*2.1. Materials*

The bacterial strain, Gluconacetobacter hansenii (ATCC 53582), was provided by China Center of Industrial Culture Collection. The m-phenylenediamine was purchased from Aladdin Industrial Co., Ltd. (Hangzhou, China). Glutaraldehyde was obtained from Macklin Biochemical Technology Co., Ltd. (Shanghai, China) and other chemical regents were provided from Sinopharm chemical reagent (Shanghai, China).
