Segura Ana, Molina Lázaro
Environmental Protection Department, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Madrid, Spain.
Front Microbiol. 2023 Jul 27;14:1205860. doi: 10.3389/fmicb.2023.1205860. eCollection 2023.
Although there is some evidence to suggest that LuxR-solo proteins participate in inter-species or even inter-kingdom communication, most of the LuxR-solo protein functions are unknown. We have characterized the LuxR402 regulator of sp. HR1a, a bacterial strain with the ability to establish high numbers in the plant rhizosphere and able to degrade a wide range of polycyclic aromatic hydrocarbons. LuxR402 controls the aggregation state of the bacterial culture; cultures of a mutant strain lacking this regulator flocculate in less than 3 h without agitation. We have demonstrated that the bacterial surface of the mutant is highly hydrophobic and that the mutant cells assimilate sugars slower than the wild-type. The flocculation mechanism has been demonstrated to be involved in the survival of the strain under unfavorable conditions; the gene is repressed and produces flocculation in the presence of salicylate, a substrate that, although being assimilated by , is toxic to cells at high concentrations. The flocculation of cultures in industrial setups has mainly been achieved through the addition of chemicals; these studies open up the possibility of controlling the flocculation by regulating the level of expression of the gene.
尽管有一些证据表明孤独型LuxR蛋白参与种间甚至跨界交流，但大多数孤独型LuxR蛋白的功能仍不清楚。我们已经对sp. HR1a菌株的LuxR402调节因子进行了表征，该细菌菌株能够在植物根际大量繁殖，并能够降解多种多环芳烃。LuxR402控制细菌培养物的聚集状态；缺乏这种调节因子的突变菌株的培养物在不搅拌的情况下不到3小时就会絮凝。我们已经证明突变体的细菌表面具有高度疏水性，并且突变体细胞比野生型细胞吸收糖分的速度更慢。絮凝机制已被证明与该菌株在不利条件下的存活有关；该基因在水杨酸盐存在下受到抑制并产生絮凝，水杨酸盐是一种底物，虽然能被该菌株同化，但在高浓度下对细胞有毒。工业装置中培养物的絮凝主要通过添加化学物质来实现；这些研究为通过调节该基因的表达水平来控制絮凝开辟了可能性。
