<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE article  PUBLIC "-//NLM//DTD Journal Publishing DTD v3.0 20080202//EN" "http://dtd.nlm.nih.gov/publishing/3.0/journalpublishing3.dtd"><article xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" dtd-version="3.0" xml:lang="en" article-type="research article"><front><journal-meta><journal-id journal-id-type="publisher-id">AMB</journal-id><journal-title-group><journal-title>Advances in Microbiology</journal-title></journal-title-group><issn pub-type="epub">2327-0810</issn><publisher><publisher-name>Scientific Research Publishing</publisher-name></publisher></journal-meta><article-meta><article-id pub-id-type="doi">10.12677/AMB.2023.122008</article-id><article-id pub-id-type="publisher-id">AMB-66857</article-id><article-categories><subj-group subj-group-type="heading"><subject>AMB20230200000_11300671.pdf</subject></subj-group><subj-group subj-group-type="Discipline-v2"><subject>生命科学</subject></subj-group></article-categories><title-group><article-title>
 
 
  抗镉细菌分离鉴定及其对镉胁迫水稻幼苗生长的影响
  Isolation and Identification of Cadmium-Resistant Bacteria and Their Influence on Growth of Cadmium-Stressed Rice Seedlings
 
</article-title></title-group><contrib-group><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>张</surname><given-names>芯瑜</given-names></name><xref ref-type="aff" rid="aff2"><sup>2</sup></xref><xref ref-type="aff" rid="aff1"><sup>1</sup></xref></contrib><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>印</surname><given-names>宁鸿</given-names></name><xref ref-type="aff" rid="aff2"><sup>2</sup></xref><xref ref-type="aff" rid="aff1"><sup>1</sup></xref></contrib><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>陈</surname><given-names>丹丹</given-names></name><xref ref-type="aff" rid="aff2"><sup>2</sup></xref><xref ref-type="aff" rid="aff1"><sup>1</sup></xref></contrib><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>徐</surname><given-names>樾</given-names></name><xref ref-type="aff" rid="aff2"><sup>2</sup></xref><xref ref-type="aff" rid="aff1"><sup>1</sup></xref></contrib><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>罗</surname><given-names>婧</given-names></name><xref ref-type="aff" rid="aff2"><sup>2</sup></xref><xref ref-type="aff" rid="aff1"><sup>1</sup></xref></contrib><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>许</surname><given-names>爱清</given-names></name><xref ref-type="aff" rid="aff3"><sup>3</sup></xref><xref ref-type="aff" rid="aff2"><sup>2</sup></xref><xref ref-type="aff" rid="aff1"><sup>1</sup></xref></contrib></contrib-group><aff id="aff3"><addr-line>湖南科技大学生命科学与健康学院，湖南 湘潭；重金属污染土壤生态修复与安全利用湖南省普通高等学校重点实验室，湖南 湘潭</addr-line></aff><aff id="aff2"><addr-line>湖南科技大学生命科学与健康学院，湖南 湘潭</addr-line></aff><aff id="aff1"><addr-line>null</addr-line></aff><pub-date pub-type="epub"><day>09</day><month>06</month><year>2023</year></pub-date><volume>12</volume><issue>02</issue><fpage>63</fpage><lpage>70</lpage><permissions><copyright-statement>&#169; Copyright  2014 by authors and Scientific Research Publishing Inc. </copyright-statement><copyright-year>2014</copyright-year><license><license-p>This work is licensed under the Creative Commons Attribution International License (CC BY). http://creativecommons.org/licenses/by/4.0/</license-p></license></permissions><abstract><p>
 
 
  目的：旨在分离筛选有利于水稻种植的抗镉菌种资源。方法：从水稻根际土壤分离纯化抗镉细菌，采用火焰原子吸收分光光度法测定菌株对镉的吸附去除率，利用水培法检测抗镉细菌对镉胁迫水稻幼苗生长的影响，运用16
  <em>S</em> rRNA基因序列分析来鉴定菌株的种属。结果：分离得到4株抗镉细菌Cdr-1~Cdr-4，其中菌株Cdr-2在含镉400 mg/L的培养液生长后，对镉离子吸附去除率为61.27%。菌株Cdr-2对无镉水稻营养液中培养的水稻幼苗具有促生长作用，但它对受10 mg/L镉离胁迫的水稻幼苗生长有加强毒害作用。经16
  <em>S</em> rRNA基因测序鉴定菌株Cdr-2为产气克雷伯氏菌。结论：从水稻根际土壤分离出一株兼有抗镉性和促生长性的产气克雷伯氏菌Cdr-2。意义：研究结果可为产气克雷伯氏菌Cdr-2在水稻种植上应用提供参考。
   Aim: Isolating and screening of the cadmium-resistant bacteria (Cd-r-BA) that were benefited to rice cultivation. Methods: The Cd-r-BA was isolated from rice rhizospheric soil. The adsorption and removal rate of cadmium when the Cd-r-BA grows in cadmium-containing broth was detected by the flame atomic absorption spectrometric method. The effects of Cd-r-BA to cadmium-stressed rice seedlings were detected by using water culture method. The identification of the object bacterium was depended on its 16
  <em>S</em> rRNA gene sequence. Results: The results showed that four Cd-r-BA strains of Cdr-1~Cdr-4 were screened out. Especially, when the strain Cdr-2 grows in broth containing 400 mg/L of cadmium, the adsorption and removal rate of 61.27% cadmium was detected. The growth of the rice seedlings was prompted by the strain Cdr-2 under cadmium-free rice culture nutrients in water culture box, while the toxic effects of the cadmium to the rice seedlings was enhanced by the strain Cdr-2 under 10 mg/L of cadmium condition. The strain Cdr-2 was identified as species Klebsiella aerogenes by 16
  <em>S</em> rRNA gene sequencing. Conclusion: The conclusion was drawn that a 
  <em>Klebsiella</em> 
  <em>aerogenes</em> strain Cdr-2 that characterized by cadmium-resistance and growth-promoting was isolated and screened from rice rhizosphericsoil. Significance: The results could provide reference data for the application of strain Cdr-2 to the rice cultivation.
