Enhanced biodegradation of pyrene by immobilized bacteria on modified biomass materials

• NaOH and H2O2 modified peanut shell powder was used as carrier for bacteria immobilization.
• Modification of peanut shell powder dramatically improved the pyrene degradation rate of bacteria immobilized into them.
• NaOH and H2O2 modified peanut shell powder improve the survival and activity of bacteria immobilized into them.
• NaOH and H2O2 modification could improve the porosity of peanut shell powder.
• NaOH and H2O2 modification decreased crystallinity of peanut shell powder and destruction of benzene ring in cellulose.

The degradation of pyrene (PYR) by Mycobacterium gilvum immobilized on peanut shell powder (PSP) was improved by chemically modifying the PSP. The physicochemical properties of the modified biomass (M-PSP) were characterized with surface area analysis, X-ray diffraction, Fourier transform infrared and solid-state CP/MAS 13C NMR spectra. The results showed that the chemical modification decreased the crystallinity of the biomass and destroyed the benzene rings in the cellulose, which improved the porosity of PSP. Fluorescein diacetate activity (FDA) of cells immobilized on the M-PSP decreased more slowly than cells immobilized on PSP. The PYR degradation efficiencies achieved by bacteria immobilized on M-PSP was higher than that achieved by immobilized bacteria on PSP after 7 d. It revealed that chemical modification of biomass could further improve bacterial activity and enhance the degradation ability of the cells compared with the raw one, as we expected.In summary, this study shows that M-PSP is a good immobilizing bio-mass for supporting pollutant-degrading bacteria and could be employed as an effective material for PYR biodegradation.