Approaches to prevent, remove and kill biofilms (2023)

The microorganisms attach themselves through the synthesis of extracellular polymeric substances and colonize living and non-living surfaces, causing serious problems for the food, dairy, medical, marine, water, gas and oil industries and municipal facilities. Biocorrosion and biofouling are major problems in various industries. These two destruction mechanisms are closely related to the formation of biofilms on material surfaces. Biofilm formation provides an active platform for diatoms and algae, leading to increased operating and maintenance costs and accelerated degradation of abiotic materials. In addition, biofouling on membranes hinders some industrial membrane-based water treatment and desalination processes such as reverse osmosis, microfiltration, ultrafiltration and nanofiltration. Due to the harmful effect of biofilms, there is an urgent need to control the microorganisms in biofilms or to prevent the attachment and formation of biofilms. Eradication of biofilms is difficult because microbial cells in biofilms tend to have higher resistance to disinfectants and antimicrobials compared to biofilms of individual species. Therefore, new strategies are being developed to control and damage biofilms, including bacteriophages, antibiofilm enzymes, natural products, lactic acid bacteria and their bacteriocins, novel surfaces for biofilm prevention, quorum sensing (QS) inhibitors, and physical treatment. This chapter addresses the problems of biofilms in various industries; common problematic microorganisms involved in biofilm formation, biocorrosion and biofouling; and problematic microbes and reviews a number of recently developed antibiofilm solutions for various industries.

This study evaluates the effectiveness of a typical clean-in-place (CIP) protocol against in vitro biofilms on whey reverse osmosis (RO) membranes developed under static conditions. Bacterial isolates obtained from RO membrane biofilms were used to develop single and multispecies biofilms under laboratory conditions. A typical commercial CIP protocol was tested on the 24 h old biofilms and included six sequential treatment steps based on alkali, surfactant, acid, enzyme, another surfactant and a disinfection treatment step. The experiments were performed in 4 replicates and the data were analyzed statistically. The results showed a variation in the resistance of mixed species biofilms to each step of the sequential CIP protocol. While the overall 6-step protocol resulted in a greater reduction, it also resulted in the detection of survivors even after the final disinfection step, reflecting the ineffectiveness of the CIP protocol for complete biofilm removal. Posttreatment counts of 0.71 log after sequential CIP of mixed-species biofilms demonstrated the resistance of biofilm-constitutive microbiota. Biofilms of mixed species that include different genera includingBazillus, Staphylococcus, AndstreptococciThey have been observed to be more resistant than most individual biofilms. However, significantly different resistance patterns were observed in the individual biofilmsBacillusIsolates compared to the other bacterial isolates. All 5 isolates fromBacillusproved to be resistant with survival rates greater than 1.0 log to the sequential CIP protocol tested. Therefore, it can be concluded that the tested CIP protocol had limited effectiveness in cleaning membrane biofilms formed on the whey RO membranes.

Zwitterionic polymers have attracted research attention in recent years due to their unique molecular structures. In the same repeating unit, there are simultaneously positive and negative charges on a pair of cationic and anionic groups; Therefore, zwitterionic polymers have a large dipole moment and numerous charged groups. Although the molecular chain of the zwitterionic polymer can be kept in an electrically neutral state as a whole, the coexistence of the oppositely charged groups gives the polymer extremely high polarity and excellent hydrophilicity. At the same time, the polymer's electricity can be further regulated by the pH and salt ions of the environment, which greatly expands the range of applications in various areas. This review presents various structures of zwitterionic polymers and analyzes the reasons why zwitterionic polymers exhibit pH response, anti-polyelectrolyte effects and superior electrical conductivity. The application areas are also summarized by generalizing the state of research of zwitterionic polymers, including applications in antifouling coatings, drug delivery, wastewater treatment and sensors, etc.

Human pathogens can develop biofilm structures on various artificial substrates common in the food industry. In this study, we investigated the inactivation efficiency of low-energy X-raysEscherichia coliO157:H7,salmonellaTyphimurium andListeria monocytogenesBiofilm on surfaces in contact with food, including polyvinyl chloride (PVC), stainless steel with finish 2B (STS 2B) and Teflon. The number of viable cells in biofilm on all test pieces was significant (P<0.05) decreased with increasing X-ray dose. Interestingly, different levels of biofilm inactivation were observed in relation to different material surfaces. Teflon showed the lowest D₅d values ​​(dose required for a 5 log reduction in cell number) in three groups of coupons, while PVC had higher D values₅d values ​​than the other two coupons. The mechanism of the X-ray antibiofilm effect was identified by measuring extracellular polymeric substances (EPS) in biofilms. X-ray irradiation could remove exopolysaccharides, which are a major component of EPS, and the removal rate increased as the irradiation dose increased. The analyzes also confirmed that EPS degradation is strongly related to biofilm inactivation tendencies on different coupon surfaces. This study is the first to show that X-ray irradiation effectively inactivates key biofilms of foodborne pathogens on various food contact surfaces and evaluates their antibiofilm mechanisms to increase safety in the food industry.

A comprehensive, real-time assessment of surface water chemistry is still a long way off, but we believe it is time to use the dynamics of recent technological, infrastructural and societal developments to move significantly closer to that goal. Procedures such as inline and online analysis (on pageor in the bypass) with near-real-time analysis and data provision are already available in several industries. In contrast, at-line and offline analysis with manual sampling and time-decoupled analysis in the laboratory is still common practice in aqueous environmental monitoring. Automated tools for data analysis, verification and evaluation are changing significantly and becoming more and more powerful with an increasing degree of automation and introduction of self-learning systems. In addition, the amount of available data will most likely increase in the near future through community awareness of water quality and citizen science. In this analysis, we highlight the significant potential of surface water monitoring techniques, present "lighthouse" projects from different sectors, and identify gaps that we need to fill in order to chart a path forward for inland surface water chemical monitoring.

