研究论文 正式出版 版本 2 Vol 10 (5) : 487-495 2019
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两株氨化菌的筛选及降解效果初步研究
Solation and degradation effect of two ammonifying bacteria
: 2018 - 11 - 10
: 2019 - 04 - 09
: 2019 - 04 - 17
94 9 0
摘要&关键词
摘要:以太湖底泥沉积物为菌源,分离筛选到两株氨化菌,分别命名为AB-1和AB-2。通过形态特征观察、生理生化特性分析及16S rDNA分子鉴定,确定菌株AB-1和AB-2分别为三叶假单胞菌(Pseudomonas migulae)和节杆菌(Arthrobacter sp.)。相同条件下,两种菌都以1%接种量接种至有机氮中培养70 h,结果表明菌株AB-2去除有机氮的效率高于AB-1,去除率为83.15%,而菌株AB-1的去除率仅为67.33%。所分离的AB-2菌株对于湖泊富营养化治理中改善水质环境有一定的应用价值。
关键词:有机氮;氨化菌;分离鉴定;降解效果
Abstract & Keywords
Abstract: Background, aim, and scope In recent years, with the rapid development of economy, a large number of nutrients such as nitrogen, phosphorus and other organic substances enter the water, causing eutrophication of the water, and water resources problems are serious. Nitrogen removal in eutrophic water has always been a research hotspot. Up to now, there have been a lot of studies on the removal of inorganic nitrogen such as ammonia nitrogen, nitrate nitrogen and nitrite nitrogen in water, among which the research on the ammoniation process of organic nitrogen is relatively less. Materials and methods In this experiment, samples were collected from the bottom sediments of Taihu Lake. After repeated screening, two strains of ammoniated bacteria were isolated, and named AB-1 and AB-2 respectively. The strains were identified by the morphological features observation, physiological and biochemical characteristics analysis, 16S rDNA molecular identification and homology analysis. In addition, the growth characteristics and degradation effects of two strains of ammoniated bacteria were compared. (1) The OD value was measured at 600 nm wavelength every 2 hours after incubation in constant temperature and dark oscillation at 28℃ for 120 r/min, and the growth characteristics were determined. (2) Inoculate 1% of the inoculated amount into organic nitrogen, incubate continuously for 70 hours under the same conditions, and measure the changes of andto compare the degradation effects of the two strains. Peptone was used as the sole organic nitrogen source in the experiment, so the content of organic nitrogen could be expressed by the difference between TN and in the initial culture medium, and the degradation rate of organic nitrogen could be expressed by the increase of . Results Through morphological analysis and 16S rDNA molecular identification, strains AB-1 and AB-2 were identified as Pseudomonas migulae. and Arthrobacter sp., respectively. Under the same culture conditions, the growth potential of strain AB-2 was greater than that of strain AB-1, and the maximum OD600 was 1.063and 0.851, respectively. Besides, two strains of ammoniating bacteria had strong ammoniation ability. Among them, the removal efficiency of organic nitrogen by strain AB-2 was higher than that of ammoniating bacteria AB-1, the removal rate was 83.15%, and that of strain AB-1 was only 67.33%. Discussion Compared with other studies on the degradation of organic nitrogen by ammoniating bacteria, it was found that the degradation rate of organic nitrogen by the two strains was slightly higher. This may be because the ammoniating ability of the two strains was improved by multiple screening in the process of selecting strains. Furthermore, the initial concentration of organic nitrogen in this study was lower, which indicated that the strains screened were indeed effective in degrading organic nitrogen. In addition, by monitoring the growth of two strains of ammoniating bacteria and the change of content, it was found that strain AB-2 could degrade organic nitrogen for a long time, which indicated that the strain could be used as a candidate strain for high-efficiency degradation of organic nitrogen, and it was feasible to apply it to lake eutrophication treatment to improve water quality and environment. However, the conditions, mechanism, enzymatic activity and application methods of ammonia nitrogen degradation need to be further explored and studied. Conclusions In the study, two strains of ammonifying bacteria AB-1 and AB-2 were isolated from sediment of Taihu Lake. Both of them had strong ammoniating ability. Among them, strain AB-2 had higher removal efficiency of organic nitrogen than strain AB-1, with removal rate of 83.15% and strain AB-1 67.33%. Compared with other studies, the initial concentration of organic nitrogen in this study is lower, which indicates that the strains selected are indeed effective in degrading organic nitrogen. Recommendations and perspectives The removal rate of organic nitrogen of AB-2 strain isolated in this study can reach more than 83%, which provides a scientific basis for solving the problem of nitrogen pollution in Taihu Lake and improving the water quality and environment of Taihu Lake. At the same time, it has certain application value to lake eutrophication management.
