Netotea Sergiu, Bertani Iris, Steindler Laura, Kerényi Adám, Venturi Vittorio, Pongor Sándor
Biological Research Center of the Hungarian Academy of Sciences, Szeged, Hungary.
Biol Direct. 2009 Feb 12;4:6. doi: 10.1186/1745-6150-4-6.
Quorum sensing (QS) is a form of gene regulation based on cell-density that depends on inter-cellular communication. While there are a variety of models for bacterial colony morphology, there is little work linking QS genes to movement in an open system.
The onset of swarming in environmental P. aeruginosa PUPa3 was described with a simplified computational model in which cells in random motion communicate via a diffusible signal (representing N-acyl homoserine lactones, AHL) as well as diffusible, secreted factors (enzymes, biosurfactans, i.e. "public goods") that regulate the intensity of movement and metabolism in a threshold-dependent manner. As a result, an "activation zone" emerges in which nutrients and other public goods are present in sufficient quantities, and swarming is the spontaneous displacement of this high cell-density zone towards nutrients and/or exogenous signals. The model correctly predicts the behaviour of genomic knockout mutants in which the QS genes responsible either for the synthesis (lasI, rhlI) or the sensing (lasR, rhlR) of AHL signals were inactivated. For wild type cells the model predicts sustained colony growth that can however be collapsed by the overconsumption of nutrients.
While in more complex models include self-orienting abilities that allow cells to follow concentration gradients of nutrients and chemotactic agents, in this model, displacement towards nutrients or environmental signals is an emergent property of the community that results from the action of a few, well-defined QS genes and their products. Still the model qualitatively describes the salient properties of QS bacteria, i.e. the density-dependent onset of swarming as well as the response to exogenous signals or cues.
群体感应（QS）是一种基于细胞密度的基因调控形式，依赖于细胞间通讯。虽然存在多种细菌菌落形态模型，但将群体感应基因与开放系统中的运动联系起来的研究较少。
利用一个简化的计算模型描述了环境中铜绿假单胞菌PUPa3群体游动的起始过程，在该模型中，随机运动的细胞通过一种可扩散信号（代表N-酰基高丝氨酸内酯，AHL）以及可扩散的分泌因子（酶、生物表面活性剂，即“公共物品”）进行通讯，这些因子以阈值依赖的方式调节运动强度和新陈代谢。结果，出现了一个“激活区”，其中存在足够数量的营养物质和其他公共物品，群体游动是这个高细胞密度区向营养物质和/或外源信号的自发移动。该模型正确地预测了基因组敲除突变体的行为，在这些突变体中，负责AHL信号合成（lasI、rhlI）或感应（lasR、rhlR）的群体感应基因被灭活。对于野生型细胞，该模型预测菌落持续生长，但营养物质的过度消耗会使其崩溃。
虽然在更复杂的模型中包括了使细胞能够跟随营养物质和趋化剂浓度梯度的自我定向能力，但在这个模型中，向营养物质或环境信号的移动是群落的一种涌现特性，是由少数几个明确的群体感应基因及其产物的作用导致的。该模型仍然定性地描述了群体感应细菌的显著特性，即群体游动的密度依赖性起始以及对外源信号或线索的反应。
