Biomedical Engineering Reference
In-Depth Information
8.
Biotechnol Bioeng
. 2010 Dec 1;
107(5):802-13. Biomass
production of hairy roots of
Artemisia annua
and
Arachis
hypogaea
in a scaled-up mist
bioreactor. Sivakumar G, Liu C,
Towler MJ, Weathers PJ.
Arkansas Biosciences Institute,
Arkansas State University,
Jonesboro, AR 72467.
Hairy roots have the potential to produce a variety of
valuable small and large molecules. The mist reactor
is a gas-phase bioreactor that has shown promise for
low-cost culture of hairy roots. Using a newer,
disposable culture bag, mist reactor performance was
studied with two species,
Artemisia annua L
. and
Arachis hypogaea
(peanut), at scales from 1 to 20 L.
Both species of hairy roots when grown at 1 L in the
mist reactor showed growth rates that surpassed that
in shake flasks. From the information gleaned at 1 L,
Arachis was scaled further to 4 and then 20 L.
Misting duty cycle, culture medium flow rate, and
timing of when flow rate was increased were varied.
In a mist reactor, increasing the misting cycle or
increasing the medium flow rate are the two
alternatives for increased delivery of liquid nutrients
to the root bed. Longer misting cycles beyond 2-3
min were generally deemed detrimental to growth.
On the other hand, increasing the medium flow rate
to the sonic nozzle, especially during the exponential
phase of root growth (weeks 2-3), was the most
important factor for increasing growth rates and
biomass yields in the 20 L reactors.
A. hypogaea
growth in 1 L reactors was µ = 0.173 day(-1) with a
biomass yield of 12.75 g DW L(-1). This exceeded that
in shake flasks at µ = 0.166 day(-1) and 11.10
g DW L(-1). Best growth rate and biomass yield at 20
L was µ = 0.147 and 7.77 g DW L(-1), which was
mainly achieved when medium flow rate delivery
was increased. The mist deposition model was
further evaluated using this newer reactor design,
and when the apparent thickness of roots (+hairs)
was taken into account, the empirical data correlated
with model predictions. Together these results
establish the most important conditions to explore
for future optimization of the mist bioreactor for the
culture of hairy roots.
