Biofilm Constituents Research Articles

Advances in understanding biofilm-based marine microbial corrosion

Abstract Microbially influenced corrosion and biofouling emerge as formidable challenges to the sustainable management and exploitation of marine resources. The primary instigator for these challenges lies in the insidious development of biofilm. Hence, the most direct and pivotal approach to counteracting microbial corrosion and biofouling resides in the advancement of anti-biofilm technologies. Conventional methodologies for combatting biofilm are efficient but have certain drawbacks, particularly environmental contamination and inefficacy. Research into innovative anti-biofilm technologies is imperative for more efficient use of marine resources and protection of the ecological equilibrium of the oceans. This paper offers a detailed examination of biofilm constituents, the complex processes involved in biofilm development, the various factors that affect biofilm formation, and the mechanisms underlying microbiologically influenced corrosion (MIC). Furthermore, the article summarizes emerging, eco-friendly anti-biofilm technologies, while providing the evolving landscape of anti-biofilm strategies and promising prospects.

Effects of slightly acidic electrolysed water spraying and ultraviolet C light-emitting diode irradiation combination on the inactivation kinetics of Escherichia coli biofilms on food contact surfaces

In this study, we aimed to quantitatively investigate the effect of ultraviolet C (UVC)-light-emitting diode (LED) irradiation and slightly acidic electrolysed water (SAEW) treatment, alone or in combination, on elimination and inactivation mechanisms and the inactivation kinetics of E. coli O157:H7 biofilms formed on stainless-steel coupons. Although E. coli biofilms were inactivated significantly up to 2.36 log and 3.23 log, respectively, by both SAEW and UVC-LED disinfection treatment alone, a lesser reduction was seen with sprayed SAEW droplet treatment than with UVC-LED irradiation, possibly due to the interactions between extracellular polymeric substances and the constituents of biofilms and the chemical composition of SAEW. The inactivation kinetics of E. coli O157:H7 biofilms were evaluated using mathematical models to fit nonlinear reduction curves (Mean Sum of Squared Error (MSSE): 0.055–0.245; Root-mean-square deviation (RMSE): 0.236–0.495; R2: 0.943–0.985). For disinfection by a combination of spraying SAEW droplets and UVC-LED irradiation, inactivation synergy effect values and synergy ratios were calculated, where synergy effect values and synergy ratios were not time-dependent. The synergistic effect of the combined treatment showed the highest value of 1.2 log10 in the 14-min treatment condition, whereas the synergistic effect value of the 19-min treatment condition, which was the longest treatment time, was 0.9 log10. Our results established that the combination of sprayed SAEW droplets and UVC-LED irradiation could have a more efficient synergistic effect in biofilm reduction on SUS food contact surface materials than sprayed SAEW droplets or UVC-LED treatment alone. Further studies are required to simulate typical commercial conditions to develop reliable combined applications of SAEW and UVC-LEDs for food safety management.

Lysine lactylation regulates metabolic pathways and biofilm formation in Streptococcus mutans.

In eukaryotes, lactate produced during glycolysis is involved in regulating multiple metabolic processes through lysine lactylation (Kla). To explore the potential link between metabolism and Kla in prokaryotes, we investigated the distribution of Kla in the cariogenic bacterium Streptococcus mutans during planktonic growth in low-sugar conditions and in biofilm-promoting, high-sugar conditions. We identified 1869 Kla sites in 469 proteins under these two conditions, with the biofilm growth state showing a greater number of lactylated sites and proteins. Although high sugar increased Kla globally, it reduced lactylation of RNA polymerase subunit α (RpoA) at Lys173. Lactylation at this residue inhibited the synthesis of extracellular polysaccharides, a major constituent of the cariogenic biofilm. The Gcn5-related N-acetyltransferase (GNAT) superfamily enzyme GNAT13 exhibited lysine lactyltransferase activity in cells and lactylated Lys173 in RpoA in vitro. Either GNAT13 overexpression or lactylation of Lys173 in RpoA inhibited biofilm formation. These results provide an overview of the distribution and potential functions of Kla and improve our understanding of the role of lactate in the metabolic regulation of prokaryotes.

