Bacterial contamination control in Chlorella sorokiniana cultivation using NVC-H antimicrobial peptide.

Abstract

Microbial contamination remains a major limitation in large-scale microalgal cultivation, leading to reduced biomass productivity and process instability. In this study, synthetic antimicrobial peptide NVC-H was evaluated as a selective agent for controlling bacterial contamination in Chlorella sorokiniana cultures. The peptide exhibited antibacterial activity against both Gram-positive and Gram-negative bacteria, with strain-dependent inhibitory and bactericidal effects. At an operational concentration of 10μg mL-1, NVC-H produced a strain-dependent reduction of 2.9-5.2 log10 CFU mL-1 after 6 h. At the same concentration, C. sorokiniana maintained approximately 86% of the untreated-control OD750 after 72 h, with no significant impairment of growth. Physiological analyses, supported by metabolomic and proteomic profiling, revealed that peptide exposure induced moderate intracellular oxidative stress and time-dependent metabolic adaptation while maintaining overall culture performance. Observed responses included changes in central carbon metabolism, peptide-processing pathways, and stress-related processes, consistent with physiological adjustment to NVC-H exposure. Algal-bacterial co-culture experiments further demonstrated transient bacterial suppression in the presence of C. sorokiniana, providing proof-of-concept evidence for contamination control under mixed cultivation conditions. Overall, NVC-H represents a promising candidate for antimicrobial contamination control in microalgal cultivation, although its long-term efficacy, dosing requirements, economic feasibility, and scalability require further evaluation.