PDF(Pubmed)
Abstract：
In recent years, the production of volatile fatty acids (VFA) through mixed culture fermentation (MCF) has been gaining attention. Most authors have focused on the fermentation of carbohydrates, while other possible substrates, such as proteins, have not been considered. Moreover, there is little information about how operational parameters affect the microbial communities involved in these processes, even though they are strongly related to reactor performance and VFA selectivity. Hence, this study aims to evaluate how microbial composition changes according to three different parameters (pH, type of protein and micronutrient addition) during anaerobic fermentation of protein-rich side streams. For this, two continuous stirred tank reactors (CSTR) were fed with two different proteins (casein and gelatine) and operated at different conditions: three pH values (5.0, 7.0 and 9.0) with only macronutrients supplementation and two pH values (5.0 and 7.0) with micronutrients\' supplementation as well. Firmicutes, Proteobacteria and Bacteroidetes were the dominant phyla in the two reactors at all operational conditions, but their relative abundance varied with the parameters studied. At pH 7.0 and 9.0, the microbial composition was mainly affected by protein type, while at acidic conditions the driving force was the pH. The influence of micronutrients was dependent on the pH and the protein type, with a special effect on Clostridiales and Bacteroidales populations. Overall, this study shows that the acidogenic microbial community is affected by the three parameters studied and the changes in the microbial community can partially explain the macroscopic results, especially the process selectivity.
摘要：
近年来,通过混合培养发酵（MCF）生产挥发性脂肪酸（VFA）已引起人们的关注。大多数作者都专注于碳水化合物的发酵，而其他可能的基板，如蛋白质，没有被考虑。此外，关于操作参数如何影响这些过程中涉及的微生物群落的信息很少，即使它们与反应器性能和VFA选择性密切相关。因此，这项研究旨在评估微生物组成如何根据三个不同的参数(pH，蛋白质和微量营养素添加的类型）在富含蛋白质的侧流的厌氧发酵过程中。为此，在两个连续搅拌釜反应器(CSTR)中加入两种不同的蛋白质(酪蛋白和明胶),并在不同的条件下操作:三个pH值(5.0、7.0和9.0),仅补充大量营养素;两个pH值(5.0和7.0),同时补充微量营养素。Firmicutes,在所有操作条件下，变形杆菌和拟杆菌是两个反应器中的优势门，但是它们的相对丰度随研究参数的变化而变化。在pH7.0和9.0时，微生物组成主要受蛋白质类型的影响，而在酸性条件下驱动力是pH。微量营养素的影响取决于pH值和蛋白质类型，对梭菌和拟杆菌种群有特殊的影响。总的来说,这项研究表明，产酸微生物群落受所研究的三个参数的影响，微生物群落的变化可以部分解释宏观结果，尤其是过程选择性。
