Microbial Fouling Research Articles

Prevention and Control of Biofouling Coatings in Limnoperna fortunei: A Review of Research Progress and Strategies.

The increasing environmental concerns of conventional antifouling coatings have led to the exploration of novel and sustainable solutions to address the biofouling caused by Limnoperna fortunei. As a rapidly expanding invasive species, the fouling process of Limnoperna fortunei is closely associated with microbial fouling, posing significant threats to the integrity of aquatic infrastructure and biodiversity. This review discusses recent progress in the development of non-toxic, eco-friendly antifouling coatings that are designed to effectively resist biofouling without using toxic chemicals. Recent research has focused on developing novel non-toxic coatings that integrate natural bioactive components with advanced material technologies. These formulations not only meet current environmental standards and exhibit minimal ecological impact, but also possess significant potential in preventing the attachment, growth, and reproduction of Limnoperna fortunei. This review aims to provide scientific guidance by proposing effective and sustainable solutions to address the ecological challenges presented by Limnoperna fortunei. The insights gained from current research not only reveal novel antifouling methods, but also identify key areas for further investigation aimed at enhancing performance and environmental compatibility.

Fungal microbiota of biodamages of various polymeric materials.

Data on microbial fouling of various synthetic polymer materials, including those used in space technology, are summarized. It has been established that the dominant groups of microbiota of polymer fouling are the genera of mitosporous fungi Aspergillus, Penicillium, Alternaria, Trichoderma. The enzymatic properties of fungal strains from the collection of microbial cultures of the Microbial Depository Center of the National Academy of Sciences of Armenia were studied. It has been shown that Aspergillus fumigatus, Penicillium chrysogenum, P. steckii, Juxtiphoma eupyrena and a number of other fungi have biofouling activity towards polyethylene, polyethylene terephthalate and some other synthetic polymers. New fungal kits have been developed and proposed to evaluate the fungal resistance of polymeric materials. They include fungi isolated from bio-damaged polymers used in space technology and contain 2 to 5 fungal strains instead of 7 to 9 strains in previously used kits. Taking into account the obtained data, a comparative assessment of the fungal resistance of samples of synthetic polymeric materials of various classes that passed accelerated climatic tests has been carried out. It has been established that the kits of biodegradant fungi, composed of cultures of bio-damaged space technology, generally exceeded the activity of the previously used kits, based on which one can judge the obvious advantages of strains isolated from bio-damaged space technology. In the future, these kits could find application not only for biodegradation of polymers, but also for testing the biostability of various polymers, to use for the construction of aviation and space techniques. Moreover, new optimized kits may be developed based on the strains involved in this study.

Coupling effects of micro/nano-scale surface modification and electric current application on fouling resistance and heat transfer

The principle of saving energy and converting waste heat into valuable resources is a core concept. Heat exchange systems are significantly compromised by microbial fouling, which impedes heat transfer and increases energy consumption. This study investigated the coupling effects of micro/nano-scale surface modifications and the application of electric currents as a novel approach to inhibit microbial fouling. Smooth copper surface, electrochemical deposition (ECD) surface, and Nickel-Phosphorus-Polytetrafluoroethylene (Ni-P-PTFE) modified surface were tested and compared. Firstly, we analyzed the average heat transfer coefficient under clean conditions, taking into account different surface characteristics. Then, we employed a series of fouling experiments to evaluate the anti-biofouling performance of smooth copper surfaces, ECD surfaces, and Ni-P-PTFE surfaces. The assessment involved flow cytometry, Scanning Electron Microscopy (SEM) and measurements of thermal resistance. Finally, we investigated the effect of external electric current on microbial fouling mitigation. Results show that the ECD surface exhibited an enhanced heat transfer and a poor fouling resistance, while the Ni-P-PTFE surface demonstrated an excellent fouling resistance and a minimal increase in thermal resistance. The application of a low direct current density at 0.51 mA/cm² significantly reduced microbial viability on all surfaces. A higher electric current can further inhibit microbial adhesion and proliferation, enhancing the anti-fouling capability of the surfaces. Compared to surfaces without electric current, the smooth copper surface, ECD, and Ni-P-PTFE surfaces at 5.1 mA/cm² displayed a reduction in thermal resistance by 45.7%, 36.8%, and 38.1%, respectively. At 51 mA/cm², the reduction in thermal resistance for smooth copper surface, ECD, and Ni-P-PTFE surfaces was 75.7%, 78.2%, and 57.1%, respectively. This comprehensive study has validated the potential of combining micro/nano-scale surface modifications with electric current application as an effective strategy for enhancing heat transfer efficiency and anti-fouling properties of heat exchange systems.

