High density cultivation of two strains of iron-oxidizing bacteria throughreduction of ferric iron by intermittent electrolysis

Electrolytic cultivation was applied to Leptospirillum ferrooxidans strains P3A and CF27, which use ferrous iron to respire aerobically. Ferrous iron was supplied to the bacteria by intermittent electrolytic reduction of ferr ic iron as electron shuttle using an electrode. The yield of L. ferrooxidan s and strain CF27 reached 20- and 50-fold, respectively, higher density tha n were achievable yields without electrolysis. The time required to obtain high density depended not on the growth ratio, but rather on the original g rowth rate of each strain. (C) 2000 John Wiley & Sons, Inc.