Keywords: organic nitrogen; ammonifying bacteria; isolation and identification; degradation effect
Abstract:Background, aim, and scope In recent years, with the rapid development of economy, a large number of nutrients such as nitrogen, phosphorus and other organic substances enter the water, causing eutrophication of the water, and water resources problems are serious. Nitrogen removal in eutrophic water has always been a research hotspot. Up to now, there have been a lot of studies on the removal of inorganic nitrogen such as ammonia nitrogen, nitrate nitrogen and nitrite nitrogen in water, among which the research on the ammoniation process of organic nitrogen is relatively less. Materials and methods In this experiment, samples were collected from the bottom sediments of Taihu Lake. After repeated screening, two strains of ammoniated bacteria were isolated, and named AB-1 and AB-2 respectively. The strains were identified by the morphological features observation, physiological and biochemical characteristics analysis, 16S rDNA molecular identification and homology analysis. In addition, the growth characteristics and degradation effects of two strains of ammoniated bacteria were compared. (1) The OD value was measured at 600 nm wavelength every 2 hours after incubation in constant temperature and dark oscillation at 28℃ for 120 r/min, and the growth characteristics were determined. (2) Inoculate 1% of the inoculated amount into organic nitrogen, incubate continuously for 70 hours under the same conditions, and measure the changes of \(\mathrm{\rho }(\mathrm{N}{\mathrm{H}}_{4}^{+}-\mathrm{N})\)and\(\mathrm{ }\mathrm{\rho }(\mathrm{T}\mathrm{N})\)to compare the degradation effects of the two strains. Peptone was used as the sole organic nitrogen source in the experiment, so the content of organic nitrogen could be expressed by the difference between TN and\(\mathrm{ }\mathrm{N}{\mathrm{H}}_{4}^{+}-\mathrm{N}\) in the initial culture medium, and the degradation rate of organic nitrogen could be expressed by the increase of \(\mathrm{N}{\mathrm{H}}_{4}^{+}-\mathrm{N}\). Results Through morphological analysis and 16S rDNA molecular identification, strains AB-1 and AB-2 were identified as Pseudomonas migulae.and Arthrobacter sp., respectively. Under the same culture conditions, the growth potential of strain AB-2 was greater than that of strain AB-1, and the maximum OD600 was 1.063and 0.851, respectively. Besides, two strains of ammoniating bacteria had strong ammoniation ability. Among them, the removal efficiency of organic nitrogen by strain AB-2 was higher than that of ammoniating bacteria AB-1, the removal rate was 83.15%, and that of strain AB-1 was only 67.33%. Discussion Compared with other studies on the degradation of organic nitrogen by ammoniating bacteria, it was found that the degradation rate of organic nitrogen by the two strains was slightly higher. This may be because the ammoniating ability of the two strains was improved by multiple screening in the process of selecting strains. Furthermore, the initial concentration of organic nitrogen in this study was lower, which indicated that the strains screened were indeed effective in degrading organic nitrogen. In addition, by monitoring the growth of two strains of ammoniating bacteria and the change of \(\mathrm{N}{\mathrm{H}}_{4}^{+}-\mathrm{N}\mathrm{ }\mathrm{ }\)content, it was found that strain AB-2 could degrade organic nitrogen for a long time, which indicated that the strain could be used as a candidate strain for high-efficiency degradation of organic nitrogen, and it was feasible to apply it to lake eutrophication treatment to improve water quality and environment. However, the conditions, mechanism, enzymatic activity and application methods of ammonia nitrogen degradation need to be further explored and studied. Conclusions In the study, two strains of ammonifying bacteria AB-1 and AB-2 were isolated from sediment of Taihu Lake. Both of them had strong ammoniating ability. Among them, strain AB-2 had higher removal efficiency of organic nitrogen than strain AB-1, with removal rate of 83.15% and strain AB-1 67.33%. Compared with other studies, the initial concentration of organic nitrogen in this study is lower, which indicates that the strains selected are indeed effective in degrading organic nitrogen. Recommendations and perspectives The removal rate of organic nitrogen of AB-2 strain isolated in this study can reach more than 83%, which provides a scientific basis for solving the problem of nitrogen pollution in Taihu Lake and improving the water quality and environment of Taihu Lake. At the same time, it has certain application value to lake eutrophication management.