DETERMINING THE EFFICACY OF DISCLOSURE DYES TO DEMONSTRATE THE PRESENCE OF BIOFILM ON IMPLANT MATERIAL USING BOTH VISUAL AND FLUORESCENT TECHNIQUES IN VITRO

Prosthetic joint infection (PJI) is an important cause of arthroplasty failure. There is no method to disclose the presence or map the distribution of the in vivo biofilm on infected arthroplasty despite the recognition that such a tool would aid intraoperative decision making and improve novel implant design. The aim of this study was to test the efficacy of four dyes to disclose bacterial biofilm in an in vitro setting.Four dyes with known affinity to bacterial biofilm were assessed to determine their efficacy to disclose biofilms in an in vitro model of PJI. Three dyes (Methylene Blue, Indocyanine Green and Rose Bengal) have established clinical utility and the other, Thioflavin T, is known to fluoresce in the presence of amyloid a known biofilm constituent. The efficacy of the dyes to discriminate between biofilms of different mass and vitality (high, low or the non-inoculated control) was determined after three minutes exposure of the biofilm to the dyes by calculating the amount of dye bound to the biofilm via sonication and spectrophotometry, quantification of the dye through standardised photographic imaging of the stained biofilm and the calculation of inter-observer agreement. Each experiment was performed in triplicate for each dye and repeated three times.For each of the disclosure dyes assessed there was significant difference demonstrated between the amount of dye bound to the high and low mass biofilms (p<0.05) as well as in the amount of dye quantified in photographic and fluorescent image assessment between biofilms of differing mass (p<0.01). There was excellent agreement between three observers, for each disclosure dye, in determining the biofilm mass of each stained disc (Kappa>0.91).This study demonstrates the efficacy of biofilm disclosure dyes in an in vitro PJI model which could one day be used to disclose and map the clinical biofilm in vivo.

Label-free visualization of photosynthetic microbial biofilms using mid-infrared photothermal and autofluorescence imaging.

The formation of photosynthetic microbial biofilms comprising multispecies biomolecules, such as extracellular polymeric substances (EPSs), and microbial cells play pivotal roles in maintaining or stimulating their biological functions. Although there are numerous studies on photosynthetic microbial biofilms, the spatial distribution of EPS components that are vital for microbial biofilm formation, such as exopolysaccharides and proteins, is not well understood. Visualization of photosynthetic microbial biofilms requires label-free methods, because labelling EPSs results in structural changes or aggregation. Raman spectroscopy is useful for label-free visualization of biofilm constituents based on chemical contrast. However, interference resulting from the bright autofluorescence of photosynthetic molecules and the low detection efficiency of Raman scattering make visualization a challenge. Herein, we visualized photosynthetic microbial biofilms in a label-free manner using a super-resolution optical infrared absorption imaging technique, called mid-infrared photothermal (MIP) microscopy. By leveraging the advantages of MIP microscopy, such as its sub-micrometer spatial resolution, autofluorescence-free features, and high detection sensitivity, the distribution of cyanobacteria and their extracellular polysaccharides in the biofilm matrix were successfully visualized. This showed that cyanobacterial cells were aligned along acidic/sulfated polysaccharides in the extracellular environment. Furthermore, spectroscopic analyses elucidated that during formation of biofilms, sulfated polysaccharides initially form linear structures followed by entrapment of cyanobacterial cells. The present study provides the foundation for further studies on the formation, structure, and biological functions of microbial biofilms.

Enhancement of Acinetobacter baumannii biofilm growth by cephem antibiotics via enrichment of protein and extracellular DNA in the biofilm matrices.

