Specifically hydrolyzes beta-1,3-galactan in an endo-fashion. Requires at least 3 contiguous beta-1,3-residues. The enzyme specifically hydrolyzes beta-1,3-galactan and beta-1,3-galactooligosaccharides. kcat is 7.56 sec(-1) with beta-1,3-galactan. kcat is 5.47 sec(-1) with beta-1,3-galactotriose. kcat is 6.50 sec(-1) with beta-1,3-galactotetraose. Optimum pH is 4.0-6.0. Optimum temperature is 50 degrees Celsius. N-glycosylated. Belongs to the glycosyl hydrolase 16 family.