随着经济迅猛发展,人为的大量氮、磷等营养元素以及其他有机物质进入水体中,致使藻类及其它水生生物过量繁殖,水体透明度下降,溶解氧减少,造成水质严重恶化,从而使水体功能和水生态系统遭到破坏,水资源问题严重。因此,水体污染已成为人类急需解决的问题(Graedel and Allenby,2010)。而氮是引起水体富营养化的关键元素,富营养化水体中N的去除一直是研究的热点,截至目前,已有大量关于去除水体中氨氮、硝态氮、亚硝酸氮等无机氮的研究。而氨化作用是脱氮的第一步,直接影响到后续脱氮过程。氨化细菌将含氮化合物降解为可被吸收利用的小分子氮,随即进行N元素迁移、转化及循环。到目前为止,有关有机氮的氨化过程研究相对较少。这是由于水体中的有机氮成分复杂,缺乏测定含氮有机物氨化的直接方法,只能间接测定(张列宇等,2010;郭端强等,2014;周家喜等,2016)。在自然界中,有机含氮化合物,包括溶解有机氮、尿素、氨基酸、烟碱等一般都通过氨化细菌的作用并进行降解。
近年来文献报道的氨化细菌有缺陷短波单胞菌(Brevundinonas dininuta),产气肠杆菌(Enterobacter aerogenes)、粪产碱杆菌(Alcanligen faecalis),芽孢杆菌属(Bacillus)、假单胞菌属(Psesudanonas)、微球菌属(Micrococcus)、变形杆菌属(Proteus Cohn)等(张庆华等,2007;李辉等,2008;张文艺等,2011)。根据2017年太湖健康状况公报,太湖平均营养指数为61.6,为中度富营养水平,氨化菌作为太湖水生生态系统中的主要功能菌群之一。本文以太湖底泥沉积物为菌源,通过平板涂布法和划线分离法筛选氨化菌,通过形态学及16S rDNA现代分子生物学手段进行鉴定,并研究其对有机氮的降解效果与氨化能力分析,为解决太湖水体中氮素污染问题,改善太湖水质环境提供科学依据。
1   材料与方法
1.1   样品来源
采自太湖湖心底泥沉积物,底泥样品均为原位柱状底泥采样器采样,并实地将沉积物样品切割分层后密封于样品袋中,低温保存带回实验室分析。
1.2   试剂与检测方法
培养基:蛋白胨5 g ∙ L−1,NaCl 0.25 g ∙ L−1,FeSO4·7H2O 0.16 g ∙ L−1,K2HPO4·3H2O 0.655 g ∙ L−1,MgSO4·7H2O 0.5 g ∙ L−1,琼脂16~18 g·L-1,蒸馏水1 L,pH7.2。
DON培养基:蛋白胨0.1 g ∙ L−1,K2HPO4·3H2O 0.4 g ∙ L−1,MgSO4·7H2O 0.05 g ∙ L−1,NaCl 0.5 g ∙ L−1,FeSO4·7H2O 0.005 g ∙ L−1,CaCl2·H2O 0.01 g ∙ L−1,蒸馏水1 L,pH7.5。培养基于121℃下灭菌30 min。
实验中所涉及试剂均为国产分析纯试剂,菌株生长量采用分光光度计测定OD600值,氨氮含量\(\mathrm{\rho }(\mathrm{N}{\mathrm{H}}_{4}^{+}-\mathrm{N})\)和总氮含量\(\mathrm{\rho }(\mathrm{T}\mathrm{N})\)均采用国标法测定。
1.3   主要仪器与设备
Ezup柱式细菌基因组DNA抽提试剂盒(上海生工)、PCR反应扩增仪(Bio-Rad100,美国伯乐生命医学产品有限公司)、紫外可见光光度计(UV-5100,上海元析)、恒温振荡培养箱(HZ-2010KAG,太仓华立达实验设备有限公司)、高压蒸汽灭菌锅(KT-30S,日本ALP公司)、临界点干燥仪(K850,英国Quorum)、离子溅射仪(日本LXRF),扫描电子显微镜(SU3500,日立株式会社日立制作所)。
