硝化细菌的分离鉴定

应用硝化细菌选择性培养基,从南京的土壤和水体中筛选到6株硝化细菌,包括3株亚硝化菌和3株硝化菌,对其生理生化特性、温度敏感性、耐盐性、抗生素抗性、及硝化能力等生物学特性进行了测定。结果表明,6株细菌均为G-,菌体杆状或球状。生长缓慢,培养120 h以后才进入对数生长期,5 d左右形成菌落。最适生长温度为25~30℃。耐受偏碱环境。不耐盐,6株菌都能耐受的盐浓度范围是0.05%~0.3%。通气量对该菌的生长没有太大影响。6株菌株对不同的抗生素具有抗性。其中,菌株J2的抗药谱最窄,只抗卡那霉素。6株菌只能在以碳酸钠或者碳酸氢钠为唯一碳源、以硫酸铵或者亚硝酸盐为唯一氮源的培养基上生长良好。菌株硝化能力不同,其中菌株J2硝化能力较强,在基础培养基中200 h,该菌转化NO2-42%左右,可以作为降解鱼塘中和饲料中亚硝酸盐的硝化菌候选株。

Isolation and identification of nitrobacteria

Six strains of nitrobacteria,which can use ammonium or nitrite as its nitrogen source,were screened by the selective culture medium from the soils and water in Nanjing.The physiological and biochemical characteristics,such as salt tolerance and antibiotic resistance,were tested.The results showed that these nitrobacteria were G-,thalli as a pole or globosity.They entered logarithm growth period after 120 h and clones were formed after five days.The proper temperature was 25~30 ℃.They were tolerated to alkali medium but not high salt.The tolerable concentration of salt in basic medium was 0.05%～0.3%.The aerated ratio had no significant influence on its growth.Six strains had different antibiotic resistance and the antibiotic resistance of strain J2 was the narrowest with only resistance to Kanamycin.They grew well only in medium with sodium carbonate or sodium bicarbonate as unique carbon resource and vitriol ammonium or sodium nitrite as unique nitrogen resource.They also had different nitrifying ability.The nitrification ratio of strain J2 was the highest as 42% when incubated in basic medium for 200 h,which was hopful to be the candidate strain as additives for aquiculture and feed.