Diseases of microbial aetiology of economic significance have surfaced in the aquaculture sector leading to high mortality and economic losses for farmers. Various environmentfriendly remedial measures have been taken up as an alternative to antibiotics to control microbial diseases. But before using any therapeutic product against bacterial diseases it is important to understand the degree of damage caused to gut microbiota as well as hostmicrobes interactions in relation to a particular pathological condition. The applications of metagenomics in aquaculture is an emerging tool to investigate the alterations of gut microbial communities during stress conditions. It also provides an opportunity to reveal microbial genetic diversity as well as their functional attributes in a comprehensive manner along with their contribution to health and disease. A study on the composition of gut microbiome of freshwater striped pangasius catfish and catla fish in healthy and during disease condition was carried out. The gut samples from healthy and Aeromonas hydrophila infected fish were collected and pooled for metagenomic analysis. To understand the gut microbiota composition of healthy and disease affected fish, the community analysis was performed by targeting the 16s rRNA gene. The OTUs consisted of four major phyla, Proteobacteria, Bacteroidota, Actinobacteriota and Firmicutes. Taxonomic abundance of the microbiota at phylum, class, order, family, genus and species levels showed Bacteroides as the most dominant phylum in healthy pangasius fish whereas Firmicutes was dominant in diseased fish. Proteobacteria was dominant in healthy catla fish and Bacteroidota was observed in abundance in infected fish. The paper further discusses various metagenomic approaches and future prospects in fish gut microbiota research.
Metagenomics, Fish gut, Microbiome, Taxonomic abundance, Health and Disease
Audience take away:
• Complete profile on the gut microbiome and its responses during pathogenesis will generate substantial report on bacterial diversity that will provide important insights into the microbial ecology and adaptability of gut microbiome during different stages of disease progression. A better understanding of the intricate microbial players will help in finding the best possible solution.
• Such studies will help to understand the utilization of gut microbes that exhibits a positive effect on the animal health and thus lead to the usage of potential microbes as probiotics.