摘要
从稳定运行的厌氧/好氧/缺氧序批式反应器(A/O/A-SBR)中筛选分离得到3株高效除磷细菌,通过形态观察、生理生化试验及16S rRNA基因序列分析进行物种分析,确定3株细菌分别为不动杆菌属(Acinetobacter)、克雷伯菌属(Klebsiella)和肠杆菌属(Enterobacter),NCBI保存登录号分别为OL519151、OL519152、OL519153。以pH值、温度及碳源种类作为影响因子,分析细菌生长特性和除磷率,同时分析无机磷和有机磷在细菌胞内、溶解性微生物产物(SMP)及胞外聚合物(EPS)中的分布转化规律。结果表明:在最佳环境条件下,Acinetobacter sp. PK01、Klebsiella sp. PK02和Enterobacter sp. PK03菌株的最高除磷率分别达到89.4%、85.43%和76.95%。其中,Acinetobacter对环境中磷的去除主要依靠吸收胞外无机磷,并以多聚磷酸盐的形式储存于体内,该途径去除了基质中54.93%的磷;Klebsiella对环境中磷的去除主要依靠EPS合成和吸附作用,该途径去除了基质中47.18%的磷;Enterobacter主要依靠多聚磷酸盐和EPS的合成作用,去除了基质中48.32%的磷。
现代污水生物除磷法是利用聚磷菌超量摄取磷酸盐,并以多聚磷酸盐的形式储存在其体内,通过排放剩余污泥以实现磷的去
鉴于此,笔者从实验室活性污泥中筛选出3株具备高效除磷能力的细菌,考察环境因素对菌株除磷能力的影响,并对其除磷过程中磷的转化分布规律进行全面分析。
取稳定运行的实验室厌氧/好氧/缺氧反应器(A/O/A-SBR)中的活性污泥作为样品。反应器SRT控制在16~20 d,DO<1.0 mg/L,MLSS保持在(3 120±200)mg/L,反应器温度控制在26 ℃。试验用水为人工配制的模拟生活污水,无水乙酸钠作为碳源,氯化铵作为氮源,磷酸二氢钾作为磷源,维持主要水质指标COD为175 mg/L,TN为50 mg/L,TP为6 mg/L。稳定期出水COD平均为29.06 mg/L,TN为14.32 mg/L,TP为0.27 mg/L。详细运行情况见文献[
Luria broth(LB)培养基(L):酵母提取物5 g,胰蛋白胨10 g,NaCl 5 g,pH值为7.0~7.2,固态培养基加20 g琼脂
富集培养基(L):CH3COONa 5.0 g,MgSO4·7H2O 0.5 g,CaCl2 0.2 g,(NH4)2SO4 2.0 g,KH2PO4 8.77~87.74 mg,微量元素1 mL,pH值为7.2~7.4。
筛选培养基(L):牛肉膏3 g,蛋白胨10 g,NaCl 5 g,KH2PO4 65.81 mg,琼脂20 g,pH值为7.2~7.
缺磷培养基(L):CH3COONa 3.23 g,NH4Cl 152.80 mg,MgSO4·7H2O 81.12 mg,K2SO4 17.83 mg,CaCl2·2H2O 11 mg,PIPES缓冲液7 g,微量元素1 mL,pH值为7.2~7.4。
富磷培养基(L):CH3COONa 3.23 g,NH4Cl 305.52 mg,MgSO4·7H2O 91.26 mg,KH2PO4 87.74 mg,CaCl2·2H2O 25.68 mg,PIPES缓冲液8.5 g,微量元素1 mL,pH值为7.2~7.
