Biofortification of green seaweed Ulva with Vitamin B12 using Lacticaseibacillus rhamnosus and Lactococcus lactis

One of the main causes of Vitamin B12 deficiency is insufficient dietary intake, especially among vegetarians and vegans. Seaweeds are emerging as sustainable biomass for producing value added products, including nutritionally enriched supplements. This study investigates the biofortification of green seaweed Ulva sp. with Vitamin B12 via co-fermentation using Lacticaseibacillus rhamnosus and Lactococcus lactis , aiming to develop a probiotic supplement. Ulva sp. was harvested from Goan shores, and the bacterial strains were obtained from cheese and cultivated for use in fermentation. The rationale behind this study was to integrate the de novo synthesis of Vitamin B12 with the conversion of Vitamin B2 into 5,6-dimethylbenzimidazole (DMB), leading to higher production of Vitamin B12, with the BluB enzyme serving as the key connecting factor. Vitamin B12 in fermented Ulva sp. was quantified using HPLC with a C18 column at 361 nm, with acetonitrile and water as the mobile phase. The highest concentration was observed after 72 hours of fermentation, reaching 19.6 μg/mL, approximately five times higher than the control. These findings highlight the potential of Ulva sp. as a substrate for Vitamin B12 production through bacterial fermentation and its promising application as a probiotic supplement.