A method for cleavage of the ether-linkage of polyethoxylates is described. A novel pure microbial culture, Pseudomonas nitroreducens TX1 (Depository No.: BCRC910228), is used under aerobic condition to cleave the ether-linkage adjacent to the carboxylated terminus or ethoxyl terminus. This method is useful to cleave sequentially ether-linkage of polyethoxylates in an aqueous buffer solution with an initial concentration of the polyethoxylates between 0.05% and 20%. This method is also effective for the cleavage of the ether-linkages in short-chain polyethoxylates with one to three ethoxyl units.