Flourishing in Darkness: Protist Communities of Water Sites in Shulgan-Tash Cave (Southern Urals, Russia)

Karst caves, formed by the erosion of soluble carbonate rocks, provide unique ecosystems characterized by stable temperatures and high humidity. These conditions support diverse microbial communities, including wall microbial fouling, aquatic biofilms, and planktonic communities. This study discloses the taxonomic diversity of protists in aquatic biotopes of Shulgan-Tash Cave, a culturally significant site and popular tourist destination, by 18S rRNA gene metabarcoding. Our findings reveal the rich protist communities in the cave’s aquatic biotopes, with the highest diversity observed in Blue Lake at the cave entrance. In contrast, Distant Lake in the depth of the cave was inhabited by specific communities of plankton, mats, and pool fingers, which exhibited lower richness and evenness, and were adapted to extreme conditions (cold, darkness, and limited nutrients). High-rank taxa including Opisthokonta, Stramenopiles, and Rhizaria dominated all biotopes, aligning with observations from other subterranean environments. Specific communities of biotopes inside the cave featured distinct dominant taxa: amoeboid stramenopile (Synchromophyceae) and flagellates (Choanoflagellatea and Sandona) in mats; flagellates (Choanoflagellatea, Bicoecaceae, Ancyromonadida) and amoeboid protists (Filasterea) in pool fingers; flagellates (Ochromonadales, Glissomonadida, Synchromophyceae), fungi-like protists (Peronosporomycetes), and fungi (Ustilaginomycotina) in plankton. The specificity of the communities was supported by LEfSe analysis, which revealed enriched or differentially abundant protist taxa in each type of biotope. The predominance of Choanoflagellatea in the communities of cave mats and pool fingers, as well as the predominance of Synchromophyceae in the cave mats, appears to be a unique feature of Shulgan-Tash Cave. The cold-tolerant yeast Malassezia recorded in other caves was present in both plankton and biofilm communities, suggesting its resilience to low temperatures. However, no potentially harmful fungi were detected, positioning this research as a baseline for future monitoring. Our results emphasize the need for ongoing surveillance and conservation efforts to protect the fragile ecosystems of Shulgan-Tash Cave from human-induced disturbances and microbial invasions.

Treatment of Synthetic Wastewater Containing Polystyrene (PS) Nanoplastics by Membrane Bioreactor (MBR): Study of the Effects on Microbial Community and Membrane Fouling.

The persistent presence of micro- and nanoplastics (MNPs) in aquatic environments, particularly via effluents from wastewater treatment plants (WWTPs), poses significant ecological risks. This study investigated the removal efficiency of polystyrene nanoplastics (PS-NPs) using a lab-scale aerobic membrane bioreactor (aMBR) equipped with different membrane types: microfiltration (MF), commercial ultrafiltration (c-UF), and recycled ultrafiltration (r-UF) membranes. Performance was assessed using synthetic urban wastewater spiked with PS-NPs, focusing on membrane efficiency, fouling behavior, and microbial community shifts. All aMBR systems achieved high organic matter removal, exceeding a 97% COD reduction in both the control and PS-exposed reactors. While low concentrations of PS-NPs did not significantly impact the sludge settleability or soluble microbial products initially, a higher accumulation increased the carbohydrate concentrations, indicating a protective bacterial response. The microbial community composition also adapted over time under polystyrene stress. All membrane types exhibited substantial NP removal; however, the presence of nano-sized PS particles negatively affected the membrane performance, enhancing the fouling phenomena and increasing transmembrane pressure. Despite this, the r-UF membrane demonstrated comparable efficiency to c-UF, suggesting its potential for sustainable applications. Advanced characterization techniques including pyrolysis gas chromatography/mass spectrometry (Py-GC/MS) were employed for NP detection and quantification.

Effects of flow-induced electromagnetic field and surface roughness on antifouling activity of phenolic compounds

Microbial fouling involves the physicochemical interactions between microorganisms and solid surfaces. An electromagnetic field (EMF) may change the diffusion rates of microbial cells and the electrical double layer around the cells and contacting surfaces. In the current study, polycardanol exhibiting antibiofouling activity was modified with ferromagnetic iron oxide (IO) to investigate the EMF effects on bacterial adhesion. When there was a flow of electrolyte that contained bacterial cells, flow-induced EMF was generated according to Faraday’s principle. It was observed that the IO-ionic solution (IS)-modified surfaces, with an induced current of 44, 53, 66 nA, showed decreases in the adhesion of bacteria cells more than the unmodified (polycardanol) and IO-nanoparticles-modified ones. In addition to the EMF effects, the nano-scale uniform roughness of the modified surfaces appeared to play an important role in the reduction of cell adhesion. The results demonstrated that the IOIS-modified surface (3.2 × 10−6 mM IO) had the highest antibiofouling activity.

