窖泥优势己酸菌株Caproicibacterium lactatifermentans XB2的分离、代谢特征和比较基因组分析

摘要/Abstract

摘要： 本研究通过富集和传统分离厌氧菌株技术从窖泥分离获得一株优势己酸生成菌XB2，经16S rRNA和全基因组测序鉴定为Caproicibacterium lactatifermentans。比较基因组显示，XB2除携带完整的β-氧化逆反应（β-oxidation，RBO）通路外，首次作为Caproicibacterium属菌株同时被发现具有脂肪酸生物合成（fatty acid biosynthesis，FAB）及L-苏氨酸降解型丙酸通路的全部关键酶基因。透射电镜观察发现，菌体呈椭圆梭状，显著区别于亲缘菌株的短棒形态。发酵结果表明，XB2代谢呈碳源依赖性：以葡萄糖为底物时微量合成己酸（0.23 g/L），乳酸为底物时丁酸增加0.59 g/L；当电子受体受限，合成丙酸质量浓度0.21 g/L，提示L-苏氨酸降解途径被激活。本研究揭示了C. lactatifermentans的形态与代谢种内多样性，突破了传统对己酸菌单一RBO代谢通路合成己酸的认知，为理解窖池微生物的功能冗余与适应性提供了新视角，也为通过调控菌群代谢以优化白酒风味品质奠定了理论基础。

关键词: 浓香型白酒, Caproicibacterium lactatifermentans XB2, β-氧化逆反应通路, 脂肪酸生物合成代谢通路, 丙酸

Abstract: In this study, a dominant Caproic acid-producing strain (abirritated as CPB), designated XB2, was isolated from pit mud using enrichment and traditional anaerobic isolation techniques. It was identified as Caproicibacterium lactatifermentans based on 16S rRNA gene and whole-genome sequencing. Comparative genomic analysis revealed that, in addition to possessing a complete reverse β-oxidation (β-oxidation, RBO) pathway, strain XB2 is the first reported Caproicibacterium strain harboring the full complement of key enzyme genes for both the fatty acid biosynthesis (fatty acid biosynthesis, FAB) pathway and the L-threonine degradation pathway for propionate synthesis. Transmission electron microscopy revealed that strain XB2 exhibits a distinct ellipsoidal fusiform morphology, differing significantly from the short-rod shape of its phylogenetic relatives. Fermentation profiling indicated carbon source-dependent metabolism: when glucose was used as the substrate, caproate was synthesized at a low concentration (0.23 g/L), whereas using lactate as the substrate increased butyrate production by 0.59 g/L. Under conditions with limited electron acceptors, propionate was produced at 0.21 g/L, suggesting the activation of the L-threonine pathway. This study elucidates the intraspecific morphological and metabolic diversity of C. lactatifermentans. It challenges the conventional view that CPBs rely solely on the RBO pathway for caproic acid synthesis, providing a new perspective for understanding functional redundancy and adaptability within pit mud microbial communities. Furthermore, it establishes a theoretical foundation for optimizing baijiu flavor profiles through the precise regulation of microbial metabolism.

Key words: Strong-flavor Baijiu, Caproicibacterium lactatifermentans XB2, Reverse β-oxidation pathway, Fatty acid biosynthesis pathway, Propionic acid

中图分类号:

TS201.3

甄莉徐康杰崔磊崔战友刘艳王秀本常强李俊增任一鸣王越张会敏. 窖泥优势己酸菌株Caproicibacterium lactatifermentans XB2的分离、代谢特征和比较基因组分析[J]. 食品科学, 2026, 47(10): 0-0 https://doi.org/

Li ZHEN Huimin Zhang. Isolation, Metabolic Characteristics and Comparative Genomic Analysis of the Dominant Caproic Acid-Producing Bacterium Caproicibacterium lactatifermentans XB2 from Pit Mud[J]. FOOD SCIENCE, 2026, 47(10): 0-0 https://doi.org/

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