biofilm thickness
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2022 ◽  
Vol 334 ◽  
pp. 08005
Author(s):  
Elisa Casula ◽  
Michele Mascia ◽  
Giorgia De Gioannis ◽  
Mirella Di Lorenzo ◽  
Marco Isipato ◽  
...  

Microbial fuel cells (MFCs) exploit the metabolic activity of electroactive microorganisms for oxidation of organic compounds and extracellular electron transfer to an external electrode. the technology is associate with very slowreaction rates, resulting in low current densities. Anodes with high specific surface should be used to increase the overall electricity generation. Carbon-based 3D materials, with high surface per unit of volume, are largely used anode materials in MFCs, although may show significant lack in efficiency due to mass transfer limitations, concentration gradients, velocity distribution and resistivity of the material. Consequently, the concomitant effect of several parameters should be assessed and quantified to design highly performing MFCs implementing 3D anode materials. In this work, miniature MFCs with 3D anodes are mathematically modelled to quantify the effect of operative parameters on performance. The model combines equations of charge conservation, mass transport phenomena, hydrodynamics, and kinetics of the involved processes under transient conditions, and provides 3D profiles with time of velocity, biofilm thickness, substrate concentration, current density and potential. The solution predicts a laminar flow, as it was expected with the low flow rates used. The concentration profiles show the consumption of substrate in the anode, with low values of local concentrations depending on organic load in the feed stream. The model also provides a versatile tool to optimise the operative conditions of the system, managing the flow arrangements to maximise either substrate removal or electricity generation.


Biosensors ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 18
Author(s):  
Andreas Netsch ◽  
Harald Horn ◽  
Michael Wagner

Biofilms growing on electrodes are the heart piece of bioelectrochemical systems (BES). Moreover, the biofilm morphology is key for the efficient performance of BES and must be monitored and controlled for a stable operation. For the industrial use of BES (i.e., microbial fuel cells for energy production), monitoring of the biofilm accumulation directly on the electrodes during operation is desirable. In this study a commercially available on-line heat transfer biofilm sensor is applied to a graphite-polypropylene (C-PP) pipe and compared to its standard version where the sensor is applied to a stainless-steel pipe. The aim was to investigate the transferability of the sensor to a carbonaceous material (C-PP), that are preferably used as electrode materials for bioelectrochemical systems, thereby enabling biofilm monitoring directly on the electrode surface. The sensor signal was correlated to the gravimetrically determined biofilm thickness in order to identify the sensitivity of the sensor for the detection and quantification of biofilm on both materials. Results confirmed the transferability of the sensor to the C-PP material, despite the sensor sensitivity being decreased by a factor of approx. 5 compared to the default biofilm sensor applied to a stainless-steel pipe.


F1000Research ◽  
2021 ◽  
Vol 10 ◽  
pp. 1093
Author(s):  
Pablo Alejandro Millones Gómez ◽  
Lidia Yileng Tay Chu Jon ◽  
Dora Jesús Maurtua Torres ◽  
Reyma Evelyn Bacilio Amaranto ◽  
Ingrit Elida Collantes Díaz ◽  
...  

Background: Natural products with antibacterial potential have begun to be tested on biofilm models, bringing us closer to understanding the response generated by the complex microbial ecosystems of the oral cavity. The objective of this study was to evaluate the antibacterial, antibiofilm, and cytotoxic activities and chemical compositions of Peruvian propolis in an in vitro biofilm of Streptococcus gordonii and Fusobacterium nucleatum. Methods: The experimental work involved a consecutive, in vitro, longitudinal, and double-blinded study design. Propolis samples were collected from 13 different regions of the Peruvian Andes. The disk diffusion method was used for the antimicrobial susceptibility test. The cytotoxic effect of propolis on human gingival fibroblasts was determined by cell viability method using the MTT (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) assay, and the effect of propolis on the biofilm was evaluated by confocal microscopy and polymerase chain reaction (PCR). Results: The 0.78 mg/mL and 1.563 mg/mL concentrations of the methanolic fraction of the chloroform residue of Oxapampa propolis showed effects on biofilm thickness and the copy numbers of the srtA gene of S. gordonii and the radD gene of F. nucleatum at 48 and 120 hours, and chromatography (UV, λ 280 nm) identified rhamnocitrin, isorhamnetin, apigenin, kaempferol, diosmetin, acacetin, glycerol, and chrysoeriol. Conclusions: Of the 13 propolis evaluated, it was found that only the methanolic fraction of Oxapampa propolis showed antibacterial and antibiofilm effects without causing damage to human gingival fibroblasts. Likewise, when evaluating the chemical composition of this fraction, eight flavonoids were identified.


