群体感应信号物质对吡咯伯克霍尔德氏菌JK-SH007在杨树内定殖的影响

为了明确杨树溃疡病生防菌吡咯伯克霍尔德氏菌JK-SH007的群体感应系统是否与其内生定殖相关,本文通过群体感应指示菌紫色杆菌CV026和液相色谱串联四级杆飞行时间质谱技术(HPLC-Q-TOF-MS)确定其群体感应信号物质种类,并利用结晶紫染色、菌体回收、GFP标记等技术,研究其群体感应信号物质对该菌株生物膜及在杨树苗内的定殖能力的影响。结果表明,菌株JK-SH007产生的群体感应信号物质为含8个碳原子酰基侧链的辛酰基-L-高丝氨酸内酯(C8-HSL)。群体感应信号物质C8-HSL的添加对该菌株生物膜及在杨树苗内的定殖能力有影响,并且呈现低浓度促进,较高浓度抑制的规律。C8-HSL的添加与菌株JK-SH007生物膜的OD值和菌体量具有显著相关性,相关系数分别为0.923和0.756。当添加1.0%C8-HSL终浓度达到5×10^-8 g/L时,菌株JK-SH007生物膜的形成量达到峰值。荧光显微镜镜检发现,当添加100μL C8-HSL时,杨树组培苗根和茎中GFP荧光标记的菌株JK-SH007的定殖数量明显较CK多。菌株JK-SH007的群体感应与其在杨树内的内生定殖能力密切相关,群体感应信号物质C8-HSL具有增强菌株JK-SH007内生定殖的能力,同时也表明该物质有利于该菌株生防效果的发挥。

Effect of Quorum Sensing Signal Substance on Endogenous Colonization of Burkholderia pyrrocinia JK-SH007 in Poplar Seedlings

In order to clarify whether the quorum sensing of Burkholderia pyrrocinia JK-SH007 with high biocontrol activity against poplar cancer is related to its endogenous colonization, the type of quorum sensing signal substance of JK-SH007 strain was determined by the quorum sensing indicator Chromobacterium violaceum CV026 and liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry (HPLC-Q-TOF-MS). The effects of quorum sensing signal substance on the biofilm and endogenous colonization of JK-SH007 strain in poplar seedlings were studied by crystal violet staining, colonization recovery and GFP labeling. The results showed that the quorum sensing signal substance produced by JK-SH007 strain was N-octanoyl-DL-homoserine lactone (C₈-HSL) containing acyl side chain of 8 carbon atoms. The addition of quorum sensing signal substance C₈-HSL had a certain effect on the biofilm of the strain and the colonization ability of the strain in poplar seedlings, showing promotion at low concentrations and inhibition at higher concentrations. The addition of C₈-HSL was significantly correlated with the OD value and the amount of bacteria in the strain JK-SH007 biofilm, which were 0.923 and 0.756, respectively. When 1.0% (volume fraction) of C₈-HSL was added (final concentration reached 5×10^-8 g/L), the amount of JK-SH007 biofilm formation peaked. Fluorescence microscopy revealed that when 100 μL of C₈-HSL were added, the number of colonized GFP fluorescently labeled strain JK-SH007 in roots and stems of poplar tissue culture was significantly higher than that of CK. The above results indicate that the quorum sensing of JK-SH007 strain is closely related to its endogenous colonization ability in poplar seedlings. The quorum sensing signal substance C₈-HSL can enhance the endogenous colonization effect of strain JK-SH007 in poplar seedlings, and also indicates that the substance is beneficial to the biocontrol effect of the strain.