 
</p></abstract><kwd-group><kwd>镉，水稻，抗镉细菌，产气克雷伯氏菌Cadmium</kwd><kwd> Rice Plant</kwd><kwd> Cadmium-Resistant Bacteria</kwd><kwd> <em>Klebsiella</em> <em>aerogenes</em></kwd></kwd-group></article-meta></front><body><sec id="s1"><title>摘要</title><p>目的：旨在分离筛选有利于水稻种植的抗镉菌种资源。方法：从水稻根际土壤分离纯化抗镉细菌，采用火焰原子吸收分光光度法测定菌株对镉的吸附去除率，利用水培法检测抗镉细菌对镉胁迫水稻幼苗生长的影响，运用16S rRNA基因序列分析来鉴定菌株的种属。结果：分离得到4株抗镉细菌Cdr-1~Cdr-4，其中菌株Cdr-2在含镉400 mg/L的培养液生长后，对镉离子吸附去除率为61.27%。菌株Cdr-2对无镉水稻营养液中培养的水稻幼苗具有促生长作用，但它对受10 mg/L镉离胁迫的水稻幼苗生长有加强毒害作用。经16S rRNA基因测序鉴定菌株Cdr-2为产气克雷伯氏菌。结论：从水稻根际土壤分离出一株兼有抗镉性和促生长性的产气克雷伯氏菌Cdr-2。意义：研究结果可为产气克雷伯氏菌Cdr-2在水稻种植上应用提供参考。</p></sec><sec id="s2"><title>关键词</title><p>镉，水稻，抗镉细菌，产气克雷伯氏菌</p></sec><sec id="s3"><title>Isolation and Identification of Cadmium-Resistant Bacteria and Their Influence on Growth of Cadmium-Stressed Rice Seedlings<sup> </sup></title><p>Xinyu Zhang<sup>1</sup>, Ninghong Yin<sup>1</sup>, Dandan Chen<sup>1</sup>, Yue Xu<sup>1</sup>, Jing Luo<sup>1</sup>, Aiqing Xu<sup>1,2*</sup></p><p><sup>1</sup>School of Life and Health Science, Hunan University of Science and Technology, Xiangtan Hunan</p><p><sup>2</sup>Ecological Remediation and Safe Utilization of Heavy Metal-Polluted Soils, College of Hunan Province, Xiangtan Hunan</p><p>Received: Mar. 28<sup>th</sup>, 2023; accepted: Jun. 1<sup>st</sup>, 2023; published: Jun. 9<sup>th</sup>, 2023</p></sec><sec id="s4"><title>ABSTRACT</title><p>Aim: Isolating and screening of the cadmium-resistant bacteria (Cd-r-BA) that were benefited to rice cultivation. Methods: The Cd-r-BA was isolated from rice rhizospheric soil. The adsorption and removal rate of cadmium when the Cd-r-BA grows in cadmium-containing broth was detected by the flame atomic absorption spectrometric method. The effects of Cd-r-BA to cadmium-stressed rice seedlings were detected by using water culture method. The identification of the object bacterium was depended on its 16S rRNA gene sequence. Results: The results showed that four Cd-r-BA strains of Cdr-1~Cdr-4 were screened out. Especially, when the strain Cdr-2 grows in broth containing 400 mg/L of cadmium, the adsorption and removal rate of 61.27% cadmium was detected. The growth of the rice seedlings was prompted by the strain Cdr-2 under cadmium-free rice culture nutrients in water culture box, while the toxic effects of the cadmium to the rice seedlings was enhanced by the strain Cdr-2 under 10 mg/L of cadmium condition. The strain Cdr-2 was identified as species Klebsiella aerogenes by 16S rRNA gene sequencing. Conclusion: The conclusion was drawn that a Klebsiella aerogenes strain Cdr-2 that characterized by cadmium-resistance and growth-promoting was isolated and screened from rice rhizosphericsoil. Significance: The results could provide reference data for the application of strain Cdr-2 to the rice cultivation.</p><p>Keywords:Cadmium, Rice Plant, Cadmium-Resistant Bacteria, Klebsiella aerogenes</p><disp-formula id="hanspub.66857-formula13"><graphic xlink:href="//html.hanspub.org/file/2-2730274x5_hanspub.png?20230612092305523"  xlink:type="simple"/></disp-formula><p>Copyright &#169; 2023 by author(s) and Hans Publishers Inc.</p><p>This work is licensed under the Creative Commons Attribution International License (CC BY 4.0).</p><p>http://creativecommons.org/licenses/by/4.0/</p><p><img src="//html.hanspub.org/file/2-2730274x6_hanspub.png?20230612092305523" /> <img src="//html.hanspub.org/file/2-2730274x7_hanspub.png?20230612092305523" /></p></sec><sec id="s5"><title>1. 引言</title><p>镉(Cadmium, Cd)是元素周期表第五周期IIB族元素。镉是生物体非必需元素，对于动植物都是一种毒性非常强的重金属，被国际癌症机构IARC列为致癌类物质。Cd由于其在环境中具有很强的迁移转化特性及对人体的高度危害性而被列为《国家重金属污染综合防治“十二五”规划》重点关注的5大重金属污染元素之一 [<xref ref-type="bibr" rid="hanspub.66857-ref1">1</xref>] [<xref ref-type="bibr" rid="hanspub.66857-ref2">2</xref>] 。