Carotenoid profile produced by Bacillus licheniformis Rt4M10 isolated from grapevines grown in high altitude and their antioxidant activity

Bacillus licheniformis (BL) strains are used for industrial production of exoenzymes, antibiotics and secondary metabolites, and also serve as probiotics. Some strains sequester heavy metals, promoting plant growth or inducing plant systemic resistance against stresses. However, investigations on the biological functions and applicability of carotenoids produced by BL had been less studied. In this study, the carotenoid profile produced by BL Rt4M10 was characterised during the accumulation period of culture and in response to diphenylamine (DPA), inhibitor of carotenoid biosynthesis. The antioxidant scavenging capacities of the carotenoid extracts against oxidative reactions inside the microbial cell and in vitro were also evaluated. Eighteen different carotenoids were analysed; their profile was modified along bacterial growth. DPA decreased carotenoid production by 70%, as well as the cells' survival in hydrogen peroxide and the antioxidant capacity, thus demonstrating the role of carotenoids from Rt4M10 in oxidative stress.