Background： Original rumen digesta, rumen liquid and solid fractions have been frequently used to assess the rumen bacterial community. However, bacterial profiles in rumen original digesta, liquid and solid fraction...Background： Original rumen digesta, rumen liquid and solid fractions have been frequently used to assess the rumen bacterial community. However, bacterial profiles in rumen original digesta, liquid and solid fractions vary from each other and need to be better established.Methods： To compare bacterial profiles in each fraction, samples of rumen digesta from six cows fed either a high fiber diet（HFD） or a high energy diet（HED） were collected via rumen fistulas. Rumen digesta was then squeezed through four layers of cheesecloth to separate liquid and solid fractions. The bacterial profiles of rumen original digesta, liquid and solid fractions were analyzed with High-throughput sequencing technique.Results： Rumen bacterial diversity was mainly affected by diet and individual cow（P 〉 0.05） rather than rumen fraction. Bias distributed bacteria were observed in solid and liquid fractions of rumen content using Venn diagram and LEf Se analysis. Fifteen out of 16 detected biomarkers（using LEf Se analysis） were found in liquid fraction, and these 15 biomarkers contributed the most to the bacterial differences among rumen content fractions.Conclusions： Similar results were found when using samples of original rumen digesta, rumen liquid or solid fractions to assess diversity of rumen bacteria; however, more attention should be draw onto bias distributed bacteria in different ruminal fractions, especially when liquid fraction has been used as a representative sample for rumen bacterial study.展开更多
Quorum sensing（QS） is a type of microbe-microbe communication system that is widespread among the microbial world, particularly among microorganisms that are symbiotic with plants and animals. Thereby, the cell-cell...Quorum sensing（QS） is a type of microbe-microbe communication system that is widespread among the microbial world, particularly among microorganisms that are symbiotic with plants and animals. Thereby, the cell-cell signalling is likely to occur in an anaerobic rumen environment, which is a complex microbial ecosystem. In this study, using six ruminally fistulated Liuyang black goats as experimental animals, we aimed to detect the activity of quorum sensing autoinducers（AI） both in vivo and in vitro and to clone the lux S gene that encoded autoinducer-2（AI-2） synthase of microbial samples that were collected from the rumen of goats. Neutral detergent fiber（NDF） and soluble starch were the two types of substrates that were used for in vitro fermentation. The fermented fluid samples were collected at 0, 2, 4, 6, 8, 12, 24, 36, and 48 h of incubation. The acyl-homoserine lactones（AHLs） activity was determined using gas chromatography-mass spectrometer（GC-MS） analysis. However, none of the rumen fluid extracts that were collected from the goat rumen showed the same or similar fragmentation pattern to AHLs standards. Meanwhile, the AI-2 activity, assayed using a Vibrio harveyi BB170 bioassay, was negative in all samples that were collected from the goat rumen and from in vitro fermentation fluids. Our results indicated that the activities of AHLs and AI-2 were not detected in the ruminal contents from six goats and in ruminal fluids obtained from in vitro fermentation at different sampling time-points. However, the homologues of lux S in Prevotella ruminicola were cloned from in vivo and in vitro ruminal fluids. We concluded that AHLs and AI-2 could not be detected in in vivo and in vitro ruminal fluids of goats using the current detection techniques under current dietary conditions. However, the microbes that inhabited the goat rumen had the potential ability to secrete AI-2 signaling molecules and to communicate with each other via AI-2-mediated QS because of the presence of lux S.展开更多
Total milk solid(TMS)content directly reflects the quality of milk.Rumen bacteria ferment dietary components,the process of which generates the precursors for the synthesis of milk solid,therefore,the variation in rum...Total milk solid(TMS)content directly reflects the quality of milk.Rumen bacteria ferment dietary components,the process of which generates the precursors for the synthesis of milk solid,therefore,the variation in rumen bacterial community could be associated with milk solid in dairy cows.In this study,45 healthy mid-lactation Holstein dairy cows with the similar body weight,lactation stage,and milk yield were initially used for the selection of 10 cows with high TMS(HS)and 10 cows with low TMS(LS).All those animals were under the same feeding management,and the individual milk yield was recorded for 14 consecutive days before milk and rumen fluid were sampled.Rumen fluid was used to determine bacterial community by 16S rRNA gene sequencing technique.The HS cows had significantly greater feed intake and milk TMS,fat,protein content than LS cows(P<0.05).Among the volatile fatty acids(VFA),propionic acid and valeric acid concentrations were significantly greater in HS cows than those in LS cows(P<0.05).There was no significant difference in the concentrations of acetate,butyrate,isobutyrate,valerate,and the total VFA(P>0.05),nor was the acetate-to-propionate ratio,pH value,ammonia nitrogen and microbial crude protein concentrations(P>0.05).Significant differences in the relative abundances of some bacterial genera were found between HS and LS cows.Spearman’s rank correlation analysis revealed that TMS content was correlated positively with the abundances of Ruminococcaceae UCG-014,Ruminococcaceae NK4A214 group,Prevotellaceae UCG-001,Butyrivibrio 2,Prevotellaceae UCG-003,Candidatus Saccharimonas,Ruminococcus 2,Lachnospiraceae XPB1014 group,probable genus 10,Eubacterium ventriosum group,but negatively correlated with Pyramidobacte.In addition,Ruminococcaceae UCG-014,Ruminococcus 2,Ruminococcaceae UCG001,probable genus 10 and Eubacterium ventriosum group might boost the total VFA production in the rumen.In conclusion,the dry matter intake of dairy cows and some special bacteria in rumen were significantly associated with TMS content,which suggests the potential function of rumen bacteria contributing to TMS content in dairy cows.展开更多
基金supported by National Dairy Industry and Technology System(CARS-37)National Natural Science Foundation of China(31402099)
文摘Background： Original rumen digesta, rumen liquid and solid fractions have been frequently used to assess the rumen bacterial community. However, bacterial profiles in rumen original digesta, liquid and solid fractions vary from each other and need to be better established.Methods： To compare bacterial profiles in each fraction, samples of rumen digesta from six cows fed either a high fiber diet（HFD） or a high energy diet（HED） were collected via rumen fistulas. Rumen digesta was then squeezed through four layers of cheesecloth to separate liquid and solid fractions. The bacterial profiles of rumen original digesta, liquid and solid fractions were analyzed with High-throughput sequencing technique.Results： Rumen bacterial diversity was mainly affected by diet and individual cow（P 〉 0.05） rather than rumen fraction. Bias distributed bacteria were observed in solid and liquid fractions of rumen content using Venn diagram and LEf Se analysis. Fifteen out of 16 detected biomarkers（using LEf Se analysis） were found in liquid fraction, and these 15 biomarkers contributed the most to the bacterial differences among rumen content fractions.Conclusions： Similar results were found when using samples of original rumen digesta, rumen liquid or solid fractions to assess diversity of rumen bacteria; however, more attention should be draw onto bias distributed bacteria in different ruminal fractions, especially when liquid fraction has been used as a representative sample for rumen bacterial study.
