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Efficacy of incorporating silver nanoparticles into maxillofacial silicone against Staphylococcus aureus, Candida albicans, and polymicrobial biofilms

Chong WX, Lai YX, Choudhury M, Amalraj FD

J Prosthet Dent, 2022 Nov;128(5):1114-1120.
PMID: 33685653 DOI: 10.1016/j.prosdent.2021.01.010

STATEMENT OF PROBLEM: The presence of biofilms on maxillofacial silicone increases the risk of infections and reduces durability. Whether silver nanoparticles (AgNPs) with potent antimicrobial effects help reduce biofilm formation is unclear.
PURPOSE: The purpose of this in vitro study was to assess the antimicrobial effect of sub 10-nm AgNPs in maxillofacial silicone against Staphylococcus aureus, Candida albicans, and mixed species biofilms containing both and to test the effectiveness of different AgNP concentrations against all 3 biofilms in vitro.
MATERIAL AND METHODS: Silicone disks (M511; Technovent Ltd) containing 0.0% (control), 0.1%, and 0.5% AgNPs were fabricated and treated with S. aureus, C. albicans, and mixed species strains of both in 24-well culture plates containing appropriate media. Each well received a 0.1-mL aliquot of the standardized suspension of microorganisms. The plates were incubated for 21 consecutive days, and colony-forming units per milliliter (CFU/mL) were measured on the first, third, fifth, seventh, fifteenth, and twenty-first day with the Miles and Misra method. Data were analyzed by 2-way ANOVA and the paired t test to evaluate the relationship between AgNP concentration, microbial strain, and time (α=.05). Mean CFU/mL differences for each time and for each biofilm category were assessed by repeated measure ANOVA.
RESULTS: AgNPs decreased the mean CFU/mL in both concentrations compared with the control. The 0.1% concentration showed sustained efficacy throughout the test, while the 0.5% concentration had high efficacy initially with a gradual decrease. However, the results were inconsistent for the mixed biofilm. The paired sample t test at day 3 and 15 and day 3 and 21 showed statistically significantly different results (P

Matched MeSH terms: Biofilms
Microalgal extract as bio-coating to enhance biofilm growth of marine microalgae on microporous membranes

Tong CY, Chua MX, Tan WH, Derek CJC

Chemosphere, 2023 Feb;315:137712.
PMID: 36592830 DOI: 10.1016/j.chemosphere.2022.137712

Microalgal biofilm is a popular platform for algal production, nutrient removal and carbon capture; however, it suffers from significant biofilm exfoliation under shear force exposure. Hence, a biologically-safe coating made up of algal extracellular polymeric substances (EPS) was utilized to secure the biofilm cell retention and cell loading on commercial microporous membrane (polyvinylidene fluoride), making the surfaces more hydrophobic (contact angle increase up to 12°). Results demonstrated that initial cell adhesion of three marine microalgae (Amphora coffeaeformis, Cylindrotheca fusiformis and Navicula incerta) was enhanced by at least 1.3 times higher than that of pristine control within only seven days with minimized biofilm exfoliation issue due to uniform distribution of sticky transparent exopolymer particles. Bounded extracellular polysaccharide gathered was approximately 23% higher on EPS-coated membranes to improve the biofilm's hydraulic resistance, whereas bounded extracellular protein would only be substantially elevated after the attached cells re-accommodate themselves onto the EPS pre-coating of themselves. In accounting the rises of hydrophobic protein content, biofilm was believed to be more stabilized, presumably via hydrophobic interactions. EPS biocoating would generate a groundswell of interest for bioprocess intensifications though there are lots of inherent technical and molecular challenges to be further investigated in future.

Matched MeSH terms: Biofilms
Fulltext Novel cationic cryptides in Penaeus vannamei demonstrate antimicrobial and anti-cancer activities

