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. May be superfluous in xyloglucan degradation compared to BoGH5A (AC A7LXT7), the other Xyloglucan-specific endo-beta-1,4-glucanase. xyloglucan + H2O = xyloglucan oligosaccharides. Optimum pH is 6.0-7.0. Glucan metabolism; xyloglucan degradation. Cell outer membrane localization is predicted by analogy with the archetypal sus locus. No visible phenotype. No effect on growth. 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 9 (cellulase E) family.