2021 ◽  
Author(s):  
Zhen Li ◽  
Sufen Dong ◽  
Ashraf Ashour ◽  
Xinyue Wang ◽  
Vijay Kumar Thakur ◽  
...  

Abstract To develop high deterioration resistance concrete for marine infrastructures, two types of nano TiO2 (NT) including anatase phase NT and silica surface-treated rutile phase NT were incorporated into concrete. The fabricated NT modified concrete was then put into the marine environment for 21 months in this study. The effects and mechanisms of two types of NT on the deterioration of concrete in the marine environment were investigated from three aspects, including seawater physical and biological and chemical actions on concrete with NT. Under the seawater physical action, the exposed degree of coarse sand particles on the surface of control concrete is greater than that of concrete with NT. Owing to the microorganism biodegradation property of NT, the elimination and inhibition rates of concrete with NT on microorganisms can reach up to 76.98% and 96.81%, respectively. In addition, the surface biofilm thickness of concrete can be reduced by 49.13% due to the inclusion of NT. In the aspect of seawater chemical action, NT can increase the pH value inside concrete by 0.81, increase the degree of polymerization of C-S-H gel, and improve the interfacial transition zone between cement paste and aggregate in concrete. Compared to concrete with anatase phase NT, silica surface-treated rutile phase NT is more effective in improving the deterioration resistance of concrete in the marine environment. It can be concluded that incorporating NT can inhibit the deterioration of concrete in the marine environment.


2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Tesfalem Atnafu ◽  
Seyoum Leta

Abstract Background The critical MFC design challenge is to increase anode surface area. A novel FAB–MFC integrated system was developed and evaluated for domestic wastewater treatment. It was operated in fed-batch flow mode at 1–3 days of HRT with 755 mg/L CODIN and 0.76 kg-COD/m3/day. The study includes anaerobic-MFC and aerobic-MFC integrated systems. Microbial electrode jacket dish (MEJ-dish) with hybrid dimension (HD) was invented, first time to authors’ knowledge, to boost anode biofilm growth. The treatment system with MEJ+ (FAB) and MEJ− (MFC) anode are called FAB–MFC and MFC, respectively. Results Fragmented variable anode biofilm thickness was observed in FAB than MFC. The FAB–MFC (FAB+) simple technique increases the anode biofilm thickness by ~ 5 times MFC. Due to HD the anode biofilm was fragmented in FAB+ system than MFC. At the end of each treatment cycle, voltage drops. All FAB+ integrated systems reduced voltage drop relative to MFC. FAB reduces voltage drops better than MFC in anaerobic-MFC from 6 to 20 mV and aerobic-MFC from 35–47 mV at 1 kΩ external load. The highest power density was achieved by FAB in anaerobic-MFC (FAB = 104 mW/m2, MFC = 98 mW/m2) and aerobic-MFC integrated system (FAB = 59 mW/m2, MFC = 42 mW/m2). Conclusions The ∆COD and CE between FAB and MFC could not be concluded because both setups were inserted in the same reactor. The integrated system COD removal (78–97%) was higher than the solitary MFC treatment (68–78%). This study findings support the FAB+ integrated system could be applied for real applications and improve performance. However, it might depend on influent COD, the microbial nature, and ∆COD in FAB+ and MFC, which requires further study. Graphic abstract


F1000Research ◽  
2021 ◽  
Vol 10 ◽  
pp. 1093
Author(s):  
Pablo Alejandro Millones Gómez ◽  
Lidia Yileng Tay Chu Jon ◽  
Dora Jesús Maurtua Torres ◽  
Reyma Evelyn Bacilio Amaranto ◽  
Ingrit Elida Collantes Díaz ◽  
...  

Background: Natural products with antibacterial potential have begun to be tested on biofilm models, bringing us closer to understanding the response generated by the complex microbial ecosystems of the oral cavity. The objective of this study was to evaluate the antibacterial, antibiofilm, and cytotoxic activities and chemical compositions of Peruvian propolis in an in vitro biofilm of Streptococcus gordonii and Fusobacterium nucleatum. Methods: The experimental work involved a consecutive, in vitro, longitudinal, and double-blinded study design. Propolis samples were collected from 13 different regions of the Peruvian Andes. The disk diffusion method was used for the antimicrobial susceptibility test. The cytotoxic effect of propolis on human gingival fibroblasts was determined by cell viability method using the MTT (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) assay, and the effect of propolis on the biofilm was evaluated by confocal microscopy and polymerase chain reaction (PCR). Results: The 0.78 mg/mL and 1.563 mg/mL concentrations of the methanolic fraction of the chloroform residue of Oxapampa propolis showed effects on biofilm thickness and the copy numbers of the srtA gene of S. gordonii and the radD gene of F. nucleatum at 48 and 120 hours, and chromatography (UV, λ 280 nm) identified rhamnocitrin, isorhamnetin, apigenin, kaempferol, diosmetin, acacetin, glycerol, and chrysoeriol. Conclusions: Of the 13 propolis evaluated, it was found that only the methanolic fraction of Oxapampa propolis showed antibacterial and antibiofilm effects without causing damage to human gingival fibroblasts. Likewise, when evaluating the chemical composition of this fraction, eight flavonoids were identified.


