Biofilms: an emergent form of bacterial life

Deciphering and designing microbial communities by genome-scale metabolic modelling

Microbial communities are shaped by the complex interactions among organisms and the environment. Genome-scale metabolic models (GEMs) can provide deeper insights into the complexity and ecological properties of various microbial communities, revealing their intricate interactions. Many researchers have modified GEMs for the microbial communities based on specific needs. Thus, GEMs need to be comprehensively summarized to better understand the trends in their development. In this review, we summarized the key developments in deciphering and designing microbial communities using different GEMs. A timeline of selected highlights in GEMs indicated that this area is evolving from the single-strain level to the microbial community level. Then, we outlined a framework for constructing GEMs of microbial communities. We also summarized the models and resources of static and dynamic community-level GEMs. We focused on the role of external environmental and intracellular resources in shaping the assembly of microbial communities. Finally, we discussed the key challenges and future directions of GEMs, focusing on the integration of GEMs with quorum sensing mechanisms, microbial ecology interactions, machine learning algorithms, and automatic modeling, all of which contribute to consortia-based applications in different fields.

Coagulation promotes the spread of antibiotic resistance genes in secondary effluents

Wastewater treatment plants (WWTPs) are biological hotspots receiving the residual antibiotics and antibiotic resistant bacteria/genes (ARB/ARGs) that greatly influence the spread of antibiotic resistance in the environment. A common method used in WWTPs for the purification of secondary effluent is coagulation. Notwithstanding the increasing health concern of antibiotic resistance in WWTPs, the impact of coagulation on the emergence and spread of antibiotic resistance remains unclear. To shed light on this, our study investigated the behavior of four representative ARB types (tetracycline, sulfamethoxazole, clindamycin, and ciprofloxacin resistance) during the coagulation process in a model wastewater treatment plant. Our search showed a significant reduction in the presence of ARBs after either PAC or FeCl3 coagulation, with removal efficiencies of 95% and 90%, respectively. However, after 4 days of storage, ARB levels in the coagulated effluent increased by 6-138 times higher than the original secondary effluent. It suggests a potential resurgence and spread of antibiotic resistance after coagulation. Detailed studies suggest that coagulants, particularly PAC, may facilitate the transfer of ARGs among different bacterial species by the enhanced cell-cell contact during coagulation-induced bacterial aggregation. This transfer is further enhanced by the factors such as auxiliary mixing, longer incubation time and ideal operating temperatures. In addition, both PAC and FeCl3 affected gene expression associated with bacterial conjugation, leading to an increase in conjugation efficiency. In conclusion, while coagulation serves as a purification method, it might inadvertently boost the spread of ARGs during tertiary wastewater treatment. This underscores the importance of implementing subsequent measures to mitigate this effect. Our findings provide a deeper understanding of the challenges posed by bacterial antibiotic resistance in wastewater and pave the way for devising more effective ARB and ARG management strategies.

Removal of intracellular and extracellular antibiotic resistance genes and virulence factor genes using electricity-intensified constructed wetlands

Constructed wetland (CW) is considered a promising technology for the removal of emerging contaminants. However, its removal performance for antibiotic resistance genes (ARGs) is not efficient and influence of virulence factor genes (VFGs) have not been elucidated. Here, removal of intracellular and extracellular ARGs as well as VFGs by electricity-intensified CWs was comprehensively evaluated. The two electrolysis-intensified CWs can improve the removal of intracellular ARGs and MGEs to 0.96- and 0.85-logs, respectively. But cell-free extracellular ARGs (CF-eARGs) were significantly enriched with 1.8-logs in the electrolysis-intensified CW. Interestingly, adding Fe-C microelectrolysis to the electrolysis-intensified CW is conducive to the reduction of CF-eARGs. However, the detected number and relative abundances of intracellular and extracellular VFGs were increased in all of the three CWs. The biofilms attached onto the substrates and rhizosphere are also hotspots of both intracellular and particle-associated extracellular ARGs and VFGs. Structural equation models and correlation analysis indicated that ARGs and VFGs were significantly cooccurred, suggesting that VFGs may affect the dynamics of ARGs. The phenotypes of VFGs, such as biofilm, may act as protective matrix for ARGs, hindering the removal of resistance genes. Our results provide novel insights into the ecological remediation technologies to enhance the removal of ARGs.

Enhancing spinach (Spinacia oleracea L.) resilience in pesticide-contaminated soil: Role of pesticide-tolerant Ciceribacter azotifigens and Serratia marcescens in root architecture, leaf gas exchange attributes and antioxidant response restoration

This study unveils the detoxification potential of insecticide-tolerant plant beneficial bacteria (PBB), i.e., Ciceribacter azotifigens SF1 and Serratia marcescens SRB1, in spinach treated with fipronil (FIP), profenofos (PF) and chlorantraniliprole (CLP) insecticides. Increasing insecticide doses (25-400 μg kg-1 soil) significantly curtailed germination attributes and growth of spinach cultivated at both bench-scale and in greenhouse experiments. Profenofos at 400 μg kg-1 exhibited maximum inhibitory effects and reduced germination by 55%; root and shoot length by 78% and 81%, respectively; dry matter accumulation in roots and shoots by 79% and 62%, respectively; leaf number by 87% and leaf area by 56%. Insecticide application caused morphological distortion in root tips/surfaces, increased levels of oxidative stress, and cell death in spinach. Application of insecticide-tolerant SF1 and SRB1 strains relieved insecticide pressure resulting in overall improvement in growth and physiology of spinach grown under insecticide stress. Ciceribacter azotifigens improved germination rate (10%); root biomass (53%); shoot biomass (25%); leaf area (10%); Chl-a (45%), Chl-b (36%) and carotenoid (48%) contents of spinach at 25 μg CLP kg-1 soil. PBB inoculation reinvigorated the stressed spinach and modulated the synthesis of phytochemicals, proline, malondialdehyde (MDA), superoxide anions (O2•-), and hydrogen peroxide (H2O2). Scanning electron microscopy (SEM) revealed recovery in root tip morphology and stomatal openings on abaxial leaf surfaces of PBB-inoculated spinach grown with insecticides. Ciceribacter azotifigens inoculation significantly increased intrinsic water use efficiency, transpiration rate, vapor pressure deficit, intracellular CO2 concentration, photosynthetic rate, and stomatal conductance in spinach exposed to 25 μg FIP kg-1. Also, C. azotifigens and S. marcescens modulated the antioxidant defense systems of insecticide-treated spinach. Bacterial strains were strongly colonized to root surfaces of insecticide-stressed spinach seedlings as revealed under SEM. The identification of insecticide-tolerant PBBs such as C. azotifigens and S. marcescens hold the potential for alleviating abiotic stress to spinach, thereby fostering enhanced and safe production within polluted agroecosystems.

Baohuoside I inhibits virulence of multidrug-resistant Staphylococcus aureus by targeting the transcription Staphylococcus accessory regulator factor SarZ

BACKGROUND

Staphylococcus aureus is a versatile pathogen that can cause a wide range of infections in humans. Biofilms play a crucial role in the pathogenicity of S. aureus and contribute to its ability to cause persistent and chronic infections. Baohuoside I has garnered increasing recognition as a natural flavonol glycoside with a wide spectrum of health-related activities.

PURPOSE

The antibacterial and anti-biofilm properties of Baohuoside I have not been extensively investigated. Our study aimed to assess its inhibitory effects and the underlying mechanisms on biofilm formation and hemolytic capacity in S. aureus.

STUDY DESIGN/METHODS

The impact of Baohuoside I on the biofilm and virulence of S. aureus was evaluated through in vitro experiments and Galleria mellonella as an in vivo infection model. The mechanisms were explored by Drug affinity responsive target stability (DARTS) and validated in genetic knockout strain and through molecular biological experiments using DARTS, molecular docking, electrophoretic mobility shift assay (EMSA), and bio-layer interferometry (BLI).

RESULTS

Baohuoside I significantly inhibits the formation of S. aureus biofilms and hemolytic activity at 6.25 µM. Proteomics analysis revealed that treatment with Baohuoside I led to a reduction in the expression of quorum-sensing system agr-regulated genes. DARTS analysis identified Staphylococcus accessory regulator factor (SarZ), a key regulator involved in the expression of virulence factors in S. aureus by acting as activator of the agr quorum-sensing system, was the direct target of Baohuoside I. Molecular docking, DARTS, BLI and EMSA assays collectively confirmed the direct binding of Baohuoside I to SarZ, inhibiting its binding to downstream promoters. Furthermore, it is found through site-directed protein mutagenesis that the Tyr27 and Phe117 residues are key for Baohuoside I binding to SarZ. Additionally, the knockout of SarZ significantly diminished the hemolytic ability of S. aureus, underscoring its crucial role as a pivotal regulator of virulence. Lastly, in vivo tests utilizing the G. mellonella infection model demonstrated the efficacy of Baohuoside I.

CONCLUSION

This study provides valuable insights into the mechanism by which Baohuoside I inhibits the virulence of S. aureus through its interaction with SarZ. These findings highlight the significance of SarZ as an effective target against the virulence of S. aureus.