据2014年全国土壤污染状况调查公报数据统计：中国受重金属污染耕地面积约为2000万hm<sup>2</sup>，占耕地面积的1/5左右，以中轻度污染为主，镉污染点位超标率达7.0%，居所有无机污染物之首 [<xref ref-type="bibr" rid="hanspub.66857-ref3">3</xref>] 。重金属铅、镉等进入土壤环境当中，会长期蓄积并破坏土壤本身的自净能力，使土壤成为污染物的“储存库”。土壤中固定态的镉，经植物根系活化转变后具有较高的可移动性，通过自由扩散或载体蛋白运输的方式经质外体或共质体途径进入植物根系，再由木质部装载经蒸腾作用向地上部分转运 [<xref ref-type="bibr" rid="hanspub.66857-ref4">4</xref>] [<xref ref-type="bibr" rid="hanspub.66857-ref5">5</xref>] [<xref ref-type="bibr" rid="hanspub.66857-ref6">6</xref>] [<xref ref-type="bibr" rid="hanspub.66857-ref7">7</xref>] ，最后转运至植物的可食用部分，通过食物链传递，危害人体健康。</p><p>水稻(Oryza sativa L.)是世界上最重要、消耗最大的粮食作物之一，对其产量的需求随着世界人口的不断增长正不断增加 [<xref ref-type="bibr" rid="hanspub.66857-ref8">8</xref>] [<xref ref-type="bibr" rid="hanspub.66857-ref9">9</xref>] 。水稻也是我国第一大粮食作物，因此保证大米中镉的低含量具有重要意义。在镉污染环境中，水稻根系从环境中吸收镉离子后，会把大部分镉离子转化成难溶态镉固定在根系组织中，只有少数可溶态镉被转运到地上部，茎基部压缩的蘖节和地上伸长的4~5个节间以及节和叶片继续对镉进行层层拦截，将其储存在茎基、节和叶片中 [<xref ref-type="bibr" rid="hanspub.66857-ref10">10</xref>] [<xref ref-type="bibr" rid="hanspub.66857-ref11">11</xref>] [<xref ref-type="bibr" rid="hanspub.66857-ref12">12</xref>] 。水稻开花以后，茎叶中储存的部分镉离子被活化，和Mn、Zn等营养元素一起向穗轴和稻米中转运 [<xref ref-type="bibr" rid="hanspub.66857-ref12">12</xref>] 。镉和营养物质流经穗轴维管束到达籽粒基部，籽粒基部对转运而来的小分子化合物进行选择性吸收后运输至籽粒内部。镉毒害也会影响农作物气孔开闭状态并减缓光合效率，破坏叶绿体膜导致叶绿素降解 [<xref ref-type="bibr" rid="hanspub.66857-ref13">13</xref>] ，从而造成水稻产量下降。</p><p>水稻从稻田吸收Cd并在稻米中积累，人们在食用含Cd的大米后，镉从消化道进入人体，则会出现呕吐、胃肠痉挛、腹疼、腹泻等症状，甚至可因肝肾综合症死亡。大部分Cd会被吸收并积累在体内产生毒性，危害人体健康。Cd在人体器官中积累，其中肾脏和肝脏的积累量占体内Cd总量的约60%。长期的Cd毒性易导致脏器功能受损，严重的甚至诱发癌变 [<xref ref-type="bibr" rid="hanspub.66857-ref14">14</xref>] [<xref ref-type="bibr" rid="hanspub.66857-ref15">15</xref>] [<xref ref-type="bibr" rid="hanspub.66857-ref16">16</xref>] 。</p><p>微生物修复即利用微生物将环境中的污染物降解或转化为其它无害物质的过程。微生物修复可应用于水体或土壤的重金属污染修复。土壤微生物群落与土壤重金属污染之间的关系是当今国内外环境科学领域的一个研究热点。一方面，重金属污染会对土壤微生物群落产生影响，如降低土壤微生物量、可培养细菌菌落数量，或明显改变土壤微生物群落的结构 [<xref ref-type="bibr" rid="hanspub.66857-ref17">17</xref>] 。一定浓度重金属能够改进水稻根际微生物群落结构和碳源利用 [<xref ref-type="bibr" rid="hanspub.66857-ref18">18</xref>] 。另一方面，某些微生物菌剂可以有效钝化土壤中的镉，有利于减轻镉对水稻的污染。当肠杆菌和丛毛单胞菌共同培养时，可以将溶液中的镉离子沉淀并完全去除，减少水稻对镉离子的吸收，使稻米中镉含量显著下降 [<xref ref-type="bibr" rid="hanspub.66857-ref19">19</xref>] 。从镉污染土壤分离筛选的一株食酸代尔夫特(Delftia acidovorans) B9，通过盆栽试验发现向早稻品种中添加B9活菌体能增加稻米重量，比对照组重量增加23.14% [<xref ref-type="bibr" rid="hanspub.66857-ref20">20</xref>] 。这些研究表明将抗镉菌种制成微生物菌剂应用在水稻种植领域时，完全有可能降低水稻体内镉含量，提高稻谷产量的同时也能保证稻谷的品质。</p><p>本研究在分离筛选抗(耐)镉细菌资源过程中，从水稻根际土壤中分离纯化得到一株兼有抗镉性和促生长性的产气克雷伯氏菌Cdr-2。研究结果为水稻栽培积累了有应用潜力菌种资源的参考性实验数据。</p></sec><sec id="s6"><title>2. 材料与方法</title><sec id="s6_1"><title>2.1. 材料与仪器</title><p>采样土壤：采自湘潭市某有色金属冶炼厂附近的水稻根际土壤样品；水稻种子：Y两优1928 (长沙利诚种业有限公司)；牛肉膏，蛋白胨，氯化钠，琼脂粉，Cd(NO<sub>3</sub>)<sub>2</sub>∙4H<sub>2</sub>O (AR，天津市科密欧化学试剂有限公司)，镉离子标准溶液(1000 μg/mL，国家有色金属及电子材料分析测试中心)；Yoshida水稻营养液(800&#215;母液)。</p><p>全自动高压蒸汽灭菌器(登冠)，电热恒温鼓风干燥箱，立式恒温振荡器，洁净工作台，人工气候培养箱(上海一恒)，高速冷冻离心机(卢湘仪)，原子吸收分光光度计(AA-7000，岛津)，植物水培盒(6孔，容积1 L)。</p></sec><sec id="s6_2"><title>2.2. 实验方法</title><sec id="s6_2_1"><title>2.2.1. 抗镉细菌的分离纯化</title><p>在湘潭市某有色金属冶炼厂附近的稻田中随机采取4份水稻根际土样。制作含Cd<sup>2+</sup> 100 mg/L的牛肉膏蛋白胨固体培养基平板，各取1 g土样分别加入50 mL灭菌生理盐水制成土样悬液，移取0.2 mL土样悬液涂布平板后置于28℃恒温培养箱中培养48 hr。每个土样挑取2个菌落用于划线分离纯化得到纯菌落，转接到斜面培养基，28℃培养48 hr后，于4℃冰箱保藏备用。</p></sec><sec id="s6_2_2"><title>2.2.2. 菌株的抗镉能力和镉去除能力检测</title><p>配制含Cd<sup>2+</sup>浓度为0，200 mg/L、400 mg/L和600 mg/L的牛肉膏蛋白胨培养液，分装成20 mL/瓶。无菌操作移取抗镉菌Cdr-1、Cdr-2、Cdr-3或Cdr-4种子液200 μL，分别接种于灭菌培养液中，28℃恒温震荡培养48 hr，观察培养液的浊度。移取1.5 ml 含Cd<sup>2+</sup> 为200 mg/L，400 mg/L，600 mg/L的48 hr培养液，转速10,000 r/min离心10 min收集培养液上清。用去离子水稀释上清液使其中Cd<sup>2+</sup>浓度为1 mg/L以下。将镉离子标准溶液(1000 mg/L)用去离子水稀释，配制Cd<sup>2+</sup>浓度分别为0.1 mg/L、0.2 mg/L、0.4 mg/L、0.6 mg/L、0.8 mg/L和1.0 mg/L的稀释液，用于制作火焰原子吸收分光光度法测镉浓度的标准曲线。利用火焰原子吸收分光光度法测量各上清液吸光值(Abs 228.8 nm)，根据标准曲线拟合公式计算上清液中的镉残留量以及镉离子的吸附去除率。