1.4   菌株的分离纯化
称取1 g底泥样品于装有99 mL生理盐水的锥形瓶,充分振荡混匀,制成10-2稀释液。然后取1 mL稀释液进行2—4个梯度稀释,最大稀释倍数1×106,分别取各梯度稀释液200 μL涂布在分离平板上,28℃条件下,于恒温培养箱黑暗孵育2—3 d进行初筛,分离出单菌落后,滴加1—2滴纳氏试剂于菌苔上,如呈现棕黄色或是褐色,即说明产生NH4+ ,可初步判定为氨化菌。随即挑选单菌落进行平板“连续划线”培养,观察菌落生长情况,重复划线分5—6次,培养过程中设空白对照。
1.5   菌株鉴定
1.5.1   形态及生理生化鉴定
将筛选出来的菌株进行形态及生理生化鉴定,生理生化鉴定试验参照《常见细菌系统鉴定手册》(蔡妙英和冬秀珠,2008)。菌株形态观察采用扫描电镜观察,步骤如下:挑取培养基上单菌落,于装有0.8%的生理盐水中,离心弃上清液,进行样品前处理,制样步骤见表1。将制备好的菌株样品放入临界点干燥仪,干燥后用离子溅射仪镀膜,最后放入日立扫描电子显微镜中观察。
表1   扫描电镜制样步骤(肖媛等,2013)
加入试剂
Additional Reagents
操作
Operation
2.5%戊二醛溶液固定2—4 h
1%PBS缓冲液(pH7.4)清洗3次
1%锇酸溶液4—5 h
1%PBS缓冲液(pH7.4)清洗3次
乙醇梯度脱水(30%、50%、70%、85%、95%各一次,100%乙醇2次)20—30 min/次
乙酸异戊酯置换2次20 min/次
1.5.2   16S rDNA分子鉴定
对筛选得到的菌株进行基因组DNA提取。按照上海生工Ezup柱式细菌基因组DNA抽提试剂盒步骤提取DNA后,用细菌通用引物(由上海生工合成)和Taq PCR Master Mix(2X,without Dye)进行PCR扩增,反应运行程序见表2。其中,正向引物27F,其碱基序列为:(5′-AGAGTTTGATCCTGGCTCAG-3′),反向引物1492R(5′-GGTTACCTTGTTACGACTT-3′)(Stackebrandt and Goodfellow,1991)。PCR产物送至生物工程(上海)股份有限公司进行16Sr DNA测序。16Sr DNA序列拼接结果上传至NCBI上BLAST得到比对结果。挑取一部分与菌株同源性较高的菌属序列,以FASTA格式保存,利用MEGA7.0.14软件中的Neighbour-Joining数据统计方法构建系统发育树。
表2   16S rDNA的PCR反应运行程序
步骤
Procedure
循环数
Cycle Number
温度(℃)
Temperature
时间
Time
预变性32945 min
变性9445 s
退火4645 s
延伸722 min
延伸1725 min
1.6   菌株的生长特征测定
挑取一环菌苔,接种至装有100 mL蛋白胨培养液的锥形瓶中,于28℃,120 r/min恒温黑暗振荡培养,以未接种的培养液为空白对照,每2 h取样在600 nm的波长下测定其OD值,绘制菌株生长曲线图(朱旭芬,2011)。
1.7   菌株降解能力研究
1.7.1   菌株对不同营养物质的吸收能力
将挑选出来的两株菌株,均按照1%的接种量分别接种于培养基中,其中,培养基氮源用蛋白胨、钼酸铵、尿素各为0.5 g替代,设置不加氮源培养基为空白对照,培养2 d后取样检测\(\mathrm{\rho }(\mathrm{N}{\mathrm{H}}_{4}^{+}-\mathrm{N})\)\(\mathrm{\rho }(\mathrm{T}\mathrm{N})\)含量。
