Cleaves high molecular weight succinoglycan to yield LMW succinoglycan. Dynamically regulates the molecular weight distribution of succinoglycan by cleaving nascent succinoglycan only during a limited period after its synthesis, perhaps before it undergoes a time-dependent change in its conformation or aggregation state (By similarity). Glycan metabolism; exopolysaccharide biosynthesis. Probably by a type-III secretion system. Belongs to the glycosyl hydrolase 16 family.