一株脱氮毕赤酵母Y-4的分离鉴定及其氨氮降解性能

Isolation and Identification of a Denitrifying Pichia sp. Y-4 and Its Ammonia Nitrogen Degradation Performance

关键词:  毕赤酵母  生物脱氮  异养硝化  好氧反硝化  条件优化

Key words:  Pichia sp.  biological nitrogen removal  heterotrophic nitrification  aerobic denitrification  condition optimization

摘要:

当前水体氨氮污染严重,环境治理迫在眉睫,筛选高效安全的脱氮菌株可为废水脱氮提供更多选择。本研究从沼气发酵污泥中分离筛选能降解氨氮的菌株,使用18S rDNA序列分析,对筛选出的优良菌株进行种类鉴定;同时采用单因素试验和正交试验,探究菌株最佳脱氮条件[培养温度、初始pH值、盐浓度、碳氮比(C/N)]及其硝化、反硝化能力。结果表明,分离筛选得到1株具有较强脱氮能力的野生型毕赤酵母(Pichia sp.)菌株Y-4。在试验优化后,得到菌株Y-4的最适脱氮条件:培养温度25℃,初始pH值8.0、盐浓度(氯化钠浓度)30 g/L、C/N为30。在培养24 h后菌株Y-4对亚硝酸氮(NO₂^--N)的降解率为80.50%,在培养48 h后菌株Y-4对氨氮(NH₄⁺-N)的降解率达99.92%,且在24 h内菌株Y-4的异养硝化和好氧反硝化的速率分别达到6.25和6.71 mg/(L·h),表明毕赤酵母菌株Y-4对废水氮污染处理以及生物修复具有一定的应用价值与潜力。

Abstract:

At present,ammonia nitrogen pollution in water resources is severe,and environmental governance is urgent. Screening efficient and safe denitrification strains can provide more choices for wastewater denitrification.Strains capable of degrading ammonia nitrogen were isolated and screened from biogas fermentation sludge in this study.The selected excellent strains were identified by 18S rDNA sequence analysis.At the same time,single factor and orthogonal experiments were used to explore the optimal nitrogen removal conditions [culture temperature,initial pH value,salt concentration,carbon-nitrogen ratio (C/N)] and the nitrification and denitrification capacity of the strain.The results showed that a wild-type strain of Pichia sp.Y-4 with strong denitrification ability was isolated and screened. After experimental optimization,the optimal denitrification conditions for strain Y-4 are temperature 25 ℃,initial pH value 8.0,salt concentration (NaCl concentration) 30 g/L,and carbon-nitrogen ratio 30.After 24 h of culture,the degradation rate of nitrite nitrogen (NO^-₂-N) by strain Y-4 was 80.50%,and the degradation rate of ammonia nitrogen (NH⁺₄-N) by strain Y-4 was 99.92% after 48 h of culture. The heterotrophic nitrification and aerobic denitrification rates of strain Y-4 within 24 h reached 6.25 mg/(L·h) and 6.71 mg/(L·h),respectively,indicating that Pichia sp.Y-4 has certain application value and potential for wastewater nitrogen pollution treatment and bioremediation.