1.7.2   菌株对有机氮的降解实验
按1%的接种量将菌株接种到低浓度氮源测定培养液中,待测氮源浓度为0.05 g/L,匡燕(2012)在水体氨化细菌的分离鉴定及特性研究中,培养基氮源浓度为0.5 g/L,远大于中度富营养水体中的氮源浓度。同时设置不加氮源的培养液作为空白对照,于28℃,120 r/min恒温摇床黑暗培养,测定\(\mathrm{\rho }(\mathrm{N}{\mathrm{H}}_{4}^{+}-\mathrm{N})\)\(\mathrm{\rho }(\mathrm{T}\mathrm{N})\)的变化情况。实验中使用蛋白胨作为唯一有机氮源,故有机氮含量可以用初始培养液中的TN与\(\mathrm{N}{\mathrm{H}}_{4}^{+}-\mathrm{N}\)含量差值表示,有机氮的降解率以\(\mathrm{N}{\mathrm{H}}_{4}^{+}-\mathrm{N}\)的增加量表示。
2   结果与分析
2.1   菌株的分离纯化
经过2—3 d蛋白胨琼脂平板培养,平板上长出若干淡黄色、乳白色、金黄色、杏黄色、橙黄色、桔黄色针尖大小菌落。然后挑取单菌落,在新鲜无菌平板表面进行“连续划线”培养3—4次,分离出6株菌株,分别编号AB-1—6。本文报道AB-1与AB-2菌株的试验结果。用纳氏试剂检验菌株AB-1与AB-2培养液中\(\mathrm{N}{\mathrm{H}}_{4}^{+}\)的产生情况,发现培养液呈现深黄色,说明该菌能将有机氮转化为\(\mathrm{N}{\mathrm{H}}_{4}^{+}\),进一步证实了两菌株为氨化细菌。
2.2   菌株鉴定
2.2.1   形态及生理生化鉴定
(1)菌株形态特征
在固体培养基上,观察菌株AB-1菌落外观形态为淡黄色圆形、较透明、有凸起、边缘清晰、菌落较大,直径为3—5 mm。菌株AB-2菌落外观形态为乳白色圆形、不透明、有凸起、边缘清晰、菌落较大、直径为3—4 mm。两菌株在扫描电子显微镜拍摄照片如图1、图2所示。其中,菌株AB-1呈杆状,不形成芽孢、鞭毛,表面光滑无褶皱,细胞体积大小为(0.43—0.52) μm × (0.77—1.18) μm;菌株AB-2呈椭球状,也不形成芽孢、鞭毛,表面光滑无褶皱,细胞体积大小为(0.51—0.59) μm × (0.65—0.72) μm。
(2)生理生化特征
菌株AB-1与AB-2生理生化特征相同点有:色氨酸脱氢酶试验、甲基红以及V-P试验无颜色变化,均呈阴性;两菌株均能使葡萄糖发酵,接触酶试验且4℃条件下均生长。不同之处:菌株AB-1革兰氏染色阴性,淀粉水解、氧化酶、脲酶实验、吲哚实验呈阳性反应,菌株AB-1革兰氏染色、蔗糖发酵为阳性,其余几项均为阴性。结合两菌株的形态学特征,初步判断菌株AB-1与三叶假单胞菌(Pseudomonas migulae),菌株AB-2与节杆菌属(Arthrobacter sp.)相似性较高。




图1   菌株AB-1扫描电镜图
Fig.1 SEM photos of strain AB-1




图2   菌株AB-2扫描电镜图
Fig.2 SEM photoes of strain AB-2
2.2.2   16S rDNA分子鉴定
