| Gut microbiota is an important part of the microecosystem of the human digestive tract,mainly composed of Firmicutes,Bacteroidota,Actinobateriota and Proteobacteria four major bacteria,the diversity and distribution of the microbiota from the stomach to the intestines showed a gradual increase trend.The gut microbiota encodes more than 3 million genes and produces thousands of metabolites that participate in the body’s nutrient absorption and metabolism,nervous system and immune system development,and the formation of gut biological barriers.In addition,gut microbiota planting begins in the fetal period,evolves gradually with the self-factors brought about by the growth and development of the host and the influence of external factors,and maintains a relatively stable ecological structure for a certain period of time.Such as gut microbiota structure is affected by maternal status,lifestyle(sleep habits,eating habits,exercise habits,etc.),drug use,and many environmental factors,including temperature,humidity and sunshine duration.In the northern region of China,there are significant seasonal changes in temperature,humidity,sunshine duration and other environmental factors,and both temperature and sunshine duration can affect the gut microbiota in the host body.Therefore,it is speculated that the structure and function of gut microbiota should show certain seasonal characteristics with the change of temperature and sunshine duration brought about by seasonal change.Therefore,in order to verify the above-mentioned research hypothesis,this study uses a long-term longitudinal study combined with self control study method to recruit young healthy people in Beijing,in four seasons of the year,the corresponding period of time for the recruitment of volunteers to carry out continuous fecal sample collection,in order to minimize the impact of individual differences.Finally,by High-Throughput Sequencing of the 16S rDNA,the structure of gut microbiota and the prediction of gut microbiota function were analyzed,and the seasonal characteristics of gut microbiota structure and function of young healthy population were explored.Objective:In the year-round,by analyzing the gut microbiota from fecal sources of the same group of young healthy people in the same region,it is hoped that the seasonal characteristics of the structure and function of the gut microbiota of the young healthy population will be revealed.Methods:Using prospective study,longitudinal research,a group of young healthy people in Beijing University of Chinese Medicine was recruited as volunteers for this study,and the final volunteer list was determined after screening for inclusion criteria,exclusion criteria and physical health examination.Throughout the year(the Spring Equinox,SP;the Summer Solstice,SU;the Autumnal Equinox,AU;the Winter Solstice,WI)continuously collects fecal samples,finalizes a full list of volunteers with a full fecal sample,organizes and sequences their fecal samples with High-Throughput Sequencing of the 16S rDNA.Based on the biological information obtained by sequencing,the structural of gut microbiota was illustrated by using R language analysis package,such as Alpha diversity,Beta diversity and species abundance,and the function prediction of gut microbiota was predicted by comparing KEGG database.Results:A total of 37 volunteers,including 26 females and 11 males,were screened by inclusion criteria,exclusion criteria and physical health examination,as well as complete samples in four seasonal collection periods.A total of 148 fresh stool samples were collected.A total of 148 samples were sequenced by High-Throughput Sequencing of the 16S rDNA according to 37 samples from each season.Sequencing obtained the following taxa:20 phylum level taxa,41 class level taxa,101 order level taxa,176 family level taxa,384 genus level taxa,743 species level taxa and 1271 OTU.In addition,Core species analysis and Rarefaction curve analysis indicated that there was sufficient sequencing depth.At the family level,the dominant species of gut microbiota in all samples were Lachnospiraceae,Ruminococcaceae,Bacteriodaceae,Bifidobacteriaceae and Enterobacteriaceae.At the genus level,the dominant species of gut microbiota in all samples were Faecalibacterium,Bacteroides,Blautia,Subdoligranulum and Agathobacter.A total of 7 taxa levels at phylum-to-species and OTU level,analyzed Alpha diversity index differences according to six grouping scheme over four seasons,found that the Alpha diversity index differences were most frequent in SP and WI,followed by SU and WI,SU and AU,SP and AU,AU and WI,and the Alpha index differences were the smallest in SP and SU.The diversity of community and richness of community in AU and WI was higher than that in SP and SU,and the evenness of community in SP and SU was higher than that in AU and WI.Beta diversity analysis was carried out at the four taxa levels of order,family,genus and OTU,and PCA did not show obvious four-season clustering,and no significant difference.PCoA and NMDS analysis showed obvious four-season clustering at the three classification levels of order,family and genus.Divided into four groups by four seasons,the top five dominant species of the four seasons were found to be Lachnospiraceae,Ruminococcaceae,Bacteriodaceae,Bifidobacteriaceae and Enterobacteriaceae.There were differences in the order of abundance of the five dominant species in four seasons.In addition,there were 789 common OTUs in four seasons,which the OTU number of SU was the least and the OTU number of WI was the most.At the genus level,a different species analysis of gut microbiota between four seasons found that Bacteroides had the highest abundance in the SU and the lowest in the WI;Lactococcus,Klebsiella and Enterobacter had the highest abundance in the AU;and Lachnospiracea NK4A136 group had the highest abundance in the SP when analyzing the varied species among the groups based on Kruskal-Wallis H test;systematically obtaining the dominant species with differences among the four seasons.Based on the Wilcoxon ranksum test analysis,the Eubacterium hallii group had highest abundance in the WI,Rhodococcus,Acinetobacter and Ralstonia had high abundance in the WI,Bacteroides and Enterobacter had the lowest abundance in the WI.Based on the analysis of LEfSe multilevel species differences,the difference species analysis of five grouping scheme(six grouping scheme without SU-AU)was found,and the most abundance species in the SP were Lachnospiraceae NK4A136 group;the most abundant species in the SU was Escherichia-Shigellas;the most abundant species in the AU were Lactococcus、Enterobacter and Klebsiella;the most abundant species in the WI were the Eubuacterium hallii group and Fusicatenibacter.In the analysis of gut microbiota function prediction between four seasons,it was found that compared in six grouping scheme,66 of which had unique pathways for each grouping scheme,35 pathways in common for the two grouping scheme,8 pathways in common for the three grouping scheme,1 pathways in common for the four grouping scheme(Bile secretion),and 1 pathways in common for the five grouping scheme(Sphingolipid signaling pathway).Conclusion:At genus levels,four seasons of species have significant characteristics.The following are as follows:Lachnospiraceae NK4A136 group was enriched in the SP;Bacteroides and Escherichia-Shigellas were enriched in the SU;Lactococcus,Enterobacter and Klebsiella were enriched in the AU;Eubacterium hallii group and Fusicatenibact were enriched in WI.Bacteroides and Enterobacter have significantly higher species abundance in the SP,SU and AU than in the WI,and there are more species in WI,such as Rhodococcus,Acinetobacter,Ralstonia,Romboutsia,Blautia and Dorea.Sphingolipid signaling pathway were most abundant in the WI,Bile secretion pathways and Renin secretion pathways were abundant in AU and WI,the former was enriched in AU,the latter was enriched in WI,and were less abundant in SU.Neurological pathways,such as the Serotonergic synapse、Cocaine addiction、Dopaminergic synapse、Alcoholism and Amphetamine addiction pathway,were the least abundant in the SU.So,the structure and function of gut microbiota present specific species and functional pathways in four seasons,which help the body adapt to the changes brought about by the seasonal change. |
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