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Fulltext Suppression of Xanthomonas oryzae pv. oryzae biofilm formation by Acacia mangium methanol leaf extract

Shafiei SNS, Ahmad K, Ikhsan NFM, Ismail SI, Sijam K

Braz J Biol, 2020 2 20;81(1):11-17.
PMID: 32074168 DOI: 10.1590/1519-6984.206124

Xanthomonas oryzae pv. oryzae (Xoo), a pathogen responsible for rice bacterial leaf blight, produces biofilm to protect viable Xoo cells from antimicrobial agents. A study was conducted to determine the potency of Acacia mangium methanol (AMMH) leaf extract as a Xoo biofilm inhibitor. Four concentrations (3.13, 6.25, 9.38, and 12.5 mg/mL) of AMMH leaf extract were tested for their ability to inhibit Xoo biofilm formation on a 96-well microtiter plate. The results showed that the negative controls had the highest O.D. values from other treatments, indicating the intense formation of biofilm. This was followed by the positive control (Streptomycin sulfate, 0.2 mg/mL) and AMMH leaf extract at concentration 3.13 mg/mL, which showed no significant differences in their O.D. values (1.96 and 1.57, respectively). All other treatments at concentrations of 6.25, 9.38, and 12.5 mg/mL showed no significant differences in their O.D. values (0.91, 0.79, and 0.53, respectively). For inhibition percentages, treatment with concentration 12.5 mg/mL gave the highest result (81.25%) followed by treatment at concentrations 6.25 and 9.38 mg/mL that showed no significant differences in their inhibition percentage (67.75% and 72.23%, respectively). Concentration 3.13 mg/mL resulted in 44.49% of biofilm inhibition and the positive control resulted in 30.75% of biofilm inhibition. Confocal laser scanning microscopy (CLSM) analysis of Xoo biofilm inhibition and breakdown showed the presence of non-viable Xoo cells and changes in aggregation size due to increase in AMMH leaf extract concentration. Control slides showed the absence of Xoo dead cells.

Matched MeSH terms: Biofilms
Effect of aquaculture salinity on nitrification and microbial community in moving bed bioreactors with immobilized microbial granules

Gao Y, Wang X, Li J, Lee CT, Ong PY, Zhang Z, et al.

Bioresour Technol, 2020 Feb;297:122427.
PMID: 31784249 DOI: 10.1016/j.biortech.2019.122427

The novel immobilized microbial granules (IMG) shows a significant effect of nitrification for freshwater aquaculture. However, there is lack of evaluation study on the performance of nitrification at high salinity due to the concentration of recycled water or seawater utilization. A laboratory scale moving bed bioreactor (MBBR) with IMG was tested on recycled synthetic aquaculture wastewater for the nitrification at 2.5 mg/L NH3-N daily. The results indicated that IMG showed a high salinity tolerance and effectively converted ammonia to nitrate up to 92% at high salinity of 35.0 g/L NaCl. As salinity increased from near zero to 35.0 g/L, the microbial activity of nitrite oxidation bacteria (NOB) in the IMG decreased by 86.32%. The microbial community analysis indicated that salinity significantly influenced the community structure. It was found that Nitrosomonas sp. and Nitrospira sp. were the dominant genera for ammonia oxidation bacteria (AOB) and NOB respectively at different salinity levels.

Matched MeSH terms: Biofilms
Properties of a modified quaternary ammonium silane formulation as a potential root canal irrigant in endodontics

Daood U, Parolia A, Matinlinna J, Yiu C, Ahmed HMA, Fawzy A

Dent Mater, 2020 12;36(12):e386-e402.
PMID: 33010944 DOI: 10.1016/j.dental.2020.09.008

