The development of lactic acid bacteria and Lactobacillus buchneri and their effects on the fermentation of alfalfa silage
The development of lactic acid bacteria and Lactobacillus buchneri and their effects on the fermentation of alfalfa silage
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DOI：
10.3168/jds.2008-1701
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发表时间：
2009-10-01
影响因子：
3.5
通讯作者：
Kung, L., Jr.
中科院分区：
文献类型：
--
作者：
Schmidt, R. J.;Hu, W.;Kung, L., Jr.
研究了不同接种剂处理的紫花苜蓿青贮料中乳酸菌(LAB)和布氏乳杆菌种群的动态变化。用蒸馏水(未处理，U)、布氏乳杆菌40788(4×10(5)cfu/g；LBPP)或3)布氏乳杆菌40788(4×10(5)cfu/g)和戊糖小球菌(1×10(5)cfu/g；LBPP)处理枯萎和切碎的紫花苜蓿(45%干物质)。每个处理将饲料包装在三个真空密封的尼龙聚乙烯袋中，青贮2、5、45、90和180d，用选择性琼脂平板法检测饲料和青贮料中的活菌(CFU)，用实时荧光定量PCR检测布氏乳杆菌(CFU-E)的数量。新鲜饲料和未处理饲料的LAB数分别为5.52logCFU/g和3.79logCFU-E/g，青贮2d后，所有青贮料的LAB数均增加到8logCFU/g。相比之下，U的布氏乳杆菌数量保持在4logCFU-E/g以下，而在LB和LBPP中达到了约7logCFU-E/g。从d5开始，U的布氏钩端螺旋体数量保持在6logCFU-E/g以下，而LB和LBPP的数量接近9logCFU-E/g。在青贮期第2天和第5天，LBPP组的pH低于U组和LBPP组，而U组的pH值低于LBPP组和LBPP组。在青贮期45d，LBPP和LBPP处理组的乙酸含量高于U组，这与1，2丙二醇的检出量一致。青贮料接种LBPP后，青贮料中1，2丙二醇浓度在青贮后180d达到最高。从第45d开始，LBPP和LBPP青贮料中残留的水溶性碳水化合物含量低于U青贮料，但氨氮含量高于U青贮料。因此，在紫花苜蓿中可以检测到附生布氏乳杆菌，但该种群不能主导青贮发酵。相反，在青贮料中添加布氏乳杆菌作为接种剂时，布氏乳杆菌(CFU-E)的数量显著增加，但直到青贮45d才能决定发酵。这些发现有助于解释为什么在青贮料中添加布氏乳杆菌的反应不是立竿见影的。
This study was conducted to document the development of populations of lactic acid bacteria ( LAB) and Lactobacillus buchneri in alfalfa silage treated with various inoculants. Wilted and chopped alfalfa (45% dry matter) was treated with 1) distilled water ( untreated, U), 2) Lactobacillus buchneri 40788 (4 x 10(5) cfu/g; LB), or 3) L. buchneri 40788 (4 x 10(5) cfu/g) and Pediococcus pentosaceus (1 x 10(5) cfu/g; LBPP). Forages were packed into triplicate vacuum-sealed, nylonpolyethylene bags per treatment, and ensiled for 2, 5, 45, 90, and 180 d. Viable (cfu) LAB in forage and silage were quantified by traditional plating on selective agar, and numbers of L. buchneri (cfu-equivalent, cfu-E) were quantified by real-time quantitative PCR. Fresh, untreated forage had 5.52 log cfu of LAB/g and 3.79 log cfu-E of L. buchneri/g. After 2 d of ensiling, numbers of LAB increased to >8 log cfu/g in all silages. In contrast, numbers of L. buchneri in U remained below 4 log cfu-E/g but reached approximately 7 log cfu-E/g in LB and LBPP. From d 5 onward, numbers of L. buchneri in U remained below 6 log cfu-E/g but approached 9 log cfu-E/g in LB and LBPP. The pH was lower in LBPP compared with U and LB after 2 and 5 d of ensiling, but pH was lower for U compared with LB and LBPP thereafter. Treatments LB and LBPP had more acetic acid than U at 45 d of ensiling, which coincided with detectable amounts of 1,2 propanediol. Inoculation with LBPP resulted in silage with the highest concentration of 1,2 propanediol after 180 d of ensiling. From d 45 onward, LB and LBPP silages had lower concentrations of residual water-soluble carbohydrates but had higher concentrations of ammonia-N than U. In conclusion, epiphytic L. buchneri can be detected in alfalfa but this population is unable to lead the silage fermentation. In contrast, when L. buchneri was added to silage as an inoculant, the numbers of L. buchneri (cfu-E) increased markedly but did not dictate fermentation until 45 d of ensiling. These findings help to explain why the response (in increased acetic acid) from the addition of L. buchneri in silages is not immediate.