</p></sec></sec><sec id="s6_3"><title>2.3. 菌株对水稻种子发芽的影响</title><p>称取水稻种子100 g放入洁净保鲜盒中，先用无菌水浮选去除瘪谷等杂质，用0.2%高锰酸钾溶液浸泡种子消毒0.5 hr，无菌水清洗后用28℃无菌水浸泡种子，置于恒温培养箱中28℃温育至种子破口露白。把破口露白的萌发种子随机分成5组，标记为CK (空白对照)、1#、2#、3#和4#组，每组平行重复3小组。处理方式是：CK (空白对照)：不接触任何细菌处理；1#组~4#组：将萌发种子分别放入用无菌生理盐水稀释100倍的Cdr-1、Cdr-2、Cdr-3或Cdr-4菌株的48 hr培养液，使种子沾上相应菌液。每小组随机挑取50颗沾上菌液的种子摆放在带湿润纱布的平板上，放入28℃恒温培养箱中培养，观察菌株对水稻种子发芽的影响情况。</p></sec><sec id="s6_4"><title>2.4. 菌株对镉胁迫水稻幼苗生长的影响</title><p>按说明书用无菌去离子水稀释水稻营养液母液制成工作液。取6个植物水培盒，分别盛装按表1处理的水稻培养液1000 mL。从2.3中随机选取各处理中长势状态基本一致的水稻芽苗，用定植海绵固定在植物水培盒定植孔中，其中5孔各定植2株水稻芽苗，留下1个空孔用于通气和观察水情，放入人工气候培养箱中培养。培养条件是28℃、湿度95%、60%光照培养12 hr；28℃、湿度95%、黑暗培养12 hr。交替培养共15天，观察记录水稻幼苗的长势。培养结束后测量水稻幼苗生理指标，包括株高、根长、叶片数、干重等，比较分析菌株对镉胁迫水稻幼苗生长的影响。</p><table-wrap id="table1" ><label><xref ref-type="table" rid="table1">Table 1</xref></label><caption><title> The treatment types of rice nutrient solution in the plant hydroponics boxe</title></caption><table><tbody><thead><tr><th align="center" valign="middle" >编号</th><th align="center" valign="middle" >组名</th><th align="center" valign="middle" >Yoshida营养液/ml</th><th align="center" valign="middle" >菌液体积(菌株)</th><th align="center" valign="middle" >硝酸镉母液(3000 mg/L)/ml</th></tr></thead><tr><td align="center" valign="middle" >1#</td><td align="center" valign="middle" >正常对照组</td><td align="center" valign="middle" >1000</td><td align="center" valign="middle" >0</td><td align="center" valign="middle" >0</td></tr><tr><td align="center" valign="middle" >2#</td><td align="center" valign="middle" >10 mg/L镉胁迫组</td><td align="center" valign="middle" >998.3</td><td align="center" valign="middle" >0</td><td align="center" valign="middle" >1.7</td></tr><tr><td align="center" valign="middle" >3#</td><td align="center" valign="middle" >Cd-2菌株处理组</td><td align="center" valign="middle" >990</td><td align="center" valign="middle" >10 ml (Cd-2)</td><td align="center" valign="middle" >0</td></tr><tr><td align="center" valign="middle" >4#</td><td align="center" valign="middle" >10 mg/L镉胁迫 + Cd-2菌株处理组</td><td align="center" valign="middle" >988.3</td><td align="center" valign="middle" >10 ml (Cd-2)</td><td align="center" valign="middle" >1.7</td></tr><tr><td align="center" valign="middle" >5#</td><td align="center" valign="middle" >Cd-3菌株处理组</td><td align="center" valign="middle" >990</td><td align="center" valign="middle" >10 ml (Cd-3)</td><td align="center" valign="middle" >0</td></tr><tr><td align="center" valign="middle" >6#</td><td align="center" valign="middle" >10 mg/L镉胁迫 + Cd-3菌株处理组</td><td align="center" valign="middle" >988.3</td><td align="center" valign="middle" >10 ml (Cd-3)</td><td align="center" valign="middle" >1.7</td></tr></tbody></table></table-wrap><p>表1. 植物水培盒中的水稻培养液处理方式</p></sec><sec id="s6_5"><title>2.5. 菌株的16S rRNA基因序列分析</title><p>用牛肉膏蛋白胨培养液培养Cdr-2菌株48 hr后，取1.5 mL含菌培养液10,000 r/min离心10 min，收集菌体细胞，委托上海生工生物工程有限公司(武汉)进行菌样的16S rRNA基因测序，测序引物为细菌16S rRNA基因的通用引物27F/1492R。所测序列提交到GenBank数据库进行BLAST比对搜索相似序列，鉴定所测菌株Cdr-2的种属类别。</p><p>在构建菌株Cdr-2与克雷伯氏菌属典型菌株的系统发育树时，首先在LPSN数据库中检索克雷伯氏菌属(Klebsiella)下列出的菌种名，找到部分典型菌株的16S rRNA基因序列在Genbank中的登录号；其次运用ClustalW1.8.3程序将所选典型菌株与待测菌株Cdr-2的16S rRNA基因序列进行多序列比对；最后运用分子进化遗传分析软件MEGA7.0.26构建N-J系统发育树。系统发育树的可靠性检测的自举值设定为1000次，以大肠杆菌(E. coli)典型菌株做外群。</p></sec></sec><sec id="s7"><title>3. 结果与分析</title><sec id="s7_1"><title>3.1. 抗镉细菌的分离纯化</title><p>从水稻根际土壤样品中分离筛选到4株抗镉细菌，Cdr-1#~Cdr-4#。其菌落呈圆形，光滑湿润，淡黄色，边缘较平整。</p></sec><sec id="s7_2"><title>3.2. 菌株的抗镉能力和镉去除率检测</title><p>根据观察各菌株在培养液中的菌体生长浑浊程度判断，菌株Cdr-1在Cd<sup>2+</sup>浓度400 mg/L和600 mg/L的培养液中不生长，其它三个菌株都能耐受Cd<sup>2+</sup>浓度600 mg/L。</p><p>实验测得镉浓度的标准曲线拟合公式：Abs = 0.61510 Conc + 0.028249 (R = 0.9987)。各抗镉菌株对镉离子吸附去除能力分析结果见表2。结果表明在实验条件下，各菌株在含镉培养基中生长繁殖后，镉离子吸附去除率在50%左右。在初始镉400 mg/L培养液生长时，菌株Cdr-4的吸附去除率最高，为65.30%，其次是菌株Cdr-2，为61.27%。