Genetic and biochemical analysis of nitrogen metabolism in ruminal anaerobic bacteria: a comparison between ruminococcus albus 8 and prevotella ruminicola 23
type: CreativeWork
description: These studies were conducted to improve the understanding of the genetic regulation and biochemical pathways utilized by the rumen bacteria, Ruminococcus albus 8 and Prevotella ruminicola 23 during growth on, and metabolism of, different nitrogen sources. Both R. albus 8 and P. ruminicola 23 were grown using different nitrogen sources; ammonia, urea, or peptides for R. albus 8 and ammonia or peptides for P. ruminicola 23 as the sole nitrogen source. Gene expression levels and enzyme activities were analyzed by RT-qPCR, and enzyme assays, as well as microarray and proteomic analyses for P. ruminicola. The results varied according to nitrogen source and also by growth phase. For R. albus 8 growth on ammonia or urea led to the synthesis of glutamate from ammonia by the NADPH-dependent glutamate dehydrogenase (NADPH-GDH). This glutamate was then transformed to glutamine by glutamine synthetase (GS). The later transformation was especially evident during early log phase, while the further transformation from glutamate to α-ketoglutarate by the up-regulated NADH-dependent glutamate dehydrogenase (NADH-GDH) was more evident during late exponential phase. During this phase an ammonium transporter was also up-regulated, apparently as an attempt to enhance ammonia uptake from the medium as the ammonia concentration became low (< 1 mM). Three different types of GS from P. ruminicola 23 were heterologously expressed in E. coli and characterized. Two different GS type III proteins (GSIII-1; ORFB01459 and GSIII-2; ORFB02034) showed GS biosynthetic activities, while no GSI biosynthetic activity was detected. We have defined the optimal conditions for enzymatic activity and these were found to be consistent with the parameters of the rumen habitat of P. ruminicola 23. Finally, we analyzed the effects on transcription and assayed key enzymatic activities on limiting (0.7 mM) and non-limiting (10 mM) concentrations of ammonia during growth in chemostat culture. These studies revealed…
abstract: These studies were conducted to improve the understanding of the genetic regulation and biochemical pathways utilized by the rumen bacteria, Ruminococcus albus 8 and Prevotella ruminicola 23 during growth on, and metabolism of, different nitrogen sources. Both R. albus 8 and P. ruminicola 23 were grown using different nitrogen sources; ammonia, urea, or peptides for R. albus 8 and ammonia or peptides for P. ruminicola 23 as the sole nitrogen source. Gene expression levels and enzyme activities were analyzed by RT-qPCR, and enzyme assays, as well as microarray and proteomic analyses for P. ruminicola. The results varied according to nitrogen source and also by growth phase. For R. albus 8 growth on ammonia or urea led to the synthesis of glutamate from ammonia by the NADPH-dependent glutamate dehydrogenase (NADPH-GDH). This glutamate was then transformed to glutamine by glutamine synthetase (GS). The later transformation was especially evident during early log phase, while the further transformation from glutamate to α-ketoglutarate by the up-regulated NADH-dependent glutamate dehydrogenase (NADH-GDH) was more evident during late exponential phase. During this phase an ammonium transporter was also up-regulated, apparently as an attempt to enhance ammonia uptake from the medium as the ammonia concentration became low (< 1 mM). Three different types of GS from P. ruminicola 23 were heterologously expressed in E. coli and characterized. Two different GS type III proteins (GSIII-1; ORFB01459 and GSIII-2; ORFB02034) showed GS biosynthetic activities, while no GSI biosynthetic activity was detected. We have defined the optimal conditions for enzymatic activity and these were found to be consistent with the parameters of the rumen habitat of P. ruminicola 23. Finally, we analyzed the effects on transcription and assayed key enzymatic activities on limiting (0.7 mM) and non-limiting (10 mM) concentrations of ammonia during growth in chemostat culture. These studies revealed…
author: Kim, Jong N.
language: en
keywords: Ruminococcus albus 8, Prevotella ruminicola 23, Nitrogen metabolism, Ammonia assimilation, Glutamate dehydrogenase, Glutamine synthetase, Glutamate synthase, Ammonium transporter
date published: 2010-05-14T20:50:59Z
date modified: 2026-07-22T22:25:08Z
provider: University of Illinois - Urbana-Champaign
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Illinois at Urbana-Champaign

PropertyValue
property ID: Handle
value: http://hdl.handle.net/2142/15572