AimsThe aims were to determine the effects of subinhibitory concentrations of eight cephem and carbapenem antibiotics on the biofilm formation of Acinetobacter baumannii cells and examine their effects on pre‐established biofilms.Methods and ResultsEffects of antibiotics on biofilm formation were assayed using microtitre plates with polystyrene peg‐lids. Cefmetazole, ceftriaxone, ceftazidime and cefpirome increased the biomass of pre‐established biofilms on pegs in the range of their sub‐minimum inhibitory concentrations (MICs), whereas none increased biofilm formation by planktonic cells. Carbapenems had a negative effect. The constituents of antibiotic‐induced biofilms were analysed. Ceftriaxone or ceftazidime treatment markedly increased the matrix constituent amounts in the biofilms (carbohydrate, 2.7‐fold; protein, 8.9–12.7‐fold; lipid, 3.3–3.6‐fold; DNA, 9.1–12.2‐fold; outer membrane vesicles, 2.7–3.8‐fold and viable cells, 6.8–10.1‐fold). The antibiotic‐enhanced biofilms had increased outer membrane protein A and were resistant to the anti‐biofilm effect of azithromycin.ConclusionsSome cephems increased the biomass of pre‐established biofilms in the ranges of their sub‐MICs. The antibiotic‐enhanced biofilms possessed more virulent characteristics than normal biofilms.Significance and Impact of the StudyIncomplete administration of certain cephems following biofilm‐related Ac. baumannii infections could adversely cause exacerbated and chronic clinical results.

A first assessment of the biocidal efficacy of plant essential oils against lichens on stone cultural heritage, and the importance of evaluating suitable application protocols

Plant essential oils (EOs) are increasingly considered as potential tools to control biodeterioration of stone cultural heritage. The application of EOs was indeed shown to devitalize photo- and hetero-trophic constituents of lithobiontic biofilms, but their effects on lichens, which are other remarkable biodeteriogens of stone surfaces, is still unexplored. In this work, we analyzed the biocidal efficacy of a commercial mixture of essential oils (Syzygium aromaticum, Thymbra capitata, Cinnamomum zeylanicum) against crustose lichen species on stone walls in Persepolis (Iran) and Saluzzo (Italy), in semi-arid and temperate bioclimatic areas, respectively. In the former site (ST1), the efficacy of EOs, quaternary ammonium and isothiazolinone biocides, applied with cellulose poultice, was compared against Acarospora cervina, Calogaya biatorina and Protoparmeliopsis usbekica. In the latter (ST2), the efficacy of different protocols to apply EOs was compared against Candelariella vitellina and Protoparmeliopsis muralis. The devitalization effect was evaluated by measuring chlorophyll a fluorescence parameters of lichen thalli (basal fluorescence, F0, and maximum quantum efficiency, Fv/Fm) and with epifluorescence microscopy. In ST1, EOs poultice application remarkably affected lichen vitality, determining in all the targets a decrease of Fv/Fm values similar or even higher than that observed for the other biocidal products. F0 values and epifluorescence microscopy, however, indicated some persistence of viable cells in A. cervina and P. usbekica. Incomplete hydration and metabolic activation of thalli during EOs application, also related to anatomical traits, may account for such partial resistance of these species of semi-arid areas. In ST2, the zeroing of Fv/Fm and a strong decrease of F0 indicated the devitalization of both the target species when EOs were applied with cellulose poultice, and also when the EOs application by brush (requiring a minor quantity of product) was combined with the immediate covering of the surface with a paper tissue, a second EOs supply and the final covering with a plastic film. Both these application protocols assured a prolonged wet condition of the surface -at least in the humid autumn climate of the temperate ST2-, and thus the metabolic activity of thalli and their susceptibility to the chemicals. The simple EOs application by brush, even if combined with the plastic film covering, was instead ineffective, likely due to the lower product supply and thallus hydration. In conclusion, the biocidal potency of EOs was also confirmed for lichens, although some species-specific resistance may be encountered, as in the case of A. cervina and P. usbekica in ST1. The set up of the application protocol, particularly with respect to the assurance of thallus hydration, was shown as crucial to make the EOs treatments effective and should be taken into particular care when targeting lichens of semi-arid areas and, in general, to plan interventions in favourable, more humid seasons.

