Kanagasabhapathy M, Yamazaki G, Ishida A, Sasaki H, Nagata S
Environmental Biochemistry Group, Research Center for Inland Seas, Kobe University, Higashinada-ku, Kobe SK-82475, Japan.
Lett Appl Microbiol. 2009 Nov;49(5):573-9. doi: 10.1111/j.1472-765X.2009.02712.x. Epub 2009 Aug 11.
Several Gram-negative bacterial species use N-acyl homoserine lactone (AHL) molecules as quorum-sensing (QS) signals to regulate various biological functions. Similarly, various bacteria can stimulate, inhibit or inactivate QS signals in other bacteria by producing molecules called as quorum-sensing inhibitors (QSI). Our aim was to screen and identify the epibiotic bacteria associated with brown algae for their ability of producing QS-inhibiting activity.
QSI screenings were conducted on several epibiotic bacteria isolated from a marine brown alga Colpomenia sinuosa, using Serratia rubidaea JCM 14263 as an indicator organism. Strain JCM 14263 controls the production of red pigment, prodigiosin by AHL QS. Out of 96 bacteria, which were isolated from the surface of the brown alga, 12% of strains showed the ability to produce QSI, which was observed from the pigmentation inhibition on Ser. rubidaea JCM 14263 without affecting its growth. Phylogenetic analysis using 16S rRNA gene sequencing method demonstrated bacterial isolates showing QS inhibition-producing bacteria belonging to the Bacillaceae (Firmicutes), Pseudomonadaceae (Proteobacteria), Pseudoalteromonadaceae (Proteobacteria) and Vibrionaceae (Proteobacteria).
An appreciable percentage of bacteria isolated from the brown alga produced QSI-like compounds.
The screening method using Ser. rubidaea described in this report will facilitate the rapid identification of QSI-producing bacteria from marine environment. This study reveals new avenue for future environmental applications. This study also suggests that these algal epibiotic bacteria may play a role in the defensive mechanism for their host by producing QSI or QSI-like compounds to suppress the settlement of other competitive bacteria.
几种革兰氏阴性细菌利用N-酰基高丝氨酸内酯（AHL）分子作为群体感应（QS）信号来调节各种生物学功能。同样，各种细菌可以通过产生称为群体感应抑制剂（QSI）的分子来刺激、抑制或使其他细菌中的QS信号失活。我们的目的是筛选和鉴定与褐藻相关的表生细菌产生QS抑制活性的能力。
以深红沙雷氏菌JCM 14263为指示生物，对从海洋褐藻袋礁膜分离的几种表生细菌进行QSI筛选。菌株JCM 14263通过AHL QS控制红色色素灵菌红素的产生。从褐藻表面分离的96株细菌中，12%的菌株表现出产生QSI的能力，可以从对深红沙雷氏菌JCM 14263色素沉着的抑制作用中观察到，而不影响其生长。使用16S rRNA基因测序方法进行的系统发育分析表明，显示QS抑制作用的细菌分离株属于芽孢杆菌科（厚壁菌门）、假单胞菌科（变形菌门）、假交替单胞菌科（变形菌门）和弧菌科（变形菌门）。
从褐藻中分离出的相当比例的细菌产生了类似QSI的化合物。
本报告中描述的使用深红沙雷氏菌的筛选方法将有助于从海洋环境中快速鉴定产生QSI的细菌。本研究揭示了未来环境应用的新途径。本研究还表明，这些藻类表生细菌可能通过产生QSI或类似QSI的化合物来抑制其他竞争性细菌的定殖，从而在其宿主的防御机制中发挥作用。
