关键词: 亚硝化细菌, 亚硝化速率, 零级反应, 培养条件, 发酵液置换

Abstract: Nitrite bacteria (also known as ammonia-oxidizing bacteria) are widely distributed in nature. They exist in soil, freshwater and oceans. And nitrite bacteria play important roles in degradation of ammonia nitrogen in sewage. However, due to the difficulty in high-density fermentation of nitrite bacteria, their practical applications are limited. Based on this situation, marine sludge was collected and enrichment cultured in shake flask, and then a nitrite bacterium was isolated from marine sludge by silicone plate and washed agar plate, which was identified as Nitrosomonas sp.. The optimum culture conditions of the strain of nitrite bacterium was determined by shake-flask culture: The optimum temperature is 30℃，the optimum pH is 8.0, and the best dissolved oxygen ≥1.8 mg/L. And the optimal combination and concentration of the medium were determined by orthogonal test, which was 0.5% NaHCO3, 0.8%(NH4)2SO4, 0.1% KH2PO4, 0.01% FeSO4. At last, under the optimal culture conditions, the high-density fermentation of the nitrite bacterium was performed by using 10 L fermentor, and the fermentation broth was replaced twice during the fermentation. The nitrosation rate of the fermentation broth reached 236 mg(N-NO-2)/L·h within a 75-hour fermentation cycle, and it was 2 times higher than that of fermentation batches without fermentation broth replacement. The research showed that replacement of fermentation broth greatly improved the fermentation efficiency, and played an important role in guiding the subsequent industrial production.

Key words: nitrite bacteria, nitrosation rate, zero-order reaction, culture condition, fermentation broth replacement