Abd El-Aal AAA, Jayakumar FA, Lahiri C, Tan KO, Reginald K

Sci Rep, 2023 Sep 06;13(1):14673.
PMID: 37673929 DOI: 10.1038/s41598-023-41581-9

Cryptides are a subfamily of bioactive peptides that exist in all living organisms. They are latently encrypted in their parent sequences and exhibit a wide range of biological activities when decrypted via in vivo or in vitro proteases. Cationic cryptides tend to be drawn to the negatively charged membranes of microbial and cancer cells, causing cell death through various mechanisms. This makes them promising candidates for alternative antimicrobial and anti-cancer therapies, as their mechanism of action is independent of gene mutations. In the current study, we employed an in silico approach to identify novel cationic cryptides with potential antimicrobial and anti-cancer activities in atypical and systematic strategy by reanalysis of a publicly available RNA-seq dataset of Pacific white shrimp (Penaus vannamei) in response to bacterial infection. Out of 12 cryptides identified, five were selected based on their net charges and potential for cell penetration. Following chemical synthesis, the cryptides were assayed in vitro to test for their biological activities. All five cryptides demonstrated a wide range of selective activity against the tested microbial and cancer cells, their anti-biofilm activities against mature biofilms, and their ability to interact with Gram-positive and negative bacterial membranes. Our research provides a framework for a comprehensive analysis of transcriptomes in various organisms to uncover novel bioactive cationic cryptides. This represents a significant step forward in combating the crisis of multi-drug-resistant microbial and cancer cells, as these cryptides neither induce mutations nor are influenced by mutations in the cells they target.

Matched MeSH terms: Biofilms
Fulltext Uncovering the role of algal organic matter biocoating on Navicula incerta cell deposition and biofilm formation

Tong CY, Lim SL, Chua MX, Derek CJC

Bioengineered, 2023 Dec;14(1):2252213.
PMID: 37695682 DOI: 10.1080/21655979.2023.2252213

Spontaneous natural biofilm concentrates microalgal biomass on solid supports. However, the biofilm is frequently susceptible to exfoliation upon nutrient deficiency, particularly found in aged biofilm. Therefore, this study highlights a novel biofilm cultivation technique by pre-depositing the algal organic matters from marine diatom, Navicula incerta onto microporous polyvinylidene fluoride membrane to further strengthen the biofilm developed. Due to the improvement in membrane surface roughness and hydrophobicity, cells adhered most abundantly to soluble extrapolymeric substances-coated (sEPS) (76×106±16×106 cells m-2), followed by bounded EPS-coated (57.67×106±0.33×106 cells m-2), internally organic matter (IOM)-coated (39.00×106±5.19×106 cells m-2), and pristine control the least (6.22×106±0.77×106 cells m-2) at 24th h. Surprisingly, only bEPS-coated membrane demonstrated an increase in cell adhesion toward the end of the experiment at 72 h. The application of the bio-coating has successfully increased the rate of cell attachment by at least 45.3% upon inoculation and achieved as high as 89.9% faster attachment at 72 hours compared to the pristine control group. Soluble polysaccharides and proteins might be carried along by the cells adhering onto membranes hence resulting in a built up of EPS hydrophobicity (>70% in average on bio-coated membranes) over time as compared with pristine (control) that only recorded an average of approximately 50% hydrophobicity. Interestingly, cells grown on bio-coated membranes accumulated more internally bounded polysaccharides, though bio-coating had no discernible impact on the production of both externally and internally bounded protein. The collective findings of this study reveal the physiological alterations of microalgal biofilms cultured on bio-coated membranes.

Matched MeSH terms: Biofilms
Sustainable lignin nanoparticles from coconut fiber waste for enhancing multifunctional properties of macroalgae biofilms

Alfatah T, Abdul Khalil HPS

Int J Biol Macromol, 2024 Feb;258(Pt 2):128858.
PMID: 38128796 DOI: 10.1016/j.ijbiomac.2023.128858

Multifunctional and sustainable packaging biofilms felicitous to changeable conditions are in large demand as substitutes to petroleum-derived synthetic films. Macroalgae with noticeable film-formation, abundant, low-cost, and edible properties is a promising bioresource for sustainable and eco-friendly packaging materials. However, the poor hydrophobicity and mechanical properties of sustainable macroalgae biofilms seriously impede their practical applications. Herein, lignin nanoparticles (LNPs) produced by a sustainable approach from black liquor of coconut fiber waste were incorporated in the macroalgae matrix to improve the water tolerance and mechanical characteristics of the biofilms. The effect of different LNPs loadings on the performance of biofilms, such as physical, morphological, surface roughness, structural, water resistance, mechanical, and thermal behaviors, were systematically evaluated and found to be considerably improved. Biofilm with 6 % LNPs presented the optimum enhancement in most ultimate performances. The optimized biofilm exhibited great hydrophobic features with a water contact angle of over 100° and high enhancement in the tensile strength of >60 %. This study proposes a facile and sustainable approach for designing and developing LNPs-macroalgae biofilms with excellent and multifunctional properties for sustainable high-performance packaging materials.

