CAZymes in animal gut microbial MAGs: distribution and novel enzyme reservoir

The gut microbiota of animals contains a vast reservoir of CAZymes. A thorough understanding of the CAZymes encoded by the gut microbiota of different animals is significant for deciphering various animal strategies for handling carbohydrates and for discovering novel, highly efficient CAZymes. Here, we collected 100,090 MAGs from humans and 10 types of animals, and annotated 8,747,365 known CAZymes. These CAZymes cover 613 carbohydrate enzyme families, accounting for 70.5% of the known total. Furthermore, we found that the Bacteroides genus encodes the largest number CAZymes. We annotated the PULs of the Bacteroides genus and identified a total of 185,715 potential novel CAZymes encoded by these PULs, which represents the largest potential novel carbohydrate enzyme library to date. To verify the reliability of this carbohydrate enzyme library, we selected Vatanent_2016_SRR4408032_bin.1, which encodes the greatest greatest number of PULs. We then identified the protein BfLac15, which has the lowest similarity to known CAZymes. Molecular docking prediction suggests that BfLac15 may be a novel multifunctional carbohydrate enzyme. Then, BfLac15 was obtained using the prokaryotic expression technology, and its ability to hydrolytic various substrates was determined. This confirmed that BfLac15 is a novel multifunctional carbohydrate enzyme and verified the reliability of the carbohydrate enzyme library. This study provides valuable resources for CAZymes applications and offers ideas for the mining and applying of massive data in the rapidly developing era of metagenomics.