Identification and characterisation of β-carotene and retinol-producing commensal probiotic bacteria from liver, intestine and rumen tissues of grass-fed cattle.

We hypothesised and investigated whether commensal probiotic bacteria from bovine organs are capable of synthesising β-carotene and retinol. A total of 111 potentially probiotic bacteria were isolated from the liver (β-carotene storage site), intestine (β-carotene bioconversion site) and rumen (β-carotene absorption site) tissues. Among these strains, 33 were screened based on vitamin A biosynthesis capability using UV spectroscopy and identified through matrix-assisted laser desorption/ionisation coupled with time-of-flight mass spectrometry analysis. Four Lactiplantibacillus plantarum (22.82 ± 1.85 to 111.95 ± 3.10 μg β-carotene g-1 dry cell weight) and one Escherichia coli (44.77 ± 2.08 μg β-carotene g-1 dry cell weight) strains with higher β-carotene and or retinol production capacity were further quantified through ultra (high) performance liquid chromatography-quadrupole-time of flight mass spectrometer. Lactiplantibacillus plantarum (VLL1) of liver origin showed good viability in gastric acid (pH 2.0) and bile salts (0.3%) and better tolerance in other probiotic properties. Hence, this study shows the β-carotene producing Lactiplantibacillus strains from the bovine origin as a potential source of vitamin A biofortification. Perhaps this study also establishes that the gut-friendly property of these probiotic strains with metabolic machinery for bioconversion of β-carotene to retinoids will be useful in eradicating vitamin A deficiency through probiotic therapy.