Matched MeSH terms: Biofilms
Insights into biofilm development on polyhydroxyalkanoate biofilm carrier for anoxic azo dye decolourization of acid orange 7

Chang JY, Syauqi TA, Sudesh K, Ng SL

Bioresour Technol, 2024 Feb;393:130054.
PMID: 37995876 DOI: 10.1016/j.biortech.2023.130054

Polyhydroxyalkanoates (PHAs) are promising alternatives to non-degradable polymers in various applications. This study explored the use of biologically recovered PHA as a biofilm carrier in a moving bed biofilm reactor for acid orange 7 treatment. The PHA was comprised of 86 ± 1 mol% of 3-hydroxybutyrate and 14 ± 1 mol% of 3-hydroxyhexanoate and was melt-fused at 140 °C into pellets. The net positive surface charge of the PHA biocarrier facilitated attachment of negatively charged activated sludge, promoting biofilm formation. A 236-µm mature biofilm developed after 26 days. The high polysaccharides-to-protein ratio (>1) in the biofilm's extracellular polymeric substances indicated a stable biofilm structure. Four main microbial strains in the biofilm were identified as Leclercia adecarboxylata, Leuconostoc citreum, Bacillus cereus, and Rhodotorula mucilaginosa, all of which exhibited decolourization abilities. In conclusion, PHA holds promise as an effective biocarrier for biofilm development, offering a sustainable alternative in wastewater treatment applications.

Matched MeSH terms: Biofilms
Fulltext Evaluation of selected tropical marine microalgal cultures for use in biophotovoltaic platforms

Tay ZH, Ng FL, Thong CH, Lee CW, Gnana Kumar G, Al-Sehemi AG, et al.

Appl Microbiol Biotechnol, 2024 Dec;108(1):1-14.
PMID: 38194143 DOI: 10.1007/s00253-023-12951-0

In this study, the bioelectrical power generation potential of four tropical marine microalgal strains native to Malaysia was investigated using BPV platforms. Chlorella UMACC 258 produced the highest power density (0.108 mW m-2), followed by Halamphora subtropica UMACC 370 (0.090 mW m-2), Synechococcus UMACC 371 (0.065 mW m-2) and Parachlorella UMACC 245 (0.017 mW m-2). The chlorophyll-a (chl-a) content was examined to have a linear positive relationship with the power density (p

Matched MeSH terms: Biofilms
Fulltext Inhibition of pathogenic and spoilage bacteria by a novel biofilm-forming Lactobacillus isolate: a potential host for the expression of heterologous proteins

Jalilsood T, Baradaran A, Song AA, Foo HL, Mustafa S, Saad WZ, et al.

Microb Cell Fact, 2015;14:96.
PMID: 26150120 DOI: 10.1186/s12934-015-0283-8

Bacterial biofilms are a preferred mode of growth for many types of microorganisms in their natural environments. The ability of pathogens to integrate within a biofilm is pivotal to their survival. The possibility of biofilm formation in Lactobacillus communities is also important in various industrial and medical settings. Lactobacilli can eliminate the colonization of different pathogenic microorganisms. Alternatively, new opportunities are now arising with the rapidly expanding potential of lactic acid bacteria biofilms as bio-control agents against food-borne pathogens.

Matched MeSH terms: Biofilms
Effect of biofilm formation on the performance of microbial fuel cell for the treatment of palm oil mill effluent

Baranitharan E, Khan MR, Prasad DM, Teo WF, Tan GY, Jose R

Bioprocess Biosyst Eng, 2015 Jan;38(1):15-24.
PMID: 24981021 DOI: 10.1007/s00449-014-1239-9