</p><table-wrap id="table2" ><label><xref ref-type="table" rid="table2">Table 2</xref></label><caption><title> Detection results of biosorption and removal of cadmium ion capability of the cadmium-resistant bacteri</title></caption><table><tbody><thead><tr><th align="center" valign="middle" >菌株编号</th><th align="center" valign="middle" >初始镉浓度(mg/L)</th><th align="center" valign="middle" >稀释倍数</th><th align="center" valign="middle" >吸光值 (228 nm)</th><th align="center" valign="middle" >测定镉浓度 (mg/L)</th><th align="center" valign="middle" >残留镉浓度 (mg/L)</th><th align="center" valign="middle" >镉去除率 (%)</th></tr></thead><tr><td align="center" valign="middle" >Cdr-1</td><td align="center" valign="middle" >200</td><td align="center" valign="middle" >200</td><td align="center" valign="middle" >0.3195</td><td align="center" valign="middle" >0.4735</td><td align="center" valign="middle" >94.70</td><td align="center" valign="middle" >52.65</td></tr><tr><td align="center" valign="middle" >Cdr-1</td><td align="center" valign="middle" >400</td><td align="center" valign="middle" >400</td><td align="center" valign="middle" >0.2897</td><td align="center" valign="middle" >0.4215</td><td align="center" valign="middle" >168.60</td><td align="center" valign="middle" >57.85</td></tr><tr><td align="center" valign="middle" >Cdr-1</td><td align="center" valign="middle" >600</td><td align="center" valign="middle" >600</td><td align="center" valign="middle" >0.3279</td><td align="center" valign="middle" >0.4872</td><td align="center" valign="middle" >292.32</td><td align="center" valign="middle" >51.28</td></tr><tr><td align="center" valign="middle" >Cdr-2</td><td align="center" valign="middle" >200</td><td align="center" valign="middle" >200</td><td align="center" valign="middle" >0.3320</td><td align="center" valign="middle" >0.4938</td><td align="center" valign="middle" >98.76</td><td align="center" valign="middle" >50.62</td></tr><tr><td align="center" valign="middle" >Cdr-2</td><td align="center" valign="middle" >400</td><td align="center" valign="middle" >400</td><td align="center" valign="middle" >0.2665</td><td align="center" valign="middle" >0.3873</td><td align="center" valign="middle" >154.92</td><td align="center" valign="middle" >61.27</td></tr><tr><td align="center" valign="middle" >Cdr-2</td><td align="center" valign="middle" >600</td><td align="center" valign="middle" >600</td><td align="center" valign="middle" >0.3581</td><td align="center" valign="middle" >0.5363</td><td align="center" valign="middle" >321.78</td><td align="center" valign="middle" >46.37</td></tr><tr><td align="center" valign="middle" >Cdr-3</td><td align="center" valign="middle" >200</td><td align="center" valign="middle" >200</td><td align="center" valign="middle" >0.3322</td><td align="center" valign="middle" >0.4941</td><td align="center" valign="middle" >98.82</td><td align="center" valign="middle" >50.59</td></tr><tr><td align="center" valign="middle" >Cdr-3</td><td align="center" valign="middle" >400</td><td align="center" valign="middle" >400</td><td align="center" valign="middle" >0.3322</td><td align="center" valign="middle" >0.4941</td><td align="center" valign="middle" >197.64</td><td align="center" valign="middle" >50.59</td></tr><tr><td align="center" valign="middle" >Cdr-3</td><td align="center" valign="middle" >600</td><td align="center" valign="middle" >600</td><td align="center" valign="middle" >0.3340</td><td align="center" valign="middle" >0.4971</td><td align="center" valign="middle" >298.26</td><td align="center" valign="middle" >50.29</td></tr><tr><td align="center" valign="middle" >Cdr-4</td><td align="center" valign="middle" >200</td><td align="center" valign="middle" >200</td><td align="center" valign="middle" >0.3239</td><td