OBJECTIVES: Evaluate a new modified quaternary ammonium silane irrigant solution for its antimicrobial, cytotoxic and mechanical properties of dentine substrate.
METHODS: Root canal preparation was performed using stainless steel K-files™ and F4 size protaper with irrigation protocols of 6% NaOCl + 2% CHX; 3.5% QIS; 2% QIS and sterile saline. Biofilms were prepared using E. faecalis adjusted and allowed to grow for 3 days, treated with irrigants, and allowed to grow for 7 days. AFM was performed and surface free energy calculated. MC3T3 cells were infected with endo irrigant treated E. faecalis biofilms. Raman spectroscopy of biofilms were performed after bacterial re-growth on root dentine and exposed to different irrigation protocols and collagen fibers analysed collagen fibers using TEM. Antimicrobial potency against E. faecalis biofilms and cytoxicity against 3T3 NIH cells were also. Resin penetration and MitoTracker green were also evaluated for sealer penetration and mitochondrial viability. Data were analysed using One-way ANOVA, principal component analysis and post-hoc Fisher's least-significant difference.
RESULTS: Elastic moduli were maintained amongst control (5.5 ± 0.9) and 3.5% QIS (4.4 ± 1.1) specimens with surface free energy higher in QIS specimens. MC3T3 cells showed reduced viability in 6%NaOCl+2%CHX specimens compared to QIS specimens. DNA/purine were expressed in increased intensities in control and 6% NaOCl + 2% CHX specimens with bands around 480-490 cm-1 reduced in QIS specimens. 3.5% QIS specimens showed intact collagen fibrillar network and predominantly dead bacterial cells in confocal microscopy. 3.5% QIS irrigant formed a thin crust-type surface layer with cytoplasmic extensions of 3T3NIH spread over root dentine. Experiments confirmed MitoTracker accumulation in 3.5% treated cells.
SIGNIFICANCE: Novel QIS root canal irrigant achieved optimum antimicrobial protection inside the root canals facilitating a toxic effect against the Enterococcus faecalis biofilm. Root dentine substrates exhibited optimum mechanical properties and there was viability of fibroblastic mitochondria.

Matched MeSH terms: Biofilms
Application of isolated halophilic microorganisms suspended and immobilized on walnut shell as biocarrier for treatment of oilfield produced water

Hasanzadeh R, Abbasi Souraki B, Pendashteh A, Khayati G, Ahmadun FR

J Hazard Mater, 2020 12 05;400:123197.
PMID: 32947738 DOI: 10.1016/j.jhazmat.2020.123197

Salinity expressed as total dissolved solids (TDS), is the most challenging parameter in bioremediation of produced water which may inhibit the microbial activities and cause sedimentation problems. The present study explores the feasibility of using walnut shell as an inexpensive and accessible adsorbent-carrier for the immobilization of isolated halophilic microorganisms for treatment of synthetic oilfield produced water. The moving bed biofilm reactor (MBBR) was examined with influent chemical oxygen demand (COD) concentrations from 900 to 3600 mg L-1, TDS concentrations from 35,000-200,000 mg L-1, and cycle times from 24 to 72 h. Comparison of the MBBR with the conventional sequencing batch reactor (SBR) indicated that both systems operated at lower influent COD and TDS concentrations satisfactorily; but at higher TDSs (above 150,000 mg L-1) the MBBR was more resistant to the shocks of toxicity (salinity) and organic load relative to the SBR. Also, the effluent turbidity was lower and the free sludge settling property was more favorable in the MBBR with average sludge volume index (SVI) of 38.8 mL g-1 compared to the SBR with SVI of 98.09 mL g-1. Microbial identification confirmed the presence of eight dominant halophilic species which were hydrocarbon degraders and/or denitrifiers.

Matched MeSH terms: Biofilms
Fulltext Physical, mechanical, chemical and biological properties data of gellan gum incorporating titanium dioxide nanoparticles biofilm

Razali MH, Ismail NA, Amin KAM

Data Brief, 2020 Jun;30:105478.
PMID: 32346560 DOI: 10.1016/j.dib.2020.105478

Gellan gum incorporating titanium dioxide nanoparticles biofilm was synthesized and characterized using UV, FTIR and XRD to study their physical and chemical properties. The mechanical properties were measured using universal mechanical testing. Meanwhile, the biological properties were investigated towards for antibacterial and cell proliferation. This comprehensive data are relevant with the research article entitled "Gellan gum incorporating titanium dioxide nanoparticles biofilm as wound dressing: Physicochemical, mechanical, antibacterial properties and wound healing studies" [1].