Life ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1046
Author(s):  
Dorina Strieth ◽  
Andreas Weber ◽  
Johannes Robert ◽  
Judith Stiefelmaier ◽  
Jonas Kollmen ◽  
...  

Phototrophic biofilms, in particular terrestrial cyanobacteria, offer a variety of biotechnologically interesting products such as natural dyes, antibiotics or dietary supplements. However, phototrophic biofilms are difficult to cultivate in submerged bioreactors. A new generation of biofilm photobioreactors imitates the natural habitat resulting in higher productivity. In this work, an aerosol-based photobioreactor is presented that was characterized for the cultivation of phototrophic biofilms. Experiments and simulation of aerosol distribution showed a uniform aerosol supply to biofilms. Compared to previous prototypes, the growth of the terrestrial cyanobacterium Nostoc sp. could be almost tripled. Different surfaces for biofilm growth were investigated regarding hydrophobicity, contact angle, light- and temperature distribution. Further, the results were successfully simulated. Finally, the growth of Nostoc sp. was investigated on different surfaces and the biofilm thickness was measured noninvasively using optical coherence tomography. It could be shown that the cultivation surface had no influence on biomass production, but did affect biofilm thickness.


2021 ◽  
Vol 9 (10) ◽  
pp. 2031
Author(s):  
Muna Aqawi ◽  
Ronit Vogt Sionov ◽  
Ruth Gallily ◽  
Michael Friedman ◽  
Doron Steinberg

Streptococcus mutans is a common cariogenic bacterium in the oral cavity involved in plaque formation. Previous studies showed that Cannabigerol (CBG) has bacteriostatic and bacteriocidic activity against S. mutans. The aim of the present study was to study its effect on S. mutans biofilm formation and dispersion. S. mutans was cultivated in the presence of CBG, and the resulting biofilms were examined by CV staining, MTT assay, qPCR, biofilm tracer, optical profilometry, and SEM. Gene expression was determined by real-time qPCR, extracellular polysaccharide (EPS) production was determined by Congo Red, and reactive oxygen species (ROS) were determined using DCFH-DA. CBG prevented the biofilm formation of S. mutans shown by reduced biofilm biomass, decreased biofilm thickness, less EPS production, reduced DNA content, diminished metabolic activity, and increased ROS levels. CBG altered the biofilm roughness profile, resulting in a smoother biofilm surface. When treating preformed biofilms, CBG reduced the metabolic activity of S. mutans with a transient effect on the biomass. CBG reduced the expression of various genes involved in essential metabolic pathways related to the cariogenic properties of S. mutans biofilms. Our data show that CBG has anti-biofilm activities against S. mutans and might be a potential drug for preventive treatment of dental caries.


Author(s):  
Feroz Shaik ◽  
◽  
Nayeemuddin Mohammed ◽  

An aerobic fluidized biofilm process of treating oil-polluted wastewater has been studied. A series of batch experiments were conducted using synthetic wastewater and the kinetic coefficients were evaluated. The maximum rate of substrate utilization per unit mass microorganisms (K) was 1.6 days-1, the substrate concentration at one-half the maximum growth rate (Ks) was 26 mg/L, the maximum specific growth rate (m) was 1.0 days-1, the ratio of the mass cells formed to the mass of substrate consumed (Y) was 0.61, and the endogenous decay coefficient (Kd ) was 0.044 days-1. The kinetic coefficients obtained were within the range of municipal wastewater. It was observed that up to 1500 mg/L oil (Motor oil SAE–40) could be degraded in a fluidized bed bioreactor (FBBR). The experiments, however, were limited to the oil concentration within a range of 1000-2600 mg/L. Average biofilm thickness () under specific conditions was found to be 22 m and average oil degradation rate of 0.053 mg oil/mg biomass/hour was measured in the FBBR. The results also support that the increase in the concentration of oil in the treatment process reduced significantly the degradation rate of non-oil carbon.


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