Metagenomics and CAZymes in Rumen: A review

Rumen converts lignocellulsic biomass to high quality food by virtue of the diverse microbiota. The composition of rumen ecosystem is shaped up by various factors including diet, individuality, age, geographic region, postfeeding time etc. Earlier culture based techniques could study rumen microbes partially for the cultivable microbes. But, now it is known that about 90% of rumen microbes are unculturable and the knowledge that we have till now seems to be meager. With the advent of new technologies as next generation sequencing which study the whole ruminal ecosystem at one time contributed tremendously to our existing knowledge. Approaches like metagenomics, metatranscriptomics etc. have made it possible to study the structure and function of rumen microbes in their natural environment. The study of CAZymes revealed that there is an array of hydrolytic enzymes in rumen that perform the deconstruction of fibrous feed material. Also, these enzymes are not only contributed by well known microbes’ viz. Fibrobacter and Ruminococcus but by a very diverse microbiota including Roseburia, Porphryomonas, Balutia etc. So, metagenomics has added to our knowledge in many spheres of rumen microbiology, its composition and interactions in rumen. But the problem in this field is that a robust database is not available to compare the data obtained. Much work is required in field of analysis of metagenomic database establishment.