Online monitoring of the redox potential in microaerobic and anaerobic Scheffersomyces stipitis fermentations

• Published in: Biotechnology letters Vol. 41; no. 6-7; pp. 753 - 761
• Main Authors: Bonan, Carolina I. D. G., Biazi, Luiz E., Santos, Samantha C., Soares, Lauren B., Dionísio, Suzane R., Hoffmam, Zaira B., Costa, Aline C., Ienczak, Jaciane L.
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01-07-2019; Springer Nature B.V
• Subjects: Anaerobiosis; Applied Microbiology; Biochemistry; Biomedical and Life Sciences; Biotechnology; Ethanol; Fermentation; Internet; Life Sciences; Microbiology; Monitoring; Original Research Paper; Oxygen transfer; Redox potential; Scheffersomyces stipitis; Substrates; Xylose; Volumetric oxygen transfer coefficients; Pentose; Oxireduction potential; Bioprocess
• ISSN: 0141-5492; 1573-6776
• DOI: 10.1007/s10529-019-02674-6

Objective
A correlation among different volumetric oxygen transfer coefficients (k
L
a) and the oxireduction potential (ORP) in batch fermentations using
Scheffersomyces stipitis
was evaluated. Experiments were performed using a mixture of xylose and glucose as the substrates.
Results
Microaerophilic condition (k
L
a = 4.9 h
−1
) have shown to be suitable when compared to complete anaerobiosis (k
L
a = 0), providing an ethanol yield and a productivity after 48 h of 64.3% and 0.45 g ethanol L
−1
h
−1
, respectively; the maximum ethanol titer obtained was 21.50 g ethanol L
−1
. Values of ORP varying from − 270 to − 330 mV resulted in high ethanol production from xylose by
S. stipitis.
Conclusions
Different ORP values were found in anaerobiosis and k
L
a 4.9 h
−1
, suggesting that for ethanol production by
S. stipitis
, values from − 270 to − 330 mV are favorable under the studied circumstances. In this ORP range, the greatest rates of xylose consumption and ethanol production were registered. ORP monitoring was demonstrated to be a suitable option for online control throughout the fermentation processes, which may provide a more efficient bioprocess operation with a very low O
2
concentration.