Intestinal biofilms: pathophysiological relevance, host defense, and therapeutic opportunities

SUMMARYThe human intestinal tract harbors a profound variety of microorganisms that live in symbiosis with the host and each other. It is a complex and highly dynamic environment whose homeostasis directly relates to human health. Dysbiosis of the gut microbiota and polymicrobial biofilms have been associated with gastrointestinal diseases, including irritable bowel syndrome, inflammatory bowel diseases, and colorectal cancers. This review covers the molecular composition and organization of intestinal biofilms, mechanistic aspects of biofilm signaling networks for bacterial communication and behavior, and synergistic effects in polymicrobial biofilms. It further describes the clinical relevance and diseases associated with gut biofilms, the role of biofilms in antimicrobial resistance, and the intestinal host defense system and therapeutic strategies counteracting biofilms. Taken together, this review summarizes the latest knowledge and research on intestinal biofilms and their role in gut disorders and provides directions toward the development of biofilm-specific treatments.

Novel DNA-Binding Activity Exhibited by Poly(aspartic acid) Hydrolase-1 Inhibits Poly(aspartic acid) Hydrolase Activity

Significant attention has been shifted toward the use and development of biodegradable polymeric materials to mitigate environmental accumulation and potential health impacts. One such material, poly(aspartic acid) (PAA), is a biodegradable alternative to superabsorbent poly(carboxylates), like poly(acrylate). Three enzymes are known to hydrolyze PAA: PahZ1KT-1 and PahZ2KT-1 from Sphingomonas sp. KT-1 and PahZ1KP-2 from Pedobacter sp. KP-2. We previously reported the X-ray crystal structure for PahZ1KT-1, which revealed a homodimer complex with a strongly cationic surface spanning one side of each monomer. Here, we report the first characterization of any polymer hydrolase binding to DNA, where modeling data predict binding of the polyanionic DNA near the cationic substrate binding surface. Our data reveal that PahZ1 homologues from Sphingomonas sp. KT-1 and Pedobacter sp. KP-2 bind ssDNA and dsDNA with nanomolar binding affinities. PahZ1KT-1 binds ssDNA and dsDNA with an apparent dissociation constant, KD,app = 81 ± 14 and 19 ± 1 nM, respectively, and these estimates are similar to the same behaviors exhibited by PahZ1KP-2. Gel permeation chromatography data reveal that dsDNA binding promotes inhibition of PahZ1-catalyzed PAA biodegradation for each homologue. We propose a working model wherein binding of PahZ1 to extracellular biofilm DNA aids in the localization of the hydrolase to the environment in which PAA would first be encountered, thereby providing a mechanism to degrade extracellular PAA and potentially harvest aspartic acid for nutritional uptake.

Nitrifying niche in estuaries is expanded by the plastisphere

The estuarine plastisphere, a novel ecological habitat in the Anthropocene, has garnered global concerns. Recent geochemical evidence has pointed out its potential role in influencing nitrogen biogeochemistry. However, the biogeochemical significance of the plastisphere and its mechanisms regulating nitrogen cycling remain elusive. Using 15N- and 13C-labelling coupled with metagenomics and metatranscriptomics, here we unveil that the plastisphere likely acts as an underappreciated nitrifying niche in estuarine ecosystems, exhibiting a 0.9 ~ 12-fold higher activity of bacteria-mediated nitrification compared to surrounding seawater and other biofilms (stone, wood and glass biofilms). The shift of active nitrifiers from O2-sensitive nitrifiers in the seawater to nitrifiers with versatile metabolisms in the plastisphere, combined with the potential interspecific cooperation of nitrifying substrate exchange observed among the plastisphere nitrifiers, collectively results in the unique nitrifying niche. Our findings highlight the plastisphere as an emerging nitrifying niche in estuarine environment, and deepen the mechanistic understanding of its contribution to marine biogeochemistry.

Bimetallic nanoparticles with sulfated galactan eliminate Vibrio parahaemolyticus in shrimp Penaeus vannamei

Bimetallic (Au/Ag) nanoparticles (BNPs) have shown enhanced antibacterial activity compared to their monometallic counterparts. Sulfated galactans (SG) are a naturally occurring polymer commonly found in red seaweed Gracilaria fisheri. They are biocompatible and biodegradable and environmentally friendly. In this study, we utilized SG in combination with BNPs to develop composite materials that potentially enhance antibacterial activity against shrimp pathogens Vibrio parahaemolyticus and Vibrio harveyi, compared to BNPs or SG alone. BNPs were coated with sulfated galactan (SGBNPs) and characterized using UV-vis spectroscopy, Fourier transform infrared (FTIR) spectroscopy, zeta potential, and transmission electron microscopy (TEM). UV-vis spectroscopy analysis revealed that the surface plasmon peaks of BNPs and SGBNPs appeared at 530 nm and 532 nm, respectively. Zeta potential measurements showed that SGBNPs had a negative charge of -32.4 mV, while the BNPs solution had a positive charge of 38.7 mV. TEM images demonstrated the spherical morphology of both BNPs and SGBNPs with narrow size distributions (3-10 nm). Analysis of the FTIR spectra indicated that SG maintained its backbone structure in SGBNPs, but some functional groups were altered. Notably, SGBNPs showed superior antimicrobial and antibiofilm activities against V. parahaemolyticus and V. harveyi compared to SG and BNPs. Furthermore, treatment with SGBNPs significantly down-regulated the expression of virulence-related genes (toxR, cpsQ, and mfpA) for V. parahaemolyticus 3HP compared to the respective control, bacteria treated with BNPs or SG. Diets supplemented with SGBNPs, BNPs, or SG showed no detrimental impact on the growth of shrimp Penaeus vannamei. Shrimp fed with SGBNPs-supplemented feed showed significantly higher survival rates than those fed with BNPs-supplemented feed when infected with 3HP after being on the supplemented feed for seven days and a subsequent number of fifteen days. These findings collectively demonstrate the benefit of using SG capped Au-Ag BNPs as an antibacterial agent for the prevention and control of Vibrio sp. Infection in shrimp while reducing the risk of environmental contamination.

Unlocking the potential of biofilm-forming plant growth-promoting rhizobacteria for growth and yield enhancement in wheat (Triticum aestivum L.)

Plant growth-promoting rhizobacteria (PGPR) boost crop yields and reduce environmental pressures through biofilm formation in natural climates. Recently, biofilm-based root colonization by these microorganisms has emerged as a promising strategy for agricultural enhancement. The current work aims to characterize biofilm-forming rhizobacteria for wheat growth and yield enhancement. For this, native rhizobacteria were isolated from the wheat rhizosphere and ten isolates were characterized for plant growth promoting traits and biofilm production under axenic conditions. Among these ten isolates, five were identified as potential biofilm-producing PGPR based on in vitro assays for plant growth-promoting traits. These were further evaluated under controlled and field conditions for their impact on wheat growth and yield attributes. Surface-enhanced Raman spectroscopy analysis further indicated that the biochemical composition of the biofilm produced by the selected bacterial strains includes proteins, carbohydrates, lipids, amino acids, and nucleic acids (DNA/RNA). Inoculated plants in growth chamber resulted in larger roots, shoots, and increase in fresh biomass than controls. Similarly, significant increases in plant height (13.3, 16.7%), grain yield (29.6, 17.5%), number of tillers (18.7, 34.8%), nitrogen content (58.8, 48.1%), and phosphorus content (63.0, 51.0%) in grains were observed in both pot and field trials, respectively. The two most promising biofilm-producing isolates were identified through 16 s rRNA partial gene sequencing as Brucella sp. (BF10), Lysinibacillus macroides (BF15). Moreover, leaf pigmentation and relative water contents were significantly increased in all treated plants. Taken together, our results revealed that biofilm forming PGPR can boost crop productivity by enhancing growth and physiological responses and thus aid in sustainable agriculture.

Adaptive Escape of Pseudomonas aeruginosa by Application of Low-Amplitude Electric Pulses

Marine antibiofouling using low-amplitude electric pulses (EP) is an energy-efficient and eco-friendly approach, but potential mechanisms for preventing biofouling remain unclear. In the present study, the 3D adhesion dynamics of a model microorganism─Pseudomonas aeruginosa (PAO1)─under low-amplitude cathodic EP were examined as a function of applying voltage and its duration (td). The results demonstrated that adhered bacteria escaped from the electrode surface even when EP was removed. The escaped bacteria ratio, induction period of escape, and duration of the detachment were influenced profoundly by EP amplitude but slightly by td when td ≥ 5 min. The acceleration of escaped PAO1 from the surface indicated that their flagellar motor was powered by EP. Particularly, EP enabled swimming bacteria to have adaptive motions that were sustainable and regulated by the gene rsmA. As a result, they had less accumulation near the surface. The propulsion of adhered bacteria and adaptive escape of swimming bacteria were enhanced in response to low-amplitude EP. Hence, low-amplitude and short-duration EP is promising for sustainable antibiofouling applications.

Inhalable Polymeric Microparticles for Phage and Photothermal Synergistic Therapy of Methicillin-Resistant Staphylococcus aureus Pneumonia

Acute methicillin-resistant Staphylococcus aureus (MRSA) pneumonia is a common and serious lung infection with high morbidity and mortality rates. Due to the increasing antibiotic resistance, toxicity, and pathogenicity of MRSA, there is an urgent need to explore effective antibacterial strategies. In this study, we developed a dry powder inhalable formulation which is composed of porous microspheres prepared from poly(lactic-co-glycolic acid) (PLGA), internally loaded with indocyanine green (ICG)-modified, heat-resistant phages that we screened for their high efficacy against MRSA. This formulation can deliver therapeutic doses of ICG-modified active phages to the deep lung tissue infection sites, avoiding rapid clearance by alveolar macrophages. Combined with the synergistic treatment of phage therapy and photothermal therapy, the formulation demonstrates potent bactericidal effects in acute MRSA pneumonia. With its long-term stability at room temperature and inhalable characteristics, this formulation has the potential to be a promising drug for the clinical treatment of MRSA pneumonia.