Anode biofilm is a crucial component in microbial fuel cells (MFCs) for electrogenesis. Better knowledge about the biofilm development process on electrode surface is believed to improve MFC performance. In this study, double-chamber microbial fuel cell was operated with diluted POME (initial COD = 1,000 mg L(-1)) and polyacrylonitrile carbon felt was used as electrode. The maximum power density, COD removal efficiency and Coulombic efficiency were found as 22 mW m(-2), 70 and 24 %, respectively. FTIR and TGA analysis confirmed the formation of biofilm on the electrode surface during MFC operation. The impact of anode biofilm on anodic polarization resistance was investigated using electrochemical impedance spectroscopy (EIS) and microbial community changes during MFC operation using denaturing gradient gel electrophoresis (DGGE). The EIS-simulated results showed the reduction of charge transfer resistance (R ct) by 16.9 % after 14 days of operation of the cell, which confirms that the development of the microbial biofilm on the anode decreases the R ct and therefore improves power generation. DGGE analysis showed the variation in the biofilm composition during the biofilm growth until it forms an initial stable microbial community, thereafter the change in the diversity would be less. The power density showed was directly dependent on the biofilm development and increased significantly during the initial biofilm development period. Furthermore, DGGE patterns obtained from 7th and 14th day suggest the presence of less diversity and probable functional redundancy within the anodic communities possibly responsible for the stable MFC performance in changing environmental conditions.

Matched MeSH terms: Biofilms*
Green biocides, a promising technology: current and future applications to industry and industrial processes

Ashraf MA, Ullah S, Ahmad I, Qureshi AK, Balkhair KS, Abdur Rehman M

J Sci Food Agric, 2014 Feb;94(3):388-403.
PMID: 23983055 DOI: 10.1002/jsfa.6371

The study of biofilms has skyrocketed in recent years due to increased awareness of the pervasiveness and impact of biofilms. It costs the USA literally billions of dollars every year in energy losses, equipment damage, product contamination and medical infections. But biofilms also offer huge potential for cleaning up hazardous waste sites, filtering municipal and industrial water and wastewater, and forming biobarriers to protect soil and groundwater from contamination. The complexity of biofilm activity and behavior requires research contributions from many disciplines such as biochemistry, engineering, mathematics and microbiology. The aim of this review is to provide a comprehensive analysis of emerging novel antimicrobial techniques, including those using myriad organic and inorganic products as well as genetic engineering techniques, the use of coordination complex molecules, composite materials and antimicrobial peptides and the use of lasers as such or their modified use in combination treatments. This review also addresses advanced and recent modifications, including methodological changes, and biocide efficacy enhancing strategies. This review will provide future planners of biofilm control technologies with a broad understanding and perspective on the use of biocides in the field of green developments for a sustainable future.

Matched MeSH terms: Biofilms*
The perspectives of the application of biofilm in the prevention of chronic infections

Ali Ahmed AB, Taha RM

Adv. Food Nutr. Res., 2011;64:403-16.
PMID: 22054964 DOI: 10.1016/B978-0-12-387669-0.00031-4

Biofilms are a natural part of the ecology of the earth. Many biofilms are quite harmful and must be treated or controlled. Other biofilms are beneficial and can be used to help fix serious problems. Biofilms can grow on many different surfaces, including rocks in water, foods, teeth, and various biomedical implants. This bacterial colonization may present the need for additional operations, amputation, or it may even lead to death. The fundamental principles of bacterial cell attachment and biofilm formation are discussed. Biofilms represents a new, wide-open field practice and research that is only going to get hotter with time. Functional organic plasma polymerized coatings are also discussed for their potential as bio-sensitive interfaces, connecting metallic electronic devices with their physiological environments.

Matched MeSH terms: Biofilms*
Improved method for the isolation of RNA from bacteria refractory to disruption, including S. aureus producing biofilm

Atshan SS, Shamsudin MN, Lung LT, Ling KH, Sekawi Z, Pei CP, et al.

Gene, 2012 Feb 25;494(2):219-24.
PMID: 22222139 DOI: 10.1016/j.gene.2011.12.010

The development of fast, reliable and inexpensive phenol protocol is described for the isolation of RNA from bacterial biofilm producers. The method was tested on Staphylococcus aureus (S. aureus) and other biofilm-producing gram-negative microorganisms and provided the highest integrity of RNA recovery in comparison to other methods reported here. In parallel experiments, bacterial lysis with Qiagen, NucleoSpin RNAII, InnuREP RNA Mini, Trizol and MasterPure RNA extraction Kits using standard protocols consistently gave low RNA yields with an absence of integrity. The boiling method presented here yielded high concentration of RNA that was free from 16S and 23S rRNA, contained 5S RNA. Higher yields due to improved biofilm bacterial cell lysis were achieved with an added hot phenol incubation step without the need for a bead mill or the enzyme. This method when used in conjunction with the Qiagen RNeasy Mini kit, RNA isolation was a success with greater integrity and contained undegraded 16S and 23S rRNA and did not require further purification. Contaminating DNA was a problem with the RNA processing samples; we used quantitative real-time PCR (RT-qPCR) to measure the recovery of RNA from bacterial biofilm cells using the method described here.

