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Medium development and production of carotenoids and exopolysaccharides by the extremophile Rhodothermus marinus DSM16675 in glucose-based defined media

Mukti, Israt Jahan LU ; Sardari, Roya R. R. LU ; Kristjansdottir, Thordis ; Hreggvidsson, Gudmundur O and Karlsson, Eva Nordberg LU orcid (2022) In Microbial Cell Factories 21.
Abstract

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... (More)

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.

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; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Carotenoids, Glucose/metabolism, Extremophiles/metabolism, Culture Media/chemistry, Trace Elements, Reproducibility of Results, Polysaccharides, Amino Acids, Vitamins, Phosphates
in
Microbial Cell Factories
volume
21
article number
220
pages
16 pages
publisher
BioMed Central (BMC)
external identifiers
  • pmid:36274123
  • scopus:85140325508
ISSN
1475-2859
DOI
10.1186/s12934-022-01946-7
language
English
LU publication?
yes
additional info
© 2022. The Author(s).
id
57b6e1d1-2a4b-420d-92c9-63f8eeb85ac6
date added to LUP
2022-10-27 09:04:39
date last changed
2024-06-10 00:16:13
@article{57b6e1d1-2a4b-420d-92c9-63f8eeb85ac6,
  abstract     = {{<p><b>Background:</b> The marine thermophilic bacterium <i>Rhodothermus marinus</i><br>
 can degrade many polysaccharides which makes it interesting as a future<br>
 cell factory. Progress using this bacterium has, however, been hampered<br>
 by limited knowledge on media and conditions for biomass production, <br>
often resulting in low cell yields and low productivity, highlighting <br>
the need to develop conditions that allow studies of the microbe on <br>
molecular level. This study presents development of defined conditions <br>
that support growth, combined with evaluation of production of <br>
carotenoids and exopolysaccharides (EPSs) by <i>R. marinus</i> strain DSM 16675.</p><p><b>Results:</b> Two<br>
 defined media were initially prepared: one including a low addition of <br>
yeast extract (modified Wolfe’s medium) and one based on specific <br>
components (defined medium base, DMB) to which two amino acids (N and <br>
Q), were added. Cultivation trials of <i>R. marinus</i> DSM 16675 in shake flasks, resulted in maximum cell densities (OD<sub>620 nm</sub>) of 2.36 ± 0.057, cell dry weight (CDW) 1.2 ± 0.14 mg/L, total carotenoids 0.59 × 10<sup>–3</sup> mg/L,<br>
 and EPSs 1.72 ± 0.03 mg/L using 2 g/L glucose in DMB. In Wolfe’s medium<br>
 (supplemented by 0.05 g/L yeast extract and 2.5 g/L glucose), maximum <br>
OD<sub>620 nm</sub> was 2.07 ± 0.05, CDW 1.05 ± 0.07 mg/L, total carotenoids 0.39 × 10<sup>–3</sup> mg/L,<br>
 and EPSs 1.74 ± 0.2 mg/L. Growth trials at 5 g/L glucose in these media<br>
 either failed or resulted in incomplete substrate utilization. To <br>
improve reproducibility and increase substrate utilization, a screening <br>
of macroelements (e.g. phosphate) in DMB, was combined with use of trace<br>
 elements and vitamins of the modified Wolfe’s medium. The resulting <br>
defined minimal <i>R. marinus</i> medium, (DRM), allowed reproducible cultivations to a final OD<sub>620nm</sub> of 6.6 ± 0.05, CDW 2.85 ± 0.07 mg/L, a maximum specific growth rate (µ<sub>max</sub>) of 0.26 h<sup>−1</sup>, total carotenoids 0.77 × 10<sup>–3</sup> mg/L and EPSs 3.4 ± 0.17 mg/L in cultivations supplemented with up to 5 g/L glucose.</p><p><b>Conclusion:</b> A<br>
 minimal defined medium (DRM) was designed that resulted in reproducible<br>
 growth and an almost doubled formation of both total carotenoids and <br>
EPSs. Such defined conditions, are necessary for systematic studies of <br>
metabolic pathways, to determine the specific requirements for growth <br>
and fully characterize metabolite production.</p>}},
  author       = {{Mukti, Israt Jahan and Sardari, Roya R. R. and Kristjansdottir, Thordis and Hreggvidsson, Gudmundur O and Karlsson, Eva Nordberg}},
  issn         = {{1475-2859}},
  keywords     = {{Carotenoids; Glucose/metabolism; Extremophiles/metabolism; Culture Media/chemistry; Trace Elements; Reproducibility of Results; Polysaccharides; Amino Acids; Vitamins; Phosphates}},
  language     = {{eng}},
  month        = {{10}},
  publisher    = {{BioMed Central (BMC)}},
  series       = {{Microbial Cell Factories}},
  title        = {{Medium development and production of carotenoids and exopolysaccharides by the extremophile <i>Rhodothermus marinus</i> DSM16675 in glucose-based defined media}},
  url          = {{http://dx.doi.org/10.1186/s12934-022-01946-7}},
  doi          = {{10.1186/s12934-022-01946-7}},
  volume       = {{21}},
  year         = {{2022}},
}