Effect of high concentration of ammonium on production of n-caproate: Recovery of a high-value biochemical from food waste via lactate-driven chain elongation
Effect of high concentration of ammonium on production of n-caproate: Recovery of a high-value biochemical from food waste via lactate-driven chain elongation
复制标题
高浓度铵对正己酸生产的影响：通过乳酸驱动的链伸长从食物垃圾中回收高价值生化物质
DOI：
10.1016/j.wasman.2021.04.015
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发表时间：
2021
期刊：
影响因子：
8.1
通讯作者：
Li Dong
中科院分区：
文献类型：
--
作者：
Wei Yong;Ren Bing;Zheng Shaorui;Feng Xin;He Yong;Zhu Xiaoyu;Zhou Lixiang;Li Dong
在食物垃圾发酵过程中不可避免地会出现氨的积累，这对将食物垃圾转化为高价值生化正己酸盐（一种中链羧酸盐）的链延伸工艺的应用提出了挑战。本研究首次探讨了铵对乳酸驱动链延伸过程的抑制作用。在1 - 4 g L−1的铵浓度下，短期暴露于梭菌iv主导的链延长反应器微生物组，n-己酸产量线性下降25-80%。高水平的铵（≥5 g L−1）可能导致链延伸失败，将产物从正己酸转移到丙酸。参与机制揭示了铵将微生物群落从梭状芽胞杆菌（Clostridium IV）主导转变为梭状芽胞杆菌（Clostridium IV）和丙酸杆菌（Propionibacterium）共同主导（基于16S rRNA测序），并降低了参与逆转β-氧化途径的关键酶的活性。根据我们的研究，我们提出了一个有效的策略，这是我们所知的第一个将未经稀释的生FW升级为n-己酸盐的策略：在设置阶段将铵积累降低到1.0 g L−1以适应，并在操作阶段延长水力停留时间（10天）以供链延伸细菌定植。这些发现为在FW上实施LCE进程奠定了基础，为缓解全球FW危机提供了另一种方法。
Ammonium accumulation is inevitable during the fermentation of food waste (FW), challenging the application of chain elongation process upgrading FW into the high-value biochemical n-caproate, which is a medium chain carboxylate. This study is the first to investigate ammonium inhibition of lactate-driven chain elongation process. The short-term exposure of a Clostridium IV-dominated chain elongating reactor microbiome at an ammonium concentration of 1–4 g L− 1 linearly decreased n-caproate production by 25–80%. High levels of ammonium (≥ 5 g L− 1) could cause failure of chain elongation, shifting the product from n-caproate to propionate. The involved mechanisms revealed that ammonium reshaped the microbial community from Clostridium IV domination to Clostridium IV and Propionibacterium co-domination (based on 16S rRNA sequencing) and reduced the activities of key enzymes involved in the reversed β-oxidization pathway. We propose an effective strategy from our study, which is the first one to do in our knowledge, to upgrade raw FW without dilution to n-caproate: lowering the ammonium accumulation to 1.0 g L− 1 at the setup phase for adaptation and prolonging the hydraulic retention time (10 days) during the operation phase for the colonization of chain-elongation bacteria. These findings lay a foundation for the implementation of the LCE process on FW, providing an alternative way to alleviate the global FW crisis.