# Screening of Functional Properties of Lactic Acid Bacteria Isolated from Animal Rennets and Their Associated Cheeses and Whey

## TL;DR

This study explores lactic acid bacteria from traditional Romanian sheep dairy products, finding diverse strains with potential for food fermentation and functional traits.

## Contribution

The study identifies novel lactic acid bacteria strains with functional properties from traditional Romanian dairy ecosystems.

## Key findings

- 63 unique lactic acid bacteria strains were identified across nine genera, with high diversity in rennet and whey samples.
- Most strains exhibited multiple functional genes and strong antibacterial activity against pathogens.
- Exopolysaccharide production was confirmed in two strains, with yield influenced by growth medium and sucrose.

## Abstract

This study investigated the diversity and functional potential of lactic acid bacteria isolated from traditional lamb rennet, cheese, and whey collected from seven artisanal sheep farms in southern Romania. A total of 31 samples were analyzed, yielding 118 Gram-positive, catalase-negative isolates. Following dereplication by rep-PCR and 16S rRNA gene sequencing, 63 unique strains were identified across nine genera, with Lactiplantibacillus, Lactococcus, and Leuconostoc being the most prevalent. Strain distribution varied by sample type and manufacturer, with rennet and whey showing greater species diversity than cheese. Technological characterization showed strain-dependent differences in acidification and growth in cow’s and goat’s milk. Genetic screening revealed a high prevalence of functional genes such as ribA, gad, and α-amy, while genes associated with bacteriocin (nisA, pln) and folate (folK) production were less common. Most strains carried multiple functional genes, indicating a genetic potential for diverse functional traits. Antibacterial activity assays demonstrated that nearly all strains inhibited at least three indicator pathogens, with ten strains, particularly Lactiplantibacillus plantarum and Lactococcus lactis strains, exhibiting strong inhibitory effects. Bacteriocin production was confirmed for three Lact. lactis strains. Exopolysaccharide (EPS) production was confirmed in two strains, with yields varying by growth medium and sucrose supplementation. Overall, the results underscore the rich microbial diversity and promising biotechnological potential of LAB from traditional Romanian dairy ecosystems, supporting their use in food fermentation and functional product development.