Anode-assisted electro-fermentation with Bacillus subtilis under oxygen-limited conditions

Table 1 Different cultivation vessels and operational parameters tested in this study

Brief name	Condition tested	Gas supplied	Liquid volume	Initial OD (600 nm)	Run time	Addition of 1.5 mM K₃Fe(CN)₆
Shake flask	Aerobic	O₂, freely diffused	20 mL	0.1	12 h	No
Serum flask	Anaerobic amended with 23.5 mM sodium nitrate	N₂ headspace, 1.4 atm	96 mL	0.5	170 h	No
Serum flask [+ 4% O₂]	Oxygen-limited amended with 23.5 mM sodium nitrate and 4% O₂	N₂ + O₂ headspace, 1 atm	96 mL	0.4	170 h	No
Anaerobic AP	Anaerobic BES, + 0.7 V	N₂ continuously purged headspace	300 mL (anolyte)	0.7	170 h	Yes
Anaerobic OC	Anaerobic BES, open-circuit control	N₂ continuously purged headspace	300 mL (anolyte)	0.7	170 h	Yes
Moderate AP	Oxygen-limited BES, aerated at 30 mL/min + 0.7 V	O₂, continuously purged medium	300 mL (anolyte)	0.5	66–75 h	Yes
Moderate OC	Oxygen-limited open-circuit control, aerated at 30 mL/min	O₂, continuously purged medium	300 mL (anolyte)	0.4	66–75 h	Yes
Limited AP	Oxygen-limited BES aerated at 5 mL/min, + 0.7 V	O₂, continuously purged medium	300 mL (anolyte)	0.6	170 h	Yes
Limited OC	Oxygen-limited open-circuit control, aerated at 5 mL/min	O₂, continuously purged medium	300 mL (anolyte)	0.6	170 h	Yes
Limited AP [-]	Oxygen-limited BES aerated at 5 mL/min, + 0.7 V	O₂, continuously purged medium	300 mL (anolyte)	0.6	170 h	No
Limited OC [-]	Oxygen-limited open-circuit control, aerated at 5 mL/min	O₂, continuously purged medium	300 mL (anolyte)	0.6	170 h	No

ISSN: 2731-3654