Inactivation of biofilm-bound bacterial cells using irradiation across UVC wavelengths

Opportunistic pathogens (OPs), such as Pseudomonas spp., Legionella spp., and mycobacteria, have been detected in biofilms in drinking water distribution systems and water storage tanks and pose potential risks to finished drinking water quality and safety. Emerging UV technologies, such as UV light emitting diodes (LEDs) and krypton chloride (KrCl*) excimers, could provide an alternative to chemical-based secondary disinfection (i.e., chlorine or chloramines) for controlling biofilm-bound OPs. UV systems offer long lifetimes, ability to select wavelength, small size with high power density, and limited-to-no disinfection by-product formation. In this study, inactivation of biofilm-bound Pseudomonas aeruginosa cells across different maturities was investigated using five UVC devices with different peak emission wavelengths, including a KrCl* excimer (222 nm), a low pressure mercury vapor lamp (254 nm), and three UV LEDs (260 nm, 270 nm, and 282 nm). The UV transmittance and absorbance through the biofilm structure was also documented for the first time using a unique approach. Our results show all UVC devices can inactivate biofilm-bound P. aeruginosa cells up to a point, among which the UV LED with peak emission at 270 nm provided the best disinfection performance. UV sensitivities of biofilm-bound cells decreased with biofilm maturity and while initial rates of inactivation were high, no more than 1.5-2.5 log reduction was possible. Re-suspended biofilm bacteria in aqueous solution were highly sensitive to UV, reaching greater than 6 log reduction. UV shielding by biofilm constituents was observed and was likely one of the reasons for UV resistance but did not fully explain the difference in UV sensitivity between biofilm-bound cells versus planktonic cells. This study improves upon fundamental knowledge and provides guidance for innovative designs using emerging UV technologies for biofilm and pathogen control in water distribution systems.

BIOFILM : AN INSIGHT TO ITS DYNAMIC STRUCTURE

Biological wastewater management schemes have a major impact on environmental safety and public health. This paper discusses numerous traditional and contemporary molecular approaches for investigating the structure, diversity, and dynamics of biofilms. The microbial species in the biofilm degrade various nutrients, such as phosphorous and nitrogen-containing chemicals, carbonaceous products, and pathogens embedded in the wastewater. Biofilm development is regarded as an important component of industrial effluent degradation. Once toxins are eliminated, biofilter filtered water is then discharged into the soil or used for irrigation and other recreational purposes. This paper discusses the factors that lead to biofilm heterogeneity. It also sheds light on the technical advances for evaluating Biofilm. Several strategies for developing biofilm in the lab are also explored. A kind of biofilm known as colony biofilm is also being studied, as well as its benefits and drawbacks. Cyanobacteria as a biofilm constituent is focused in this paper.

Fighting Antibiotic-Resistant Bacteria: Promising Strategies Orchestrated by Molecularly Imprinted Polymers.

Infections caused by antibiotic-resistant bacteria are difficult and sometimes impossible to treat, making them one of the major public health problems of our time. We highlight how one unique material, molecularly imprinted polymers (MIPs), can orchestrate several strategies to fight this serious societal issue. MIPs are tailor-made biomimetic supramolecular receptors that recognize and bind target molecules with high affinity and selectivity, comparable to those of antibodies. While research on MIPs for combatting cancer has flourished, comprehensive work on their involvement in combatting resistant superbugs has been rather scarce. This review aims at filling this gap. We will describe the causes of bacterial resistance and at which level MIPs can deploy their weapons. MIPs' targets can be biofilm constituents, quorum sensing messengers, bacterial surface proteins and antibiotic-deactivating enzymes, among others. We will conclude with the current challenges and future developments in this field.

