The misuse of disinfectants is a disaster for the environment. Compounds containing chlorine, such as bleach, can produce potentially dangerous byproducts by reacting with other chemicals. Other potential greener disinfectants are based on phenol or its chemical relatives, but they can be expensive and energy-intensive to create.
Phenolic structures, however, abound in wood, as well as some of the large branched molecules that make up the cell walls of plants. This is why the environmental engineer Shicheng Zhang of Fudan University in Shanghai and his colleagues questioned whether sawdust waste could provide a greener source of antimicrobial compounds.
Water and sawdust for a terrific disinfectant
The researchers cooked water and sawdust mixtures for an hour under pressure, filtered them and examined the results. Then the team tested the sawdust mixes for their ability to kill it staphylococcus epidermis, skin microbe that can cause infections in immunocompromised individuals, and E. coli, a bacterium that can cause foodborne illness. Depending on the concentration, this disinfectant can kill more than 99% of microbes, the team reported Proceedings of January 18 of the National Academy of Sciences .
Sawdust disinfectant, the study reads, has been equally successful in inactivating anthrax and influenza viruses.. It is also highly effective against spores, dormant forms of bacteria that can be difficult to kill. The tests have so far shown efficacy on the Bacillus subtilis (which, however, is already harmless in its own right).
Chemical analysis of this sort of "sawdust soup" revealed high amounts of phenolic compounds. The molecular chains of wood are likely to be disrupted during pressure cooking, releasing antimicrobial phenolic molecules.
Under the microscope, the scientists saw that their disinfectant damaged the cell walls of E. E. coli coli e S. epidermis. Phenolic compounds can also damage the proteins and genetic material of bacteria and viruses, Zhang says.
More sustainable than that.