Matched MeSH terms: Biofilms*
Modelling on the effect of diffusive and convective substrate transport for biofilm

Khabibor Rahman N, Bakar MZ, Hekarl Uzir M, Harun Kamaruddin A

Math Biosci, 2009 Apr;218(2):130-7.
PMID: 19563738 DOI: 10.1016/j.mbs.2009.01.007

A one-dimensional biofilm model was developed based on the basic principle of conservation of mass. Three simple, generic processes were combined in the model which includes microbial growth, diffusive and convective mass transport. The final model could generate a quantitative description of the relationship between the microbial growth and the consumption of substrate (oxygen) within the fixed biofilm thickness. Mass transfer resistance contributes large influence on the substrates and microbial concentration across the biofilm thickness due to the effect of biofilm structure.

Matched MeSH terms: Biofilms/growth & development*
Influences of metal ions on microcystin-LR degradation capacity and dynamics in microbial distribution of biofilm collected from water treatment plant nearby Kasumigaura Lake

Wang X, Utsumi M, Gao Y, Li Q, Tian X, Shimizu K, et al.

Chemosphere, 2016 Mar;147:230-8.
PMID: 26766360 DOI: 10.1016/j.chemosphere.2015.12.067

Microcystins-LR (MC-LR) which is a kind of potent hepatotoxin for humans and wildlife can be biodegraded by microbial community. In this study, the capacity of biofilm in degrading MC-LR was investigated with and without additional metal ions (Mn(2+), Zn(2+) and Cu(2+)) at the concentration of 1 mg L(-1). The results indicated that the degradation rate of MC-LR by biofilm was inhibited by introduced Mn(2+) and Cu(2+) during the whole culture period. MC-LR cannot be degraded until a period of culture time passed both in the cases with Zn(2+) and Cu(2+) (2 and 8 days for Zn(2+) and Cu(2+), respectively). The results of mlrA gene analysis showed that the abundance of MC-LR degradation bacteria (MCLDB) in the microbial community under Mn(2+) condition was generally lower than that under no additional metal ion condition. Meanwhile, a two days lag phase for the proliferation of MCLDB occurred after introducing Zn(2+). And a dynamic change of MCLDB from Cu(2+) inhibited species to Cu(2+) promoted species was observed under Cu(2+) condition. The maximum ratio of MCLDB to overall bacteria under various conditions during culture process was found to follow the tendency as: Cu(2+) > Zn(2+) ≈ no additional metal ion (Control) > Mn(2+), suggesting the adverse effect of Mn(2+), no obvious effect of Zn(2+) and positive effect of Cu(2+) on the distribution ratio of MCLDB over the biofilm.

Matched MeSH terms: Biofilms*
Engineering S. oneidensis for Performance Improvement of Microbial Fuel Cell-a Mini Review

Leung DHL, Lim YS, Uma K, Pan GT, Lin JH, Chong S, et al.

Appl Biochem Biotechnol, 2021 Apr;193(4):1170-1186.
PMID: 33200267 DOI: 10.1007/s12010-020-03469-6

Microbial fuel cell (MFC) is a promising technology that utilizes exoelectrogens cultivated in the form of biofilm to generate power from various types of sources supplied. A metal-reducing pathway is utilized by these organisms to transfer electrons obtained from the metabolism of substrate from anaerobic respiration extracellularly. A widely established model organism that is capable of extracellular electron transfer (EET) is Shewanella oneidensis. This review highlights the strategies used in the transformation of S. oneidensis and the recent development of MFC in terms of intervention through genetic modifications. S. oneidensis was genetically engineered for several aims including the study on the underlying mechanisms of EET, and the enhancement of power generation and wastewater treating potential when used in an MFC. Through engineering S. oneidensis, genes responsible for EET are identified and strategies on enhancing the EET efficiency are studied. Overexpressing genes related to EET to enhance biofilm formation, mediator biosynthesis, and respiration appears as one of the common approaches.