经测定,AB-1与AB-2菌株的16S rDNA基因片段大小分别为1445 bp和1424 bp。将AB-1与AB-2菌株测序结果在NCBI上进行BLAST分析,结果表明:菌株AB-1与Pseudomonas migulae 序列相似最高,为98%;AB-2与 Arthrobacter sp.相似性达99%。一般认为,基因组DNA相似性在99%—100%的细菌,判定为同一个种,相似性97%—99%为同一个属(Drancourt et al,2008;Janda and Abbott,2002)。为进一步印证两菌株的分类地位,选取同源性较高的序列构建系统发育树如图3、图4所示。菌株AB-1与AB-2分别三叶假单胞菌、节杆菌属细菌聚类在同一个进化分支,有较高的置信水平,结合两菌株的形态特征、生理生化分析和分子生物学特征,可初步鉴定菌株AB-1与AB-2分别PseudomonasmigulaeArthrobacter sp.。


图3   菌株AB-1的系统发育树
Fig.3 Phylogenetic tree of strain AB-1


图4   菌株AB-2的系统发育树
Fig.4 Phylogenetic tree of strain AB-2
2.3   菌株生长曲线测定
菌株AB-1与AB-2的生长曲线测定结果如图5所示,在相同的培养条件下,菌株AB-2长势大于AB-1,OD600最大值分别为1.063、0.851;两菌株接种后有4 h在适应环境,处于停滞期,4 h后迅速进入对数生长期,OD600值从0.330、0.235迅速增长到20 h的1.012、0.849,20 h后菌体出生率和死亡率达到平衡,菌株AB-1与AB-2分别从28 h、34 h菌体死亡率升高开始进入衰亡期。可以看出菌株AB-2稳定期较长,表明其发挥作用时间较长。王娟等(2010)筛选的zjc05菌株在8 h就达到最大生长量,本研究筛选的AB-1与AB-2菌株虽低于此生长速度,但生长量从8 h后远远高出zjc05菌株。


图5   两株氨化菌的生长曲线
Fig.5 Growth curves of two ammonifying bacteria
2.4   菌株降解有机氮实验结果
2.4.1   菌株对不同营养物质的吸收能力
有机氮成分包括DON、氨基酸氨基糖类、尿素等等,本次实验选择了三种常见的有机氮源物质,结果表明:培养条件相同下,菌株AB-1与菌株AB-2利用不同有机氮源物质有较大差异,其中,钼酸铵利用率最大,蛋白胨次之,尿素最小(图6)。总体上来看,菌株AB-2利用有机氮能力高于菌株AB-1,这可能与菌株的生长特性有关。


图6   两菌氨化菌对不同物质的吸收能力
Fig.6 The utilization of different substances by two ammonifying bacteria
2.4.2   菌株对有机氮的降解能力比较
两株氨化菌对有机氮的降解效果如图7、图8所示,两菌株在利用有机氮转化过程中\(\mathrm{\rho }(\mathrm{T}\mathrm{N})\)波动较小,维持在95 mg/L左右,\(\mathrm{N}{\mathrm{H}}_{4}^{+}-\mathrm{N}\)浓度不断升高,表明有机氮被氨化菌不断的转化为\(\mathrm{N}{\mathrm{H}}_{4}^{+}-\mathrm{N}\)。5 h时,氨化菌AB-1与AB-2对有机氮的去除率分别为11%、13%,随着培养时间的增加,去除率不断升高。菌株AB-1在第30 h时去除率达到67%以上,AB-2在第35 h时,去除率达83%以上,此后两株氨化菌对有机氮的降解趋于稳定,增长极为缓慢。菌株AB-1与AB-2分别在第45 h与50 h后呈现下降趋势,这可能由于菌株死亡率远远大于生长率,且氨氮逐渐挥发。氨化菌AB-2对有机氮的去除效果高于氨化菌AB-1,去除率为83.15%。
