Which of the following help(s) the helical bacteria, spirochetes to travel through viscous substances such as mucus or mud?

Spirochetes have two or more specialized flagella (endoflagella) arising from opposite poles of the cell, which together constitute the so called axial filament that is located within the periplasmic space between the flexible cell wall and an outer sheath. The rotation of the axial filament relative to the cell body causes the entire bacterium to move forward in a corkscrew-like motion even through material viscous enough to prevent the passage of normally flagellated bacteria. Each axial filament is composed of fibrils extending toward each other between two layers of the cell wall.