Carbon/nitrogen ratios determine biofilm formation and characteristics in model microbial cultures

Pia Ramos; Ryo Honda; Eric M V Hoek; Shaily Mahendra

doi:10.1016/j.chemosphere.2022.137628

Carbon/nitrogen ratios determine biofilm formation and characteristics in model microbial cultures

Chemosphere. 2023 Feb:313:137628. doi: 10.1016/j.chemosphere.2022.137628. Epub 2022 Dec 21.

Authors

Pia Ramos¹, Ryo Honda², Eric M V Hoek³, Shaily Mahendra⁴

Affiliations

¹ Department of Civil and Environmental Engineering, University of California Los Angeles, 5732 Boelter Hall, Los Angeles, CA, 90095, USA.
² Faculty of Geoscience and Civil Engineering, Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa, 920-1192, Japan.
³ Department of Civil and Environmental Engineering, University of California Los Angeles, 5732 Boelter Hall, Los Angeles, CA, 90095, USA; UCLA California NanoSystems Institute, Los Angeles, CA, 90095, USA; UCLA Institute of the Environment & Sustainability, Los Angeles, CA, 90095, USA.
⁴ Department of Civil and Environmental Engineering, University of California Los Angeles, 5732 Boelter Hall, Los Angeles, CA, 90095, USA; UCLA California NanoSystems Institute, Los Angeles, CA, 90095, USA; UCLA Institute of the Environment & Sustainability, Los Angeles, CA, 90095, USA. Electronic address: mahendra@seas.ucla.edu.

PMID: 36565767
DOI: 10.1016/j.chemosphere.2022.137628

Abstract

The influence of growth medium water chemistry, specifically carbon/nitrogen (C/N) molar ratios, on the characteristics and development of biofilms of the model microorganism Pseudomonas aeruginosa was investigated. C/N = 9 had a unique effect on biofilm composition as well as quorum sensing (QS) pathways, with higher concentrations of carbohydrates and proteins in the biofilm and a significant upregulation of the QS gene lasI in planktonic cells. The effect of C/N ratio on total attached biomass was negligible. Principal component analysis revealed a different behavior of most outputs such as carbohydrates and QS chemicals at C/N = 9, and pointed to correlations between parameters of biofilm formation and steady state distribution of cells and extracellular components. C/N ratio was also shown to influence organic compound utilization by both planktonic and sessile organisms, with a maximum chemical oxygen demand (COD) removal of 83% achieved by biofilms at C/N = 21. Planktonic cells achieved higher COD removal rates, but greater overall rates after six days occurred in biofilms. The development of a dual-species biofilm of P. aeruginosa and Nitrobacter winogradskyi was also influenced by C/N, with increase in the relative abundance of the slower-growing N. winogradskyi above C/N = 9. These results indicate that altering operational parameters related to C/N would be relevant for mitigating or promoting biofilm formation and function depending on the desired industrial application or treatment configuration.

Keywords: Bioaugmentation; Biofouling; Biological treatment; Fouling; Heterotrophic; Wastewater.

MeSH terms

Biofilms
Carbohydrates
Carbon* / metabolism
Nitrogen* / pharmacology
Pseudomonas aeruginosa
Quorum Sensing

Substances

Carbon
Nitrogen
Carbohydrates