基金financially support of the Chinese Academy of Sciences (KZCX2-YW-455)the CAS/SAFEA International Partnership Program for Creative Research Teams,China (KZCX2-YW-T07) and K C Wong Education, Hong Kong
文摘Quorum sensing（QS） is a type of microbe-microbe communication system that is widespread among the microbial world, particularly among microorganisms that are symbiotic with plants and animals. Thereby, the cell-cell signalling is likely to occur in an anaerobic rumen environment, which is a complex microbial ecosystem. In this study, using six ruminally fistulated Liuyang black goats as experimental animals, we aimed to detect the activity of quorum sensing autoinducers（AI） both in vivo and in vitro and to clone the lux S gene that encoded autoinducer-2（AI-2） synthase of microbial samples that were collected from the rumen of goats. Neutral detergent fiber（NDF） and soluble starch were the two types of substrates that were used for in vitro fermentation. The fermented fluid samples were collected at 0, 2, 4, 6, 8, 12, 24, 36, and 48 h of incubation. The acyl-homoserine lactones（AHLs） activity was determined using gas chromatography-mass spectrometer（GC-MS） analysis. However, none of the rumen fluid extracts that were collected from the goat rumen showed the same or similar fragmentation pattern to AHLs standards. Meanwhile, the AI-2 activity, assayed using a Vibrio harveyi BB170 bioassay, was negative in all samples that were collected from the goat rumen and from in vitro fermentation fluids. Our results indicated that the activities of AHLs and AI-2 were not detected in the ruminal contents from six goats and in ruminal fluids obtained from in vitro fermentation at different sampling time-points. However, the homologues of lux S in Prevotella ruminicola were cloned from in vivo and in vitro ruminal fluids. We concluded that AHLs and AI-2 could not be detected in in vivo and in vitro ruminal fluids of goats using the current detection techniques under current dietary conditions. However, the microbes that inhabited the goat rumen had the potential ability to secrete AI-2 signaling molecules and to communicate with each other via AI-2-mediated QS because of the presence of lux S.
基金the Scientific Research Project for Major Achievements of the Agricultural Science and Technology Innovation Program(CAAS ZDXT2019004)the Agricultural Science and Technology Innovation Program(ASTIP-IAS12)Modern Agro-Industry Technology Research System of the PR China(CARS-36).
文摘Total milk solid(TMS)content directly reflects the quality of milk.Rumen bacteria ferment dietary components,the process of which generates the precursors for the synthesis of milk solid,therefore,the variation in rumen bacterial community could be associated with milk solid in dairy cows.In this study,45 healthy mid-lactation Holstein dairy cows with the similar body weight,lactation stage,and milk yield were initially used for the selection of 10 cows with high TMS(HS)and 10 cows with low TMS(LS).All those animals were under the same feeding management,and the individual milk yield was recorded for 14 consecutive days before milk and rumen fluid were sampled.Rumen fluid was used to determine bacterial community by 16S rRNA gene sequencing technique.The HS cows had significantly greater feed intake and milk TMS,fat,protein content than LS cows(P<0.05).Among the volatile fatty acids(VFA),propionic acid and valeric acid concentrations were significantly greater in HS cows than those in LS cows(P<0.05).There was no significant difference in the concentrations of acetate,butyrate,isobutyrate,valerate,and the total VFA(P>0.05),nor was the acetate-to-propionate ratio,pH value,ammonia nitrogen and microbial crude protein concentrations(P>0.05).Significant differences in the relative abundances of some bacterial genera were found between HS and LS cows.Spearman’s rank correlation analysis revealed that TMS content was correlated positively with the abundances of Ruminococcaceae UCG-014,Ruminococcaceae NK4A214 group,Prevotellaceae UCG-001,Butyrivibrio 2,Prevotellaceae UCG-003,Candidatus Saccharimonas,Ruminococcus 2,Lachnospiraceae XPB1014 group,probable genus 10,Eubacterium ventriosum group,but negatively correlated with Pyramidobacte.In addition,Ruminococcaceae UCG-014,Ruminococcus 2,Ruminococcaceae UCG001,probable genus 10 and Eubacterium ventriosum group might boost the total VFA production in the rumen.In conclusion,the dry matter intake of dairy cows and some special bacteria in rumen were significantly associated with TMS content,which suggests the potential function of rumen bacteria contributing to TMS content in dairy cows.
