Dispersive biofilm from membrane bioreactor strains: effects of diffusible signal factor addition and characterization by dispersion index

Wonjung Song; Junhee Ryu; Jaehyun Jung; Youngjae Yu; Suyoung Choi; Jihyang Kweon

doi:10.3389/fmicb.2023.1211761

Dispersive biofilm from membrane bioreactor strains: effects of diffusible signal factor addition and characterization by dispersion index

Front Microbiol. 2023 Jul 25:14:1211761. doi: 10.3389/fmicb.2023.1211761. eCollection 2023.

Authors

Wonjung Song¹, Junhee Ryu², Jaehyun Jung³, Youngjae Yu⁴, Suyoung Choi¹, Jihyang Kweon⁵

Affiliations

¹ The Academy of Applied Science and Technology, Konkuk University, Seoul, Republic of Korea.
² Department of Civil and Environmental Engineering, Konkuk University, Seoul, Republic of Korea.
³ HANSU Technical Service Ltd, Sungnam-si, Gyeonggi-do, Republic of Korea.
⁴ Department of Chemical and Environmental Engineering, University of Arizona, Tucson, AZ, United States.
⁵ Department of Environmental Engineering Konkuk University, Seoul, Republic of Korea.

Abstract

Introduction: Biofilm occurs ubiquitously in water system. Excessive biofilm formation deteriorates severely system performance in several water and wastewater treatment processes. Quorum sensing systems were controlled in this study with a signal compound cis-2-Decenoic acid (CDA) to regulate various functions of microbial communities, including motility, enzyme production, and extracellular polymeric substance (EPS) production in biofilm.

Methods: The addition of CDA to six strains extracted from membrane bioreactor sludge and the Pseudomonas aeruginosa PAO1 strain was examined for modulating biofilm development by regulating DSF expression.

Results and discussion: As the CDA doses increased, optical density of the biofilm dispersion assay increased, and the decrease in EPS of the biofilm was obvious on membrane surfaces. The three-dimensional visual images and quantitative analyses of biofilm formation with CDA proved thinner, less massive, and more dispersive than those without; to evaluate its dispersive intensity, a dispersion index was proposed. This could compare the dispersive effects of CDA dosing to other biofilms or efficiencies of biofouling control practices such as backwashing or new cleaning methods.

Keywords: biofilm; cis-2-Decenoic acid; diffusible signal factor (DSF); extracellular polymeric substances (EPS); membrane bioreactor; quorum sensing.