A novel multiplex fluorescent-labeling method for the visualization of mixed-species biofilms in vitro

In nature, bacteria usually exist as mixed-species biofilms, where they engage in a range of synergistic and antagonistic interactions that increase their resistance to environmental challenges. Biofilms are a major cause of persistent infections, and dispersal from initial foci can cause new infections at distal sites thus warranting further investigation. Studies of development and spatial interactions in mixed-species biofilms can be challenging due to difficulties in identifying the different bacterial species in situ. Here, we apply CellTrace dyes to studies of biofilm bacteria and present a novel application for multiplex labeling, allowing identification of different bacteria in mixed-species, in vitro biofilm models. Oral bacteria labeled with CellTrace dyes (far red, yellow, violet, and CFSE [green]) were used to create single- and mixed-species biofilms, which were analyzed with confocal spinning disk microscopy (CSDM). Biofilm supernatants were studied with flow cytometry (FC). Both Gram-positive and Gram-negative bacteria were well labeled and CSDM revealed biofilms with clear morphology and stable staining for up to 4 days. Analysis of CellTrace labeled cells in supernatants using FC showed differences in the biofilm dispersal between bacterial species. Multiplexing with different colored dyes allowed visualization of spatial relationships between bacteria in mixed-species biofilms and relative coverage by the different species was revealed through segmentation of the CSDM images. This novel application, thus, offers a powerful tool for studying structure and composition of mixed-species biofilms in vitro.IMPORTANCEAlthough most chronic infections are caused by mixed-species biofilms, much of our knowledge still comes from planktonic cultures of single bacterial species. Studies of formation and development of mixed-species biofilms are, therefore, required. This work describes a method applicable to labeling of bacteria for in vitro studies of biofilm structure and dispersal. Critically, labeled bacteria can be multiplexed for identification of different species in mixed-species biofilms using confocal spinning disk microscopy, facilitating investigation of biofilm development and spatial interactions under different environmental conditions. The study is an important step in increasing the tools available for such complex and challenging studies.

Maggot therapy for resistant infections: the disconnect between scientific evidence, clinical acceptance and practice

OBJECTIVE

Practitioners and scientists are re-examining marginalised wound care therapies to find strategies that combat the growing problem of antimicrobial resistance (AMR) without compromising patient outcomes. Maggot therapy (MT) makes up just an estimated 0.02% of UK's National Health Service spending on wound care. This study aims to uncover why MT is not used more often, despite its affordability and high level of efficacy for both debridement and disinfection, particularly in the context of AMR infections, and to determine what can be done to ensure MT is more effectively used in the future to improve patient outcomes and manage the growing problem of AMR.

METHOD

For this investigation, a qualitative review of case studies using MT against AMR infections and a quantitative analysis of randomised control trials (RCTs) were performed using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses framework.

RESULTS

Analysis showed that MT is highly effective against a range of infections and wound types, and compares well against conventional therapies. The low use of MT may be due in part to the documented 'yuck factor', often associated with maggots as well as misconceptions around the cost, efficacy and accessibility of MT. To overcome these factors, more RCTs on the spectrum and efficacy of MT across various clinical manifestations are needed, as well as professional and public engagement campaigns.

CONCLUSION

MT is an underused therapy, particularly regarding AMR infections, and expanding its use in these circumstances appears warranted. MT could play a vital role in conserving the efficacy of the existing pool of antimicrobials available and should be considered in the development of antimicrobial stewardship programmes.

DECLARATION OF INTEREST

This work was supported by the Swansea Employability Academy, Swansea University (internal funding). The authors have no conflicts of interest to declare.

The complex world of kefir: Structural insights and symbiotic relationships

Kefir milk, known for its high nutritional value and health benefits, is traditionally produced by fermenting milk with kefir grains. These grains are a complex symbiotic community of lactic acid bacteria, acetic acid bacteria, yeasts, and other microorganisms. However, the intricate coexistence mechanisms within these microbial colonies remain a mystery, posing challenges in predicting their biological and functional traits. This uncertainty often leads to variability in kefir milk's quality and safety. This review delves into the unique structural characteristics of kefir grains, particularly their distinctive hollow structure. We propose hypotheses on their formation, which appears to be influenced by the aggregation behaviors of the community members and their alliances. In kefir milk, a systematic colonization process is driven by metabolite release, orchestrating the spatiotemporal rearrangement of ecological niches. We place special emphasis on the dynamic spatiotemporal changes within the kefir microbial community. Spatially, we observe variations in species morphology and distribution across different locations within the grain structure. Temporally, the review highlights the succession patterns of the microbial community, shedding light on their evolving interactions.Furthermore, we explore the ecological mechanisms underpinning the formation of a stable community composition. The interplay of cooperative and competitive species within these microorganisms ensures a dynamic balance, contributing to the community's richness and stability. In kefir community, competitive species foster diversity and stability, whereas cooperative species bolster mutualistic symbiosis. By deepening our understanding of the behaviors of these complex microbial communities, we can pave the way for future advancements in the development and diversification of starter cultures for food fermentation processes.

Bacteria-organelle communication in physiology and disease

Bacteria, omnipresent in our environment and coexisting within our body, exert dual beneficial and pathogenic influences. These microorganisms engage in intricate interactions with the human body, impacting both human health and disease. Simultaneously, certain organelles within our cells share an evolutionary relationship with bacteria, particularly mitochondria, best known for their energy production role and their dynamic interaction with each other and other organelles. In recent years, communication between bacteria and mitochondria has emerged as a new mechanism for regulating the host's physiology and pathology. In this review, we delve into the dynamic communications between bacteria and host mitochondria, shedding light on their collaborative regulation of host immune response, metabolism, aging, and longevity. Additionally, we discuss bacterial interactions with other organelles, including chloroplasts, lysosomes, and the endoplasmic reticulum (ER).

Integrating Multiple Bacterial Phenotypes and Bayesian Network for Analyzing Health Risks of Pathogens in Plastisphere

Plastic pollution represents a critical threat to soil ecosystems and even humans, as plastics can serve as a habitat for breeding and refuging pathogenic microorganisms against stresses. However, evaluating the health risk of plastispheres is difficult due to the lack of risk factors and quantification model. Here, DNA sequencing, single-cell Raman-D2O labeling, and transformation assay were used to quantify key risk factors of plastisphere, including pathogen abundance, phenotypic resistance to various stresses (antibiotic and pesticide), and ability to acquire antibiotic resistance genes. A Bayesian network model was newly introduced to integrate these three factors and infer their causal relationships. Using this model, the risk of pathogen in the plastisphere is found to be nearly 3 magnitudes higher than that in free-living state. Furthermore, this model exhibits robustness for risk prediction, even in the absence of one factor. Our framework offers a novel and practical approach to assessing the health risk of plastispheres, contributing to the management of plastic-related threats to human health.

Optimization and Production of Exopolysaccharides (EPS) and Indole-3-Acetic Acid (IAA) Under Chromium by Halophilic Bacteria Oceanobacillus oncorhynchi W4

The current study assessed the levels of exopolysaccharides (EPS) and indole-3-acetic acid (IAA) and the impacts of halophilic bacteria Oceanobacillus oncorhynchi W4 under Cr (VI). The effects of W4 were tested for its ability to remove Cr (VI) at several concentrations, the removal rate was reached after 48 h at 58.4%, 53.3%, 49.2%, and 43.1%). After 12-48 h, the maximum removal rate of 29-58% was found at an initial concentration of 50 mg/L (Cr (VI)). The Box-Behnken design based on response surface methodology was utilized to optimize the EPS, including pH, sucrose concentration, and incubation period. The highest EPS yield (314.5 mg/L) was obtained under 96 h at pH 7.0, with 5% sucrose concentration. The strain Oceanobacillus oncorhynchi W4 was tested for its ability to create EPS at various concentrations of Cr (VI). After 96 h, it generated the maximum amount of EPS (216.3 mg/L) at a concentration of 50 mg/L. By using FT-IR spectrum measurements, it was confirmed that hexavalent chromium and EPS had surface chemical interactions. At various Cr (VI) concentrations, the isolate W4 was tested for its ability to secrete Indole-3 acetic acid. IAA secretion (control) without Cr (VI) achieved a maximum of 1.45 mg/ml at 120 h. At 200 mg/L Cr (VI) concentration, 1.65 mg/ml of IAA was also produced after 48 h. According to the findings, Oceanobacillus oncorhynchi W4 was a promising isolate in a stressful environment.

