## 4 Discussion
### Metabolic Pathways of Top Scoring Enzymes  
The etiology of CRC is influenced by the bacterial communities that colonize the gastrointestinal tract. These microorganisms, through their intricate interactions with the gut environment, play a crucial role in shaping the physiology and pathology of the host. Within the intricate ecosystem of the gut microbiome, various bacterial species derive essential nutrients from otherwise indigestible dietary components or host-derived compounds. This process not only aids in the maintenance of microbial populations, but also contributes to the overall health of the host. Moreover, these bacteria have been found to activate the molecular signaling pathways that are vital for maintaining normal tissue function and supporting immune responses within the gut. By modulating these molecular pathways, the gut bacteria can influence the host's susceptibility to various diseases, including colorectal cancer. The dynamic interplay between the gut microbiome and host physiology underscores the importance of understanding the intricate relationships between bacterial communities and disease development. The tumor microenvironment and the gut microbiota (microenvironment) are play important role in the formation and progression of colorectal cancer. The balance of bacterial metabolism plays a crucial role in the health of the intestine. Bacterial side-products may affect the colon surface area and result in cancer formation. The increased incidence of CRC can be attributed to various factors, such as an aging population, the prevalence of unhealthy dietary practices, smoking, a sedentary lifestyle, and obesity. There is a documented positive correlation between alcohol consumption and elevated rates of colorectal cancer globally, especially in developed nations [68]. In terms of dietary factors, certain anti-inflammatory components have been associated with potential benefits in reducing the risk of colorectal cancer. These components include the following: monounsaturated fatty acids, polyunsaturated fatty acids, omega-3 fatty acids, vitamins (B12, A, C, D, E, folic acid), minerals (zinc, magnesium, selenium), and bioactive compounds such as flavonoids, anthocyanins, and certain herbs and spices (e.g., garlic, ginger, turmeric, and tea) [69; 70; 71]. Conversely, pro-inflammatory food components have been linked to a potential increase in the risk of developing colorectal cancer. These components include energy dense foods, total fat, trans fat, cholesterol, saturated fatty acids [72]. As shown in Figure 8, glycosidases (EC: 3.2.1), hydro-lyses (EC:4.2.1), and CoA-transferases (EC: 2.8.3) have been found to be the top three scoring CRC-associated enzyme groups. Glycosidases (EC: 3.2.1) play a role in several metabolic activities, especially for starch and sucrose metabolism (Figure 11A), sphingolipid metabolism (Figure 11B),  
Figure 19: Commonalities among the top 100 features that were selected by different feature selection algorithms and the EC-nomenclature-based G-S-M approach when tested on CRC-associated metagenomic dataset, including relative abundance values of the enzymes. galactose metabolism (Figure 11C), N-glycan biosynthesis (Figure 11D), and glucuronate interconversions (Figure 11E). In starch and sucrose metabolism and galactose metabolism, glycosases (EC: 3.2.1), such as oligo-1,6-glucosidase (EC: 3.2.1.10) and alpha-glucosidase (EC: 3.2.1.20), result in an increasing amount of D-Glucose from different sources (Figure 11A,C). Especially in galactose metabolism, glycosases (EC: 3.2.1) and alpha-galactosidase (EC: 3.2.1.22) activation result in the formation of D-Galactose and D-Glucose. Additionally, oligo-1,6-glucosidase (EC: 3.2.1.10) and alpha-glucosidase (EC: 3.2.1.20) activation results in increasing amounts of D-Fructose (Figure 11C). Also, other glycosases (EC: 3.2.1) have different roles in these pathways in terms of contributing to D-Glucose, D-Galactose, and D-Fructose formation.