微量元素(L):CuCl2·2H2O 35 mg,NiCl2·6H2O 36 mg,MgSO4·7H2O 5 000 mg,FeCl2·4H2O 6 000 mg,CoCl2·4H2O 880 mg,H3BO3 100 mg,ZnSO4·7H2O 100 mg和 MnCl2·4H2O 500 m
从A/O/A-SBR中取10 mL活性污泥转移至装有90 mL超纯水和玻璃珠的锥形瓶中,充分振荡以打碎活性污泥。以8 000 r/min 离心5 min后弃掉上清液,用超纯水水洗3次。处理后的样品转入装有100 mL富集培养基的锥形瓶中,在30 ℃下以150 r/min振荡培养。每12 h取10 mL菌悬液转入新的装有90 mL富集培养基的锥形瓶中,培养基磷梯度变化为2、5、8、10、15、20 mg/L(以P浓度计)。
取1 mL富集培养基中的菌悬液,采用稀释涂布法分别在筛选培养基上培养3~5 d,挑取形态清晰的单菌落纯化,直至菌落特征一致,无异常菌落出现,最后划线接种至LB固体培养基中保存备用。
对各菌株进行除磷率分析:挑取菌种接种至50 mL LB培养基中过夜培养,以8 000 r/min离心后用超纯水洗涤3次,重悬菌种并置于50 mL缺磷培养基中预培养,即30 ℃、150 r/min培养12 h。收集菌液在8 000 r/min离心后用超纯水洗涤3次,重悬菌种并按照5%接种至50 mL 富磷培养基中,在30 ℃、150 r/min条件下培养。整个过程在无菌条件下进行,每2 h取2 mL样品先测定OD600,经过0.45 μm滤膜过滤后用于后续磷分析,试验重复3次。
选取目标菌种,使用TSINGKE细菌DNA提取试剂盒提取菌株总DNA,利用细菌菌种鉴定通用引物27F/1492 R进行PCR扩增,通用引物序列为(27F:5’- AGTTTGATCMTGGCTCAG-3’; 1492R:5’- GGTTACCTTGTTACGACTT-3’)。提取测序过程全部交由北京擎科生物科技有限公司完成。测序结果提交至GenBank,并进行BLAST比对,采用Clustal X进行多序列比对,使用MEGA4.1软件中的NJ法构建系统发育树。
菌种预培养后按照5%接种至50 mL富磷培养基中,设置平行培养基共24个,pH值控制在7.0~7.2,温度控制在30 ℃,碳源采用乙酸钠。取样:将50 mL培养液转移至无菌离心管中,在4 ℃ 下以10 000 r/min离心10 min,提取上清液测定COD、乙酸、无机磷(IP)及总磷(TP)。其中,TP与IP浓度差值代表OP浓度,IP浓度代表基质(培养基固定成分)中的P浓度(CBS-IP),OP浓度代表SMP中的P浓度(CSMP-OP)。剩余底物利用0.01 mol/L NaCl重悬至50 mL后在60 ℃水浴加热20 min,在4 ℃以10 000 r/min离心10 min,收集上清液测定COD来表征EPS的量,并测定IP和TP。这里的IP浓度代表EPS中IP浓度(CEPS-IP),OP浓度代表EPS中OP浓度(CEPS-OP)。离心底物利用0.01 mol/L NaCl重悬至10 ml后以120 W在超声破碎仪中破碎10 min,取1 mL收集液用于测定IP和TP。这里的IP浓度代表细菌胞内IP浓度(CIN-IP),OP浓度代表细菌胞内OP浓度(CIN-OP)。根据浓度计算培养基中各部分P质量变化,各部分P质量与培养基中TP质量的比值代表了不同途径下的除磷率,从而分析细菌培养过程中P的转化分布。培养基中TP质量计算式为
MTP=MBS-IP+MSMP-OP+MEPS-IP+MEPS-OP+ MIN-IP+MIN-OP
式中:MTP为培养基中总磷质量;MBS-IP为培养基基质中无机磷质量;MSMP-OP为培养基SMP中有机磷质量;MEPS-IP为培养基EPS中无机磷质量;MEPS-OP为培养基EPS中有机磷质量;MIN-IP为培养基细菌胞内无机磷质量;MIN-OP为培养基细菌胞内有机磷质量。
剩余收集液过0.45 μm滤膜后测定细菌干重。上述取样测定过程每4 h进行一次,试验重复3次。
从筛选培养基中分离得到6株不同形态的细菌,分别以1~6标记,对这6株细菌进行吸磷试验。先将6株菌种置于缺磷培养基中进行预培养,目的是先消耗细菌体内的磷酸盐,然后再转接到富磷培养基中,富磷培养基中的磷浓度达到了20 mg/L左右(一般生活污水中磷浓度小于10 mg/L)。所有细菌的除磷率及OD600如

图1 菌株1~6的除磷率和OD600
Fig. 1 Phosphorous removal rate and OD600 of strains1-6
选取除磷率最高的3株细菌,分别为2、5、6号,根据除磷率分别命名5号为PK01,2号为PK02,6号为PK03,并对3株菌种进行生理生化分析,如
项目 | PK01 | PK02 | PK03 |
---|---|---|---|
菌落形状 | 圆形扁平 | 圆形突起 | 圆形小突起 |
菌落颜色 | 黄色 | 乳白色 | 淡黄色 |
菌落透明度 | 半透明 | 半透明 | 半透明 |
菌落表面 | 光滑 | 光滑 | 光滑 |
菌落黏度 | 较黏 | 较黏 | 较黏 |
细胞形态 | 杆状 | 杆状 | 杆状 |
氧化酶试验 | + | - | - |
甲基红试验 | + | - | + |
V-P试验 | + | + | + |
明胶液化试验 | + | - | - |
柠檬酸盐利用试验 | + | + | + |
糖发酵试验 | + | + | + |
硝酸盐还原试验 | + | + | + |
吲哚试验 | + | - | - |
淀粉水解试验 | - | - | - |
产硫化氢试验 | + | - | - |