Augmentation of physiology and productivity, and reduction of lead accumulation in lettuce grown in lead contaminated soil by rhizobacteria-assisted rhizoengineeing

Microbial-assisted rhizoengineering is a promising biotechnology for improving crop productivity. In this study, lettuce roots were bacterized with two lead (Pb) tolerant rhizobacteria including Pseudomonas azotoformans ESR4 and P. poae ESR6, and a consortium consisted of ESR4 and ESR6 to increase productivity, physiology and antioxidants, and reduce Pb accumulation grown in Pb-contaminated soil i.e., 80 (Pb in native soil), 400 and 800 mg kg-1 Pb. In vitro studies showed that these strains and the consortium produced biofilms, synthesized indole-3-acetic acid and NH3, and solubilized phosphate challenging to 0, 100, 200 and 400 mg L-1 of Pb. In static conditions and 400 mg L-1 Pb, ESR4, ESR6 and the consortium adsorbed 317.0, 339.5 and 357.4 mg L-1 Pb, respectively, while 384.7, 380.7 and 373.2 mg L-1 Pb, respectively, in shaking conditions. Fourier transform infrared spectroscopy results revealed that several functional groups [Pb-S, M - O, O-M-O (M = metal ions), S-S, PO, CO, -NH, -NH2, C-C-O, and C-H] were involved in Pb adsorption. ESR4, ESR6 and the consortium-assisted rhizoengineering (i) increased leaf numbers and biomass production, (ii) reduced H2O2 production, malondialdehyde, electrolyte leakages, and transpiration rate, (iii) augmented photosynthetic pigments, photosynthetic rate, water use efficiency, total antioxidant capacity, total flavonoid content, total phenolic content, and minerals like Ca2+ and Mg2+ in comparison to non-rhizoengineering plants grown in Pb-contaminated soil. Principal component analysis revealed that higher pigment production and photosynthetic rate, improved water use efficiency and increased uptake of Ca2+ were interlinked to increased productivity by bacterial rhizoengineering of lettuce grown in different levels of Pb exposures. Surprisingly, Pb accumulation in lettuce roots and shoots was remarkably decreased by rhizoengineering than in non-rhizoengineering. Thus, these bacterial strains and this consortium could be utilized to improve productivity and reduce Pb accumulation in lettuce.

Bacteriocins against biogenic amine-accumulating lactic acid bacteria in cheese: Nisin A shows the broadest antimicrobial spectrum and prevents the formation of biofilms

Cheese is a food in which toxic concentrations of biogenic amines (BA) may be reached, mainly as a consequence of the decarboxylation of determined amino acids by certain lactic acid bacteria (LAB). To maintain the food safety of cheese, environmentally friendly strategies are needed that specifically prevent the growth of BA-producing LAB and the accumulation of BA. The bacteriocins produced by LAB are natural compounds with great potential as food biopreservatives. This work examines the antimicrobial potential of 7 bacteriocin-containing, cell-free supernatants (CFS: coagulin A-CFS, enterocin A-CFS, enterocin P-CFS, lacticin 481-CFS, nisin A-CFS, nisin Z-CFS and plantaricin A-CFS) produced by LAB against 48 strains of the LAB species largely responsible for the accumulation of the most important BA in cheese, that is, histamine, tyramine, and putrescine. Susceptibility to the different CFS was strain-dependent. The histamine-producing species with the broadest sensitivity spectrum were Lentilactobacillus parabuchneri (the species mainly responsible for the accumulation of histamine in cheese) and Pediococcus parvulus. The tyramine-producing species with the broadest sensitivity spectrum was Enterococcus faecium, and Enterococcus faecalis and Enterococcus hirae were among the most sensitive putrescine producers. Nisin A-CFS was active against 31 of the 48 BA-producing strains (the broadest antimicrobial spectrum recorded). Moreover, commercial nisin A prevented biofilm formation by 67% of the BA-producing, biofilm-forming LAB strains. These findings underscore the potential of bacteriocins in the control of BA-producing LAB and support the use of nisin A as a food-grade biopreservative for keeping BA-producing LAB in check and reducing BA accumulation in cheese.

Morpholinium-based Ionic Liquids as Potent Antibiofilm and Sensitizing Agents for the Control of Pseudomonas aeruginosa

Rising antimicrobial resistance is a critical threat to worldwide public health. To address the increasing antibiotic tolerance, diverse antimicrobial agents are examined for their ability to decrease bacterial resistance. One of the most relevant and persistent human pathogens is Pseudomonas aeruginosa. Our study investigates the anti-biofilm and sensitizing activity of 12 morpholinium-based ionic liquids with herbicidal anions on four clinically relevant P. aeruginosa strains. Among all tested compounds, four ionic liquids prevented biofilm formation at sub-minimum inhibitory concentrations for all investigated strains. For the first time, we established a hormetic effect on biofilm formation for P. aeruginosa strains subjected to an ionic liquid treatment. Interestingly, while ionic liquids with 4,4-didecylmorpholinium [Dec2Mor]+ are more efficient against planktonic bacteria, 4-decyl-4-ethylmorpholinium [DecEtMor]+ showed more potent inhibition of biofilm formation. Ionic liquids with 4,4-didecylmorpholinium ([Dec2Mor]+) cations even induced biofilm formation by strain 39016 at high concentrations due to flocculation. Morpholinium-based ionic liquids were also shown to enhance the efficacy of commonly used antibiotics from different chemical groups. We demonstrate that this synergy is associated with the mode of action of the antibiotics.

Nanoformulations for dismantling fungal biofilms: The latest arsenals of antifungal therapy

Globally, fungal infections have evolved as a strenuous challenge for clinicians, particularly in patients with compromised immunity in intensive care units. Fungal co-infection in Covid-19 patients has made the situation more formidable for healthcare practitioners. Surface adhered fungal population known as biofilm often develop at the diseased site to elicit antifungal tolerance and recalcitrant traits. Thus, an innovative strategy is required to impede/eradicate developed biofilm and avoid the formation of new colonies. The development of nanocomposite-based antibiofilm solutions is the most appropriate way to withstand and dismantle biofilm structures. Nanocomposites can be utilized as a drug delivery medium and for fabrication of anti-biofilm surfaces capable to resist fungal colonization. In this context, the present review comprehensively described different forms of nanocomposites and mode of their action against fungal biofilms. Amongst various nanocomposites, efficacy of metal/organic nanoparticles and nanofibers are particularly emphasized to highlight their role in the pursuit of antibiofilm strategies. Further, the inevitable concern of nanotoxicology has also been introduced and discussed with the exigent need of addressing it while developing nano-based therapies. Further, a list of FDA-approved nano-based antifungal formulations for therapeutic usage available to date has been described. Collectively, the review highlights the potential, scope, and future of nanocomposite-based antibiofilm therapeutics to address the fungal biofilm management issue.

A H₂S-Evolving Alternately-Catalytic Enzyme Bio-Heterojunction with Antibacterial and Macrophage-Reprogramming Activity for All-Stage Infectious Wound Regeneration

The disorder of the macrophage phenotype and the hostile by-product of lactate evoked by pathogenic infection in hypoxic deep wound inevitably lead to the stagnant skin regeneration. In this study, hydrogen sulfide (H2S)-evolving alternately catalytic bio-heterojunction enzyme (AC-BioHJzyme) consisting of CuFe2S3 and lactate oxidase (LOD) named as CuFe2S3@LOD is developed. AC-BioHJzyme exhibits circular enzyme-mimetic antibacterial (EMA) activity and macrophage re-rousing capability, which can be activated by near-infrared-II (NIR-II) light. In this system, LOD exhausts lactate derived from bacterial anaerobic respiration and generated hydrogen peroxide (H2O2), which provides an abundant stock for the peroxidase-mimetic activity to convert the produced H2O2 into germicidal •OH. The GPx-mimetic activity endows AC-BioHJzyme with a glutathione consumption property to block the antioxidant systems in bacterial metabolism, while the O2 provided by the CAT-mimetic activity can generate 1O2 under the NIR-II irradiation. Synchronously, the H2S gas liberated from CuFe2S3@LOD under the infectious micromilieu allows the reduction of Fe(III)/Cu(II) to Fe(II)/Cu(І), resulting in sustained circular EMA activity. In vitro and in vivo assays indicate that the CuFe2S3@LOD AC-BioHJzyme significantly facilitates the infectious cutaneous regeneration by killing bacteria, facilitating epithelialization/collagen deposition, promoting angiogenesis, and reprogramming macrophages. This study provides a countermeasure for deep infectious wound healing via circular enzyme-mimetic antibiosis and macrophage re-rousing.

Self-Assembled Borneol-Guanidine-Based Amphiphilic Polymers as an Efficient Antibiofilm Agent

Biofilm-associated infections remain a tremendous obstacle to the treatment of microbial infections globally. However, the poor penetrability to a dense extracellular polymeric substance matrix of traditional antibacterial agents limits their antibiofilm activity. Here, we show that nanoaggregates formed by self-assembly of amphiphilic borneol-guanidine-based cationic polymers (BGNx-n) possess strong antibacterial activity and can eliminate mature Staphylococcus aureus (S. aureus) biofilms. The introduction of the guanidine moiety improves the hydrophilicity and membrane penetrability of BGNx-n. The self-assembled nanoaggregates with highly localized positive charges are expected to enhance their interaction with negatively charged bacteria and biofilms. Furthermore, nanoaggregates dissociate on the surface of biofilms into smaller BGNx-n polymers, which enhances their ability to penetrate biofilms. BGNx-n nanoaggregates that exhibit superior antibacterial activity have the minimum inhibitory concentration (MIC) of 62.5 μg·mL-1 against S. aureus and eradicate mature biofilms at 4 × MIC with negligible hemolysis. Taken together, this size-variable self-assembly system offers a promising strategy for the development of effective antibiofilm agents.

Intrinsic antimicrobial resistance: Molecular biomaterials to combat microbial biofilms and bacterial persisters

The escalating rise in antimicrobial resistance (AMR) coupled with a declining arsenal of new antibiotics is imposing serious threats to global public health. A pervasive aspect of many acquired AMR infections is that the pathogenic microorganisms exist as biofilms, which are equipped with superior survival strategies. In addition, persistent and recalcitrant infections are seeded with bacterial persister cells at infection sites. Together, conventional antibiotic therapeutics often fail in the complete treatment of infections associated with bacterial persisters and biofilms. Novel therapeutics have been attempted to tackle AMR, biofilms, and persister-associated complex infections. This review focuses on the progress in designing molecular biomaterials and therapeutics to address acquired and intrinsic AMR, and the fundamental microbiology behind biofilms and persisters. Starting with a brief introduction of AMR basics and approaches to tackling acquired AMR, the emphasis is placed on various biomaterial approaches to combating intrinsic AMR, including (1) semi-synthetic antibiotics; (2) macromolecular or polymeric biomaterials mimicking antimicrobial peptides; (3) adjuvant effects in synergy; (4) nano-therapeutics; (5) nitric oxide-releasing antimicrobials; (6) antimicrobial hydrogels; (7) antimicrobial coatings. Particularly, the structure-activity relationship is elucidated in each category of these biomaterials. Finally, illuminating perspectives are provided for the future design of molecular biomaterials to bypass AMR and cure chronic multi-drug resistant (MDR) infections.

