The Analysis Of Relationship Between Intestinal Microbiota Structure And Growth Speed Of Anguilla Marmorata

The intestinal microbiota is a dynamic ecosystem governed by genetic,nutritional,and environmental factors and complex intestinal microbial communities are believed to influence growth and health of host and are therefore receiving increasing attention,it is considered as an indispensable “organ” to the host.The marbled eel,Anguilla marmorata,is one of the largest eel species and is widely distributed across tropical and subtropical oceans as well as fresh-water systems.The eels are an important and valuable source of fish to many communities and it is regarded as a second-class protected species in China.There has been an increasing amount of cultivation,but with a limit in breeding technology,the marbled eel breeding level is unequal.During breeding,some eels are farmed for a long period of time,but grow slowly due to malnutrition and improper management.They are known as retarded-growth eels and usually have a large head and a small tail,with a brown or black body color.In this study,using culture-dependent technologies and high-throughput sequencing technology to unveil the intestinal bacterial communities of Anguilla marmorata at different growth stages and combining with feeding experiment to discuss the influence of key intestinal microflora on culture marbled eels.There were three fish groups(rapid-,slow-,and retarded-growth samples)and two culture-associated environmental groups(water and feed samples).The results of the study were as follows:1.Using culture-dependent technologies to sperated intestinal microbiota from marbled eels in Am-R and Am-F groups,it all contained 14 genus: Lactococcus,Enterococcus,Aeromonas,Pseudomonas,Enterobacter,Proteus,Klebsiella,Serratia,Acinetobacter,Plesiomonas,Citrobacter,Escherichia,Edwardsiella and Microbacterium.Among all,Lactococcus and Enterococcus were only sperated from Am-R groups.2.Using pyrosequencing to analyze intestinal microbiota structure of marbled eels,there were gathered 625,583 valid reads and 36,863 OTUs after filtering and trimming in total.The average of Shannon was Am-W > Am-B > Am-F > Am-R > Am-S,the average of Shannon was Am-W < Am-B < Am-F < Am-R < Am-S,the avarage of ACE and Chao were Am-B > Am-W >Am-S > Am-R >Am-F.Above all,the Am-W groups had highest bacteria diversity and Am-B groups had highest abundance.Among all fish gut samples,Am-S samples had lowest diversitybut highest abundance.In the Am-R and Am-S groups,there were have similar structure,Cetobacterium,Clostridium,Lactococcus,and Bacteroides were the predominant genera present in these two groups,while Am-F groups showed different composition compared to other guts groups and the dominant genus was: Sipiroplasma.The core bacteria in Am-W groups was Flavobacterium,Novosphingobium,Pseudomonas and in Am-B groups was Corynebacterium.Morever,comprehensive analysis showed that main different bacteria between Am-R and Am-F were Cetobacterium,Clostridium,Lactococcus,Bacteroides,Edwardsiella,Plesiomonas,Weissella,Enterococcaceae,Spiroplasma and so on.3.Three feed additives all had benecial for growth-retarded eels,among all additives,Bacteroides & Clostridium group(BC group)have the best effective,there was no significant difference between Lactococcus & Enterococcus group(LE group)and MOS group(MO group)on promoting effective.The present study will elucidate the basic composition of intestinal microbiota of Anguilla marmorata,identify key bacteria that influence growth of marbled eels,provide a basis for subsequent research on the protection and cultivation of eels,and will enrich the field of intestinal microorganismand feed additives studies.