Matched MeSH terms: Biofilms/growth & development*
Pharmacological importance of TG12 from tachykinin and its toxicological behavior against multidrug-resistant bacteria Klebsiella pneumonia

Raju SV, Sarkar P, Pasupuleti M, Saraswathi NT, Arasu MV, Al-Dhabi NA, et al.

Comp Biochem Physiol C Toxicol Pharmacol, 2021 Jul;245:108974.
PMID: 33465517 DOI: 10.1016/j.cbpc.2021.108974

Development of antimicrobial drugs against multidrug-resistant (MDR) bacteria is a great focus in recent years. TG12, a short peptide molecule used in this study was screened from tachykinin (Tac) protein of an established teleost Channa striatus (Cs) transcriptome. Tachykinin cDNA has 345 coding sequence, that denotes a protein contained 115 amino acids; in which a short peptide (TG12) was identified at 83-94. Tachykinin mRNA upregulated in C. striatus treated with Aeromonas hydrophila and Escherichia coli lipopolysaccharide (LPS). The mRNA up-regulation was studied using real-time PCR. The up-regulation tachykinin mRNA pattern confirmed the immune involvement of tachykinin in C. striatus during infection. Further, the identified peptide, TG12 was synthesized and its toxicity was demonstrated in hemolytic and cytotoxic assays using human erythrocytes and human dermal fibroblast cells, respectively. The toxicity study exhibited that the toxicity of TG12 was similar to negative control, phosphate buffer saline (PBS). Moreover, the antibiogram of TG12 was active against Klebsiella pneumonia ATCC 27736, a major MDR bacterial pathogen. Further, the antimicrobial activity of TG12 against pathogenic bacteria was screened using minimum inhibitory concentration (MIC) and anti-biofilm assays, altogether TG12 showed potential activity against K. pneumonia. Fluorescence assisted cell sorter flow cytometer analysis (FACS) and field emission scanning electron microscopy (FESEM) was carried on TG12 with K. pneumonia; the results showed that TG12 significantly reduced K. pneumonia viability as well as TG12 disrupt its membrane. In conclusion, TG12 of CsTac is potentially involved in the antibacterial immune mechanisms, which has a prospectus efficiency in pharma industry against MDR strains, especially K. pneumonia.

Matched MeSH terms: Biofilms/drug effects*
Enhanced Degradation of Diesel Oil by Using Biofilms Formed by Indigenous Purple Photosynthetic Bacteria from Oil-Contaminated Coasts of Vietnam on Different Carriers

Nhi-Cong LT, Lien DT, Gupta BS, Mai CTN, Ha HP, Nguyet NTM, et al.

Appl Biochem Biotechnol, 2020 May;191(1):313-330.
PMID: 31853877 DOI: 10.1007/s12010-019-03203-x

Oil pollution in marine environment caused by oil spillage has been a main threat to the ecosystem including the ocean life and to the human being. In this research, three indigenous purple photosynthetic strains Rhodopseudomonas sp. DD4, DQ41, and FO2 were isolated from oil-contaminated coastal zones in Vietnam. The cells of these strains were immobilized on different carriers including cinder beads (CB), coconut fiber (CF), and polyurethane foam (PUF) for diesel oil removal from artificial seawater. The mixed biofilm formed by using CB, CF, and PUF as immobilization supports degraded 90, 91, and 95% of diesel oil (DO) with the initial concentration of 17.2 g/L, respectively, after 14 days of incubation. The adsorption of DO on different systems was accountable for the removal of 12-16% hydrocarbons for different carriers. To the best of our knowledge, this is the first report on diesel oil degradation by purple photosynthetic bacterial biofilms on different carriers. Moreover, using carriers attaching purple photosynthetic bacteria to remove diesel oil in large scale is considered as an essential method for the improvement of a cost-effective and efficient bioremediation manner. This study can be a promising approach to eliminate DO from oil-contaminated seawater.