Quantification of early biofilm growth in microtiter plates through a novel image analysis software

Given the significant impact of biofilms on human health and material corrosion, research in this field urgently needs more accessible techniques to facilitate the testing of new control agents and general understanding of biofilm biology. Microtiter plates offer a convenient format for standardized evaluations, including high-throughput assays of alternative treatments and molecular modulators. This study introduces a novel Biofilm Analysis Software (BAS) for quantifying biofilms from microtiter plate images. We focused on early biofilm growth stages and compared BAS quantification to common techniques: direct turbidity measurement, intrinsic fluorescence detection linked to pyoverdine production, and standard crystal violet staining which enables image analysis and optical density measurement. We also assessed their sensitivity for detecting subtle growth effects caused by cyclic AMP and gentamicin. Our results show that BAS image analysis is at least as sensitive as the standard method of spectrophotometrically quantifying the crystal violet retained by biofilms. Furthermore, we demonstrated that bacteria adhered after short incubations (from 10 min to 4 h), isolated from planktonic populations by a simple rinse, can be monitored until their growth is detectable by intrinsic fluorescence, BAS analysis, or resolubilized crystal violet. These procedures are widely accessible for many laboratories, including those with limited resources, as they do not require a spectrophotometer or other specialized equipment.

Novel strategy of S. mutans gcrR gene over-expression plus antibacterial dimethylaminohexadecyl methacrylate suppresses biofilm acids and reduces dental caries in rats

OBJECTIVE

Streptococcus mutans (S. mutans) is a major contributor to dental caries, with its ability to synthesize extracellular polysaccharides (EPS) and biofilms. The gcrR gene is a regulator of EPS synthesis and biofilm formation. The objectives of this study were to investigate a novel strategy of combining gcrR gene over-expression with dimethylaminohexadecyl methacrylate (DMAHDM), and to determine their in vivo efficacy in reducing caries in rats for the first time.

METHODS

Two types of S. mutans were tested: Parent S. mutans; and gcrR gene over-expressed S. mutans (gcrR OE S. mutans). Bacterial minimum inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) were measured with DMAHDM and chlorhexidine (CHX). Biofilm biomass, polysaccharide, lactic acid production, live/dead staining, colony-forming units (CFUs), and metabolic activity (MTT) were evaluated. A Sprague-Dawley rat model was used with parent S. mutans and gcrR OE S. mutans colonization to determine caries-inhibition in vivo.

RESULTS

Drug-susceptibility of gcrR OE S. mutans to DMAHDM or CHX was 2-fold higher than that of parent S. mutans. DMAHDM reduced biofilm CFU by 3-4 logs. Importantly, the combined gcrR OE S. mutans+ DMAHDM dual strategy reduced biofilm CFU by 5 logs. In the rat model, the parent S. mutans group had a higher cariogenicity in dentinal (Dm) and extensive dentinal (Dx) regions. The DMAHDM + gcrR OE group reduced the Dm and Dx caries to only 20 % and 0 %, those of parent S. mutans + PBS control group (p < 0.05). The total caries severity of gcrR OE + DMAHDM group was decreased to 51 % that of parent S. mutans control (p < 0.05).

SIGNIFICANCE

The strategy of combining S. mutans gcrR over-expression with antibacterial monomer reducing biofilm acids by 97 %, and reduced in vivo total caries in rats by 48 %. The gcrR over-expression + DMAHDM strategy is promising for a wide range of dental applications to inhibit caries and protect tooth structures.

A Comprehensive Review of Microbial Biofilms on Contact Lenses: Challenges and Solutions

Contact lenses (CL) have become an immensely popular means of vision correction, offering comfort to millions worldwide. However, the persistent issue of biofilm formation on lenses raises significant problems, leading to various ocular complications and discomfort. The aim of this review is to develop safer and more effective strategies for preventing and managing microbial biofilms on CL, improving the eye health and comfort of wearers. Taking these into consideration, the present study investigates the intricate mechanisms of biofilm formation, by exploring the interplay between microbial adhesion, the production of extracellular polymeric substances, and the properties of the lens material itself. Moreover, it emphasizes the diverse range of microorganisms involved, encompassing bacteria, fungi, and other opportunistic pathogens, elucidating their implications within lenses and other medical device-related infections and inflammatory responses. Going beyond the challenges posed by biofilms on CL, this work explores the advancements in biofilm detection techniques and their clinical relevance. It discusses diagnostic tools like confocal microscopy, genetic assays, and emerging technologies, assessing their capacity to identify and quantify biofilm-related infections. Finally, the paper delves into contemporary strategies and innovative approaches for managing and preventing biofilms development on CL. In Conclusion, this review provides insights for eye care practitioners, lens manufacturers, and microbiology researchers. It highlights the intricate interactions between biofilms and CL, serving as a foundation for the development of effective preventive measures and innovative solutions to enhance CL safety, comfort, and overall ocular health. Research into microbial biofilms on CL is continuously evolving, with several future directions being explored to address challenges and improve eye health outcomes as far as CL wearers are concerned.

Deconstructing synthetic biology across scales: a conceptual approach for training synthetic biologists

Synthetic biology allows us to reuse, repurpose, and reconfigure biological systems to address society's most pressing challenges. Developing biotechnologies in this way requires integrating concepts across disciplines, posing challenges to educating students with diverse expertise. We created a framework for synthetic biology training that deconstructs biotechnologies across scales-molecular, circuit/network, cell/cell-free systems, biological communities, and societal-giving students a holistic toolkit to integrate cross-disciplinary concepts towards responsible innovation of successful biotechnologies. We present this framework, lessons learned, and inclusive teaching materials to allow its adaption to train the next generation of synthetic biologists.

Inhibition of zinc ions in sulfur-driven autotrophic denitrification process: What is the behavior of extracellular polymeric substances?

Sulfur-driven autotrophic denitrification (SAD) process is a cost-effective and sustainable method for nitrogen removal from wastewater. However, a higher concentration of zinc ions (Zn(II)) flowing into wastewater treatment plants poses a potential threat to the SAD process. This study examined that a half maximal inhibitory concentration (IC50) of Zn(II) was 7 mg·L-1 in the SAD process. Additionally, the addition of 20 mg·L-1 Zn(II) resulted in a severe accumulation of nitrite to 150.20 ± 6.00 mg·L-1 when the initial concentration of nitrate was 500 mg·L-1. Moreover, the activities of nitrate reductase, nitrite reductase, dehydrogenase and electron transport system were significantly inhibited under Zn(II) stress. The addition of Zn(II) inhibited EPS secretion and worsened electrochemical properties. The result was attributed to the spontaneous binding between EPS and Zn(II), with a ΔG of -17.50 KJ·mol-1 and a binding constant of 1.77 × 104 M-1, respectively. Meanwhile, the protein, fulvic acid, and humic-like substances occurred static quenching after Zn(II) addition, with -OH and -C=O groups providing binding sites. The binding sequence was fulvic acid→protein→humic acid and -OH → -C=O. Zn(II) also reduced the content of α-helix, which was unfavorable for electron transfer. Additionally, the Zn(II) loosened protein structure, resulting in a 50 % decrease in α-helix/(β-sheet+random coil). This study reveals the effect of Zn(II) on the SAD process and enhances our understanding of EPS behavior under metal ions stress.

Biofilm-forming Ability of Bacillus thuringiensis Strains from Biopesticides on Polystyrene and their Attachment on Spinach

Bacillus thuringiensis-based commercial products as a biopesticide have been used for more than 60 years in agriculture. However, as one of the species in B. cereus group, B. thuringiensis has been considered as an emerging hazard with the potential to cause food toxico-infections. The present study aimed to evaluate the biofilm-forming ability of B. thuringiensis biopesticide strains and their attachment on spinach, compared to foodborne B. cereus strains. Biofilm formations of tested strains were found to be strain-specific and affected by the nutrient conditions more than the incubation time. Nutrient starvation conditions generally reduced the biofilm formation of tested B. thuringiensis and B. cereus strains, particularly B. thuringiensis ABTS-1857 strain was found as the nonbiofilm former in starvation conditions. It is worth mentioning that B. thuringiensis SA-11 strain showed stronger biofilm-forming ability with more air-liquid interface biofilm than the other two B. thuringiensis biopesticide strains, but no such higher attachment of B. thuringiensis SA-11 to spinach was observed. These results indicate that B. thuringiensis SA-11 strain can enter the food processing lines by the attachment on spinach leaves, and it has the potential to form biofilms throughout the processing lines or the production environment when sufficient nutrients are available. However, more biofilm tests of B. thuringiensis biopesticide strains in the vegetable production chain should be performed. The dry formulation of commercial B. thuringiensis biopesticides enhanced their adhesion on spinach leaves, whereas the strength of adhesion was not improved by the formulation. In addition, 1-2 log reductions of spores after the intensive washing of spinach leaves in the lab were detected. However, the log reduction due to the actual washing done by the food processing companies in large-volume washing baths or by consumers at home would be limited and less than this lab simulation.