UiO-66-NH2/hydrothermal carbon nanocomposite assembled mesh membrane with photocatalytic self-cleaning and antibacterial properties for on-demand oily wastewater separation

The poor wettability, limited permeation flux and unsatisfactory anti-fouling property of oil/water separation membranes significantly hinder their practical application. This study developed a novel UiO-66-NH2/hydrothermal carbon@stainless steel mesh (UiO/HC@SSM) membrane, fabricated through a straightforward dip-coating strategy that offers membrane thickness control. The resulting membrane exhibited superhydrophilic/underwater superoleophobic property and high porosity, enabling gravity-driven separation of emulsified and stratified oil/water mixtures on-demand with high separation efficiency and superior flux. Specifically, UiO/HC@SSM-5 (dip-coating five times) showed ultrahigh permeate fluxes of 51428–56425 L m−2 h−1 for stratified oil/water mixtures separation, and UiO/HC@SSM-10 exhibited interface demulsification and gravity separation ability for emulsified oil/water mixtures with high fluxes of 4050–4504 L m−2 h−1. Notably, UiO/HC nanocomposite endowed the membrane with exceptional photocatalytic self-cleaning and antibacterial activities, effectively addressing both oil and microbial fouling. High-viscosity crude oil fouling can be light-induced decontaminated from the composite membrane surface with superior flux recovery ratio (FRR) up to 97 %. The as-prepared UiO/HC@SSM also exhibited near-complete bacterial inactivation activity after 10 min of visible light irradiation. Encouragingly, UiO/HC@SSM demonstrated superior separation and photocatalytic capabilities compared to UiO@SSM, attributed to the dual promoting role of cost-effective hydrothermal carbon in hydrophilicity and photoelectric properties. Moreover, UiO/HC modified SSM membrane displayed robust chemical and mechanical stability, coupled with superior harsh environments and oil pressure resistances. This membrane, boasting desirable wettability, high permeability, exceptional photocatalytic activity, and excellent stability, offers a reliable solution for treating complex oily wastewater. Additionally, the demulsification and photocatalysis mechanisms of UiO/HC@SSM membrane were examined in depth. This study holds significant potential in advancing the development of novel SSM membranes functionalized with MOF/carbon material, thereby enhancing their practical applications in purifying oily wastewater.

Оценка коррозионных свойств вольфрамового покрытия контейнеров для РАО, нанесенного газофазным методом

The article summarizes the study exploring the anti-corrosion characteristics of tungsten coatings produced by chemical gas-phase deposition in a solution simulating the geochemical conditions at the Yeniseiskiy site. The study shows that a 30-micron-thick tungsten-based coating appears to be quite stable with an average corrosion rate of 1.4 microns/year. It also notes the high stability of tungsten coatings under microbial fouling conditions.

Modification of passive film on Ti–6Al–4V alloy induced by Bacillus vietnamensis

The utilization of Ti–6Al–4V alloy in marine infrastructures is somehow limited by susceptibility to biofouling and bacteria attachment, making studies on microbes-induced passive film degradation timely matter. The impact of Bacillus vietnamensis on passive film integrity of Ti–6Al–4V alloy was investigated. Electrochemical measurements and surface analysis revealed that, B. vietnamensis, which adhered preferentially on the α phase, accelerated dissolution of Ti2O3 in the passive film of Ti–6Al–4V alloy. Power-law model (PLM) revealed the changes in resistivity after exposure to B. vietnamensis. After 21 days of incubation, the icorr value in biotic medium (6.50 ± 3.4 nA cm−2) was slightly higher than that in sterile medium (1.89 ± 1.1 nA cm−2), suggesting corrosivity of B. vietnamensis against Ti–6Al–4V alloy. This study established comprehensive understanding of interaction between passive film and marine-corrosive microbial fouling.

