Microbial synthesis of β-carotene has gained more
interest as an alternative to synthetic β-carotene due
to easy extraction and high yield. The vitamin
microbial production is mainly dependent on culture
conditions and the medium compositions. In this
study, the β-carotene production by the Rhodo-
torula glutinis ASU6 (KU550702) was evaluated
under different growth conditions and nutrient
composition. Different agro-renewable wastes were
tested as carbon source for R. glutinis to obtain
maximum amount of β-carotene. Meanwhile, it is
clear that R. glutinis could grow well on acid extract
of onion peels and produced large amount of
β-carotene. Initial statistical screening using a
Plackett-Burman design showed temperature,
incubation time, fermentation type, non-treated
onion waste, KH2PO4 and L-asparagine as
significantly, influencing β-carotene production.
Response surface methodology was applied to determine the mutual interactions between these
parameters and optimal levels for β-carotene
production. The maximum value of β-carotene
production was 204.29 mg/l (7.5-fold) of value
observed as central point of the central composite
design. All the experimental data are in good agreement with predicted ones, confirming the
responsibility of the proposed empirical model in
describing β-carotene production by R. glutinis. In
the whole, the outcomes of this study support the
exploitation of onion peels through microbial
fermentation for β-carotene production.