align="center" valign="middle" >0.4907</td><td align="center" valign="middle" >98.14</td><td align="center" valign="middle" >50.93</td></tr><tr><td align="center" valign="middle" >Cdr-4</td><td align="center" valign="middle" >400</td><td align="center" valign="middle" >400</td><td align="center" valign="middle" >0.2417</td><td align="center" valign="middle" >0.3470</td><td align="center" valign="middle" >138.80</td><td align="center" valign="middle" >65.30</td></tr><tr><td align="center" valign="middle" >Cdr-4</td><td align="center" valign="middle" >600</td><td align="center" valign="middle" >600</td><td align="center" valign="middle" >0.3286</td><td align="center" valign="middle" >0.4883</td><td align="center" valign="middle" >292.98</td><td align="center" valign="middle" >51.17</td></tr></tbody></table></table-wrap><p>表2. 抗镉菌株对镉离子吸附去除能力检测分析结果</p></sec><sec id="s7_3"><title>3.3. 菌株对水稻种子萌发的影响</title><p>种子催芽48 hr后，所有水稻种子已破口露白，都能正常萌发，说明水稻种子的活力正常。培养48 hr 后观察，2#组、3#组水稻芽苗的长势与空白对照基本一致，1#组显得稍矮，4#组较差。结果表明Cdr-2菌株和Cdr-3菌株对水稻芽苗没有病害感染作用。</p></sec><sec id="s7_4"><title>3.4. 菌株对镉胁迫水稻幼苗生长的影响</title><p>培养15天后，各水培盒中水稻幼苗的长势情况见图1。直观显示1#和2#长势相当；3#与1#相比株高增加非常明显；4#、5#、6#的幼苗有营养不良、黄化萎蔫迹象。结果表明，10 mg/L的镉离子对水稻幼苗茎秆部分生长的胁迫作用不明显；Cdr-2菌株对无镉胁迫水稻幼苗的正常生长具有促进作用；Cdr-2菌株与10 mg/L的镉离子处理组(4#)、Cdr-3菌株处理组(5#)、Cdr-3菌株与10 mg/L的镉离子处理组(6#)中水稻幼苗的生长遭受胁迫抑制。</p><p>图1. 各水培盒中水稻幼苗的长势情况照片(左→右处理编号1#~6#)</p><p>水稻幼苗的生理指标测量及其分析结果见表3。数据显示，10 mg/L镉胁迫组(编号2#)的根长比正常对照组(编号1#)显著降低，表明镉离子能够引起对根细胞的生长发育直接毒害作用。菌株Cdr-2处理组(编号3#)的株高值、干重值都最大，表明菌株Cdr-2对水稻幼苗生长有显著的促进作用。菌株Cdr-3处理组(编号5#)、含10 mg/L镉离子处理组(编号2#、4#、6#)株高、根长、干重的指标值都较正常对照组(编号1#)低，表明在含10 mg/L的镉离子水培环境中，菌株Cdr-2更加重了对水稻幼苗的胁迫作用，在不含镉或者含10 mg/L的镉离子水培环境中，Cdr-3菌株都抑制水稻幼苗的生长。</p><table-wrap id="table3" ><label><xref ref-type="table" rid="table3">Table 3</xref></label><caption><title> Detection and analysis results of the physiological indexes of rice-seedling</title></caption><table><tbody><thead><tr><th align="center" valign="middle"  rowspan="2"  >编号</th><th align="center" valign="middle"  rowspan="2"  >组名</th><th align="center" valign="middle"  rowspan="2"  >叶片众数</th><th align="center" valign="middle"  colspan="2"  >株高/cm</th><th align="center" valign="middle"  colspan="2"  >根长/cm</th><th align="center" valign="middle"  rowspan="2"  >干重均值/g</th></tr></thead><tr><td align="center" valign="middle" >均值</td><td align="center" valign="middle" >标准差</td><td align="center" valign="middle" >均值</td><td align="center" valign="middle" >标准差</td></tr><tr><td align="center" valign="middle" >1#</td><td align="center" valign="middle" >正常对照组</td><td align="center" valign="middle" >4</td><td align="center" valign="middle" >16.1</td><td align="center" valign="middle" >2.132</td><td align="center" valign="middle" >17.4</td><td align="center" valign="middle" >3.017</td><td align="center" valign="middle" >0.7163</td></tr><tr><td align="center" valign="middle" >2#</td><td align="center" valign="middle" >10 mg/L镉胁迫组</td><td align="center" valign="middle" >4</td><td align="center" valign="middle" >15.5</td><td align="center" valign="middle" >3.697</td><td align="center" valign="middle" >9.3</td><td align="center" valign="middle" >2.139</td><td align="center" valign="middle" >0.5324</td></tr><tr><td align="center" valign="middle" >3#</td><td align="center" valign="middle" >Cd-2菌株处理组</td><td align="center" valign="middle" >4</td><td align="center" valign="middle" >28.7</td><td align="center" valign="middle" >4.138</td><td align="center" valign="middle" >12.3</td><td align="center" valign="middle" >1.231</td><td align="center" valign="middle" >0.9203</td></tr><tr><td align="center" valign="middle" >4#</td><td align="center" valign="middle" >10 mg/L镉胁迫 + Cd-2菌株处理组</td><td align="center" valign="middle" >3</td><td