Genotypic and phenotypic characterization of Enterococcus faecalis isolates from periprosthetic joint infections

Over 2.5 million prosthetic joint implantation surgeries occur annually in the United States. Periprosthetic joint infections (PJIs), though occurring in only 1-2% of patients receiving replacement joints, are challenging to diagnose and treat and are associated with significant morbidity. The Gram-positive bacterium Enterococcus faecalis, which can be highly antibiotic-resistant and is a robust biofilm producer on indwelling medical devices, accounts for 2-11% of PJIs. E. faecalis PJIs are understudied compared to those caused by other pathogens, such as Staphylococcus aureus. This motivates the need to generate a comprehensive understanding of E. faecalis PJIs to guide future treatments for these infections. To address this, we describe a panel of E. faecalis strains isolated from the surface of prosthetic joints in a cohort of individuals treated at the Mayo Clinic in Rochester, MN. Here, we present the first complete genome assemblage of E. faecalis PJI isolates. Comparative genomics shows differences in genome size, virulence factors, antimicrobial resistance genes, plasmids, and prophages, underscoring the genetic diversity of these strains. These isolates have strain-specific differences in in vitro biofilm biomass, biofilm burden, and biofilm morphology. We measured robust changes in biofilm architecture and aggregation for all isolates when grown in simulated synovial fluid (SSF). Finally, we evaluated the antibiotic efficacy of these isolates and found strain-specific changes across all strains when grown in SSF. Results of this study highlight the existence of genetic and phenotypic heterogeneity among E. faecalis PJI isolates which will provide valuable insight and resources for future E. faecalis PJI research.

IMPORTANCE

Periprosthetic joint infections (PJIs) affect ~1-2% of those who undergo joint replacement surgery. Enterococcus faecalis is a Gram-positive opportunistic pathogen that causes ~10% of PJIs in the United States each year, but our understanding of how and why E. faecalis causes PJIs is limited. E. faecalis infections are typically biofilm-associated and can be difficult to clear with antibiotic therapy. Here, we provide complete genomes for four E. faecalis PJI isolates from the Mayo Clinic. These isolates have strain-specific differences in biofilm formation, aggregation, and antibiotic susceptibility in simulated synovial fluid. These results provide important insight into the genomic and phenotypic features of E. faecalis isolates from PJI.

Earthworm gut digestion drives the transfer behavior of antibiotic resistance genes in layers of extracellular polymeric substances during vermicomposting of dewatered sludge

Gut digestion by earthworms (GDE) is a crucial step in vermicomposting, affecting the fate of antibiotic resistance genes (ARGs) in vermicompost sludge. The extracellular polymeric substance (EPS) matrix of sludge is an important space for ARG transfer. However, the effect of GDE on EPS-associated ARGs remains unclear. Therefore, this study explored the role of GDE in driving the transfer of ARGs within different EPS layers in sludge. For this, the changes in intracellular ARGs and EPS-associated ARGs in sludge were analyzed after 5 days of the GDE process. The results showed that after the GDE process, both nitrate and dissolved organic carbon significantly increased in all EPS layers of sludge, while the proteins and polysaccharides only enhanced in soluble and loosely bound EPS of sludge. In addition, a 7.0% decrease in bacterial diversity was recorded after the GDE process, with a functional bacterial community structure emerging. Moreover, the absolute abundance of total ARGs and mobile genetic elements decreased by 90.71% and 61.83%, respectively, after the GDE process. Intracellular ARGs decreased by 92.1%, while EPS-associated ARGs increased by 4.9%, indicative of intracellular ARG translocation into the EPS during the GDE process. Notably, the ARGs exhibited significant enrichment in both the soluble and loosely bound EPS, whereas they were reduced in the tightly bound EPS. The structural equation modeling revealed that the GDE process effectively mitigated the ARG dissemination risk by modulating both the EPS structure and microenvironment, with the organic structure representing a primary factor influencing ARGs in the EPS.

Reciprocal sharing of extracellular proteases and extracellular matrix molecules facilitates Bacillus subtilis biofilm formation

Extracellular proteases are a class of public good that support growth of Bacillus subtilis when nutrients are in a polymeric form. Bacillus subtilis biofilm matrix molecules are another class of public good that are needed for biofilm formation and are prone to exploitation. In this study, we investigated the role of extracellular proteases in B.  subtilis biofilm formation and explored interactions between different public good producer strains across various conditions. We confirmed that extracellular proteases support biofilm formation even when glutamic acid provides a freely available nitrogen source. Removal of AprE from the NCIB 3610 secretome adversely affects colony biofilm architecture, while sole induction of WprA activity into an otherwise extracellular protease-free strain is sufficient to promote wrinkle development within the colony biofilm. We found that changing the nutrient source used to support growth affected B. subtilis biofilm structure, hydrophobicity and architecture. We propose that the different phenotypes observed may be due to increased protease dependency for growth when a polymorphic protein presents the sole nitrogen source. We however cannot exclude that the phenotypic changes are due to alternative matrix molecules being made. Co-culture of biofilm matrix and extracellular protease mutants can rescue biofilm structure, yet reliance on extracellular proteases for growth influences population coexistence dynamics. Our findings highlight the intricate interplay between these two classes of public goods, providing insights into microbial social dynamics during biofilm formation across different ecological niches.

Acinetobacter baumannii biofilm was inhibited by tryptanthrin through disrupting its different stages and genes expression

Biofilm formation plays a significant role in antibiotic resistance, necessitating the search for alternative therapies against biofilm-associated infections. This study demonstrates that 20 μg/mL tryptanthrin can hinder biofilm formation above 50% in various A. baumannii strains. Tryptanthrin impacts various stages of biofilm formation, including the inhibition of surface motility and eDNA release in A. baumannii, as well as an increase in its sensitivity to H202. RT-qPCR analysis reveals that tryptanthrin significantly decreases the expression of the following genes: abaI (19.07%), abaR (33.47%), bfmR (43.41%), csuA/B (64.16%), csuE (50.20%), ompA (67.93%), and katE (72.53%), which are related to biofilm formation and quorum sensing. Furthermore, tryptanthrin is relatively safe and can reduce the virulence of A. baumannii in a Galleria mellonella infection model. Overall, our study demonstrates the potential of tryptanthrin in controlling biofilm formation and virulence of A. baumannii by disrupting different stages of biofilm formation and intercellular signaling communication.

The mouse epididymal amyloid matrix is a mammalian counterpart of a bacterial biofilm

The mouse epididymis is a long tubule connecting the testis to the vas deferens. Its primary functions are to mature spermatozoa into motile and fertile cells and to protect them from pathogens that ascend the male tract. We previously demonstrated that a functional extracellular amyloid matrix surrounds spermatozoa in the epididymal lumen and has host defense functions, properties not unlike that of an extracellular biofilm that encloses and protects a bacterial community. Here we show the epididymal amyloid matrix also structurally resembles a biofilm by containing eDNA, eRNA, and mucin-like polysaccharides. Further these structural components exhibit comparable behaviors and perform functions such as their counterparts in bacterial biofilms. Our studies suggest that nature has used the ancient building blocks of bacterial biofilms to form an analogous structure that nurtures and protects the mammalian male germline.

A systematic review of antibiotics and antibiotic resistance genes (ARGs) in mariculture wastewater: Antibiotics removal by microalgal-bacterial symbiotic system (MBSS), ARGs characterization on the metagenomic

Antibiotic residues in mariculture wastewater seriously affect the aquatic environment. Antibiotic Resistance Genes (ARGs) produced under antibiotic stress flow through the environment and eventually enter the human body, seriously affecting human health. Microalgal-bacterial symbiotic system (MBSS) can remove antibiotics from mariculture and reduce the flow of ARGs into the environment. This review encapsulates the present scenario of mariculture wastewater, the removal mechanism of MBSS for antibiotics, and the biomolecular information under metagenomic assay. When confronted with antibiotics, there was a notable augmentation in the extracellular polymeric substances (EPS) content within MBSS, along with a concurrent elevation in the proportion of protein (PN) constituents within the EPS, which limits the entry of antibiotics into the cellular interior. Quorum sensing stimulates the microorganisms to produce biological responses (DNA synthesis - for adhesion) through signaling. Oxidative stress promotes gene expression (coupling, conjugation) to enhance horizontal gene transfer (HGT) in MBSS. The microbial community under metagenomic detection is dominated by aerobic bacteria in the bacterial-microalgal system. Compared to aerobic bacteria, anaerobic bacteria had the significant advantage of decreasing the distribution of ARGs. Overall, MBSS exhibits remarkable efficacy in mitigating the challenges posed by antibiotics and resistant genes from mariculture wastewater.

Antibiofilm Efficacy and Mechanism of the Marine Chlorinated Indole Sesquiterpene Against Methicillin-Resistant Staphylococcus aureus

Methicillin-resistant Staphylococcus aureus (MRSA) can easily form biofilms on food surfaces, thus leading to cross-contamination, which is difficult to remove. Therefore, there is an urgent need to find alternatives with good antibacterial and antibiofilm effects. In this study, two indole sesquiterpene compounds, xiamycin (1) and chlorinated metabolite chloroxiamycin (2), were isolated from the fermentation liquid of marine Streptomyces sp. NBU3429 for the first time. The chemical structures of the two compounds were characterized by spectroscopic data interpretation, including 1D NMR and HRESIMS analysis. Antimicrobial test showed that chloroxiamycin (2) (minimum inhibitory concentration, MIC = 16 μg/mL) exhibited superior antibacterial activity than xiamycin (1) (MIC = 32 μg/mL) against MRSA ATCC43300. Moreover, compound (2) decreased the biofilm formation rate of MRSA ATCC43300 by 12.7%-84.6% in the concentration range of 32-512 μg/mL, which is relatively stronger than xiamycin (1) (4.1%-49.9%) as well. Antibacterial/antibiofilm mechanism investigation indicated that chloroxiamycin (2) could disrupt the cell wall and membrane of MRSA, inhibiting the production of biofilm extracellular polysaccharides. All these results illustrated that chloroxiamycin (2) is an effective antibacterial/antibiofilm agent, which makes it an attractive candidate for food preservatives.

