利用乙烯释放化合物，2-氯乙基膦酸，作为一种工具来研究细菌乙烯反应
Summary
The protocols outlined herein facilitate the convenient investigation of bacterial ethylene responses by utilizing 2-chloroethylphosphonic acid (CEPA). Ethylene is produced in situ through the decomposition of CEPA in an aqueous bacterial growth medium, circumventing the requirement for pure ethylene gas.
Abstract
Ethylene (C2H4) is a gaseous phytohormone that is involved in numerous aspects of plant development, playing a dominant role in senescence and fruit ripening. Exogenous ethylene applied during early plant development triggers the triple response phenotype; a shorter and thicker hypocotyl with an exaggerated apical hook. Despite the intimate relationship between plants and bacteria, the effect of exogenous ethylene on bacteria has been greatly overlooked. This is partly due to the difficulty of controlling gaseous ethylene within the laboratory without specialized equipment. 2-Chloroethylphosphonic acid (CEPA) is a compound that decomposes into ethylene, chlorine, and phosphate in a 1:1:1:1 molar ratio when dissolved in an aqueous medium of pH 3.5 or greater. Here we describe the use of CEPA to produce in situ ethylene for the investigation of ethylene response in bacteria using the fruit-associated, cellulose-producing bacterium Komagataeibacter xylinus as a model organism. The protocols described herein include both the verification of ethylene production from CEPA via the Arabidopsis thaliana triple response assay and the effects of exogenous ethylene on K. xylinus cellulose production, pellicle properties and colonial morphology. These protocols can be adapted to examine the effect of ethylene on other microbes using appropriate growth media and phenotype analyses. The use of CEPA provides researchers with a simple and efficient alternative to pure ethylene gas for the routine determination of bacterial ethylene response.
Introduction
烯烃乙烯（C 2 H 4）首次被发现在1901年的植物激素被观察到，豌豆苗，在使用煤气灯一个实验室中生长，显示出不正常的形态，其中茎（胚轴）为较短时，较厚的和弯曲相比普通豌豆苗横盘整理;表型后称为三重反应1,2。随后的研究表明，乙烯是一种调节多种发育过程如生长，应激反应，果实成熟衰老3。 拟南芥植物生物学研究模式生物的重要激素，已在关于其对乙烯反应得到很好的研究。几个乙烯反应突变体已经被分离通过利用在黑暗生长的答中观察到的三联反应表型拟南芥秧苗在乙烯1,4,5的存在。生物合成的前体为乙烯生产厂是1-一个minocyclopropane羧酸（ACC）6和三重反应测定期间通常用于增加内源性乙烯产量，导致三联响应表型1,4,5。
虽然乙烯反应被广泛研究在植物中，外源乙烯对细菌的效果大大充分研究，尽管细菌与植物的密切联系。一项研究报告指出某些假单胞菌株可以使用乙烯作为碳源和能源7的唯一来源生存。然而，只有两个研究已经证明，细菌乙烯反应。第一项研究表明， 铜绿假单胞菌 ，P的菌株荧光假单胞菌 ，P.恶臭 ，和P.丁香使用琼脂糖塞测定，其中熔融的琼脂糖用纯乙烯气8平衡的趋化性缓冲液混合分别朝向乙烯趋化。但是，据我们所知，没有出现过菲尔特采用纯乙烯气体呃报告表征细菌乙烯反应，可能是由于处理实验室气体没有专业设备的困难。细菌乙烯反应的第二份报告表明，乙烯增加细菌纤维素生产的影响基因表达的水果相关的细菌，Komagataeibacter（原Gluconacetobacter）xylinus 9。在这种情况下，乙烯-释放化合物，2-氯乙基膦酸（CEPA）用于细菌生长介质内就地产生乙烯，绕过用于纯乙烯气体或专门的设备的需要。
– 14通过一碱催化的，一级反应12 1的摩尔比高于pH 3.5 10,11：CEPA在1产生乙烯。 CEPA的降解在生产乙酯与pH和温度13,14和结果正相关烯，氯和磷酸盐。 CEPA提供兴趣研究细菌反应，乙烯与方便的替代乙烯气体的研究。
以下协议的总体目标是提供一种简单而有效的方法来研究细菌乙烯反应，并且包括从安排分解细菌生长培养基中生产乙烯的生理相关水平的验证，培养物pH的分析，以确保CEPA分解期间不受损细菌生长，和的乙烯对细菌形态和表型的影响的评估。我们演示使用K.这些协议xylinus，然而，这些协议可以适于通过使用适当的生长培养基中和表型分析，以研究在其它细菌乙烯反应。
Protocol
Representative Results
Discussion
此处所描述的方法使用的模式生物，K勾勒出在从CEPA 就地产生乙烯的细菌乙烯反应的研究xylinus。这种方法是非常有用的乙烯可以通过补充有pH值大于3.5 10,11-用CEPA否定为纯乙烯气或专门的实验室设备的需要的任何含水介质来制备。这种方法不限定于学习CEPA衍生乙烯对细菌的效果，但也可以适用于研究在真核生物乙烯反应。重要的是平行的对照实验，用磷酸盐和?…
Divulgations
The authors have nothing to disclose.