菌株PK01、PK02和PK03的16S rRNA基因扩增片段长分别1357、1451、1532 bp。通过在GenBank中进行Blast比对,菌株PK01与Acinetobacter tandoii(KU877626.1)同源性达到了99%,PK02与Klebsiella pneumoniae(MN989349.1)同源性达到了99%,PK03与Enterobacter cloacae(KJ541760.1)同源性达到了99%。Acinetobacter、Klebsiella和Enterobacter同属于γ-变形菌纲,但Acinetobacter属于莫拉菌科,一直被认为是聚磷菌的主要菌

图2 3株细菌的系统发育树
Fig. 2 The phylogenetic trees of three strains
初始pH值会影响细胞在培养基中的氧化还原电位和带电状态,从而影响微生物对营养物质的吸收和酶促反应,因此,pH值的变化会对菌株的除磷效果产生影

图3 pH值对3株细菌生长及除磷率的影响
Fig. 3 Effects of pH value on growth and phosphorus removal rate of three strains
生物除磷系统受温度影响十分明显,之前有研究分析了夏季(26.7±1.4) ℃、秋季(19.7±2.0) ℃和冬季(16.4±0.7) ℃ EBPR系统生物除磷性能的变化,结果表明,随着温度降低,常规PAOs的丰度和系统磷去除性能显著提

图4 温度对3株细菌生长及除磷率的影响
Fig. 4 Effects of temperature on growth and phosphorus removal rate of three strains
碳是微生物生长代谢最重要的营养物质,不同类型的碳源组成成分及分解速率并不相同,从而影响聚磷菌的活性。利用乙酸钠、丙酸钠、琥珀酸钠、柠檬酸钠和葡萄糖考察不同碳源对3株细菌除磷率的影响。由

图5 碳源对3株细菌生长及除磷率的影响
Fig. 5 Effects of carbon source on growth and phosphorus removal rate of three strains
通过好氧除磷试验测定分析了3株细菌的磷转化分布过程,

图6 3株细菌的菌体干重、SMP和EPS产量
Fig. 6 Biomass, SMP and EPS production of three strains
通过测定菌体和环境中的总磷(TP)与无机磷(IP),将培养基中的磷分成培养基中溶解性无机磷(BS-IP)、培养基中溶解性有机磷即SMP中的有机磷(SMP-OP)、细菌胞内无机磷(IN-IP)、细菌胞内有机磷(IN-OP)、EPS中无机磷(EPS-IP)和EPS中有机磷(EPS-OP),24 h磷转化分布如

图7 Acinetobacter sp. PK01的磷转化分布
Fig. 7 Phosphorus transformation and distribution of Acinetobacter sp. PK01

图8 Klebsiella sp. PK02的磷转化分布
Fig. 8 Phosphorus transformation and distribution of Klebsiella sp. PK02

图9 Enterobacter sp. PK03的磷转化分布
Fig. 9 Phosphorus transformation and distribution of Enterobacter sp. PK03
PK01的磷转化分布如
PK02的磷转化分布如
PK03的磷转化分布如
1)从活性污泥中筛选出3株高效除磷细菌PK01、PK02和PK03,通过形态观察、生理生化试验及16S rRNA基因序列分析进行物种鉴定,将3株细菌命名为Acinetobacter sp. PK01、Klebsiella sp. PK02和Enterobacter sp. PK03,登录号分别为OL519151、OL519152、OL519153。
2)Acinetobacter sp. PK01在pH值为6~9和温度为25~35 ℃时都表现出较好的除磷效果,在pH值为7、温度为25 ℃时除磷率达到了89.4%;Klebsiella sp. PK02和Enterobacter sp. PK03更偏向于在中性偏碱性环境下除磷,在pH值为8、温度为30 ℃时,Klebsiella sp. PK02除磷率达到了85.43%;Enterobacter sp. PK03更适应20~30 ℃的环境,在pH值为7且温度为25 ℃时,其除磷率达到了76.95%。3株细菌在乙酸钠和丙酸钠作碳源时都表现出较好的除磷率,Acinetobacter sp. PK01和Enterobacter sp. PK03分别以琥珀酸钠和葡萄糖为碳源时也表现出较好的除磷效果。
3)Acinetobacter sp. PK01对环境中磷的去除主要依靠吸收胞外无机磷存储于体内,24 h后IN-IP占环境总磷的54.93%;Klebsiella sp. PK02对环境中磷的去除主要依靠EPS合成和吸附作用,24 h后EPS-IP和EPS-OP占环境总磷的47.18%;Enterobacter sp. PK03的EPS-IP和EPS-OP共达到环境总磷的38.17%,而SMP-OP和IN-OP都高于前两种菌。
参考文献
邓荣森, 郎建, 王涛, 等. 城市污水生物除磷脱氮机理研究探讨[J]. 重庆建筑大学学报, 2002, 24(3): 106-111. [百度学术]
