Abudoleh Suha M, Mahasneh Adel M
Faculty of Pharmacy, Isra University, Amman, Jordan.
Department of Biological Sciences, Faculty of Science, The University of Jordan, Amman, Jordan.
Avicenna J Med Biotechnol. 2017 Jan-Mar;9(1):23-30.
Quorum Sensing (QS) is a mechanism used by bacteria to determine their physiological activities and coordinate gene expression based on cell to cell signaling. Many bacterial physiological functions are under the regulation of quorum sensing such as virulence, luminescence, motility, sporulation and biofilm formation. The aim of the present study was to isolate and characterize Quorum Sensing Inhibitory (QSI) substances from epiphytic bacteria residing on wild berries surfaces.
Fifty nine bacterial isolates out of 600 screened bacteria were successfully isolated. These bacteria were obtained from berry surfaces of different plants in the wild forests of Ajloun-Jordan. Screening for QSI activity using ATCC 12472 monitor strain, resulted in isolating 6 isolates exhibiting QSI activity only, 11 isolates with QSI and antibacterial activity, and 42 isolates with antibacterial activity only. Three potential isolates S 130, S 153, and S 664, were gram positive rods and spore formers, catalase positive and oxidase negative. These were chosen for further testing and characterization.
Different solvent extraction of the QSI substances based on polarity indicated that the activity of S 130 was in the butanol extract, S 153 activity in both chloroform and butanol; and for S 664, the activity was detected in the hexane extract. The chloroform extract of S 153 and hexane extract of S 664 were proteinaceous in nature while QSI substances of the butanol extract of S 130 and S 153 were non-proteinaceous. All the tested QSI substances showed a marked thermal stability when subjected at several time intervals to 70°, with the highest stability observed for the butanol extract of S 153. Assessing the QSI substances using violacein quantification assay revealed varying degrees of activity depending upon the extracting solvent, type of the producer bacteria and the concentration of the substances.
This study highlighted the potential of untapped reservoirs in nature to be used as a source of unique metabolite that may be further developed for therapy. The potential QSI substances included in this study are just one aspect to be further analyzed for use as biopharmaceutical agents.
群体感应（QS）是细菌用于根据细胞间信号传导来确定其生理活动并协调基因表达的一种机制。许多细菌的生理功能都受群体感应的调控，如毒力、发光、运动性、孢子形成和生物膜形成。本研究的目的是从野生浆果表面的附生细菌中分离并鉴定群体感应抑制（QSI）物质。
在筛选的600株细菌中成功分离出59株细菌分离物。这些细菌取自约旦阿杰伦野生森林中不同植物的浆果表面。使用ATCC 12472监测菌株筛选QSI活性，结果分离出6株仅表现出QSI活性的分离物、11株具有QSI和抗菌活性的分离物以及42株仅具有抗菌活性的分离物。三株潜在的分离物S 130、S 153和S 664为革兰氏阳性杆菌且形成孢子，过氧化氢酶阳性，氧化酶阴性。选择它们进行进一步测试和鉴定。
基于极性对QSI物质进行不同溶剂萃取表明，S 130的活性存在于丁醇提取物中，S 153的活性存在于氯仿和丁醇提取物中；对于S 664，在己烷提取物中检测到活性。S 153的氯仿提取物和S 664的己烷提取物本质上是蛋白质性的，而S 130和S 153丁醇提取物中的QSI物质是非蛋白质性的。当在几个时间间隔内将所有测试的QSI物质置于70°时，它们均表现出显著的热稳定性，其中S 153丁醇提取物的稳定性最高。使用紫色杆菌素定量测定法评估QSI物质，结果显示其活性程度因萃取溶剂、产生菌类型和物质浓度而异。
本研究突出了自然界中未开发资源作为独特代谢物来源的潜力，这些代谢物可进一步开发用于治疗。本研究中包含的潜在QSI物质只是作为生物制药剂需进一步分析的一个方面。