Acknowledgements
The authors thank Dr. Dario Bonetta for providing Arabidopsis thaliana seeds and for technical assistance in regards to the triple response assay, as well as Simone Quaranta for help with FT-IR. This work was supported by a Natural Sciences and Engineering Research Council of Canada Discovery Grant (NSERC-DG) to JLS, an Ontario Graduate Scholarship (OGS) to RVA, and a Queen Elizabeth II Graduate Scholarship in Science and Technology (QEII-GSST) to AJV.
Materials
| 1-aminocyclopropane carboxylic acid (ACC) | Sigma | A3903 | Biosynthetic precursor of ethylene in plants |
| 4-sector Petri dish | Phoenix Biomedical | CA73370-022 | For testing triple response |
| Agar | BioShop | AGR001.1 | To solidify medium |
| Canon Rebel T1i DLSR camera | Canon | 3818B004 | For pictures of pellicles |
| Cellulase from Trichoderma reesei ATCC 26921 | Sigma | C2730 | Aqueous solution |
| Citric acid | BioShop | CIT002.500 | For SH medium |
| Commercial bleach | Life Brand | 57800861874 | Bleach for seed sterilization |
| Concentrated HCl | BioShop | HCL666.500 | Hydrochloric acid for pH adjustment |
| Digital USB microscope | Plugable | N/A | For pictures of colonies |
| Ethephon (≥ 96%; 2-chloroethylphosphonic acid) | Sigma | C0143 | Ethylene-releasing compound |
| Glucose | BioBasic | GB0219 | For SH medium |
| Komagataeibacter xylinus ATCC 53582 | ATCC | 53582 | Bacterial cellulose-producing alphaproteobacterium |
| Microcentrifuge tube | LifeGene | LMCT1.7B | 1.7 mL microcentrifuge tube |
| Murashige and Skoog (MS) basal medium | Sigma | M5519 | Arabidopsis thaliana growth medium |
| Na2HPO4·7H2O | BioShop | SPD579.500 | Sodium phosphate, dibasic heptahydrate for SH medium |
| NaCl | BioBasic | SOD001.1 | Sodium chloride for saline and control solution |
| NaH2PO4·H2O | BioShop | SPM306.500 | Sodium phosphate, monobasic monohydrate for control solution |
| NaOH | BioShop | SHY700.500 | Sodium hydroxide for pH adjustment |
| Paraffin film | Parafilm | PM996 | For sealing plates and flasks |
| Peptone (bacteriological) | BioShop | PEP403.1 | For SH medium |
| Petroff-Hausser counting chamber | Hausser scientific | 3900 | Bacterial cell counting chamber |
| Polyethersulfone sterilization filter 0.2 µm | VWR | 28145-501 | For sterilizing cellulase |
| Sucrose | BioShop | SUC600.1 | Sucrose for MS medium |
| Yeast extract | BioBasic | G0961 | For SH medium |
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