DENG R S, LANG J, WANG T, et al. A study on mechanism of biological denitrification and phosphorus removal for urban wastewater [J]. Journal of Chongqing Jianzhu University, 2002, 24(3): 106-111. (in Chinese) [百度学术]
FUHS G W, CHEN M. Microbiological basis of phosphate removal in the activated sludge process for the treatment of wastewater [J]. Microbial Ecology, 1975, 2(2): 119-138. [百度学术]
王楠, 蔡曼莎, 李亚静, 等.运行条件对强化生物除磷颗粒污泥系统性能及微生物群落的影响[J].土木与环境工程学报(中英文),2021,43(4):202-210. [百度学术]
WANG N, CAI M S, LI Y J, et al. Effect of operation conditions on the performance and microbial community of an enhanced biological phosphorus removal granular sludge system [J]. Journal of Civil and Environmental Engineering, 2021, 43(4): 202-210. (in Chinese) [百度学术]
汪昆平, 邓荣森, 李伟民, 等. 氧化沟脱氮除磷强化途径[J]. 重庆建筑大学学报, 2006, 28(6): 79-83. [百度学术]
WANG K P, DENG R S, LI W M, et al. Approach to the enhancement of removal of phosphorus and nitrogen in oxidation ditch [J]. Journal of Chongqing Jianzhu University, 2006, 28(6): 79-83. (in Chinese) [百度学术]
张园, 罗固源, 许晓毅, 等. UCT工艺进水COD浓度与C/N对除磷效果的影响[J]. 环境科学, 2010, 31(8): 1846-1850. [百度学术]
ZHANG Y, LUO G Y, XU X Y, et al. Effect of the influent COD and C/N ratio on phosphorus removal of UCT system [J]. Environmental Science, 2010, 31(8): 1846-1850. (in Chinese) [百度学术]
ALMOMANI F, BOHSALE R R. Optimizing nutrient removal of moving bed biofilm reactor process using response surface methodology [J]. Bioresource Technology, 2020, 305: 123059. [百度学术]
庄志刚, 韩永和, 章文贤, 等. 高效聚磷菌Alcaligenes sp.ED-12菌株的分离鉴定及其除磷特性[J]. 环境科学学报, 2014, 34(3): 678-687. [百度学术]
ZHUANG Z G, HAN Y H, ZHANG W X, et al. Isolation, identification and phosphorus-removal characterization of bacteria Alcaligenes sp. strain ED-12 for phosphorus-accumulation [J]. Acta Scientiae Circumstantiae, 2014, 34(3): 678-687. (in Chinese) [百度学术]
FAN Z W, ZENG W, WANG B G, et al. Transcriptional responses of Candidatus Accumulibacter clades to environmental dynamics in enhanced biological phosphorus removal [J]. Bioresource Technology, 2020, 306: 123108. [百度学术]
WU L W, NING D L, ZHANG B, et al. Global diversity and biogeography of bacterial communities in wastewater treatment plants [J]. Nature Microbiology, 2019, 4(7): 1183-1195. [百度学术]
吴云, 范丙全, 隋新华, 等. 适应菲胁迫的高效聚磷菌筛选及聚磷特性研究[J]. 环境科学, 2008, 29(11): 3172-3178. [百度学术]
WU Y, FAN B Q, SUI X H, et al. Screening of two phenanthrene-utilizing and high-effective phosphorus-accumulating bacteria and their effects on phosphorus-accumulating characteristics [J]. Environmental Science, 2008, 29(11): 3172-3178. (in Chinese) [百度学术]