In this study, we investigated the possibility of using spent coffee grounds (SCGs) as a photothermal material to kill bacteria. Photothermal materials can convert light energy into thermal energy and are widely used in energy and biomedicine. However, it is still a challenge to produce efficient, cheap, and easy-to-manufacture green photothermal materials using a low-emission, low-cost method. To address this challenge, we propose the use of natural SCGs as photothermal materials to kill planktonic bacteria and remove biofilms. First, SCGs and faded SCGs were exposed to near-infrared (NIR) irradiation to confirm their photothermal effect. The SCGs showed a rapid photothermal effect and reached a temperature of up to 344 °C within 2 min of irradiation, whereas the faded SCGs did not show a rapid photothermal effect because melanoidin aggregates were dissociated in them. Furthermore, the SCGs showed excellent thermal reproducibility and photothermal stability and could be repeatedly heated at least 12 times. Furthermore, the SCGs generated heat upon NIR irradiation, which led them to show excellent photothermal killing effect on planktonic bacteria and even biofilms. The generated heat killed 6 logs of planktonic bacteria and removed more than 90% of the biofilm within 30 minutes. Finally, the SCGs were embedded in a SiO₂Coating to achieve repeated in situ photothermal sterilization. This study provides extremely valuable results for the reuse and recycling of SCGs.

Drug Discovery Today, Band 23, Ausgabe 4, 2018, S. 848-856

Bacterial biofilms are extremely resistant to the effects of antibiotics. The presence of persisters, phenotypically resistant populations of bacterial cells, is thought to contribute to biofilm resilience. Phage-derived lysins have the unique ability to kill resting cells due to their ability to enzymatically cleave the peptidoglycan from bacterial cells. Several lysines have shown strong antibiofilm activityin vitro. The fact that lysins have shown better efficacy than conventional drugs in animal models of endocarditis and other biofilm-borne infections suggests that the lysins may be engineered to target difficult-to-treat bacterial infections.

Ultrasound in Medicine and Biology, bind 45, udgave 5, 2019, s. 1044-1055

Bacterial biofilms are a source of contamination in numerous medical and biological fields. Ultrasound is mechanical energy that can remove these biofilms through cavitation and acoustic flow, creating shear forces to disrupt the biofilm from a surface. The purpose of this narrative review is to review the literature on mechanical biofilm removal using acoustic cavitation to identify the various operating parameters that affect removal using this method. The properties of the liquid and the properties of the ultrasound greatly influence the type of cavitation that is generated. These include gas content, temperature, surface tension, ultrasonic frequency and sound pressure. For many of these parameters, further research is needed to understand their mechanisms in ultrasonic biofilm removal, and further research will help optimize this method for effective biofilm removal from various surfaces.

Biomedicine and Pharmacotherapy, Volume 128, 2020, Article 110184

Bacterial biofilms are widespread in nature and pose a serious threat to public health worldwide. Biofilms always lead to persistent infections and significantly increase the incidence of antibiotic resistance, making bacterial infections more difficult to treat. Current conventional therapies such as antibiotics, bacteriophage, and quorum-sensing inhibitors are widely used to combat biofilms. However, these therapies are insufficient to safely and effectively treat biofilms. Antibiotics often induce resistance in treated bacteria, and antibacterial peptides are easily degraded by proteases, reducing their effectiveness. These results suggest that biofilm treatment needs to be further improved. There is increasing evidence that naturopathic therapies have significant inhibitory effects on biofilms. In this review, the efficacy characteristics and corresponding mechanisms of conventional and naturopathic biofilm-fighting therapies have been summarized and analyzed. For comparison, the advantages and disadvantages of these therapies were classified and interpreted, leading us to conclude that combined medicine with natural remedies will be a more effective strategy against biofilm. This review lays a promising foundation for the development of antibiofilm drugs and provides new perspectives for the treatment of bacterial biofilm infections.

Engineered Regeneration, Band 1, 2020, S. 64-75

The formation of biofilms in wounds and implants can have several negative effects on a patient's health, including delayed healing and implant removal. Current treatments for biofilms do not completely eliminate or prevent microbial colonies from forming, so further study is needed. Current research in the treatment of wound and implant biofilm infections focuses on nanotechnology-based drug delivery mechanisms, combination therapies and implant modifications. Ultrasonic debridement and hydrogels as well as new developments in implant modifications have great potential for use in wound and implant treatments. The purpose of this review is to summarize recent developments in biofilm treatment and to understand the direction of current research.

Biofilms and Implantable Medical Devices, 2017, s. 159-180

Bacterial colonization represents a current challenge in environmental, industrial and medical applications and can be considered a "global security problem" for humanity. Therefore, much research is devoted to overcoming this deficiency by developing new surfaces or materials or by modifying existing surfaces or materials through chemical and physical methods. This chapter summarizes the most representative possibilities for modifying the surfaces of metals, polymers and ceramics and identifies the new trends and challenges in this field. Special emphasis is placed on chemical surface modification.

Journal of Endodontics, Band 42, Ausgabe 2, 2016, S. 320–323