Metabolic networks for nitrogen utilization in Prevotella ruminicola 23

Abstract

Nitrogen metabolism in gut systems remains poorly studied in spite of its importance for microbial growth and its implications for the metabolism of the host. Prevotella spp. are the most predominant bacteria detected in the rumen, but their presence has also been related to health and disease states in the human gut and oral cavity. To explore the metabolic networks for nitrogen assimilation in this bacterium, changes in gene expression profiles in response to variations in the available nitrogen source and to different concentrations of ammonium were analyzed by microarray and reverse transcription quantitative PCR, and linked with function by further proteomic analysis. The observed patterns of transcript abundances for genes involved in ammonium assimilation differed from the classical “enteric paradigm” for nitrogen utilization. Expression of genes encoding high substrate affinity nitrogen assimilation enzymes (GS-GOGAT system) was similar in growth-limiting and non-limiting nitrogen concentrations in P. ruminicola 23, whereas E. coli and Salmonella spp. responses to excess nitrogen involve only low substrate affinity enzymes. This versatile behavior might be a key feature for ecological success in habitats such as the rumen and human colon where nitrogen is rarely limiting for growth, and might be linked to previously reported Prevotella spp. population imbalances relative to other bacterial species in gut systems.

Bacterial communities in the solid, liquid, dorsal, and ventral epithelium fractions of yak (Bos grunniens) rumen

“…Rikenellaceae RC9 can reportedly degrade structural carbohydrates and starch in the rumen of cows (Asma et al, ), while Prevotella spp. have high genetic and metabolic diversity (Bekele, Koike, & Kobayashi, ; Purushe et al, ), and play key roles in metabolism of carbohydrates, such as hemicellulose, starch, xylan, and pectin (Cotta, ; Dehority, ; Gardner, Wells, Russell, & Wilson, ; Kabel et al, ), and nitrogen (Kim et al, ; Stevenson & Weimer, ). Thus, these results indicate that Rikenellaceae RC9 and Prevotella play crucial roles in basic metabolic processes in the yak rumen.…”

Evaluation of Microbial Communities Associated With the Liquid and Solid Phases of the Rumen of Cattle Offered a Diet of Perennial Ryegrass or White Clover

“…Differences in dietary treatment is often the main source of variability in rumen microbial communities ( Petri et al, 2013 ), with different communities preferring particular substrates and metabolites. For example, Prevotella has previously been identified as a carbohydrate and nitrogen utilizing bacteria ( Gasparic et al, 1995 ; Kim et al, 2017 ). The lack of significant diet effects on the relative abundances of Prevotella in the present study is likely caused by higher levels of protein in white clover counteracting the effects of higher water soluble carbohydrate in perennial ryegrass ( Table 1 ).…”

Changes in the Solid-, Liquid-, and Epithelium-Associated Bacterial Communities in the Rumen of Hu Lambs in Response to Dietary Urea Supplementation

“…This result is consistent with findings regarding the rumen solid and liquid fractions of dairy cattle fed ryegrass or white clover (Bowen et al, 2018) and a TMR (forage:concentrate = 70:30, forage = prewilted grass and maize silage) (De Mulder et al, 2017) and the rumen contents and epithelium of dairy cattle fed a TMR (forage:concentrate = 55:45, forage = corn silage and corn stover) (Liu et al, 2016). Prevotella represents one of the most abundant genera in the rumen; this genus exhibits genetic and metabolic diversity (Bekele et al, 2010) and plays roles in carbohydrate utilization (Dehority, 1966;Cotta, 1992;Gardner et al, 1995;Kabel et al, 2011), nitrogen metabolism (Kim et al, 2017), and fiber degradation (Mayorga et al, 2016). The results of these study suggest the importance of Prevotella spp.…”