As shown in Table 1, cell growth, residual nitrate and nitrite, and glucose are shown after 3 d culture when the glucose was almost consumed in the control experiment (no addition of PVA and boric acid). In the PVA added experiments, a similar level of nitrite accumulation (36.9-67.0mg/l) was observed as in the resting cells, however, no growth was observed in the boric acidadded experiments due to the long-term contact of cells with boric acid.