Microorganisms, in addition to many positive effects such as biological decomposition of organic matters, represent a problem because they cause infectious diseases and adversely affect functional properties of textiles. The main aim of the research was to study the influence of ZnO nanoparticles on the antimicrobial activity and biodegradation of natural cellulose fibre blends including different proportions of lyocell antimicrobial fibres. Antimicrobial tests for Staphylococcus aureus and Escherichia coli were carried out according the ASTM E 2149-01 standard method. A significant trend in the increase of antimicrobial activity with the increase of the proportion of antimicrobial fibres in the blends was observed for E. coli. Additional tests of bacterial growth and adhesion to individual fibres were performed to clarify the divergent results which were obtained for S. aureus. It was found out that the flax fibres represent a suitable substrate for the growth of S. aureus and that the bacteria adhere to the fibres after a certain period of time and protect themselves by forming a biofilm. In the second part of the research, a fibre blend including 25% lyocell fibres, that provided a satisfactory antimicrobial protection for E. coli, was chosen for biodegradation experiments. In this study, the fibre blend and the control samples were buried into the humus soil. Physical and chemical properties of fibres were analysed after certain intervals of soil burial. To determine the level of the soil contamination, the seed germination was also studied. The results showed that an increase in the proportion of antimicrobial fibres in the blend caused a decrease in the blend biodegradability and at the same time had no effect on the soil contamination.
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