Abstract:

To explore the antimicrobial property of naturally brown cotton, plate colony counting method and turbidimetry method were used to test the antibacterial properties against gram-positive bacteria S.aureus and gram-negative bacteria  E.coli. Meanwhile,  the antimicrobial activity and antimicrobial mechanism of the pigment extract were also studied by disk diffusion method, fluorescence microscope and scanning electron microscope. The results showed that brown cotton fibers have good inhibitory effect on the growth of two test bacteria and its antibacterial ratio are 87.9 % and 79.5 %, respectively, showing significant antimicrobial properties of brown cotton fibers. Conventional alkali scouring and enzyme scouring can improve the antibacterial performance of brown cotton fibers to a certain extent. Brown cotton fibers’ antibacterial properties derives from its pigment. The pigment may destroy the transport capacity of cell membrane by combination with membrane structure of bacteria and then inhibit the normal growth and reproduction process of bacteria to achieve the effect of killing bacteria.

Key words: natural brown cotton, pigment, antimicrobial mechanism, cell membrane