# Optimizing the Bioprocesses of Bacteriocin Production in Lacticaseibacillus paracasei HD1.7 by the “Acetate Switch”: Novel Insights into the Labor Division Between Energy Metabolism, Quorum Sensing, and Acetate

## TL;DR

This study explores how acetate influences bacteriocin production in Lacticaseibacillus paracasei HD1.7 through energy metabolism and quorum sensing.

## Contribution

The study reveals the 'acetate switch' as a regulatory mechanism linking energy metabolism and quorum sensing to optimize Paracin 1.7 production.

## Key findings

- Acetate acts as a signaling molecule regulating Paracin 1.7 via quorum sensing.
- The 'acetate switch' correlates with changes in ATP levels and NAD+/NADH ratios.
- Transcriptomic analysis shows acetate influences metabolic pathways and QS gene expression.

## Abstract

Acetate may act as a signaling molecule, regulating Paracin 1.7 production via quorum sensing (QS) in Lacticaseibacillus paracasei HD1.7. The “acetate switch” phenomenon requires mechanistic exploration to optimize Paracin 1.7 production. The “acetate switch” phenomenon delays with higher glucose levels (30 h, 36 h, and 96 h). Before the occurrence of the “acetate switch”, the ATP content increases and peaks at the “acetate switch” point and the NAD+/NADH ratio decreases, indicating energy changes. Moreover, the QS genes used for the pre-regulation of bacteriocin, such as prcKR, comCDE, were highly expressed. After the “acetate switch”, the ATP content decreased and the QS genes for the post-regulation of bacteriocin were highly expressed, such as rggs234 and sigma70-1/70-2. The “acetate switch” could act as an energy switch, regulating bacterial growth and QS genes. Before and after the “acetate switch”, some metabolic pathways were significantly altered according to the transcriptomic analysis by HD1.7 and HD1.7-Δpta. In this study, acetate was used as an input signal to regulate the two-component system, significantly influencing the bacteriocin expression system. And this study clarifies the roles of acetate, energy, and quorum sensing in promoting Paracin 1.7 production, providing a theoretical basis for optimizing the bacteriocin fermentation process of HD1.7.