Each fed-batch operation began as a batch operation as above
and was switched to the fed-batch mode at 24 h when foaming was
observed Three feeding strategies were tested: a pH-stat operation,
a foaming-dependent feeding and specific growth rate control feeding Foaming was suppressed by adding palm oil with each feeding
as an alternative to the commercial antifoam agents All culture
conditions were as previously specified for the batch operation.
The agitation speed remained fixed at 600 rpm in all experiments
In pH-statfeeding,the automatic pH control system ofthe batch
operation was switched off.The limiting substrate (see below) was
fed when the pH rose to above 7.0 indicating a depletion of the substrate ) was
fed when the pH rose to above 7.0 indicating