Bacterial communities communicate, regulate and coordinate their cooperative activities and physiological process by releasing, sensing and responding to small diffusible signal molecules such as acyl homoserine lactones (AHLs), auto-inducing oligo-peptides (AIPs) and autoinducer-2, a process referred to as Quorum sensing (QS). The QS mediated communication in rhizosphere associated bacterial communities significantly influence traits governing plant-microbe interactions. This study aimed to identify AHL-mediated QS signals in bacterial communities associated with rice rhizosphere using two AHL biosensors reporter strains Chromobacterium violaceum CV026 and Agrobacterium tumefaciens NTL4 (pZLR4). Approximately 375 bacterial isolates isolated from rice rhizosphere and screened using both the biosensors, detected 49 (13%) AHL positive isolates. The BOX-Polymerase Chain reaction (BOX-PCR) fingerprinting profiles of the 49 AHL positive isolates represented 11 distinct cluster groups. Subsequent 16S rRNA gene sequence analysis identified 11 different species affiliated to two different phyla; predominantly γ-proteobacteria, representing 5 genera and 1 genus in α-proteobacteria. Thin-layer chromatography (TLC) analysis detected diverse AHL profiles among the 11 AHL positive isolates with both substituted and unsubstituted acyl side chains of C4, C6 and C8 carbon. Further, AHL production in Acinetobacter lactucae, Aeromonas popoffii, Serratia oryzae, and Rhizobium wuzhouense is being reported for the first time. Detection of diverse AHLs from different groups of rhizobacteria associated with rice indicates that these signalling molecules may be involved in the regulation of rhizobacterial behaviour and symbiotic plant-microbe interactions. Future research on the role of AHLs in trans-kingdom communication particularly plant-microbe interaction using synthetic microbial community will enable in evaluating and developing potential plant specific bioproducts.

中文翻译：

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水稻根际相关细菌中多种N-酰基高丝氨酸内酯信号分子的检测

细菌群落通过释放、感知和响应小的可扩散信号分子，如酰基高丝氨酸内酯 (AHL)、自诱导寡肽 (AIP) 和自诱导剂-2，来交流、调节和协调它们的合作活动和生理过程，这一过程称为作为群体感应（QS）。根际相关细菌群落中 QS 介导的通信显着影响控制植物-微生物相互作用的性状。本研究旨在使用两种 AHL 生物传感器报告菌株紫色色杆菌 CV026 和根癌农杆菌 NTL4 (pZLR4) 在与水稻根际相关的细菌群落中鉴定 AHL 介导的 QS 信号。从水稻根际分离出大约 375 个细菌分离株并使用两种生物传感器进行筛选，检测到 49 个（13%）AHL 阳性分离株。49 个 AHL 阳性分离株的 BOX-聚合酶链反应 (BOX-PCR) 指纹图谱代表了 11 个不同的簇组。随后的 16S rRNA 基因序列分析确定了隶属于两个不同门的 11 个不同物种；主要是γ-变形菌，代表α-变形菌中的5个属和1个属。薄层色谱 (TLC) 分析在 11 个 AHL 阳性分离株中检测到不同的 AHL 谱，它们具有 C4、C6 和 C8 碳的取代和未取代酰基侧链。此外，首次报道了在乳酸不动杆菌、流行气单胞菌、米沙雷氏菌和五洲根瘤菌中产生 AHL。检测到来自与水稻相关的不同根际细菌群的不同 AHL，表明这些信号分子可能参与了根际细菌行为和植物-微生物共生相互作用的调节。未来关于 AHLs 在跨界交流中的作用的研究，特别是使用合成微生物群落的植物 - 微生物相互作用，将有助于评估和开发潜在的植物特异性生物产品。