Construct a novel anti-bacteria pool from hydrothermal liquefaction aqueous family

Hydrothermal liquefaction aqueous phase (HTL-AP) is complex and toxic, which severely hinders the scale-up of HTL technology. Distinguished from degrading organics and extracting chemical energy or nutrients from HTL-AP via biological fermentation or algae cultivation, here, we propose an innovative strategy to valorize the HTL-AP as a powerful anti-bacterial pool. Six model ingredients, i.e. lipids, cellulose, xylan, lignin, protein and the mixture were employed, to obtain a thirty-HTL-AP pool for characteristics database construction. We found that the xylan group at 230 °C on Escherichia coli (E. coli) and at 200 °C on Staphylococcus aureus (S. aureus) exhibited the highest anti-bacterial activities via plate experiments, nearly equal to 100 μg/ml streptomycin which far exceeded the working concentration of streptomycin (10-50 μg/ml). The liquid cultivation studies further revealed HTL-APs from the mixture feedstock, protein, real biomass microalgae and cornstalk had more stable anti-bacterial activities as chemically stable substances. Interestingly, the Gram-positive strain S. aureus was more susceptible than the Gram-negative E. coli on the HTL-APs, probably owing to the outer selectively permeable membrane difference and the strong reducibility and acidity of HTL-APs. This study provides a new vision to seek the anti-bacterial potential of HTL aqueous, supporting further investigations on its molecular mechanism and new bactericide development.