Natural materials, such as bamboo, is able to withstand the rough conditions posed by its environment, such as resistance to degradation by microorganisms, due to notable antibacterial characteristics. The methods of extraction exert a significant influence on the effectiveness of bamboo-derived antibacterial agents. In this study, the antibacterial characteristics of various types of Japanese bamboo, namely, Kyoto-Moso, Kyushu-Moso and Kyushu-Madake were investigated by considering an extraction and a non-extraction method. The characterization of the efficacy of antibacterial agents of various bamboo samples derived from both methods of extractions was conducted using an in vitro cultured bacteria technique consisting of E. coli and S. aureus. Antibacterial test results based on colony-forming units showed that antibacterial agents derived from the non-extraction method yielded better efficacy when tested against E. coli and S. aureus. Most specimens displayed maximum antibacterial efficacy following a 48-h period. The antibacterial agents derived from thermally modified bamboo powder via the non-extraction method showed improved antibacterial activity against S. aureus specifically. In contrast, absorbance results indicated that antibacterial agents derived from the extraction method yielded poor efficacy when tested against both E. coli and S. aureus. From FTIR analysis, characteristic bands assigned to the C-O and C-H functional groups in lignin were recognized as responsible for the antibacterial trait observed in both natural and thermally modified Japanese bamboo powder. Techniques to exploit the antibacterial characteristics present in bamboo by identification of antibacterial source and adoption of adequate methods of extraction are key steps in taking advantage of this attribute in numerous applications involving bamboo-derived products such as laminates and textile fabrics.
Keywords: FTIR spectroscopy; antibacterial; bamboo; extraction; lignin; thermally modified.