Diet Shift May Trigger LuxS/AI-2 Quorum Sensing in Rumen Bacteria

Abstract

Recent studies have revealed that LuxS/AI-2 quorum sensing (QS) is the most universal cell-to-cell communication in rumen bacteria; however, it remains unknown how they respond to nutritional stress from a diet shift. This study aimed to explore whether a diet shift could trigger rumen bacterial LuxS/AI-2 QS and its influences on rumen fermentation characteristics and bacterial community diversity and composition. A total of fifteen Hu sheep were selected to undergo a pre-shift diet (Pre, concentrate to forage ratio 75:25) for one month and then abruptly switch to a post-shift diet (Post, concentrate to forage ratio 49:51). Results showed that the serum cortisol and immunoglobulin G concentrations were higher in Post than in Pre (p < 0.05). The microbial density, AI-2 concentration, biofilm formation, and gene expression of ftsH were higher in Post when compared with Pre (p < 0.05), whilst the expression of luxS tended to be lower in Post (p = 0.054). The molar concentration of valerate and fermentation efficiency decreased after the diet shift, while the acetate to propionate ratio and the molar proportion of butyrate were higher in Post compared to Pre (p < 0.05). Moreover, the diet shift increased the richness of ruminal bacteria and the relative abundance of Roseburia, and decreased the relative abundances of Prevotella, Megasphaera, Dialister, Prevotellaceae UCG-001, and Lachnospira (p < 0.05). A difference in trends was also observed in an analysis of similarity (R = 0.1208 and p = 0.064). This study suggests that a diet shift could trigger rumen bacterial LuxS/AI-2 QS by altering microbial density, AI-2 concentration, biofilm formation, and related gene expression, as well as affect the rumen fermentation pattern and bacterial community diversity and composition. This study may provide insight into a potential strategy for relieving nutritional stress via regulating bacterial communication.

Effect of Preservation Temperature and Time on Fermentation Characteristics, Bacterial Diversity and Community Composition of Rumen Fluid Collected from High-Grain Feeding Sheep

“…A total of 54 examples of high-purity and high-quality DNA were delivered to Allwegene Gene Technology Co., LTD (Nanjing, China) for subsequent amplification and sequencing. The V3-V4 region was selected as the target region for amplification to reveal the bacterial diversity and bacterial community, with the barcoded primers according to Wei et al [22] as follows: 338F (5 -ACTCCTACGGGAGGCAGCAG-3 ) and 806R (5 -GGACTACNNGGGTATCTAAT-3 ). The amplification procedure and its reaction system were the same as described in Qiu et al [21].…”

“…The raw data were analyzed using QIIME 2 (https://qiime2.org/, accessed on 30 December 2022; [23]). The criteria of data filtration were according to Wei et al [22], which allowed sequence lengths of between 250 bp and 500 bp and a quality score greater than 20, as well as removing sequences with ambiguous bases or those mismatched to primers and barcodes. The filtered sequences were merged into tags by Paired-End reAd mergeR (PEAR, version 0.9.6, [24]), where the minimum overlap was set to 10 bp, and allowed a maximum mismatch rate of 0.10.…”