Construction of a cold-resistant shelter: Assembly of bacteria on hierarchical porous material for low-temperature phenol bio-degradation and machine learning prediction

Abstract

Low temperature significantly limit microbial growth and metabolism, thereby reducing the efficiency of pollutant degradation by environmental microorganisms. In this study, a hierarchical porous material (BF-PU-PI) was fabricated by the breath figure method. Through electrostatic interactions with the multifunctional groups on the microbial surface, Bacillus cereus ZWB3 was effectively assembled within the material, forming BF-PU-PI@ZWB3. Compared to ZWB3, BF-PU-PI@ZWB3 exhibited a 40 % higher phenol degradation rate. Interestingly, at 15 °C, it maintained high degradation efficiency, with a 36 % improvement over the ZWB3. The protective microenvironment provided by BF-PU-PI significantly enhanced the activities of key enzymes (phenol hydroxylase and catechol 1,2-dioxygenase), while alleviating intracellular oxidative stress. Furthermore, the thermal conductivity of BF-PU-PI was reduced to 0.0167–0.0333 W/(m·K) compared to PU, partially substituting for extracellular polysaccharides and free fatty acids to offer thermal insulation. This thermal regulation promoted the low-temperature metabolic activity of ZWB3 for phenol degradation. Machine learning models further predicted that BF-PU-PI@ZWB3 could sustain phenol degradation activity even at 8 °C. This hierarchical porous material acts as a “cold-resistant shelter” for microorganisms, enabling efficient biodegradation under low-temperature.