张文艺, 陈晶, 邓文, 等. 反硝化聚磷菌菌剂种子液制备条件及除磷机理[J]. 土木建筑与环境工程, 2014, 36(6): 99-105. [百度学术]
ZHANG W Y, CHEN J, DENG W, et al. Preparation of denitrifying phosphorus accumulating bacterial seed liquid and analysis of phosphorus removal mechanism [J]. Journal of Civil, Architectural & Environmental Engineering, 2014, 36(6): 99-105. (in Chinese) [百度学术]
CLOSE K, MARQUES R, CARVALHO V C F, et al. The storage compounds associated with Tetrasphaera PAO metabolism and the relationship between diversity and P removal [J]. Water Research, 2021, 204: 117621. [百度学术]
REN T, CHI Y L, WANG Y, et al. Diversified metabolism makes novel Thauera strain highly competitive in low carbon wastewater treatment [J]. Water Research, 2021, 206: 117742. [百度学术]
张娟, 方祥位, 刘汉龙, 等. 石油污染土中微生物的分离鉴定及降解特性[J]. 土木与环境工程学报(中英文), 2020, 42(1): 144-152. [百度学术]
ZHANG J, FANG X W, LIU H L, et al. Isolation, identification and degradation characteristics of microorganisms in petroleum contaminated soil [J]. Journal of Civil and Environmental Engineering, 2020, 42(1): 144-152. (in Chinese) [百度学术]
陈亚松, 金文标, 闫韫, 等. 高效聚磷菌的筛选及其应用[J]. 净水技术, 2011, 30(2): 19-22. [百度学术]
CHEN Y S, JIN W B, YAN Y, et al. Screening and application of high efficient phosphate-accumulating organisms (PAOs) [J]. Water Purification Technology, 2011, 30(2): 19-22. (in Chinese) [百度学术]
马放, 杨菲菲, 李昂, 等. 1株高效反硝化聚磷菌的生物学特性研究[J]. 环境科学, 2011, 32(9): 2710-2715. [百度学术]
MA F, YANG F F, LI A, et al. Biological characteristics of denitrifying polyphosphate-accumulating organisms [J]. Environmental Science, 2011, 32(9): 2710-2715. (in Chinese) [百度学术]
蔡天明, 陈立伟, 吴守中, 等. 1株脱氮除磷菌的筛选及其特性研究[J]. 环境科学, 2010, 31(10): 2487-2492. [百度学术]
CAI T M, CHEN L W, WU S Z, et al. Selection of denitrifying phosphorus-removing bacteria and its characteristic [J]. Environmental Science, 2010, 31(10): 2487-2492. (in Chinese) [百度学术]
欧阳彤, 涂保华, 李乔, 等. 多级AO+潜流湿地对生活污水中的EDCs及常规污染物的去除试验研究[J]. 土木与环境工程学报(中英文), 2020, 42(3): 156-164. [百度学术]
OUYANG T, TU B H, LI Q, et al. Experimental study on the removal of EDCs and conventional pollutants indomestic sewage by multi-stage AO + subsurface flow constructed wetland [J]. Journal of Civil and Environmental Engineering, 2020, 42(3): 156-164. (in Chinese) [百度学术]
翟俊, 李岳. 微曝气强化人工湿地处理生活污水试验研究[J]. 土木与环境工程学报(中英文), 2020, 42(6): 178-184. [百度学术]
ZHAI J, LI Y. The effects of domestic wastewater treatment by micro-aerated hybrid constructed wetland [J]. Journal of Civil and Environmental Engineering, 2020, 42(6): 178-184. (in Chinese) [百度学术]