align="center" valign="middle" >10.5</td><td align="center" valign="middle" >4.137</td><td align="center" valign="middle" >6.5</td><td align="center" valign="middle" >2.082</td><td align="center" valign="middle" >0.3176</td></tr><tr><td align="center" valign="middle" >5#</td><td align="center" valign="middle" >Cd-3菌株处理组</td><td align="center" valign="middle" >3</td><td align="center" valign="middle" >7.7</td><td align="center" valign="middle" >1.824</td><td align="center" valign="middle" >6.5</td><td align="center" valign="middle" >1.743</td><td align="center" valign="middle" >0.3019</td></tr><tr><td align="center" valign="middle" >6#</td><td align="center" valign="middle" >10 mg/L镉胁迫 + Cd-3菌株处理组</td><td align="center" valign="middle" >3</td><td align="center" valign="middle" >6.5</td><td align="center" valign="middle" >2.227</td><td align="center" valign="middle" >5.3</td><td align="center" valign="middle" >1.419</td><td align="center" valign="middle" >0.2003</td></tr></tbody></table></table-wrap><p>表3. 水稻幼苗生理指标测量与分析结果</p></sec><sec id="s7_5"><title>3.5. 菌株Cdr-2的16S rRNA基因序列分析</title><p>测得Cdr-2菌株16S rRNA基因序列在GenBank中进行BLAST搜索比对分析，显示所测序列仅与Klebsiella aerogenes的一些菌株的16S rRNA基因具有99%以上的同源性一致性。结果表明菌株Cdr-2的亲缘种是Klebsiella aerogenes (产气克雷伯氏菌)。菌株Cdr-2与克雷伯氏菌属的一些典型菌株构建的系统发育树见图2，表明菌株Cdr-2与Klebsiella aerogenes G3_AM (登录号MT373520)聚类在一个分枝，两者的亲缘关系最近。</p><p>图2. 基于16S rRNA基因构建菌株Cdr-2与克雷伯氏菌属典型菌株的N-J系统发育树</p></sec></sec><sec id="s8"><title>4. 结论</title><p>从水稻根际土壤中分离纯化得到4株抗镉细菌，菌株Cdr-1~Cdr-4。在实验条件下，各菌株在含镉培养液中生长繁殖后，镉离子吸附去除率在50%左右。其中在含镉400 mg/L培养液中，菌株Cdr-4的镉离子吸附去除率为65.30%，菌株Cdr-2为61.27%。水培结果表明，10 mg/L的镉离子对水稻幼苗茎秆生长的胁迫作用不明显，但对根的生长发育有明显的毒害作用；Cdr-2菌株对无镉胁迫水稻幼苗的正常生长具有促进作用；在含10 mg/L的镉离子水培环境中，菌株Cdr-2更加重了对水稻幼苗的胁迫作用；在不含镉或者含10 mg/L的镉离子水培环境中，Cdr-3菌株都抑制水稻幼苗的生长。经16S rRNA基因测序，鉴定Cdr-2菌株为产气克雷伯氏菌(Klebsiella aerogenes)。研究发现了产气克雷伯氏菌Cdr-2菌株的强抗镉性以及促水稻幼苗生长性能，为该菌株的进一步开发利用奠定了基础。</p></sec><sec id="s9"><title>基金项目</title><p>湖南省教育厅资助科研项目(19K030)；湖南省自然科学基金项目(2020JJ6026)。</p></sec><sec id="s10"><title>文章引用</title><p>张芯瑜,印宁鸿,陈丹丹,徐 樾,罗 婧,许爱清. 抗镉细菌分离鉴定及其对镉胁迫水稻幼苗生长的影响Isolation and Identification of Cadmium-Resistant Bacteria and Their Influence on Growth of Cadmium-Stressed Rice Seedlings[J]. 微生物前沿, 2023, 12(02): 63-70. https://doi.org/10.12677/AMB.2023.122008</p></sec><sec id="s11"><title>参考文献</title></sec></body><back><ref-list><title>References</title><ref id="hanspub.66857-ref1"><label>1</label><mixed-citation publication-type="other" xlink:type="simple">龚伟群, 潘根兴. 中国水稻中Cd吸收及其健康风险的有关问题[J]. 科技导报, 2006, 24(5): 43-48.</mixed-citation></ref><ref id="hanspub.66857-ref2"><label>2</label><mixed-citation publication-type="other" xlink:type="simple">李鑫. 土壤重金属污染防治法律制度研究[D]: [硕士学位论文]. 太原: 山西财经大学, 2012.</mixed-citation></ref><ref id="hanspub.66857-ref3"><label>3</label><mixed-citation publication-type="other" xlink:type="simple">李剑睿, 徐应明, 林大松, 等. 农田重金属污染原位钝化修复研究进展[J]. 生态环境学报, 2014, 23(4): 721-728.</mixed-citation></ref><ref id="hanspub.66857-ref4"><label>4</label><mixed-citation publication-type="other" xlink:type="simple">Liu, Z. (2014) Research Advance on the Mechanism of Cadmium Transport in Rice. Meteorological and Environmental Research, 5, 48-52.</mixed-citation></ref><ref id="hanspub.66857-ref5"><label>5</label><mixed-citation publication-type="other" xlink:type="simple">Clemens, S., Aarts, M.G.M., Thomine, S. and Verbruggen, N. (2013) Plant Science: The Key to Preventing Slow Cadmium Poisoning. Trends in Plant Science, 18, 92-99. &lt;br&gt;https://doi.org/10.1016/j.tplants.2012.08.003</mixed-citation></ref><ref id="hanspub.66857-ref6"><label>6</label><mixed-citation publication-type="other" xlink:type="simple">王学华, 戴力. 作物根系镉滞留作用及其生理生化机制[J]. 中国农业科学, 2016, 49(22): 4323-4341.</mixed-citation></ref><ref id="hanspub.66857-ref7"><label>7</label><mixed-citation publication-type="other" xlink:type="simple">吴博晗, 吴向阳, 李霞, 等. 