TY - JOUR
T1 - Medium development and production of carotenoids and exopolysaccharides by the extremophile Rhodothermus marinus DSM16675 in glucose-based defined media
AU - Mukti, Israt Jahan
AU - Sardari, Roya R. R.
AU - Kristjansdottir, Thordis
AU - Hreggvidsson, Gudmundur O
AU - Karlsson, Eva Nordberg
N1 - © 2022. The Author(s).
PY - 2022/10/23
Y1 - 2022/10/23
N2 - Background: The marine thermophilic bacterium Rhodothermus marinus
can degrade many polysaccharides which makes it interesting as a future
cell factory. Progress using this bacterium has, however, been hampered
by limited knowledge on media and conditions for biomass production,
often resulting in low cell yields and low productivity, highlighting
the need to develop conditions that allow studies of the microbe on
molecular level. This study presents development of defined conditions
that support growth, combined with evaluation of production of
carotenoids and exopolysaccharides (EPSs) by R. marinus strain DSM 16675.Results: Two
defined media were initially prepared: one including a low addition of
yeast extract (modified Wolfe’s medium) and one based on specific
components (defined medium base, DMB) to which two amino acids (N and
Q), were added. Cultivation trials of R. marinus DSM 16675 in shake flasks, resulted in maximum cell densities (OD620 nm) of 2.36 ± 0.057, cell dry weight (CDW) 1.2 ± 0.14 mg/L, total carotenoids 0.59 × 10–3 mg/L,
and EPSs 1.72 ± 0.03 mg/L using 2 g/L glucose in DMB. In Wolfe’s medium
(supplemented by 0.05 g/L yeast extract and 2.5 g/L glucose), maximum
OD620 nm was 2.07 ± 0.05, CDW 1.05 ± 0.07 mg/L, total carotenoids 0.39 × 10–3 mg/L,
and EPSs 1.74 ± 0.2 mg/L. Growth trials at 5 g/L glucose in these media
either failed or resulted in incomplete substrate utilization. To
improve reproducibility and increase substrate utilization, a screening
of macroelements (e.g. phosphate) in DMB, was combined with use of trace
elements and vitamins of the modified Wolfe’s medium. The resulting
defined minimal R. marinus medium, (DRM), allowed reproducible cultivations to a final OD620nm of 6.6 ± 0.05, CDW 2.85 ± 0.07 mg/L, a maximum specific growth rate (µmax) of 0.26 h−1, total carotenoids 0.77 × 10–3 mg/L and EPSs 3.4 ± 0.17 mg/L in cultivations supplemented with up to 5 g/L glucose.Conclusion: A
minimal defined medium (DRM) was designed that resulted in reproducible
growth and an almost doubled formation of both total carotenoids and
EPSs. Such defined conditions, are necessary for systematic studies of
metabolic pathways, to determine the specific requirements for growth
and fully characterize metabolite production.
AB - Background: The marine thermophilic bacterium Rhodothermus marinus
can degrade many polysaccharides which makes it interesting as a future
cell factory. Progress using this bacterium has, however, been hampered
by limited knowledge on media and conditions for biomass production,
often resulting in low cell yields and low productivity, highlighting
the need to develop conditions that allow studies of the microbe on
molecular level. This study presents development of defined conditions
that support growth, combined with evaluation of production of
carotenoids and exopolysaccharides (EPSs) by R. marinus strain DSM 16675.Results: Two
defined media were initially prepared: one including a low addition of
yeast extract (modified Wolfe’s medium) and one based on specific
components (defined medium base, DMB) to which two amino acids (N and
Q), were added. Cultivation trials of R. marinus DSM 16675 in shake flasks, resulted in maximum cell densities (OD620 nm) of 2.36 ± 0.057, cell dry weight (CDW) 1.2 ± 0.14 mg/L, total carotenoids 0.59 × 10–3 mg/L,
and EPSs 1.72 ± 0.03 mg/L using 2 g/L glucose in DMB. In Wolfe’s medium
(supplemented by 0.05 g/L yeast extract and 2.5 g/L glucose), maximum
OD620 nm was 2.07 ± 0.05, CDW 1.05 ± 0.07 mg/L, total carotenoids 0.39 × 10–3 mg/L,
and EPSs 1.74 ± 0.2 mg/L. Growth trials at 5 g/L glucose in these media
either failed or resulted in incomplete substrate utilization. To
improve reproducibility and increase substrate utilization, a screening
of macroelements (e.g. phosphate) in DMB, was combined with use of trace
elements and vitamins of the modified Wolfe’s medium. The resulting
defined minimal R. marinus medium, (DRM), allowed reproducible cultivations to a final OD620nm of 6.6 ± 0.05, CDW 2.85 ± 0.07 mg/L, a maximum specific growth rate (µmax) of 0.26 h−1, total carotenoids 0.77 × 10–3 mg/L and EPSs 3.4 ± 0.17 mg/L in cultivations supplemented with up to 5 g/L glucose.Conclusion: A
minimal defined medium (DRM) was designed that resulted in reproducible
growth and an almost doubled formation of both total carotenoids and
EPSs. Such defined conditions, are necessary for systematic studies of
metabolic pathways, to determine the specific requirements for growth
and fully characterize metabolite production.
KW - Carotenoids
KW - Glucose/metabolism
KW - Extremophiles/metabolism
KW - Culture Media/chemistry
KW - Trace Elements
KW - Reproducibility of Results
KW - Polysaccharides
KW - Amino Acids
KW - Vitamins
KW - Phosphates
UR - https://doi.org/10.1186/s12934-023-02048-8
U2 - 10.1186/s12934-022-01946-7
DO - 10.1186/s12934-022-01946-7
M3 - Article
C2 - 36274123
SN - 1475-2859
VL - 21
JO - Microbial Cell Factories
JF - Microbial Cell Factories
M1 - 220
ER -