The potential role of biofilms in promoting fouling formation in radioactive discharge pipelines

Nuclear facility discharge pipelines accumulate inorganic and microbial fouling and radioactive contamination, however, research investigating the mechanisms that lead to their accumulation is limited. Using the Sellafield discharge pipeline as a model system, this study utilised modified Robbins devices to investigate the potential interplay between inorganic and biological processes in supporting fouling formation and radionuclide uptake. Initial experiments showed polyelectrolytes (present in pipeline effluents), had minimal effects on fouling formation. Biofilms were, however, found to be the key component promoting fouling, leading to increased uptake of inorganic particulates and metal contaminants (Cs, Sr, Co, Eu and Ru) compared to a non-biofilm control system. Biologically-mediated uptake mechanisms were implicated in Co and Ru accumulation, with a potential bioreduced Ru species identified on the biofilm system. This research emphasised the key role of biofilms in promoting fouling in discharge pipelines, advocating for the use of biocide treatments methods.

Effect of free nitrous acid on extracellular polymeric substances production and membrane fouling in a nitritation membrane bioreactor

The membrane bioreactor (MBR) with nitritation based nitrogen removal processes has attracted growing interest in recent years, although membrane fouling in the nitritation MBR is a challenging issue. In this study, the inhibitory effect of free nitrous acid (FNA) on microbial extracellular polymeric substances (EPS) production and membrane fouling in a nitritation MBR was investigated. Results showed that EPS played a critical role in the biofouling process, and EPS production was affected by FNA concentration. As FNA concentration increased from 5.10 × 10−3 mg N/L to 1.34 × 10−2 mg N/L, protein (PN) and polysaccharide (PS) contents increased from 8.20 to 60.28 mg/g VSS and 4.74–30.46 mg/g VSS, respectively. However, when FNA concentration was 1.48 × 10−2 mg N/L, PN and PS reduced by 20.0% and 10.9%, respectively, indicating that the higher FNA concentration could reduce EPS production. The EPS reduction could be attributed to reduction in the loosely bound (LB) and tightly bound (TB) EPS but not the soluble microbial products (SMP). It was further revealed that higher FNA concentrations up to 1.48 × 10−2 mg N/L consequently mitigate trans-membrane pressure (TMP) rate in terms of dTMP/dt by 25.5% in the nitritation MBR. High throughput sequencing analysis revealed that the increase in FNA led to enrichment of Nitrosomonas but reduction in heterotrophic bacteria. This study showed that the appropriate FNA concentration affected EPS production and hence membrane fouling, leading to the possibility of membrane fouling mitigation by in-situ generated FNA in the nitritation MBR.

Surface Treatment of Polymer Membranes for Effective Biofouling Control.

Membrane biofouling is the consequence of the deposition of microorganisms on polymer membrane surfaces. Polymeric membranes have garnered more attention for filtering and purifying water because of their ease of handling, low cost, effortless surface modification, and mechanical, chemical, and thermal properties. The sizes of the pores in the membranes enable micro- and nanofiltration, ultrafiltration, and reverse osmosis. Commonly used polymers for water filter membranes are polyvinyl chloride (PVA), polyvinylidene fluoride (PVDF), polyamide (PA), polyethylene glycol (PEG), polyethersulfone (PES), polyimide (PI), polyacrylonitrile (PAN), polyvinyl alcohol (PA), poly (methacrylic acid) (PMAA), polyaniline nanoparticles (PANI), poly (arylene ether ketone) (PAEK), polyvinylidene fluoride polysulfone (PSF), poly (ether imide) (PEI), etc. However, these polymer membranes are often susceptible to biofouling because of inorganic, organic, and microbial fouling, which deteriorates the membranes and minimizes their lives, and increases operating costs. Biofouling infection on polymer membranes is responsible for many chronic diseases in humans. This contamination cannot be eliminated by periodic pre- or post-treatment processes using biocides and other chemicals. For this reason, it is imperative to modify polymer membranes by surface treatments to enhance their efficiency and longevity. The main objective of this manuscript is to discuss application-oriented approaches to control biofouling on polymer membranes using various surface treatment methods, including nanomaterials and fouling characterizations utilizing advanced microscopy and spectroscopy techniques.

