Abstract :

In vertebrates, microbes colonize gut since birth but significantly alter host physiology, immunity and metabolism. Recently, zebrafish, Danio rerio has become an excellent model for gnotobiotic research for investigating metabolic disorders. Zebrafish offers the possibility to raise germ free or gnotobiotic larvae for better understanding the influence of gut microbiome on host physiology, immunity and gene expression in health and disease. The aim of the present study is to investigate the possibility of generating germfree zebrafish and optimize faecal microbial transplantation protocols for facilitating gut metagenomics research in zebrafish. Survival of sterile zebrafish larvae was >28 % after 6 days post fertilization (dpf) but succumbed within 11 dpf due to infections confirming a weak immune system. However, successful colonization of gnotobiotic larvae by faecal transplantation of microbes from control and obese zebrafish resulted in higher survival (>67%). Gnotobiotic strains may help in better understanding microbial regulation of host immunity and for investigating diet-induced obesity. Further, identification of beneficial microbial strains may pave way for developing novel probiotics for augmenting growth and immunity in farmed fishes. Advantages and disadvantages of generating gnotobiotic zebrafish, faecal transplantation therapy and host-microbe interactions upon immunity and lipid metabolism are discussed.