PDF(Pubmed)
Abstract：
Microbial conversion of agri-food waste to valuable compounds offers a sustainable route to develop the bioeconomy and contribute to sustainable biorefinery. Clostridium tyrobutyricum displays a series of native traits suitable for high productivity conversion of agri-food waste, which make it a promising host for the production of various compounds, such as the short-chain fatty acids and their derivative esters products. In this study, a butanol synthetic pathway was constructed in C. tyrobutyricum, and then efficient butyl butyrate production through in situ esterification was achieved by the supplementation of lipase into the fermentation. The butyryl-CoA/acyl-CoA transferase (cat1) was overexpressed to balance the ratio between precursors butyrate and butanol. Then, a suitable fermentation medium for butyl butyrate production was obtained with xylose as the sole carbon source and shrimp shell waste as the sole nitrogen source. Ultimately, 5.9 g/L of butyl butyrate with a selectivity of 100%, and a productivity of 0.03 g/L·h was achieved under xylose and shrimp shell waste with batch fermentation in a 5 L bioreactor. Transcriptome analyses exhibited an increase in the expression of genes related to the xylose metabolism, nitrogen metabolism, and amino acid metabolism and transport, which reveal the mechanism for the synergistic utilization of xylose and shrimp shell waste. This study presents a novel approach for utilizing xylose and shrimp shell waste to produce butyl butyrate by using an anaerobic fermentative platform based on C. tyrobutyricum. This innovative fermentation medium could save the cost of nitrogen sources (~97%) and open up possibilities for converting agri-food waste into other high-value products.
摘要：
微生物将农业食品废物转化为有价值的化合物提供了发展生物经济的可持续途径，并有助于可持续的生物炼制。酪丁酸梭菌表现出一系列适用于农业食品垃圾高产转化的天然性状,这使得它成为生产各种化合物的有前途的宿主，如短链脂肪酸及其衍生酯产品。在这项研究中,在酪丁酸梭菌中构建了丁醇合成途径，然后通过向发酵中添加脂肪酶，通过原位酯化实现高效生产丁酸丁酯。丁酰-CoA/酰基-CoA转移酶(cat1)被过表达以平衡前体丁酸和丁醇之间的比例。然后，以木糖为唯一碳源，虾壳废物为唯一氮源，获得了适合丁酸丁酯生产的发酵培养基。最终,5.9g/L的丁酸丁酯，选择性为100％，在5L生物反应器中分批发酵的木糖和虾壳废物下，生产率达到0.03g/L·h。转录组分析显示与木糖代谢相关的基因表达增加，氮代谢，氨基酸代谢和运输，揭示了木糖与虾壳废弃物协同利用的机理。本研究提出了一种利用木糖和虾壳废物生产丁酸丁酯的新方法，方法是使用基于酪丁酸梭菌的厌氧发酵平台。这种创新的发酵培养基可以节省氮源的成本（约97％），并为将农业食品垃圾转化为其他高价值产品开辟了可能性。