Fighting Antibiotic‐Resistant Bacteria: Promising Strategies Orchestrated by Molecularly Imprinted Polymers

AbstractInfections caused by antibiotic‐resistant bacteria are difficult and sometimes impossible to treat, making them one of the major public health problems of our time. We highlight how one unique material, molecularly imprinted polymers (MIPs), can orchestrate several strategies to fight this serious societal issue. MIPs are tailor‐made biomimetic supramolecular receptors that recognize and bind target molecules with high affinity and selectivity, comparable to those of antibodies. While research on MIPs for combatting cancer has flourished, comprehensive work on their involvement in combatting resistant superbugs has been rather scarce. This review aims at filling this gap. We will describe the causes of bacterial resistance and at which level MIPs can deploy their weapons. MIPs’ targets can be biofilm constituents, quorum sensing messengers, bacterial surface proteins and antibiotic‐deactivating enzymes, among others. We will conclude with the current challenges and future developments in this field.

Micrococcal Nuclease stimulates Staphylococcus aureus Biofilm Formation in a Murine Implant Infection Model.

Advancements in contemporary medicine have led to an increasing life expectancy which has broadened the application of biomaterial implants. As each implant procedure has an innate risk of infection, the number of biomaterial-associated infections keeps rising. Staphylococcus aureus causes 34% of such infections and is known as a potent biofilm producer. By secreting micrococcal nuclease S. aureus is able to escape neutrophil extracellular traps by cleaving their DNA-backbone. Also, micrococcal nuclease potentially limits biofilm growth and adhesion by cleaving extracellular DNA, an important constituent of biofilms. This study aimed to evaluate the impact of micrococcal nuclease on infection persistence and biofilm formation in a murine biomaterial-associated infection-model with polyvinylidene-fluoride mesh implants inoculated with bioluminescent S. aureus or its isogenic micrococcal nuclease deficient mutant. Supported by results based on in-vivo bioluminescence imaging, ex-vivo colony forming unit counts, and histological analysis it was found that production of micrococcal nuclease enables S. aureus bacteria to evade the immune response around an implant resulting in a persistent infection. As a novel finding, histological analysis provided clear indications that the production of micrococcal nuclease stimulates S. aureus to form biofilms, the presence of which extended neutrophil extracellular trap formation up to 13 days after mesh implantation. Since micrococcal nuclease production appeared vital for the persistence of S. aureus biomaterial-associated infection, targeting its production could be a novel strategy in preventing biomaterial-associated infection.

Removal of a Model Biofilm by Sophorolipid Solutions: A QCM-D Study.

Biofilms are communities of microorganisms that have been widely studied because they can cause hospital-acquired infections and skin disorders. Polysaccharides secreted by microorganisms are constituents of biofilms, contributing to their adhesion and mechanical stability. Sophorolipids are biosurfactants with the ability to disrupt and remove biofilms. Biosurfactants have been targeted as potential substitutes for classical petrochemical-based surfactants in cosmetics. In this study, we fabricate a β-glucan film as a model biofilm, and quartz crystal microbalance with dissipation monitoring (QCM-D) measurements are used to assess the biofilm removal. The viscoelasticity of the β-glucan films is monitored while sophorolipid solutions are introduced into the system, and we found that the film removal performance increases with the sophorolipid concentration. In addition, Δf (change in frequency)-ΔD (change in energy dissipation) plot analyses reveal that two processes are involved in the removal mechanism. The first process involves the adsorption of water (hydration) on the β-glucan film. The second process involves the removal of the β-glucan film from the sensor surface. Furthermore, it is suggested that sophorolipids interfere with the hydration of the β-glucan film and suppress increases in its viscosity. This is expected to be an essential factor for the removal of the β-glucan film. Sophorolipids, therefore, show potential for use in cosmetics as an eco-friendly agent for biofilm removal.

