Abstract
Biofilms are ubiquitous and notoriously difficult to eradicate and control, complicating human infections and industrial and agricultural biofouling. However, most of the study had used the biofilm model that attached to solid surface and developed in liquid submerged environments which generally have neglected the impact of interfaces. In our study, a reusable dual-chamber microreactor with interchangeable porous membranes was developed to establish multiple growth interfaces for biofilm culture and test. Protocol for culturing Pseudomonas aeruginosa (PAO1) on the air–liquid interface (ALI) and liquid–liquid interface (LLI) under static environmental conditions for 48 h was optimized using this novel device. This study shows that LLI model biofilms are more susceptible to physical disruption compared to ALI model biofilm. SEM images revealed a unique “dome-shaped” microcolonies morphological feature, which is more distinct on ALI biofilms than LLI. Furthermore, the study showed that ALI and LLI biofilms produced a similar amount of extracellular polymeric substances (EPS). As differences in biofilm structure and properties may lead to different outcomes when using the same eradication approaches, the antimicrobial effect of an antibiotic, ciprofloxacin (CIP), was chosen to test the susceptibility of a 48-h-old P. aeruginosa biofilms grown on ALI and LLI. Our results show that the minimum biofilm eradication concentration (MBEC) of 6-h CIP exposure for ALI and LLI biofilms is significantly different, which are 400 μg/mL and 200 μg/mL, respectively. These results highlight the importance of growth interface when developing more targeted biofilm management strategies, and our novel device provides a promising tool that enables manipulation of realistic biofilm growth.Key points• A novel dual-chamber microreactor device that enables the establishment of different interfaces for biofilm culture has been developed.• ALI model biofilms and LLI model biofilms show differences in resistance to physical disruption and antibiotic susceptibility.
Highlights
Biofilms are the dominant surviving model of bacteria that exist on earth (Donlan 2002)
Biofilms can grow on surfaces that are subjected to the air–liquid interface (ALI) which when colonized provides bacteria with access to both the gaseous and liquid phases or on the liquid–liquid interface (LLI) where biofilm intact to the liquid phases from two sides
Biofilms formation in the respiratory system and on the roots or leaves of plants can be modeled as ALI biofilm, while biofilms that developed in the urinary tract, on porous medical indwelling devices, and porous membrane used in wastewater treatment plant can be best characterized as LLI biofilm
Summary
Biofilms are the dominant surviving model of bacteria that exist on earth (Donlan 2002). Biofilms protect the microorganism from hostile physical and chemical environments such as altered pH, osmolarity, nutrients scarcity, and mechanical and shear forces and block bacterial biofilm communities’ access from antibiotics and host’s immune cells (Sharma et al 2019). Pseudomonas aeruginosa is a ubiquitous pathogen that could colonize multiple environments and establish a biofilm within 24 h (Webster et al 2015) and matured within 48 h (Borriello et al 2004) It can cause a variety of infections, such as chronic lung infection (Faure et al 2018) and urinary tract infections (UTIs) (Mittal et al 2009), and its accentuated antibiotic resistance during biofilm growth poses a significant threat to the medical community. The model that better mimic the biofilm attaching interface will help to investigate the drug efficacy delivered though different ways
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