THE INVITRO METABOLISM OF D,L-LACTIC ACID BY RUMEN MICROORGANISMS
THE INVITRO METABOLISM OF D,L-LACTIC ACID BY RUMEN MICROORGANISMS
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DOI：
10.1002/jsfa.2740380104
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发表时间：
1987-01-01
影响因子：
4.1
通讯作者：
CHAMBERLAIN, DG
中科院分区：
文献类型：
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作者：
NEWBOLD, CJ;WILLIAMS, AG;CHAMBERLAIN, DG
用从绵羊瘤胃中分离出的细菌和原生动物组分，研究了乳酸的D(-)和L(+)异构体在体外的代谢。在原生动物孵育中，D-乳酸和L-乳酸异构体的消失率比细菌孵育中的消失率高出15倍，而从不同饲料中恢复的动物细胞的消失率相对恒定在每克蛋白质0.04-0.073个乳酸。然而，原生动物部分的乳酸消失率从大麦/干草饲料的每克蛋白质每小时0.133克到青贮饲料的每克蛋白质每小时1.12g不等。在所有原生动物孵化过程中，L乳酸的消失速度均快于D-乳酸。通过差示过滤对原生动物种群进行了进一步的分级，结果表明乳酸盐只有在与内生原生动物孵育时才会消失，而与全毛原虫孵育时不会消失。在乳酸盐存在的情况下，内生纤毛虫内源丙酸和丁酸的产生被100%地刺激。据计算，在某些饮食中，乳酸盐形成的挥发性脂肪酸中高达30%可能是原生动物。
Bacterial and protozoal fractions, isolated by centrifugation and filtration from the rumen of sheep given various diets, were used to examine the in‐vitro metabolism of both the D(‐) and L(+) isomers of lactic acid. The rate of disappearance of both the D‐ and L‐lactic acid isomers in protozoal incubations was up to 15 × higher than the rate of disappearance in bacterial incubations, which was relatively constant at between 0.04 and 0.073 lactate per g protein per h for cells recovered from animals receiving various diets. However, the rate of lactate disappearance in the protozoal fraction varied from 0.133 g per g protein per h with a barley/hay diet to 1.12 g per g protein per h with a silage diet. L‐Lactate disappeared more rapidly than the D‐lactate in all protozoal incubations. It was confirmed that the disappearance of lactate associated with the protozoal fraction did not originate from adherent or associated bacteria.Further fractionation of the protozoal population by differential filtration showed that lactate only disappeared when incubated with entodiniomorphid protozoa and not with holotrich protozoa.Endogenous propionate and butyrate production by the entodiniomorphid ciliates was stimulated by 100% in the presence of lactate. It was calculated that on certain diets up to 30% of the volatile fatty acids formed from lactate could be protozoal in origin.