Impact of salinity on anaerobic ceramic membrane bioreactor for textile wastewater treatment: Process performance, membrane fouling and machine learning models

Anaerobic membrane bioreactor (AnMBR) shows great potential for textile wastewater treatment, but high salinity in the influent may undermine its performance. This study evaluated the impact of salinity on the treatment performance of an upflow anaerobic sludge blanket (UASB) configured AnMBR using a flat sheet ceramic membrane. The salinity was stepwise increased (0, 5, 10 and 20 g/L) in four phases of the AnMBR operation. Results indicated that increased salinity jeopardized the COD removal efficiency of AnMBR from 92% to 73%, but had a marginal effect on dye removal efficacy (90–96%). Low salinity (5 g/L) boosted the biogas production whilst high salinity (>10 g/L) had a negative impact. Additionally, the increase of salinity resulted in the soluble microbial production (SMP) concentration soar and membrane fouling rate increase, peaking at a salinity of 10 g/L (Phase III) and recovering back to a lower level at a salinity of 20 g/L (Phase IV). This indicated a transition occurrence at a salinity of 10 g/L (Phase III). The microbial diversity analyses further suggested a transition from salinity-sensitive microbes (Aminiphilus, Caldatribacterium, Mesotoga, Methanobrevibacter, Methanobacterium, Methanosaeta) to salinity-tolerant microbes (Longilinea, Ignavibacterium, Rhodovarius, Bosea and Flexilinea). This transition can be associated with the increase SMP concentration and more severe membrane fouling in Phase III, which were mitigated after a new equilibrium was reached when the microbial consortium acclimatized to the high salinity. Finally, a machine learning model of the Adaboost algorithm was established to predict COD removal under different salinities. Importantly, this study revealed that AnMBR process performance and membrane operation can be maintained for high salinity textile wastewater treatment with a halophilic microbial community growth under high-salinity selection pressure.

Development of a Method for Assessing the Resistance of Building Coatings to Phoatoautotrophic Biofouling

The aim of this study was to develop a method for assessing the growth of photoautotrophs on plaster coatings, which will be used to reliably assess the resistance of these materials to photoautotrophic growth in the simulation of long-term exposure. In the course of the study, mineral and silicone plaster substrates were inoculated with a mixture of Stichococcus bacillaris, Nostoc commune, Pseudochlorella signiensis, and Coenochloris signiensis, and incubated for 28 days in model conditions. At 14 and 28 days after inoculation, the degree of photoautotrophic growth was determined using hemocytometer cell counting, a HY-LiTE 2 ATP measuring system, chlorophyll a concentration quantification, CIE L*a*b spectrophotometric color change evaluation, and visual assessment. The acquired results allowed us to select visual assessment and spectrophotometric color change evaluation as quick-to-perform and reliable techniques for further laboratory studies. The impact of minor changes introduced in the inoculation and incubation procedures on the rate of biofilm formation and severity of microbial fouling was studied. Differences in inoculation and incubation procedures strongly affected the results of the performed tests. Both methods have shown high potential and should be further expanded upon in environmental studies.

Experimental study on the prevention of microbial fouling accumulation on a Ni-Cu-P modified heat exchange surface

Microbial fouling on heat exchange surface is common for large amount of microorganisms in circulating cooling water. In this article, a modified surface technology is used to suppress and reduce the accumulation of microbial fouling on the heat transfer surface. Firstly a Ni-Cu-P modified surface is prepared by electroless plating, and a Ni-P surface applied commonly in industry is also prepared as a comparison. With the help of the designed and constructed experimental system for dynamic monitoring of microbial fouling, the microbial fouling tests of the Ni-Cu-P, Ni- P and carbon steel surface are carried out. The results show that the Ni-Cu-P modified surface has excellent antifouling performance. Compared with carbon steel, the microbial fouling on the Ni-P and Ni-Cu-P modified surface are decreased by 90.6 % and 92.0 % respectively. Further the effects of temperature, flow rate, and initial bacterial concentration on microbial fouling heat resistance of Ni-Cu-P modified surface are investigated and analyzed. With the cooling water inlet temperature increasing (25–40 °C), the fouling heat resistance of the Ni-Cu-P modified surface is increased first and then reduced. With the flow rate increasing (0.2 m/s-0.3 m/s), the fouling heat resistance of Ni-Cu-P modified surface is decreased by 78.3 %. With the initial bacteria concentration in cooling water increasing (8.364 × 109 CFU/mL −51.456 × 109 CFU/mL), the fouling heat resistance is increased by 57.4 % accordingly. By rationally adjusting the operating conditions, such as regulating the temperature of cooling water far away from the suitable temperature of bacteria and increasing the flow rate of circulating cooling water as much as possible, the accumulation of microbial fouling on the Ni-Cu-P modified surface can be further reduced, allowing for long-term cleaning and effective heat transfer of the Ni-Cu-P modified heat exchange surface.

