Biodegradation of sodium benzoate by Pseudomonas biofilm consortium in a fluidized bed bioreactor

摘要

Many strains of Gram-negative bacteria, such as Pseudomonas, are able to utilize audvariety of unusual chemicals, including a wide range or aromatic hydrocarbons and theirudderivatives for growth. Bacteria with the potential to degrade sodium benzoate wereudisolated, identified and grown as biofilms on sodium benzoate in a laboratory-scaleudfluidized bed biofilm bioreactor. Four Pseudomonas strains identified as P. aeruginosaud(BDS2) P. putida (BDS1 and GR1) and Burkholderia cepecia (GR3FAR) were used in audlaboratory-scale FBBR together with two Bacillus strains - Bacillus macroides (SBSY4)udand Bacillus simplex (MAR). Sodium benzoate biodegradation capacities of these speciesudwere compared under batch and continuous operations. Biofilm and planktonic bacterialudgrowth dynamics were monitored by plate counts, and optical density measurementsud(230nm) determined benzoate biodegradation. Overall, higher attached and planktonicudbacterial counts were determined under batch compared to continuous mode. In additionudto this, the ability of attached cells to use sodium benzoate as their sole carbon sourceudwas compared to their suspended counterparts in a batch system. There were moreudattached counts compared to suspended cells and attached cells apparently degradedudsodium benzoate better than planktonic cells. Similarly, higher rates of benzoateuddepletion were found to occur under batch compared to the continuous system. It thusudappeared that more cell growth implied more substrate consumption. SEM showedudattached cells and microcolonies of all the isolates on GAC, indicating their biofilmformingudabilities.