ZHOU Y, NGUYEN B T, ZHOU C, et al. The distribution of phosphorus and its transformations during batch growth of Synechocystis [J]. Water Research, 2017, 122: 355-362. [百度学术]
RODGERS M, WU G X. Production of polyhydroxybutyrate by activated sludge performing enhanced biological phosphorus removal [J]. Bioresource Technology, 2010, 101(3): 1049-1053. [百度学术]
LI H K, ZHONG Y M, HUANG H, et al. Simultaneous nitrogen and phosphorus removal by interactions between phosphate accumulating organisms (PAOs) and denitrifying phosphate accumulating organisms (DPAOs) in a sequencing batch reactor [J]. The Science of the Total Environment, 2020, 744: 140852. [百度学术]
WANG D B, ZHENG W, LIAO D X, et al. Effect of initial pH control on biological phosphorus removal induced by the aerobic/extended-idle regime [J]. Chemosphere, 2013, 90(8): 2279-2287. [百度学术]
ZHANG T, LIU Y, FANG H H P. Effect of pH change on the performance and microbial community of enhanced biological phosphate removal process [J]. Biotechnology and Bioengineering, 2005, 92(2): 173-182. [百度学术]
YUAN C S, WANG B, PENG Y Z, et al. Simultaneous enhanced biological phosphorus removal and semi-nitritation (EBPR-SN) followed by anammox process treating municipal wastewater at seasonal temperatures: From summer to winter [J]. Science of the Total Environment, 2021, 757: 144048. [百度学术]
LASPIDOU C S, RITTMANN B E. A unified theory for extracellular polymeric substances, soluble microbial products, and active and inert biomass [J]. Water Research, 2002, 36(11): 2711-2720. [百度学术]
DIXON M, FLINT S, PALMER J, et al. Analysis of culturable and non-culturable bacteria and their potential to form biofilms in a primary treated dairy wastewater system [J]. Environmental Technology, 2018, 39(17): 2185-2192. [百度学术]
YANG J X, WEI W, PI S S, et al. Competitive adsorption of heavy metals by extracellular polymeric substances extracted from Klebsiella sp. J1 [J]. Bioresource Technology, 2015, 196: 533-539. [百度学术]
李雅婷. 氮磷同化海洋菌-藻共生系统的建立及其在含盐污水处理中的研究[D]. 济南: 山东大学, 2018. [百度学术]
LI Y T. Establishment of nitrogen-phosphorus assimilation marine bacterial-algal mutualistic system and its application in saline sewage treatment [D]. Jinan: Shandong University, 2018. (in Chinese) [百度学术]
ZHANG H L, FANG W, WANG Y P, et al. Phosphorus removal in an enhanced biological phosphorus removal process: Roles of extracellular polymeric substances [J]. Environmental Science & Technology, 2013, 47(20): 11482-11489. [百度学术]