Sewage Sludge Promotes the Accumulation of Antibiotic Resistance Genes in Tomato Xylem

Xylem serves as a conduit linking soil to the aboveground plant parts and facilitating the upward movement of microbes into leaves and fruits. Despite this potential, the composition of the xylem microbiome and its associated risks, including antibiotic resistance, are understudied. Here, we cultivated tomatoes and analyzed their xylem sap to assess the microbiome and antibiotic resistance profiles following treatment with sewage sludge. Our findings show that xylem microbes primarily originate from soil, albeit with reduced diversity in comparison to those of their soil microbiomes. Using single-cell Raman spectroscopy coupled with D2O labeling, we detected significantly higher metabolic activity in xylem microbes than in rhizosphere soil, with 87% of xylem microbes active compared to just 36% in the soil. Additionally, xylem was pinpointed as a reservoir for antibiotic resistance genes (ARGs), with their abundance being 2.4-6.9 times higher than in rhizosphere soil. Sludge addition dramatically increased the abundance of ARGs in xylem and also increased their mobility and host pathogenicity. Xylem represents a distinct ecological niche for microbes and is a significant reservoir for ARGs. These results could be used to manage the resistome in crops and improve food safety.

Flexible nanoplatform facilitates antibacterial phototherapy by simultaneously enhancing photosensitizer permeation and relieving hypoxia in bacterial biofilms

Antimicrobial phototherapy has gained recognition as a promising approach for addressing bacterial biofilms, however, its effectiveness is often impeded by the robust physical and chemical defenses of the biofilms. Traditional antibacterial nanoplatforms face challenges in breaching the extracellular polymeric substances barrier to efficiently deliver photosensitizers deep into biofilms. Moreover, the prevalent hypoxia within biofilms restricts the success of oxygen-reliant phototherapy. In this study, we engineered a soft mesoporous organosilica nanoplatform (SMONs) by incorporating polyethylene glycol (PEG), catalase (CAT), and indocyanine green (ICG), forming SMONs-PEG-CAT-ICG (SPCI). We compared the antimicrobial efficacy of SPCI with more rigid nanoplatforms. Our results demonstrated that unique flexible mechanical properties of SPCI enable it to navigate through biofilm barriers, markedly enhancing ICG penetration in methicillin-resistant Staphylococcus aureus (MRSA) biofilms. Notably, in a murine subcutaneous MRSA biofilm infection model, SPCI showed superior biofilm penetration and pharmacokinetic benefits over its rigid counterparts. The embedded catalase in SPCI effectively converts excess H2O2 present in infected tissues into O2, alleviating hypoxia and significantly boosting the antibacterial performance of phototherapy. Both in vitro and in vivo experiments confirmed that SPCI surpasses traditional rigid nanoplatforms in overcoming biofilm barriers, offering improved treatment outcomes for infections associated with bacterial biofilms. This study presents a viable strategy for managing bacterial biofilm-induced diseases by leveraging the unique attributes of a soft mesoporous organosilica-based nanoplatform. STATEMENT OF SIGNIFICANCE: This research introduces an innovative antimicrobial phototherapy soft nanoplatform that overcomes the inherent limitations posed by the protective barriers of bacterial biofilms. By soft nanoplatform with flexible mechanical properties, we enhance the penetration and delivery of photosensitizers into biofilms. The inclusion of catalase within this soft nanoplatform addresses the hypoxia in biofilms by converting hydrogen peroxide into oxygen in infected tissues, thereby amplifying the antibacterial effectiveness of phototherapy. Compared to traditional rigid nanoplatforms, this flexible nanoplatform not only promotes the delivery of therapeutic agents but also sets a new direction for treating bacterial biofilm infections, offering significant implications for future antimicrobial therapies.

Graphene Oxide-Silver-Coated Sulfonated Polyetheretherketone (Ag/GO-SPEEK): A Broad-Spectrum Antibacterial Artificial Bone Implants

Polyetheretherketone (PEEK), particularly its sulfonated form (SPEEK), has emerged as a promising synthetic biomaterial for artificial bone implants, providing an alternative to conventional titanium metal. However, postoperative infections pose a critical challenge, driven by diverse and antibiotic-resistant bacteria. To address this issue, we propose the modification of the SPEEK surface using a thin graphene oxide (GO) film containing silver (Ag) ions. The resulting coating exhibits substantial antibacterial effects against various pathogens, including Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, and Candida albicans. Experimental assessments elucidate the coating's impact on bacterial adhesion, biofilm formation, and morphology. The results suggest that hindered bacterial growth stems from reduced biofilm production and the controlled release of Ag ions facilitated by the GO coating. The Ag/GO-SPEEK material holds promise as a bioactive implant, addressing the challenges associated with bacterial targeting in bone tissue engineering applications.

Mycobacterial biofilms: A therapeutic target against bacterial persistence and generation of antibiotic resistance

Mycobacterium tuberculosis (M. tb) is the causative agent of Tuberculosis, one of the deadliest infectious diseases. According to the WHO Report 2023, in 2022, approximately 10.6 million people got infected with TB, and 1.6 million died. It has multiple antibiotics for treatment, but the major drawback of anti-tuberculosis therapy (ATT) is, its prolonged treatment duration. The major contributors to the lengthy treatment period are mycobacterial persistence and drug tolerance. Persistent M. tb is phenotypically drug tolerant and metabolically slow down which makes it difficult to be eliminated during ATT. These persisting bacteria are a huge reservoir of impending disease, waiting to get reactivated upon the onset of an immune compromising state. Directly Observed Treatment Short-course, although effective against replicating bacteria; fails to eliminate the drug-tolerant persisters making TB still the second-highest killer globally. There are different mechanisms for the development of drug-tolerant mycobacterial populations being investigated. Recently, the role of biofilms in the survival and host-evasion mechanism of persisters has come to light. Therefore, it is crucial to understand the mechanism of adaptation, survival and attainment of drug tolerance by persisting M. tb-populations, in order to design better immune responses and therapeutics for the effective elimination of these bacteria by reducing the duration of treatment and also circumvent the generation of drug-resistance to achieve the goal of global eradication of TB. This review summarizes the drug-tolerance mechanism and biofilms' role in providing a niche to dormant-M.tb. We also discuss methods of targeting biofilms to achieve sterile eradication of the mycobacteria and prevent its reactivation by achieving adequate immune responses.

Adhesion pilus retraction powers twitching motility in the thermoacidophilic crenarchaeon Sulfolobus acidocaldarius

Type IV pili are filamentous appendages found in most bacteria and archaea, where they can support functions such as surface adhesion, DNA uptake, aggregation, and motility. In most bacteria, PilT-family ATPases disassemble adhesion pili, causing them to rapidly retract and produce twitching motility, important for surface colonization. As archaea do not possess PilT homologs, it was thought that archaeal pili cannot retract and that archaea do not exhibit twitching motility. Here, we use live-cell imaging, automated cell tracking, fluorescence imaging, and genetic manipulation to show that the hyperthermophilic archaeon Sulfolobus acidocaldarius exhibits twitching motility, driven by retractable adhesion (Aap) pili, under physiologically relevant conditions (75 °C, pH 2). Aap pili are thus capable of retraction in the absence of a PilT homolog, suggesting that the ancestral type IV pili in the last universal common ancestor (LUCA) were capable of retraction.

Gastrointestinal Biofilms: Endoscopic Detection, Disease Relevance, and Therapeutic Strategies

Gastrointestinal biofilms are highly heterogenic and spatially organized polymicrobial communities that can expand and cover large areas in the gastrointestinal tract. Gut microbiota dysbiosis, mucus disruption, and epithelial invasion are associated with pathogenic biofilms that have been linked to gastrointestinal disorders such as irritable bowel syndrome, inflammatory bowel diseases, gastric cancer, and colon cancer. Intestinal biofilms are highly prevalent in ulcerative colitis and irritable bowel syndrome patients, and most endoscopists will have observed such biofilms during colonoscopy, maybe without appreciating their biological and clinical importance. Gut biofilms have a protective extracellular matrix that renders them challenging to treat, and effective therapies are yet to be developed. This review covers gastrointestinal biofilm formation, growth, appearance and detection, biofilm architecture and signalling, human host defence mechanisms, disease and clinical relevance of biofilms, therapeutic approaches, and future perspectives. Critical knowledge gaps and open research questions regarding the biofilm's exact pathophysiological relevance and key hurdles in translating therapeutic advances into the clinic are discussed. Taken together, this review summarizes the status quo in gut biofilm research and provides perspectives and guidance for future research and therapeutic strategies.