杜小波等(2014)对一株氨化菌的分离鉴定及其氨化特性研究,筛选出一株高效氨化菌,其对有机氮的转化率为30%以上;与之相比,本次筛选的氨化菌有机氮去除率远远高出,,且初始浓度较低,这可能是因为高浓度的有机氮污染对微生物有抑制作用,较低浓度下微生物的生长活性较高(Fork and Heffernan,2014)。


图7   菌株AB-1对有机氮的降解效果
Fig.7 Degradation of organic nitrogen by strain AB-1


图8   菌株AB-2对有机氮的降解效果
Fig.8 Degradation of organic nitrogen by strain AB-8
3   讨论
本研究以蛋白胨为唯一氮源,从太湖底泥沉积物中分离出2株氨化菌AB-1与AB-2,根据常见细菌系统鉴定手册和16S rDNA分子鉴定,初步确定菌株AB-1为三叶假单胞菌(Pseudomonas migulae),AB-2为节杆菌(Arthrobacter sp.)。并对氨化菌AB-1、AB-2进行生长曲线的测定,在相同的培养条件下,菌株AB-2长势大于AB-1,OD600最大值分别为1.063、0.851。2株氨化菌都有较强的氨化能力,其中菌株AB-2对有机氮的去除效果高于氨化菌AB-1,去除率为83.15%,菌株AB-1的去除率仅为67.33%。
李辉等(2008)对人工湿地中氨化细菌去除有机氮的效果进行了研究,从中筛选出5株氨化细菌,其中氨化细菌-1、氨化细菌-2与氨化细菌-5对有机氮的转化率分别达到46.2%、49.4%、52.6%;匡燕和梁运祥(2013)在一株水体高效氨化菌的分离及特性研究中,以10%接种量接入含有浓度5 g/L藻细胞残体培养基中,其有机氮的降解率最高为44.82%。发现筛选的两菌株对有机氮的降解速率略高出一些,说明本研究中所筛选的氨化菌AB-1和AB-2对低浓度有机氮有很好的转化效果。
在自然界中,调控有机态氮素的分解速率, 氨化细菌、亚硝化细菌、硝化细菌起决定作用(姜天翔等,2017)。本文通过对两株氨化菌生长量及\(\mathrm{N}{\mathrm{H}}_{4}^{+}-\mathrm{N}\)含量的变化监测,发现菌株AB-2可在较长时间内发挥有机氮降解作用,说明该菌株可以作为高效降解有机氮的候选菌株,将其应用到湖泊富营养化治理中改善水质环境是可行的。但还需要对其降解氨氮条件、降解机理、酶的活性以及使用方法等做进一步的探讨与研究。
4   结论
通过对2株氨化菌鉴定、生长特性及降解效果研究,得出以下结论:(1)鉴定结果AB-1为三叶假单胞菌(Pseudomonas migulae),AB-2为节杆菌(Arthrobacter sp.)。(2)对2株氨化菌进行有机氮降解效果研究,发现菌株AB-2对有机氮的去除效果高于氨化菌AB-1,两菌株有机氮去除率分别为83.15%和67.33%,说明AB-2菌株可以作为高效降解有机氮的候选菌株。该菌株对解决太湖水体中氮素污染问题,改善太湖水质环境及在湖泊富营养化治理中具有一定的应用价值。
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稿件与作者信息
王红
WANG Hong
徐洁
XU Jie
阮爱东
RUAN Aidong
徐耀飞
XU YAOfei
韦琪
WEI Qi
李思言
LI Siyan
基金项目:国家自然科学基金项目(51378175)
National Natural Science Foundation of China (51378175)
出版历史
出版时间: 2019年4月17日 (版本2
参考文献列表中查看
地球环境学报
Journal of Earth Environment