A Multiphysics Modeling of Electromagnetic Signaling Phenomena at kHz-GHz Frequencies in Bacterial Biofilms

This paper presents a model that describes a possible mechanism for electromagnetic (EM) signal transmission and reception by bacterial cells within their biofilm communities. Bacterial cells in biofilms are embedded into a complex extracellular matrix containing, among other components, charged helical nanofibrils from amyloid-forming peptides. Based on the current knowledge about the nanoscale structure and dynamics of the amyloids, we explore a hypothetical model that the mechanical vibration of these nanofibrils allows the cells to transmit EM signals to their neighboring cells and the surrounding environment. For the reception, the induced electric field can either exert force on the charges of adjacent nanofibrils associated with the neighboring cells or affect the placement/conformation of a certain charged messenger protein within the cell. The proposed model is based on a coupled system of electrical and mechanical nanoscale structures, which predicts signal transmission and reception within kHz-GHz frequency ranges. Different mechanisms for generating EM signals at various frequency bands related to the structure of the cell and their biofilm constituents are discussed.

Antibiofilm effect of sodium butyrate against Vibrio parahaemolyticus

Vibrio parahaemolyticus (V. parahaemolyticus) is an important foodborne pathogen, which is frequently associated with seafood consumption and commonly causes gastroenteritis. The biofilm formed by V. parahaemolyticus in the food production chain poses a continuous threat to food safety, therefore effective antibiofilm strategy is in urgent need. Sodium butyrate is widely used in food, feed, cosmetics and other industries, and could be used as a flavoring agent in food as well as a dietary supplement for health. This study aims to examine the antibiofilm effect of sodium butyrate against V. parahaemolyticus. We found that sodium butyrate could inhibit biofilm formation at subinhibitory concentrations (SICs). Microscopic images coupled with extracellular polysaccharide quantification showed that V. parahaemolyticus biofilm was loosely structured with fewer biofilm constituents when treated with sodium butyrate. XTT reduction assay illustrated that sodium butyrate interfered with the metabolic activity of cells encased inside biofilm and decreased their viability. Sodium butyrate decreased the motility and surface hydrophobicity of V. parahaemolyticus, and interfered with quorum sensing by using two reporter strains. The RT-qPCR analysis revealed that sodium butyrate down-regulated genes associated with biofilm formation. These findings suggest that sodium butyrate has the potential to be developed as a potent agent against V. parahaemolyticus biofilm in food industries.

Post-translational Modifications in Oral Bacteria and Their Functional Impact

Oral bacteria colonize the oral cavity, surrounding complex and variable environments. Post-translational modifications (PTMs) are an efficient biochemical mechanism across all domains of life. Oral bacteria could depend on PTMs to quickly regulate their metabolic processes in the face of external stimuli. In recent years, thanks to advances in enrichment strategies, the number and variety of PTMs that have been identified and characterized in oral bacteria have increased. PTMs, covalently modified by diverse enzymes, occur in amino acid residues of the target substrate, altering the functions of proteins involved in different biological processes. For example, Ptk1 reciprocally phosphorylates Php1 on tyrosine residues 159 and 161, required for Porphyromonas gingivalis EPS production and community development with the antecedent oral biofilm constituent Streptococcus gordonii, and in turn Php1 dephosphorylates Ptk1 and rapidly causes the conversion of Ptk1 to a state of low tyrosine phosphorylation. Protein acetylation is also widespread in oral bacteria. In the acetylome of Streptococcus mutans, 973 acetylation sites were identified in 445 proteins, accounting for 22.7% of overall proteins involving virulence factors and pathogenic processes. Other PTMs in oral bacteria include serine or threonine glycosylation in Cnm involving intracerebral hemorrhage, arginine citrullination in peptidylarginine deiminases (PADs), leading to inflammation, lysine succinylation in P. gingivalis virulence factors (gingipains, fimbriae, RagB, and PorR), and cysteine glutathionylation in thioredoxin-like protein (Tlp) in response to oxidative stress in S. mutans. Here we review oral bacterial PTMs, focusing on acetylation, phosphorylation, glycosylation, citrullination, succinylation, and glutathionylation, and corresponding modifying enzymes. We describe different PTMs in association with some examples, discussing their potential role and function in oral bacteria physiological processes and regulatory networks. Identification and characterization of PTMs not only contribute to understanding their role in oral bacterial virulence, adaption, and resistance but will open new avenues to treat oral infectious diseases.

