Assessing a method for single- and multidomain biofilm growth in a novel biofilm reactor: shear stress, ruggedness, repeatability, and reproducibility

Abstract

Numerous lab-scale bioreactor systems exist to cultivate biofilms under desired growth conditions. However, existing systems have not been able to simultaneously deliver low shear stress, high gas transfer, and intermittent wetting. The industrial surfaces biofilm reactor (ISBR) was specifically developed to overcome these limitations by simultaneously providing these conditions. This study presents the first standard operating procedure (SOP) for the growth of a model biofilm-forming organism, Pseudomonas aeruginosa, within the ISBR, providing a reproducible framework for investigating biofilm development under conditions that closely mimic industrial environments. Statistical analyses confirmed the SOP's repeatability, ruggedness, and reproducibility using biofilm density and biovolume data, supported by an analytical shear stress model for ISBR coupons. Biofilm densities were rugged to recycle and rotation rate deviations but increased with influent feed rate. Conversely, biovolumes were rugged to influent feed and rotation rate changes but declined with higher recycle rates. Both metrics demonstrated excellent repeatability and reproducibility, underscoring the need to assess these characteristics for consistent biofilm formation. Additionally, as a proof-of-concept, two multidomain biofilms (a Legionella pneumophila-Vermamoeba vermiformis model and a Rhodotorula mucilaginosa yeast-P. aeruginosa bacterial coculture) were cultivated and analyzed. Both exhibited high repeatability, and the coculture remained stable over a month-long growth period.