through membrane disruption, leakage of intracellular components, and Na+/K+-ATPase activity reduced. After in silico screening, peptide EWRPF showed high affinity potential against LuxS of −132.4 with six hydrogen bonds and two π-stacking, and GyraseA C-terminal domain of −133.6 with two hydrogen bonds and three π-stacking. This work provided the first evidence of antimicrobial peptides from C. reinhardtii hydrolysates, combining experimental validation with in silico prediction to highlight their potential as novel bio-preservatives.

•Strong inhibition of Salmonella spp. by C. reinhardtii protein hydrolysate (TC3–10).•Dual antibacterial mechanism: membrane disruption and enzyme activity reduction.•Peptide EWRPF with high binding affinity to Salmonella enzymes (molecular docking).•C. reinhardtii-derived peptides as promising natural food preservatives.

Strong inhibition of Salmonella spp. by C. reinhardtii protein hydrolysate (TC3–10).

Dual antibacterial mechanism: membrane disruption and enzyme activity reduction.

Peptide EWRPF with high binding affinity to Salmonella enzymes (molecular docking).

C. reinhardtii-derived peptides as promising natural food preservatives.