Staphylococcus aureus Biofilm: Morphology, Genetics, Pathogenesis and Treatment Strategies.

Staphylococcus aureus is a nosocomial bacterium causing different infectious diseases, ranging from skin and soft tissue infections to more serious and life-threatening infections such as septicaemia. S. aureus forms a complex structure of extracellular polymeric biofilm that provides a fully secured and functional environment for the formation of microcolonies, their sustenance and recolonization of sessile cells after its dispersal. Staphylococcus aureus biofilm protects the cells against hostile conditions, i.e., changes in temperature, limitations or deprivation of nutrients and dehydration, and, more importantly, protects the cells against antibacterial drugs. Drugs are increasingly becoming partially or fully inactive against S. aureus as they are either less penetrable or totally impenetrable due to the presence of biofilms surrounding the bacterial cells. Other factors, such as evasion of innate host immune system, genome plasticity and adaptability through gene evolution and exchange of genetic material, also contribute to the ineffectiveness of antibacterial drugs. This increasing tolerance to antibiotics has contributed to the emergence and rise of antimicrobial resistance (AMR), a serious problem that has resulted in increased morbidity and mortality of human and animal populations globally, in addition to causing huge financial losses to the global economy. The purpose of this review is to highlight different aspects of S. aureus biofilm formation and its overall architecture, individual biofilm constituents, clinical implications and role in pathogenesis and drug resistance. The review also discusses different techniques used in the qualitative and quantitative investigation of S. aureus biofilm and various strategies that can be employed to inhibit and eradicate S. aureus biofilm.

Microalgae biofilm cultured in nutrient-rich water as a tool for the phycoremediation of petroleum-contaminated water

This study aimed at studying the phycoremediation of petroleum-contaminated water using microalgae biofilm cultured in nutrient-rich water. Microalgae biofilm was grown in a photobioreactor containing water rich in calcium nitrate, manganese chloride, sodium potassium tartrate, calcium phosphate, and ammonium sulfate. Petroleum contaminated water was poured into a photobioreactor, and the substrate containing microalgae biofilm was inserted into the photobioreactor and allowed for eight weeks for biofilm formation. Physicochemical parameters (pH, turbidity, conductivity, sulfate, alkalinity, chloride, TDS, TSS, nitrate, salinity, iron, potassium, phosphate, chlorine, chromium, magnesium, zinc, COD, BOD, and total petroleum hydrocarbon (TPH) of the petroleum contaminated water before and after treatment were determined. The microalgae biofilm used for the treatment was characterized before and after treatment using a Scanning Electron Microscope, X-Ray Fluorescence, and Fourier-transform infrared spectroscopy. The phytochemical constituent of the microalgae biofilm was also determined before and after treatment of the petroleum-contaminated water. The result obtained shows highest removal efficiency of physicochemical parameters (turbidity (81%), conductivity (51.2), sulfate (17.5%), alkalinity 28.4%), chloride (14.6%), TDS (7.9), TSS (26%), nitrate (33%), salinity (23.4), iron (16%), potassium (22%), phosphate (28.2%), chlorine (14%), chromium (13.6%), magnesium (30.3%), zinc (40.5%), COD (8%), BOD (16.7%) and total petroleum hydrocarbon (15%)). The microalgae's characterization shows microalgae biofilm's ability to adsorb pollutants in petroleum-contaminated water due to the presence of microspores and larger surface area of the cells of the microalgae forming the biofilm or due to the absorption efficiency of the extracellular polymeric substances (EPS). The analysis of the microalgae biofilm's phytochemical parameters shows the involvement of the chemicals components in pollutants degradation and antioxidant response of the microalgae to counteract the oxidative effect resulting from the exposure of the microalgae to the contaminated water. NOVELTY STATEMENT This is the first study that attempts the phycoremediation of petroleum contaminated water using microalgae biofilm. The reduction efficiency of the parameters treated in this study is very low compared to that reported in the literature but increases with the retention day. This low reduction efficiency is attributed to the slow assimilation of organic and inorganic pollutants due to the initial growth condition. This study is the first to re-affirm that microalgae biofilm can phycoremediate petroleum-contaminated water by adsorption and assimilation due to the presence of microspores and a larger surface area the cells of the microalgae forming the biofilm or the extracellular polymetric surface covering the biofilm. Several studies have reported that phytochemicals present in microalgae play an antioxidant response role to prevent the microalgae from oxidative damage resulting from water pollution. However, this study is the first to strongly link phytochemicals to the enhancement of pollutants degradation and adsorption by microalgae biofilm.

