Coexistence in the chemostat as a result of metabolic by-products
Coexistence in the chemostat as a result of metabolic by-products
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DOI：
10.1007/s00285-006-0012-3
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发表时间：
2006-10-01
影响因子：
1.9
通讯作者：
Flockerzi, Dietrich
中科院分区：
文献类型：
--
作者：
Hesseler, Julia;Schmidt, Julia K.;Flockerzi, Dietrich
经典恒化器模型假设竞争纯粹是剥削性的，并通过共同的、有限的和单一的资源来调节。然而，在实验室对与遗传性疾病囊性纤维化相关的病原体进行的实验中，发现了代谢副产物醋酸酯的产生、抑制和消费的特定物种特性。这些假设被实施到一个数学恒化器模型中，该模型由四个描述开放系统中两个物种竞争一个限制性营养物质的非线性常微分方程组组成。我们得到了经典的恒化器结果，发现我们的基本模型支持竞争排斥原理、系统的双稳态以及稳定共存。用实验测量的参数值进行了数值模拟，对分析结果进行了说明。作为我们基本模型的一个变体，模拟在混合培养中而不是在纯培养中进行治疗抗生素的测试，我们考虑引入一种致命的抑制剂，它不能被一个物种消除，并且对更强大的竞争对手具有选择性。我们讨论了与我们的实验模型系统相关的理论结果，并发现在代谢副产物作为一个物种的第二碳源而不是生产者的情况下，模拟与实验结果的定性行为一致。
Classical chemostat models assume that competition is purely exploitative and mediated via a common, limiting and single resource. However, in laboratory experiments with pathogens related to the genetic disease Cystic Fibrosis, species specific properties of production, inhibition and consumption of a metabolic by-product, acetate, were found. These assumptions were implemented into a mathematical chemostat model which consists of four nonlinear ordinary differential equations describing two species competing for one limiting nutrient in an open system. We derive classical chemostat results and find that our basic model supports the competitive exclusion principle, the bistability of the system as well as stable coexistence. The analytical results are illustrated by numerical simulations performed with experimentally measured parameter values. As a variant of our basic model, mimicking testing of antibiotics for therapeutic treatments in mixed cultures instead of pure ones, we consider the introduction of a lethal inhibitor, which cannot be eliminated by one of the species and is selective for the stronger competitor. We discuss our theoretical results in relation to our experimental model system and find that simulations coincide with the qualitative behavior of the experimental result in the case where the metabolic by-product serves as a second carbon source for one of the species, but not the producer.