Acceleration of biofilm formation in start-up of sequencing batch biofilm reactor using carriers immobilized with Pseudomonas stutzeri strain XL-2

P. stutzeri strain XL-2 initially immobilized on polypropylene carriers accelerated the biofilm formation in start-up of sequencing batch biofilm reactor (SBBR) (denoted R1). The biofilm formation in R1 was approximately completed in 36 days, which was shorter than that of 48 days in an identical SBBR (denoted R2) without strain XL-2. Meanwhile, R1 presented a rapid stabilization of NH4+-N and TN removal to 81.7% and 72.4% respectively. Surface plasmon resonance demonstrated that strain XL-2 enhanced the initial adhesion of carrier surface due to the production of extracellular polymeric substances (EPS), which made it easier for other EPS-producing strains, such as Thauera and Flavobacterium, to adhere to the carriers. PICRUSt revealed that biofilm in R1 presented relatively higher activity of EPS biosynthesis enzymes (glycosyltransferase and asparagine synthase). Thus, high EPS content was obtained due to the application of carriers immobilized with strain XL-2 and finally promoted the biofilm formation.