cerevisiae strains, LBG H620 and DSM 2155, with different floatabilities were
investigated with regard to their properties [122, 123].
The yeast cells were cultivated in continuous operation mode under carbon
(C)-limited, phosphorous (P)-limited and nitrogen (N)-limited growth conditions. Cell and protein concentrations in feed, foam and residue liquids as well
as the enrichment E * and separation S* factors were evaluated at different
dilution rates (D). The concentration of LBG H620 cells diminished and that of
DSM 2155 cells enriched in the foam. The highest enrichment factors E * in DSM
2155 cells were obtained if they were cultivated under strong P-limitation at a
low dilution rate. Fairly high E * values were attained under C-limitation, but
under N-limitation the E * values were meager with low values of D. At the
beginning of the continuous cultivations, all of the cells were recovered, but
with advanced time the degree of recovery and cell concentration and enrichment factor diminished. The cellular properties of the yeasts were characterized
by flow cytometry, measurement of surface properties, hydrophobicity, electrophoretic mobility, and chemical composition (using X-ray photoelectron spectroscopy, XPS).
The protein content in a medium of DSM 2155 yeast was always higher than
that of the LBG yeast. There was no significant difference between the lipid contents of these two strains. The average size of the cells in the liquid residue was
larger than the size of the cells in the foam. This can be explained by the obRecovery of Proteins and Microorganisms from Cultivation Media by Foam Flotation
227
Table 7. Flotation performances of various microorganisms [120]
Microorganism
Medium
C* P
C* S
C* R
E*
S*
operation
(g l –1 ) (g l –1 ) (g l –1 )
Clostridium acetobutylicum complex
1.6
1.6
1.7
1.0
1.0
C. acetobutylicum
synthetic
0.65
4.0
0.5
6.12
16.0
Acetobacter peroxidans
0.85
0.83
Klebsiella pneumoniae
0.78
0.75
Escherichia coli
synthetic
3.0
22.5
2.25
7.5
10.0
Rhodococcus erythropolis
batch
2.5
25.5
0.06
10.2
396
R. erythropolis
continuous
4.4
27.0
0.91
6
29.5
Candida intermedia+s
O 2 -limited,
11.9
13
t F < 7 h
C. intermedia
O 2 -limited,
3.5
140
0.3
40
425
t F < 7 h
Hansenula polymorpha
synthetic
3.5
70
0.00
20
∞
H. polymorpha
synthetic
0.6
72
0.00 120
∞
Candida boidinii
synth.
2.5
3.0
11.5
1.2
1.95
methanol
C. boidinii
synth. glucose 4.2
10.9
1.03
2.6
10.5
Saccharomyces cerevisiae
complex
10–20 350–545
S. cerevisiae
synthetic
26–45 ∞
investigated with regard to their properties [122, 123].
The yeast cells were cultivated in continuous operation mode under carbon
(C)-limited, phosphorous (P)-limited and nitrogen (N)-limited growth conditions. Cell and protein concentrations in feed, foam and residue liquids as well
as the enrichment E * and separation S* factors were evaluated at different
dilution rates (D). The concentration of LBG H620 cells diminished and that of
DSM 2155 cells enriched in the foam. The highest enrichment factors E * in DSM
2155 cells were obtained if they were cultivated under strong P-limitation at a
low dilution rate. Fairly high E * values were attained under C-limitation, but
under N-limitation the E * values were meager with low values of D. At the
beginning of the continuous cultivations, all of the cells were recovered, but
with advanced time the degree of recovery and cell concentration and enrichment factor diminished. The cellular properties of the yeasts were characterized
by flow cytometry, measurement of surface properties, hydrophobicity, electrophoretic mobility, and chemical composition (using X-ray photoelectron spectroscopy, XPS).
The protein content in a medium of DSM 2155 yeast was always higher than
that of the LBG yeast. There was no significant difference between the lipid contents of these two strains. The average size of the cells in the liquid residue was
larger than the size of the cells in the foam. This can be explained by the obRecovery of Proteins and Microorganisms from Cultivation Media by Foam Flotation
227
Table 7. Flotation performances of various microorganisms [120]
Microorganism
Medium
C* P
C* S
C* R
E*
S*
operation
(g l –1 ) (g l –1 ) (g l –1 )
Clostridium acetobutylicum complex
1.6
1.6
1.7
1.0
1.0
C. acetobutylicum
synthetic
0.65
4.0
0.5
6.12
16.0
Acetobacter peroxidans
0.85
0.83
Klebsiella pneumoniae
0.78
0.75
Escherichia coli
synthetic
3.0
22.5
2.25
7.5
10.0
Rhodococcus erythropolis
batch
2.5
25.5
0.06
10.2
396
R. erythropolis
continuous
4.4
27.0
0.91
6
29.5
Candida intermedia+s
O 2 -limited,
11.9
13
t F < 7 h
C. intermedia
O 2 -limited,
3.5
140
0.3
40
425
t F < 7 h
Hansenula polymorpha
synthetic
3.5
70
0.00
20
∞
H. polymorpha
synthetic
0.6
72
0.00 120
∞
Candida boidinii
synth.
2.5
3.0
11.5
1.2
1.95
methanol
C. boidinii
synth. glucose 4.2
10.9
1.03
2.6
10.5
Saccharomyces cerevisiae
complex
10–20 350–545
S. cerevisiae
synthetic
26–45 ∞