Rapid production of Pediococcus halophilus salt-tolerant cells by a cultivation method employing gradual increases in NaCl concentration using a fermentor with a microfiltration module

A new fermentation system employing gradual increases in the NaCl concentration of the culture medium was developed for the rapid production of Pediococcus halophilus NaCl-tolerant cells. A fermentation system with cross-flow filtration using a micro-filtration module allowed the continuous removal of inhibitory metabolites and complete recycling of the cells to the fermentor. By increasing the NaCl concentrations stepwise or linearly in the feeding media, cells of 8.48 or 9.86 g-dry weight per liter were obtained. The productivities of NaCl-tolerant cells per unit time in a cultivation with a stepwise or linear increase in NaCl concentration in the feeding media were 46 or 56-fold as high, repectively, as that in conventional batch cultivation.