Literature Review on Effect of Sludge Age on Microbial Community Structure in HMBR

The composite membrane biological treatment process has the characteristics of high quality effluent and low membrane pollution, which is widely used in domestic and international water treatment industry. Based on the review of the basic research on membrane fouling mechanism and the comparison of the research results of MBR at home and abroad, from the perspective of microbial ecology, based on the new generation of environmental microbial analysis technology of high-throughput sequencing, this paper expounds the microbial ecological mechanism that sludge age changes the content of microbial metabolites and membrane fouling process by affecting the microbial community structure and physiological characteristics.

Composition of Microbial Fouling on the Surface of Plastics and Steel Exposed in a Pond at a Solid Waste Landfill

Composition of Microbial Fouling on the Surface of Plastics and Steel Exposed in a Pond at a Solid Waste Landfill

Performance and implications of forward osmosis-membrane distillation hybrid system for simultaneous treatment of different real produced water streams

This study investigates the simultaneous treatment of different real produced water streams using forward osmosis-membrane distillation (FO-MD) hybrid system. The water–oil separator outlet (WO) was used simultaneously as FO draw solution (DS) and MD feed solution (FS). The FO process generated stable average fluxes of 13.6 L/m2/h and 15.8 L/m2/h with desalter effluent (DE) and wash water (WW) as FO feed streams, while MD produced 13.2 L/m2/h and 11 L/m2/h, respectively. Monovalent ions induced internal concentration polarization and CaSiO3 colloidal scaling on the support layer reduced the FO flux. Further FO flux reduction was caused by CaSO4 and NaCl crystals on the active layer. Moreover, CaSO4 created partial pore covering while oil and grease depicted pore clogging of the MD membrane, which decreased the MD flux. Volatile fatty acids and organic nano pollutants reached MD permeate and FO FS. Humic acid scaling was fully recovered by ethylenediaminetetraacetic acid by masking calcium ions and reducing the pH. No membrane wetting was observed in the system. No bacteria were found in real streams as analyzed with Epifluorescence microscopy, eliminating the potential of microbial fouling. The hybrid system showed > 93 % removal of oil, inorganics and organics, making the permeate quality excellent for re-injection or industrial reuse. The FS streams were concentrated by 77–84 % resulting in smaller disposal volumes. No utilization of chemicals and water makes this hybrid concept practical and sustainable. The findings of this study can serve as design criteria for future onsite pilot plant applications.

Impact of cathode biofouling in microbial fuel cells and mitigation techniques

The unwanted biofilm development on the surface of the cathode in microbial fuel cell (MFC) may hinder the transfer of protons, thereby limiting the transfer of the protons into the cathodes. Cathode biofouling is one of the major drawback impairing the use of MFC to a larger extent for energy generation. Numerous attempts are been made to overcome this and improve the performance in MFC. Extensive research has been done in recent times to tackle biofouling of cathode and minimize these losses and make this technology practically applicable. This review focuses on the effect of biofouling on the cathode material in MFC. The article deeply provides the basic principles of microbial mediated fouling on cathode and highlights the details of biofouling of cathode in an MFC vis-à-vis research that are been conducted across globe.

Desulfoluna spp. form a cosmopolitan group of anaerobic dehalogenating bacteria widely distributed in marine sponges.

Host-specific microbial communities thrive within sponge tissues and this association between sponge and associated microbiota may be driven by the organohalogen chemistry of the sponge animal. Several sponge species produce diverse organobromine secondary metabolites (e.g. brominated phenolics, indoles, and pyrroles) that may function as a chemical defense against microbial fouling, infection or predation. In this study, anaerobic cultures prepared from marine sponges were amended with 2,6-dibromophenol as the electron acceptor and short chain organic acids as electron donors. We observed reductive dehalogenation from diverse sponge species collected at disparate temperate and tropical waters suggesting that biogenic organohalides appear to enrich for populations of dehalogenating microorganisms in the sponge animal. Further enrichment by successive transfers with 2,6-dibromophenol as the sole electron acceptor demonstrated the presence of dehalogenating bacteria in over 20 sponge species collected from temperate and tropical ecoregions in the Atlantic and Pacific Oceans and the Mediterranean Sea. The enriched dehalogenating strains were closely related to Desulfoluna spongiiphila and Desulfoluna butyratoxydans, suggesting a cosmopolitan association between Desulfoluna spp. and various marine sponges. In vivo reductive dehalogenation in intact sponges was also demonstrated. Organobromide-rich sponges may thus provide a specialized habitat for organohalide-respiring microbes and D. spongiiphila and/or its close relatives are responsible for reductive dehalogenation in geographically widely distributed sponge species.