Fixed Volume Fed-batch Reactors
In this type of fed-batch reactor, the limiting substrate is fed without diluting the culture. The culture volume can also be maintained practically constant by feeding the growth-limiting substrate in undiluted form, for example, as a solid, or a very concentrated liquid. Alternatively, the substrate can be added by dialysis without affecting the culture volume.
In a fixed volume cyclic fed-batch culture a periodic withdrawal of a portion of the culture is required. The residual culture is then used as the starting point for a further fed-batch process. Then it is diluted to the original volume with sterile water or medium containing the feed substrate. The dilution decreases the biomass concentration and results in an increase in the specific growth rate. Subsequently,
|
Biomass |
Pretreatment and Saccharification |
Fermentation type/Microorganism |
Reference |
|
Corncobs |
1% (v/v) sulfuric acid for 30 min at a solid-to-liquid ratio of 1:10 |
Saccharomyces cerevisiae BCRC 21812 |
[6] |
|
Cellulose |
Clostridium thermocellum LQRI |
Cocultivation of cellulolytic and sac — charolytic microbial populations saccharolytic Thermoanaerobacter pseude — thanolicus strain X514 |
[7] |
|
Wild sugarcane variety, Saccharum spontaneum |
Three different hydrolysis experiments using dilute sulfuric acid, dilute sodium hydroxide, and aqueous ammonia treatments followed by enzymatic hydrolysis |
Pichia stipitis NCIM3498 |
[8] |
|
Spruce |
Dilute-acid |
Saccharomyces cerevisiae with no prior detoxification |
[9] |
|
Corn stover |
Steam explosion |
Simultaneous saccharification and fermentation |
[10] |
|
344 Handbook of Cellulosic Ethanol |
as feeding continues, the growth rate will decline gradually as biomass increases and approaches the maximum sustainable in the vessel once more, at which point the culture may be diluted again.