Characteristics and influencing factors of biofilm formation by a pyridine-degrading bacterium Pseudomonas sp. ZX08

XIONG Fu-Zhong1 ZHAO Xiao-Xi1 WEN Dong-Hui1 LI Qi-Lin2

(1.College of Environmental Sciences and Engineering, Peking University, Beijing, China 100871)
(2.Department of Civil and Environmental Engineering, Rice University, Houston, TX 77005, USA)

【Abstract】[Background] The wastewater discharged by coal chemical industry contains a large number of refractory and highly toxic organic pollutants. It is an economically feasible strategy to treat the wastewater with bioaugmentation technology based on effective degrading bacteria. Promoting the biofilm formation of degrading bacteria is proved to be beneficial to the performance of the biofilm wastewater treatment system. [Objective] To investigate the biofilm formation process and characteristics of a pyridine-degrading bacterium Pseudomonas sp. ZX08, and to identify the influence of different environmental factors such as temperature, pH, Na+, K+, Ca2+, and Mg2+ on biofilm formation, and finally to provide reference for regulating biofilm formation in wastewater treatment systems. [Methods] A modified microtiter dish biofilm formation assay was used to determine the biofilm formation and the planktonic bacteria growth in the 12-well plate under different conditions; the structural characteristics of biofilm was observed using a confocal laser scanning microscope (CLSM). [Results] Pseudomonas sp. ZX08 showed good pyridine-degrading performance and biofilm-forming abilities. According to the CLSM analysis, the thickness of its biofilms formed at the surface reached 40–50 μm, and the proportion of live cells and protein/cell ratio were higher in the outer layer of the biofilms. A periodic variation was observed in the biofilm formation process in 72 h, and the biofilm biomass at the time points of 12 h and 48 h were relative peaks. The optimum temperature for ZX08 biofilm formation was 25°C, and the optimum pH range was 7.0–9.0. Higher concentrations of NaCl (> 0.6 mol/L) and KCl (> 0.4 mol/L) significantly inhibited the biofilm formation of ZX08. Within a certain range (0–16 mmol/L), the increase of Ca2+ concentration could promote the biofilm formation at the solid-liquid interface of the 12-well plate bottom. Adding 0–16 mmol/L Mg2+ also led to a slight increase in the biofilm formation of ZX08. [Conclusion] The pyridine-degrading bacterium Pseudomonas sp. ZX08 can form thick and stable biofilm, and it needs to comprehensively consider the influence of environmental factors on the biofilm formation of this strain in the future application.

【Keywords】 Pyridine; Effective degrading bacteria; Biofilm; Environmental factors;


【Funds】 National Natural Science Foundation of China (51378019, 51529801)

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This Article


CN: 11-1996/Q

Vol 47, No. 05, Pages 1342-1353

May 2020


Article Outline


  • 1 Materials and methods
  • 2 Results
  • 3 Discussion and conclusion
  • References