Acid tolerance of lactate-utilizing bacteria of the order Bacteroidales contributes to prevention of ruminal acidosis in goats adapted to a high-concentrate diet  

作　　者：Zhongyan Lu Lingmeng Kong Shenhao Ren Jorg RAschenbach Hong Shen 

机构地区：[1]Key Lab of Animal Physiology and Biochemistry,College of Veterinary Medicine,Nanjing Agricultural University,Nanjing,Jiangsu,China [2]College of Life Science,Nanjing Agricultural University,Nanjing,Jiangsu,China [3]Institute of Veterinary Physiology,Freie Universitat Berlin,Berlin,Germany [4]Bioinformatics Center,Academy for Advanced Interdisciplinary Studies,Nanjing Agricultural University,Nanjing,Jiangsu,China

出　　处：《Animal Nutrition》2023年第3期130-140,共11页动物营养（英文版）

基　　金：supported by the National Natural Science Foundation of China(31802155)。

摘　　要：The rapid accumulation of organic acids,particularly lactate,has been suggested as the main cause of ruminal acidosis(RA)for ruminants fed high-concentrate diets.Previous research has shown that a gradual shift from low-to high-concentrate diets within 4 to 5 weeks effectively reduces the risk for RA.However,the mechanisms remain unknown.In this study,20 goats were randomly allocated into four groups(n=5)and fed with a diet containing a weekly increasing concentrate portion of 20%,40%,60%,and 80%over 28 d.At d 7,14,21,and 28,one group(named C20,C40,C60,and C80 according to the last concentrate level that they received)was killed and the ruminal microbiome was collected.Ruminal acidosis was not detected in any of the goats during the experiment.Nonetheless,ruminal pH dropped sharply from 6.2 to 5.7(P<0.05)when dietary concentrate increased from 40%to 60%.A combined metagenome and metatranscriptome sequencing approach identified that this was linked to a sharp decrease in the abundance and expression of genes encoding nicotinamide adenine dinucleotide(NAD)-dependent lactate dehydrogenase(nLDH),catalyzing the enzymatic conversion of pyruvate to lactate(P<0.01),whereas the expression of two genes encoding NAD-independent lactate dehydrogenase(iLDH),catalyzing lactate oxidation to pyruvate,showed no significant concomitant change.Abundance and expression alterations for nLDH-and iLDH-encoding genes were attributable to bacteria from Clostridiales and Bacteroidales,respectively.By analyzing the gene profiles of 9 metagenome bins(MAG)with nLDH-encoding genes and 5 MAG with iLDH-encoding genes,we identified primary and secondary active transporters as being the major types of sugar transporter for lactate-producing bacteria(LPB)and lactate-utilizing bacteria(LUB),respectively.Furthermore,more adenosine triphosphate was required for the phosphorylation of sugars to initiate their catabolic pathways in LPB compared to LUB.Thus,the low dependence of sugar transport systems and catabolic pathways on primary energy sources su

关 键 词：Ruminal microbiome Ruminal acidosis Acid tolerance Lactate metabolism 

分 类 号：R73[医药卫生—肿瘤]