镉对水稻及种植土壤影响的研究进展[J]. 江苏农业科学, 2021, 49(18): 25-33.</mixed-citation></ref><ref id="hanspub.66857-ref8"><label>8</label><mixed-citation publication-type="other" xlink:type="simple">韩笑, 卢磊. 根际促生菌提高水稻对非生物胁迫耐受性的研究进展[J]. 生命科学, 2019, 31(3): 289-295.</mixed-citation></ref><ref id="hanspub.66857-ref9"><label>9</label><mixed-citation publication-type="other" xlink:type="simple">张亚东, 刘海学, 赵里曼. 作物镉胁迫研究进展及其在水稻中的应用展望[J]. 种子科技, 2021, 39(2): 30-31, 34.</mixed-citation></ref><ref id="hanspub.66857-ref10"><label>10</label><mixed-citation publication-type="other" xlink:type="simple">刘仲齐, 张长波, 黄永春. 水稻各器官镉阻控功能的研究进展[J]. 农业环境科学学报, 2019, 38(4): 721-727.</mixed-citation></ref><ref id="hanspub.66857-ref11"><label>11</label><mixed-citation publication-type="other" xlink:type="simple">黄永春, 张长波, 任兴华, 等. 土壤和茎基部镉含量对稻米镉污染风险的影响[J]. 农业环境科学学报, 2020, 297(5): 989-999.</mixed-citation></ref><ref id="hanspub.66857-ref12"><label>12</label><mixed-citation publication-type="other" xlink:type="simple">Xue, W., Wang, P., Tang, L., et al. (2021) Citric Acid Inhibits Cd Uptake by Improving the Preferential Transport of Mn and Triggering the Defense Response of Amino Acids in Grains. Ecotoxicology and Environmental Safety, 211, Article ID: 111921. &lt;br&gt;https://doi.org/10.1016/j.ecoenv.2021.111921</mixed-citation></ref><ref id="hanspub.66857-ref13"><label>13</label><mixed-citation publication-type="other" xlink:type="simple">Sebastian, A. and Prasad, M.N.V. (2018) Exogenous Citrate and Malate Alleviate Cadmium Stress in Oryza sativa L.: Probing Role of Cadmium Localization and Iron Nutrition. Ecotoxicology and Environmental Safety, 166, 215-222.  
&lt;br&gt;https://doi.org/10.1016/j.ecoenv.2018.09.084</mixed-citation></ref><ref id="hanspub.66857-ref14"><label>14</label><mixed-citation publication-type="other" xlink:type="simple">Hansen, J.C., Grn, P., Jespersen, B.A., et al. (1989) Cadmium Exposure in Denmark. Based on Analyses of Liver and Kidney Tissues. Danish Medical Bulletin, 36, 499-502.</mixed-citation></ref><ref id="hanspub.66857-ref15"><label>15</label><mixed-citation publication-type="other" xlink:type="simple">Satarug, S., Baker, J.R., Reilly, P.E.B., et al. (2002) Cadmium Levels in the Lung, Liver, Kidney Cortex and Urine Samples from Australians without Occupational Exposure to Metals. Archives of Environmental Health, 57, 69-77.  
&lt;br&gt;https://doi.org/10.1080/00039890209602919</mixed-citation></ref><ref id="hanspub.66857-ref16"><label>16</label><mixed-citation publication-type="other" xlink:type="simple">Lech, T. and Sadlik, J.K. (2017) Cadmium Concentration in Human Autopsy Tissues. Biological Trace Element Research, 179, 172-177. &lt;br&gt;https://doi.org/10.1007/s12011-017-0959-5</mixed-citation></ref><ref id="hanspub.66857-ref17"><label>17</label><mixed-citation publication-type="other" xlink:type="simple">曾晓希. 抗重金属微生物的筛选及其抗镉机理和镉吸附特性研究[D]: [博士学位论文]. 长沙: 中南大学, 2010.</mixed-citation></ref><ref id="hanspub.66857-ref18"><label>18</label><mixed-citation publication-type="other" xlink:type="simple">丁自立. 抗耐镉, 铬重金属菌株筛选及水稻根际土壤微生态效应研究[D]: [博士学位论文]. 武汉: 华中农业大学, 2016.</mixed-citation></ref><ref id="hanspub.66857-ref19"><label>19</label><mixed-citation publication-type="other" xlink:type="simple">Wang, X., Xu, Q., Hu, K., et al. (2023) A Coculture of Enterobacter and Comamonas Reduces Cd Accumulation in Rice. Molecular Plant-Microbe Interactions, 36, 95-108. &lt;br&gt;https://doi.org/10.1094/MPMI-09-22-0186-R</mixed-citation></ref><ref id="hanspub.66857-ref20"><label>20</label><mixed-citation publication-type="other" xlink:type="simple">刘玉玲. 抗镉细菌的筛选及其对水稻吸收积累镉的影响[D]: [硕士学位论文]. 长沙: 湖南农业大学, 2018.</mixed-citation></ref></ref-list></back></article>