Matched MeSH terms: Biofilms/growth & development*
Fulltext Transcriptomic study of Salmonella enterica subspecies enterica serovar Typhi biofilm

Chin KCJ, Taylor TD, Hebrard M, Anbalagan K, Dashti MG, Phua KK

BMC Genomics, 2017 Oct 31;18(1):836.
PMID: 29089020 DOI: 10.1186/s12864-017-4212-6

BACKGROUND: Typhoid fever is an acute systemic infection of humans caused by Salmonella enterica subspecies enterica serovar Typhi (S. Typhi). In chronic carriers, the bacteria survive the harsh environment of the gallbladder by producing biofilm. The phenotype of S. Typhi biofilm cells is significantly different from the free-swimming planktonic cells, and studies have shown that they are associated with antibiotic resistance, immune system evasion, and bacterial persistence. However, the mechanism of this transition and the events leading to biofilm formation are unknown. High throughput sequencing was performed to identify the genes involved in biofilm formation and to postulate the mechanism of action.
RESULTS: Planktonic S. Typhi cells were cultured using standard nutrient broth whereas biofilm cells were cultured in a stressful environment using high shearing-force and bile to mimic the gallbladder. Sequencing libraries were prepared from S. Typhi planktonic cells and mature biofilm cells using the Illumina HiSeq 2500 platform, and the transcriptome data obtained were processed using Cufflinks bioinformatics suite of programs to investigate differential gene expression between the two phenotypes. A total of 35 up-regulated and 29 down-regulated genes were identified. The identities of the differentially expressed genes were confirmed using NCBI BLAST and their functions were analyzed. The results showed that the genes associated with metabolic processes and biofilm regulations were down-regulated while those associated with the membrane matrix and antibiotic resistance were highly up-regulated.
CONCLUSIONS: It is proposed that the biofilm phenotype of S. Typhi allows the bacteria to increase production of the membrane matrix in order to serve as a physical shield and to adhere to surfaces, and enter an energy conservation state in response to the stressful environment. Conversely, the planktonic phenotype allows the bacteria to produce flagella and increase metabolic activity to enable the bacteria to migrate and form new colonies of infection. This data provide a basis for further studies to uncover the mechanism of biofilm formation in S. Typhi and to discover novel genes or pathways associated with the development of the typhoid carrier state.

Matched MeSH terms: Biofilms/growth & development*
Fulltext Biofilms in Endodontics-Current Status and Future Directions

Neelakantan P, Romero M, Vera J, Daood U, Khan AU, Yan A, et al.

Int J Mol Sci, 2017 Aug 11;18(8).
PMID: 28800075 DOI: 10.3390/ijms18081748

Microbiota are found in highly organized and complex entities, known as biofilms, the characteristics of which are fundamentally different from microbes in planktonic suspensions. Root canal infections are biofilm mediated. The complexity and variability of the root canal system, together with the multi-species nature of biofilms, make disinfection of this system extremely challenging. Microbial persistence appears to be the most important factor for failure of root canal treatment and this could further have an impact on pain and quality of life. Biofilm removal is accomplished by a chemo-mechanical process, using specific instruments and disinfecting chemicals in the form of irrigants and/or intracanal medicaments. Endodontic research has focused on the characterization of root canal biofilms and the clinical methods to disrupt the biofilms in addition to achieving microbial killing. In this narrative review, we discuss the role of microbial biofilms in endodontics and review the literature on the role of root canal disinfectants and disinfectant-activating methods on biofilm removal.

Matched MeSH terms: Biofilms*
Biofilm formation of filamentous fungi Coriolopsis sp. on simple muslin cloth to enhance removal of triphenylmethane dyes

Munck C, Thierry E, Gräßle S, Chen SH, Ting ASY

J Environ Manage, 2018 May 15;214:261-266.
PMID: 29533823 DOI: 10.1016/j.jenvman.2018.03.025

The isolate Coriolopsis sp. (1c3) was cultured on muslin cloth to induce formation of filamentous biofilm. The biofilm and the free-mycelium forms (control) were then used to treat two triphenylmethane dyes; Cotton Blue (CB) and Crystal Violet (CV). The biofilm comprised primarily of a compact mass of mycelium while sparse mycelium network was detected in free-mycelium forms. Results revealed significant decolourization activities by filamentous biofilm of 1c3 for CB (79.6%) and CV (85.1%), compared to free-mycelium forms (72.6 and 58.3%, for CB and CV, respectively). Biodegradation occurred in both biofilm and free-mycelium forms. FTIR spectra revealed that biofilm formation (stacking of mycelium), did not have severe implications to the number and types of functional groups available for dye biosorption. The findings here suggested that formation of biofilm in 1c3 was induced effectively on muslin cloth, leading to enhanced decolourization activities. This technology is simple, feasible and can be adopted and further improved to obtain biofilm to enhance their dye removal efficiency in aqueous solutions.

Matched MeSH terms: Biofilms*

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