Journal of Integrative Agriculture ›› 2026, Vol. 25 ›› Issue (3): 1165-1179.DOI: 10.1016/j.jia.2024.05.007

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紫花苜蓿青贮饲料β-胡萝卜素含量提高的己酸作用机制

  

  • 收稿日期:2023-12-14 修回日期:2024-05-28 接受日期:2024-03-04 出版日期:2026-03-20 发布日期:2026-02-06

Hexanoic acid addition helps to clarify the possible mechanisms of the increased β-carotene content during alfalfa fermentation

Cheng Zong2*, Yuhong Zhao3*, Wanqi Jiang2, Tao Shao2, Xinyu Liang2, Aili Wu2, Qinhua Liu1, 2#   

  1. 1 Faculty of Animal Science and Technology, Yunnan Agricultural University, Kunming 650201, China

    2 Institute of Ensiling and Processing of Grass, College of Agro-grassland Science, Nanjing Agricultural University, Nanjing 210095, China 

    3 College of Animal Science and Technology, Xizang Agricultural and Animal Husbandry University, Nyingchi 860000, China

  • Received:2023-12-14 Revised:2024-05-28 Accepted:2024-03-04 Online:2026-03-20 Published:2026-02-06
  • About author:#Correspondence Qinhua Liu, E-mail: liuqinhua@njau.edu.cn * These authors contributed equally to this study.
  • Supported by:
    This work was supported by the National Natural Science Foundation of China (31971765), the Fundamental Research Funds for the Central Universities, China (KYYZ2023002), the Anhui Province International Joint Research Center of Forage Bio-breeding, China (AHIJRCFB202305), the Key Research and Development Projects of Hainan Province, China (ZDYF2022XDNY153), and the Fundamental Research Funds for the Central Universities, China (XUEKEN2022020).   

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摘要：

β-胡萝卜素是维生素A原，具有丰富的生物学功能和广阔的应用前景。最近，我们在β-胡萝卜素损失低的紫花苜蓿青贮饲料中发现了特异性物质—己酸，但己酸对β-胡萝卜素的青贮作用机制尚不清楚。本研究以紫花苜蓿为试验材料，设计了4个己酸添加水平（0，0.05，0.1和0.2%）和遮光黑暗青贮时间（0，10，40和80天）双因素试验，旨在运用crtNM操纵子鉴定法、crtE基因qPCR定量分析和单分子实时测序技术，解析紫花苜蓿在青贮过程中的β-胡萝卜素含量、β-胡萝卜素相关酶活性和细菌群落的动态变化，阐明己酸影响β-胡萝卜素含量的因素和方式。结果显示，青贮80天后，相对于新鲜紫花苜蓿，添加己酸提高了紫花苜蓿青贮饲料β-胡萝卜素含量分别为85.8, 159和133%，增强了Lactobacillus kullabergensis丰度，促进演替出了L. senioris。多元线性回归模型预测出L. kullabergensis, L. apis, L. saniviri和L. senioris，过氧化物酶、八氢番茄红素脱氢酶和番茄红素β-环化酶促进了β-胡萝卜素合成，而L. rennini和L. brevis抑制了β-胡萝卜素的产生，且前者的合成作用强于后者。综上所述，添加己酸提高紫花苜蓿青贮饲料β-胡萝卜素含量很可能依赖于多个关键调控因子，如4种特异性乳酸菌（L. kullabergensis, L. apis, L. saniviri和L. senioris）和3种β-胡萝卜素相关酶（过氧化物酶、八氢番茄红素脱氢酶和番茄红素β-环化酶）。本研究初步探明了紫花苜蓿青贮饲料β-胡萝卜素含量提高的己酸作用机制，为功能性优质青贮饲料的研究和生产奠定了理论基础和添加剂技术支持。

Abstract:

The objectives of this study were to evaluate the effect of hexanoic acid (HA) supplementations (0, as the control, CON; 0.05%, HA1; 0.1%, HA2; 0.2%, HA3) on β-carotene, and ascertain the way and key factors of HA influencing β-carotene content of alfalfa (Medicago sativa L.) after ensiled in an oxygen-free and dark conditions for 10, 40, and 80 d (from May to August, 2021).  This was achieved by examining the dynamic change of β-carotene, activities of β-carotene-related enzymes, and bacterial community succession of ensiled alfalfa, using operon crtNM identification, crtE gene quantitation, and single-molecule real-time sequencing technology.  The results revealed that when compared with the fresh material, terminal alfalfa silage treated with different level of HA supplementations (0, 0.05, 0.1, 0.2%; fresh weight basis) increased β-carotene content up to 2.86, 85.8, 159, and 133%, accordingly.  Meanwhile, alfalfa silage treated with higher levels of HA (0.1 and 0.2%) showed superior effects compared to those treated with lower levels of supplementation (0 and 0.05%).  HA supplementation specifically facilitated the increase abundance of Lactobacillus kullabergensis and the emergence of L. senioris. Multiple linear regression models inferred that L. kullabergensis, L. apis, L. saniviri, L. senioris, peroxidase, phytoene desaturase, and lycopene β-cyclase positively regulated β-carotene.  Conversely, Lactobacillus rennini and L. brevis adjusted β-carotene, negatively.  Positive regulations of the above bacterial species and enzymes had a stronger role in increasing β-carotene than L. rennini and L. brevis. In conclusion, the β-carotene increase of ensiled alfalfa may be regulated by HA supplementation via multiple positive factors, including 4 special Lactobacillus species (L. kullabergensis, L. apis, L. saniviri, and L. senioris), and 3 vegetative β-carotene-related enzymes (peroxidase, phytoene desaturase, and lycopene β-cyclase). 

Key words: Hexanoic acid , alfalfa silage , β-carotene , Lactobacillus species