The role of DNA in the pathogenesis of SLE: DNA as a molecular chameleon

Systemic lupus erythematosus (SLE) is a prototypic autoimmune disease characterised by antibodies to DNA (anti-DNA) and other nuclear macromolecules. Anti-DNA antibodies are markers for classification and disease activity and promote pathogenesis by forming immune complexes that deposit in the tissue or stimulate cytokine production. Studies on the antibody response to DNA have focused primarily on a conformation of DNA known as B-DNA, the classic right-handed double helix. Among other conformations of DNA, Z-DNA is a left-handed helix with a zig-zag backbone; hence, the term Z-DNA. Z-DNA formation is favoured by certain base sequences, with the energetically unfavourable flip from B-DNA to Z-DNA dependent on conditions. Z-DNA differs from B-DNA in its immunogenicity in animal models. Furthermore, anti-Z-DNA antibodies, but not anti-B-DNA antibodies, can be present in otherwise healthy individuals. In SLE, antibodies to Z-DNA can occur in association with antibodies to B-DNA as a cross-reactive response, rising and falling together. While formed transiently in chromosomal DNA, Z-DNA is stably present in bacterial biofilms; biofilms can provide protection against antibiotics and other challenges including elements of host defence. The high GC content of certain bacterial DNA also favours Z-DNA formation as do DNA-binding proteins of bacterial or host origin. Together, these findings suggest that sources of Z-DNA can enhance the immunogenicity of DNA and, in SLE, stimulate the production of cross-reactive antibodies that bind both B-DNA and Z-DNA. As such, DNA can act as a molecular chameleon that, when stabilised in the Z-DNA conformation, can drive autoimmunity.

Ambient Synthesis of Porphyrin-Based Fe-Covalent Organic Frameworks for Efficient Infected Skin Wound Healing

Reactive oxygen species (ROS) have emerged as a promising treatment option for antibacterial and biofilm eradication. However, their therapeutic efficacy is significantly hampered by the unique microenvironments of diabetic wounds. In this study, we designed and synthesized porphyrin-based Fe covalent organic frameworks (Fe-COF) through a Schiff base condensation reaction. Subsequently, Fe-COF were encapsulated with hyaluronic acid (HA) through electrostatic adsorption, resulting in a novel formulation named HA-Fe-COF for diabetic wound healing. HA-Fe-COF were engineered to respond to hyaluronidase in the infected wound, leading to the controlled release of Fe-COF. Those released Fe-COF served a dual role as photosensitizers, generating singlet oxygen and localized heating when exposed to dual light sources. Additionally, they acted as peroxidase-like nanozymes, facilitating the production of ROS through enzymatic reactions. This innovative approach enabled a synergistic therapeutic effect combining photodynamic, photothermal, and chemodynamic modalities. Furthermore, the sustained release of HA from HA-Fe-COF promoted angiogenesis, collagen deposition, and re-epithelialization during the diabetic wound healing process. This "all-in-one" strategy offers a novel approach for the development of antimicrobial and biofilm eradication strategies that minimize damage to healthy tissues in vivo.

Fabrication of photo-induced molecular superoxide radical generator for highly efficient therapy against bacterial wound infection

The pressing need for highly efficient antibacterial strategies arises from the prevalence of microbial biofilm infections and the emergence of rapidly evolving antibiotic-resistant strains of pathogenic bacteria. Photodynamic therapy represents a highly efficient and compelling antibacterial approach, offering promising prospects for effective control of the development of bacterial resistance. However, the effectiveness of many photosensitizers is limited due to the reduced generation of reactive oxygen species (ROS) in hypoxic microenvironment, which commonly occur in pathological conditions such as inflammatory and bacteria-infected wounds. Herein, we designed and prepared two phenothiazine-derived photosensitizers (NB-1 and NB-2), which can effectively generate superoxide anion radicals (O2●-) through the type I process. Both photosensitizers demonstrate significant efficacy in vitro for the eradication of broad-spectrum bacteria. Moreover, NB-2 possesses distinct advantages including strong membrane binding and strong generation of O2●-, rendering it an exceptionally efficient antibacterial agent against mature biofilms. In addition, laser activated NB-2 could be applied to treat MRSA-infected wound in vivo, which offers new opportunities for potential practical applications.

S. aureus develops biofilms on titanium within 2 weeks in vitro

BACKGROUND

The formation of biofilms, characterized by cell aggregation and extracellular polymeric substance (EPS) production, is a common feature of periprosthetic joint infections (PJI).

OBJECTIVE

The current study aimed to investigate the development of biofilm features in vitro within less than 3 weeks by Staphylococcus aureus isolated from PJIs.

METHODS

Biofilms were grown on sandblasted titanium discs, and fluorescence spectroscopy and microscopy were used to observe biofilm maturation for 21 days.

RESULTS

DNA mass decreased initially, then increased from day 5 onwards, and decreased again after day 7. The proportion of living to dead bacteria oscillated until day 7 and increased at day 10 for strain A and day 14 for strain B. EPS mass decreased initially and then continuously increased. Multilayer bacterial organization was observed at day 7.

CONCLUSION

Cell aggregation occurred during the first week, followed by EPS production in the second week, and characteristic biofilm features were observed within 1 to 2 weeks.

Evaluating a polymicrobial biofilm model for structural components by co-culturing Komagataeibacter hansenii produced bacterial cellulose with Pseudomonas aeruginosa PAO1

A polymicrobial biofilm model of Komagataeibacter hansenii and Pseudomonas aeruginosa was developed to understand whether a pre-existing matrix affects the ability of another species to build a biofilm. P. aeruginosa was inoculated onto the preformed K. hansenii biofilm consisting of a cellulose matrix. P. aeruginosa PAO1 colonized and infiltrated the K. hansenii bacterial cellulose biofilm (BC), as indicated by the presence of cells at 19 μm depth in the translucent hydrogel matrix. Bacterial cell density increased along the imaged depth of the biofilm (17-19 μm). On day 5, the average bacterial count across sections was 67 ± 4 % P. aeruginosa PAO1 and 33 ± 6 % K. hansenii. Biophysical characterization of the biofilm indicated that colonization by P. aeruginosa modified the biophysical properties of the BC matrix, which inlcuded increased density, heterogeneity, degradation temperature and thermal stability, and reduced crystallinity, swelling ability and moisture content. This further indicates colonization of the biofilm by P. aeruginosa. While eDNA fibres - a key viscoelastic component of P. aeruginosa biofilm - were present on the surface of the co-cultured biofilm on day 1, their abundance decreased over time, and by day 5, no eDNA was observed, either on the surface or within the matrix. P. aeruginosa-colonized biofilm devoid of eDNA retained its mechanical properties. The observations demonstrate that a pre-existing biofilm scaffold of K. hansenii inhibits P. aeruginosa PAO1 eDNA production and suggest that eDNA production is a response by P. aeruginosa to the viscoelastic properties of its environment.

Cetyltrimethylammonium-chloride assisted in situ metabolic incorporation of nano-sized ROS-generating cascade-reaction containers in Gram-positive and Gram-negative peptidoglycan layers for the control of bacterially-induced sepsis

Cascade-reaction containers generating reactive oxygen species (ROS) as an alternative for antibiotic-based strategies for bacterial infection control, require endogenous oxygen-sources and ROS-generation close to or preferably inside target bacteria. Here, this is achieved by cetyltrimethylammonium-chloride (CTAC) assisted in situ metabolic labeling and incorporation of mesoporous SiO2-nanoparticles, dual-loaded with glucose-oxidase and Fe3O4-nanoparticles as cascade-reaction containers, inside bacterial cell walls. First, azide-functionalized d-alanine (D-Ala-N3) was inserted in cell wall peptidoglycan layers of growing Gram-positive pathogens. In Gram-negatives, this could only be achieved after outer lipid-membrane permeabilization, using a low concentration of CTAC. Low concentrations of CTAC had no adverse effect on in vitro blood clotting or hemolysis nor on the health of mice when blood-injected. Next, dibenzocyclooctyne-polyethylene-glycol modified, SiO2-nanoparticles were in situ click-reacted with d-Ala-N3 in bacterial cell wall peptidoglycan layers. Herewith, a two-step cascade-reaction is facilitated inside bacteria, in which glucose-oxidase generates H2O2 at endogenously-available glucose concentrations, while subsequently Fe3O4-nanoparticles catalyze generation of •OH from the H2O2 generated. Generation of •OH inside bacterial cell walls by dual-loaded mesoporous SiO2-nanoparticles yielded more effective in vitro killing of both planktonic Gram-positive and Gram-negative bacteria suspended in 10 % plasma than SiO2-nanoparticles solely loaded with glucose-oxidase. Gram-positive or Gram-negative bacterially induced sepsis in mice could be effectively treated by in situ pre-treatment with tail-vein injected CTAC and d-Ala-N3, followed by injection of dual-loaded cascade-reaction containers without using antibiotics. This makes in situ metabolic incorporation of cascade-reaction containers as described attractive for further investigation with respect to the control of other types of infections comprising planktonic bacteria. STATEMENT OF SIGNIFICANCE: In situ metabolic-incorporation of cascade-reaction-containers loaded with glucose-oxidase and Fe3O4 nanoparticles into bacterial cell-wall peptidoglycan is described, yielding ROS-generation from endogenous glucose, non-antibiotically killing bacteria before ROS inactivates. Hitherto, only Gram-positives could be metabolically-labeled, because Gram-negatives possess two lipid-membranes. The outer membrane impedes direct access to the peptidoglycan. This problem was solved by outer-membrane permeabilization using a quaternary-ammonium compound. Several studies on metabolic-labeling perform crucial labeling steps during bacterial-culturing that in real-life should be part of a treatment. In situ metabolic-incorporation as described, can be applied in well-plates during in vitro experiments or in the body as during in vivo animal experiments. Surprisingly, metabolic-incorporation proceeded unhampered in blood and a murine, bacterially-induced sepsis could be well treated.