Optimization of The Addition Of Polivinil Alcohol (PVA) as A Plasticizer In Biofilm with Tapioca-Chitosan Flour Material

The addition of a plasticizer, namely polyvinyl alcohol (PVA) as a plasticizer, will increase flexibility and prevent the polymer from cracking. The purpose of this study was to compare the mechanical properties of biofilms from tapioca-chitosan flour with or without the addition of polyvinyl alcohol (PVA) and determine the mass of polyvinyl alcohol (PVA) which can provide optimum mechanical properties of biofilms, test the biodegradability of biofilms and polypropylene plastics and to analyze biofilms using FT-IR. The making of biofilm from 4% tapioca flour and 2% chitosan was carried out by adding variations of polyvinyl alcohol as much as 0, 1, 2, 3, 4 and 5 grams to each tapioca-chitosan flour solution. The effect of adding polyvinyl alcohol (PVA) can be seen from the results of the tensile strength test, the breaking length test, the water resistance test and the biodegradability test. The resulting biofilm functional group analysis was performed by FT-IR. The results showed that the addition of PVA could increase the tensile strength and breaking length, but decreased the water resistance of the biofilm. The optimum mechanical properties of tapioca-chitosan flour biofilm resulted from the addition of 3 grams of PVA with a tensile strength of 2.163 kgf / cm2, the breaking length of 13.64% and 12.46% of absorbed water. Biofilms can be degraded by the fungus Aspergilus niger. The results of biofilm analysis using FTIR indicate the presence of functional groups (CH, NH2, NH, OH, CO and CN) which are the functional groups of the biofilm constituent materials. The optimum mechanical properties of tapioca-chitosan flour biofilm resulted from the addition of 3 grams of PVA with a tensile strength of 2.163 kgf / cm2, the breaking length of 13.64% and 12.46% of absorbed water. Biofilms can be degraded by the fungus Aspergilus niger. The results of biofilm analysis using FT-IR indicate the presence of functional groups (CH, NH2, NH, OH, CO and CN) which are the functional groups of the biofilm constituent materials.

1H-31P home-built solid-state NMR probe with a scroll coil for 400-MHz NB magnet for biological lossy sample

Phosphorus is one of the most important constituents of human biofilms, in particular lipid bilayer packing, phase transition (gel phase, physiological liquid crystal phase, ripple phase, non-biphasic), lipid head group orientation/mechanics, and pure lipid bilayers. Phosphorus observations in biofilms play an important role in the study of the interaction of many types of proteins and biofilms in the human body. The design and construction of a 1H-31P double resonance probe with a scroll coil for solid-state NMR experiment are introduced. For good efficiency at the relatively high frequency, minimal RF sample heating during the experiment with a lossy sample, and a wide range of tuning frequency, this probe adapted the low inductance of a scroll coil. The 31P NMR spectra obtained on the biological lossy sample were used to demonstrate the possibility for monitoring the protein dynamics on biomembrane mimetic system and phase change of phospholipid.