Effects of Co-Cultivating Lacticaseibacillus rhamnosus ATCC 7469 and Lactococcus lactis ATCC 11454 on Riboflavin and Nisin Production

Increasing health concerns and awareness among consumers have driven a significant shift toward healthier food choices, fuelling demand for functional foods that are minimally processed and rich in bioactive compounds. Exploiting microbial co-cultivation that can trigger quorum sensing shows tremendous potential for synthesising valuable functional food compounds. This study explored the influence of co-cultivation between two lactic acid bacteria (LAB), Lactococcus lactis (LL) and Lacticaseibacillus rhamnosus (LR) with various fermentation parameters (temperature, pH, agitation, carbon, and nitrogen sources) to determine its potential for enhancing the production of riboflavin and nisin. The highest riboflavin production (40.6 ng/mL) was attained in co-culture at 37°C with 100 rpm agitation, while the highest nisin activities for co-cultivation against Listeria monocytogenes (11.5 mm) and Bacillus subtilis (8.8 mm) were at 200 and 100 rpm, respectively. This study provides a fundmental exploration of the interspecies dynamics between L. lactis and L. rhamnosus through one-factor-at-a-time (OFAT) approach in shake-flask fermentations. These findings serve as a preliminary proof-of-concept for co-cultivation efficiency that could improve targeted compound production.