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A Novel Bioflocculant Produced by Cobetia marina MCCC1113: Optimization of Fermentation Conditions by Response Surface Methodology and Evaluation of Flocculation Performance when Harvesting Microalgae

Siyu Zeng
Siyu Zeng
, 
Yinghua Lu
Yinghua Lu
, 
Xueshan Pan
Xueshan Pan
 and 
Xueping Ling
Xueping Ling
   | Sep 24, 2022
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Article Category: Original Paper
Published Online: Sep 24, 2022
Page range: 341 - 351
Received: Mar 14, 2022
Accepted: Jul 03, 2022
DOI: https://doi.org/10.33073/pjm-2022-030
Keywords
© 2022 Siyu Zeng et al., published by Sciendo
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Fig. 1

Temporal courses of the a) bioflocculant, b) yield of biomass, and c) consumption of glucose, under different initial levels of glucose.
Temporal courses of the a) bioflocculant, b) yield of biomass, and c) consumption of glucose, under different initial levels of glucose.

Fig. 2

a) Effects of the N source alone on the biomass and bioflocculant production, b) effect of the ratio of combined N source on the biomass and bioflocculant production. A/YE – yeast extract, B/Glu – glutamate, C – tryptone, D – ammonium nitrate, E – ammonia chloride, F – urea. The control group was cultured in a minimal medium.
a) Effects of the N source alone on the biomass and bioflocculant production, b) effect of the ratio of combined N source on the biomass and bioflocculant production. A/YE – yeast extract, B/Glu – glutamate, C – tryptone, D – ammonium nitrate, E – ammonia chloride, F – urea. The control group was cultured in a minimal medium.

Fig. 3

The change curve of pH for the a) biomass and b) bioflocculant.
The change curve of pH for the a) biomass and b) bioflocculant.

Fig. 4

RSM and contour plots illustrating the interplaying effects of various factors on bioflocculant production; a–b) glucose (g/l) and yeast extract (g/l), c–d) glucose (g/l) and glutamate (g/l), e–f) yeast extract (g/l) and glutamate (g/l).
RSM and contour plots illustrating the interplaying effects of various factors on bioflocculant production; a–b) glucose (g/l) and yeast extract (g/l), c–d) glucose (g/l) and glutamate (g/l), e–f) yeast extract (g/l) and glutamate (g/l).

Fig. 5

Temporal courses of cellular growth, bioflocculant production, and pH for C. marina MCCC1113 cultivated in the optimal medium inside a rotary shaker at 150 rpm and 28°C for 72 h.
Temporal courses of cellular growth, bioflocculant production, and pH for C. marina MCCC1113 cultivated in the optimal medium inside a rotary shaker at 150 rpm and 28°C for 72 h.

Flocculation efficiency of bioflocculant produced by C. marina on various microalgae.

Flocculation time (min) Group H. pluvialis C. vulgaris S. platensis
FE (%)
5 Treatment 32.1 – 69.4
Control 26.4 – 32.9

Effect analysis of independent variables in Plackett-Burman design.

Factor Level p Significant
–1 1
Glucose 25 35 0.0022 ++
Yeast extract 5 15 0.004 ++
Glutamate 1 3 0.025 +
Culture time 28 36 0.85 –
pH 7 8 0.861 –

ANOVA for response surface quadratic model.

Source Sum of square DF Mean square F-value Prob > F
Model 0.76   9 0.084 7.02 0.0088
Residual   0.084   7 0.012
Lack of fit   0.039   3 0.013 1.16 0.4282
Pure error   0.045   4
Cor total 0.84 16
R2 = 0.9803 R2adj = 0.7721 R2pred = 0.1744 CV = 13.53 Adeq. precision = 7.526

Determination of the optimum ratio of bioflocculant/microalgae (v/v).

FE (%) of different algae Amount of BF/algae added (%)
0 5 10 15 20
H. pluvialis 20 34.8 36.7 47.2 63
S. platensis 32.9 86.4 87.8 89.4 93.9
C. vulgaris 29.1 48.1 53.2 53.1 51.1

Box-Behnken design arrangement and responses.

RUN Glucose Yeast extract Glutamate Bioflocculant
(g/l) (g/l) (g/l) (g/l)
1 30 10 2 1.30
2 30 10 2 1.19
3 30 5 1 0.9
4 35 5 2 0.65
5 30 15 3 0.95
6 30 10 2 0.89
7 35 10 3 0.79
8 25 15 2 0.57
9 30 5 3 0.87
10 25 10 1 0.32
11 25 5 2 0.54
12 35 10 1 0.79
13 30 10 2 1.22
14 30 10 2 1.28
15 30 15 1 0.92
16 25 10 3 0.58
17 35 15 2 0.65
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