Hydrogen cross-feeding microbes form a functionally important subset of the human colonic microbiota. The three major hydrogenotrophic functional groups of the colon: sulphate-reducing bacteria (SRB), methanogens and reductive acetogens, have been linked to wide ranging impacts on host physiology, health and wellbeing. An existing mathematical model for microbial community growth and metabolism was combined with models for each of the three hydrogenotrophic functional groups. The model was further developed for application to the colonic environment via inclusion of responsive pH, host metabolite absorption and the inclusion of host mucins. Predictions of the model, using two existing metabolic parameter sets, were compared to experimental faecal culture datasets. Model accuracy varied between experiments and measured variables and was most successful in predicting the growth of high relative abundance functional groups, such as the Bacteroides, and short chain fatty acid (SCFA) production. Two versions of the colonic model were developed: one representing the colon with sequential compartments and one utilising a continuous spatial representation. When applied to the colonic environment, the model predicted pH dynamics within the ranges measured in vivo and SCFA ratios comparable to those in the literature. The continuous version of the model simulated relative abundances of microbial functional groups comparable to measured values, but predictions were sensitive to the metabolic parameter values used for each functional group. Sulphate availability was found to strongly influence hydrogenotroph activity in the continuous version of the model, correlating positively with SRB and sulphide concentration and negatively with methanogen concentration, but had no effect in the compartmentalised model version. Although the model predictions compared well to only some experimental measurements, the important features of the colon environment included make it a novel and useful contribution to modelling the colonic microbiota.

中文翻译：

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使用结肠微生物群模型检查氢交叉供料器

氢交叉喂养微生物形成了人类结肠微生物群的重要功能子集。结肠的三个主要的氢营养功能基团：硫酸盐还原细菌（SRB），产甲烷菌和还原性产乙酸菌，与对宿主生理，健康和福祉的广泛影响相关。现有的微生物群落生长和代谢的数学模型与三个氢营养功能基团的模型相结合。通过包含响应性pH，宿主代谢物吸收和包含宿主粘蛋白，进一步开发了该模型以应用于结肠环境。使用两个现有的代谢参数集对该模型的预测与实验性粪便培养数据集进行了比较。模型精度在实验和测量变量之间有所不同，并且在预测高相对丰度官能团（如拟杆菌和短链脂肪酸（SCFA）生产）的增长方面最成功。开发了两种版本的结肠模型：一种代表具有连续隔室的结肠，另一种利用连续的空间表示。当应用于结肠环境时，该模型可预测在体内测量的范围内的pH动态以及与文献中可比的SCFA比。该模型的连续版本模拟了与测量值相当的微生物功能组的相对丰度，但预测对用于每个功能组的代谢参数值敏感。在连续模型中，发现硫酸盐的可用性对氢营养活性有很大影响，与SRB和硫化物浓度呈正相关，与产甲烷菌浓度呈负相关，但在分区模型中则没有影响。尽管模型预测与仅一些实验测量结果进行了很好的比较，但结肠环境的重要特征包括它对建模结肠微生物群具有新颖而有用的贡献。