Catalyzes endohydrolysis of 1,4-beta-D-glucosidic linkages in xyloglucan with retention of the beta-configuration of the glycosyl residues in xyloglucan degradation. Cleaves the backbone of the 3 major types of natural xyloglucans (seed galactoxyloglucan from tamarind kernel, dicot fucogalactoxyloglucan from lettuce leaves, and solanaceous arabinogalactoxyloglucan from tomato fruit), to produce xyloglucan oligosaccharides. xyloglucan + H2O = xyloglucan oligosaccharides. kcat is 10.5 sec(-1) for XXXG-beta-CNP. kcat is 11.1 sec(-1) for XLLG-beta-CNP. kcat is 0.12 sec(-1) for GGGG-beta-CNP. Optimum pH is 6.0-7.0. Glucan metabolism; xyloglucan degradation. Cell outer membrane localization is predicted by analogy with the archetypal sus locus. The BACON domain was initially thought to act as a carbohydrate-binding domain. However, it does not bind carbohydrates and may rather be required to distance the catalytic module from the cell surface and confer additional mobility to the catalytic domain for attack of the polysaccharide (PubMed:24463512). Cells are not able to growth on xyloglucan polysaccharide, This phenotype can be directly rescued by the addition of xyloglucan oligosaccharides. Gut bacteria supply the human body with energy from dietary polysaccharides through glycosidases that are absent in the human genome. Xyloglucans are a ubiquitous family of highly branched plant cell wall polysaccharides present in the vegetables we consume. Enzymes involved in xyloglucan degradation mediate the conversion of otherwise indigestible plant polysaccharides to short-chain fatty acids (PubMed:24463512). Belongs to the glycosyl hydrolase 5 (cellulase A) family.