PNNL-13501 - Pacific Northwest National Laboratory

Figure 1. Two different glucose fermentation setups for
aeration/agitation: 500-mL blubbler flasks (top), and 250mL
baffled shaker flasks (bottom)
Biomass (g/mL/d)
0.0004
0.00035
0.0003
0.00025
0.0002
0.00015
0.0001
0.00005
Change in Biomass over Time for Fungal Strain 13
250 m l Experim ent"
40 m L Experim ent"
0
0 1 2 3 4 5
Time in Days
Figure 2. Comparison of biomass for fungal strain 13 using
two different fermentation methods
The relative quantity of malonic acid in the cell-free
extract of all fungal strains tested was variable between
the two fermentation methods. Some cell-free extracts
had increased quantities of malonic acid when the baffled
flask was used, whereas other extracts showed increased
malonic acid levels when bubbler flask was used. Table 1
is a summary of relative malonic acid yield by both
fermentation methods. The yields in cultures by both
methods were low with respect to the amount of glucose
present. Therefore, estimates of malonic acid yield in
grams per liter could not be determined.
72 FY 2000 Laboratory Directed Research and Development Annual Report
Table 1. Summary of malonic acid presence in cell-free
extract of selected fungal strains
Species
Shaker
(40 mL)
Bubbler
(250 mL)
Week 1
H7 0 1
F 3 3
V 3 1,3
C 0 1
13 0 1,2
Control NM NM
Week 3
CV 0 1
X 0 1
Control 0 1
Week 4
CC-2 0 0
I 0 0
M 0 0
O 0 0
NAM 0 0
Control 0 0
Week 5
ZZZZ 0 0
HC 0 0
V8 0 0
Z 0 0
Control 0 0
Week 6
Y 0 0
V 0 0
Control 0 0
Week 7
Lp 0 0
K 0 0
0 = nondetect
1 = S (spike)
2 = SP (spike/peak)
3 = P (peak)
Control 0 0
NM = not measured
Summary and Conclusions
The relative amount of malonic acid was estimated for
20 fungal strains. The levels of malonic acid were
relatively small, typically less than 0.1 g/L. From this
data set, it does not appear that one fermentation method
is more effective than the other for increasing the yield of
malonic acid. However, overall biomass gain was slightly
higher when the baffled flasks were used. Future work
will apply methods to increase the yield of malonic acid
and may involve preconditioning of strains on glucose
and the addition of macro-and/or micronutrients to
increase the robustness of the fungal strains. The results
will form the basis for creating a process to produce
malonic acid on larger scales with significant energy
savings over those of current practices.