Antibacterial action of rush.  It has been shown that rush has an antibacterial activity against food poisoning bacteria such as enterohemorrhagic colitis O157, Salmonella and Staphylococcus aureus.

It has the same effect on spoilage bacteria such as Bacillus and Micrococcus.

(Journal of the Japan Society of Microbiology. 2002)

From such facts, tatami mats are a natural antibacterial material.  Recent studies have also shown antibacterial activity against Legionella bacteria, which cause pneumonia.