# Genome-Driven Insights into Lactococcus sp. KTH0-1S Highlights Its Biotechnological Potential as a Cell Factory

## TL;DR

A new Lactococcus strain is shown to be a safe and efficient microbial host for producing valuable proteins, with potential as a probiotic and in biotechnology.

## Contribution

Lactococcus sp. KTH0-1S is identified as a novel, safe, and versatile microbial cell factory with auto-induction properties and the ability to use agricultural by-products.

## Key findings

- Lactococcus sp. KTH0-1S naturally produces nisin and has auto-induction properties for protein expression.
- The strain is genetically safe, with no antimicrobial resistance or virulence genes.
- It can utilize diverse sugars and has probiotic traits like stress tolerance and biofilm formation.

## Abstract

This study investigates the bacterial strain Lactococcus sp. KTH0-1S as a potential alternative expression host and microbial cell factory. We confirmed that it is safe, carrying no harmful genes, and possesses traits that support survival in the digestive system and fermentation environments. Uniquely, the strain naturally produces nisin, which can act as an inducer for the NICE system, providing auto-induction properties that offer a simpler and more cost-effective alternative to conventional hosts. The strain also grows efficiently with nutrient support and can utilize a variety of sugars, including those from agricultural by-products. These characteristics make Lactococcus sp. KTH0-1S a promising next-generation probiotic and a versatile, food-grade microbial host for producing valuable proteins.

The safety, genetic distinctiveness, and functional capabilities of Lactococcus sp. KTH0-1S, a strain isolated from Thai fermented shrimp (Kung-Som), were investigated to assess its potential as a next-generation probiotic and microbial cell factory. Whole-genome sequencing and multilocus sequence typing (MLST) analysis revealed that Lactococcus sp. KTH0-1S is a novel, phylogenetically distinct strain within the Lactococcus genus. Comprehensive in silico safety evaluation confirmed the absence of antimicrobial resistance genes and major virulence factors, supporting its suitability for food-grade applications. The genome encodes multiple probiotic-relevant traits, including stress tolerance (e.g., dnaK, clpP), adhesion and biofilm formation (e.g., gapA, luxS, glf2), and nutrient acquisition genes, enabling adaptation to gastrointestinal and fermentation environments. Notably, Lactococcus sp. KTH0-1S harbors a chromosomally encoded nisin Z biosynthesis gene cluster with auto-induction capability, providing a self-regulated and stable alternative to conventional plasmid-based NICE systems in Lactococcus lactis. The strain also exhibits nisin immunity, allowing tolerance to high nisin concentrations, thus supporting robust protein production. Genomic evidence and phenotypic assays confirmed a functional respiration metabolism activated by heme supplementation, enhancing biomass yield and culture stability. Furthermore, the presence of diverse CAZyme families (GHs, GTs, CEs) enables utilization of various carbohydrate substrates, including lignocellulosic and starchy agro-industrial residues. These properties collectively underscore Lactococcus sp. KTH0-1S as a safe, stable, and metabolically versatile candidate for probiotic applications and as a cost-effective, food-grade expression host for biotechnological production.