Matched MeSH terms: Biofilms
First Report of Environmental Isolation of Exophiala spp. in Malaysia

Jayaram M, Nagao H

Curr Microbiol, 2020 Oct;77(10):2915-2924.
PMID: 32661678 DOI: 10.1007/s00284-020-02109-w

The opportunistic pathogen Exophiala dermatitidis has been frequently isolated from tropical regions of the world. However, there is no report of environmental isolation of Exophiala spp. from Malaysia. The information regarding the ecology of this microbe is important for a better understanding of the opportunism. This study aims to conduct a survey of natural distribution of Exophiala spp. in Malaysia. Forty-seven strains of Exophiala-like was isolated by using selective media. These isolates from the fields were molecularly identified based on the ITS region. The biochemical activity of these microbes was tested by conducting various tests, i.e. DNase test, proteinase activity, and urea hydrolysis. Overall, 22 strains of E. dermatitidis were successfully obtained and identified from burnt tree bark, oil dripped soil sample, hot spring biofilm, railway track stones, tar road contaminated with petrol hydrocarbon, drain and deep mud of Sungai Pinang besides the new discovery from pigeon droppings. A single strain of E. heteromorpha was identified from tar road contaminated with petrol hydrocarbon. Genotypes of the isolated E. dermatitidis were identified by the neighbor-joining tree and grouped into Genotype A, A2 and B. The existence of new Genotype A4 was confirmed by a similar cladogram position in both neighbor-joining and maximum likelihood tree. The survival of E. dermatitidis in the hydrocarbon contaminated environment was studied by supplying engine oil and observing the growth pattern. The results of this study suggest that the opportunistic Exophiala spp. was isolated from nutrient limited and harsh conditions in the natural environment.

Matched MeSH terms: Biofilms
Recent progress in integrated fixed-film activated sludge process for wastewater treatment: A review

Waqas S, Bilad MR, Man Z, Wibisono Y, Jaafar J, Indra Mahlia TM, et al.

J Environ Manage, 2020 Aug 15;268:110718.
PMID: 32510449 DOI: 10.1016/j.jenvman.2020.110718

Integrated fixed-film activated sludge (IFAS) process is considered as one of the leading-edge processes that provides a sustainable solution for wastewater treatment. IFAS was introduced as an advancement of the moving bed biofilm reactor by integrating the attached and the suspended growth systems. IFAS offers advantages over the conventional activated sludge process such as reduced footprint, enhanced nutrient removal, complete nitrification, longer solids retention time and better removal of anthropogenic composites. IFAS has been recognized as an attractive option as stated from the results of many pilot and full scales studies. Generally, IFAS achieves >90% removals for combined chemical oxygen demand and ammonia, improves sludge settling properties and enhances operational stability. Recently developed IFAS reactors incorporate frameworks for either methane production, energy generation through algae, or microbial fuel cells. This review details the recent development in IFAS with the focus on the pilot and full-scale applications. The microbial community analyses of IFAS biofilm and floc are underlined along with the special emphasis on organics and nitrogen removals, as well as the future research perspectives.

Matched MeSH terms: Biofilms
Fulltext Anti-biofilm potential and mode of action of Malaysian plant species: a review

Nur Anisah Johari, Siti Sarah Diyana Amran, Alya Nur Athirah Kamaruzzaman, Che Amira Izzati Che Man, Mohd Fakharul Zaman Raja Yahya

Science Letters, 2020;14(2):34-46.
MyJurnal

Biofilm is a microbial community that attaches to a surface and is enclosed in extracellular polymeric substance (EPS) matrix. Formation of biofilm often develops resistance towards a wide spectrum of antimicrobial agents. Since the biofilm-mediated diseases are commonly difficult to treat, there is need to find new anti-biofilm agent. The studies on anti-biofilm activities of plant species have received a great deal of attention over the last few decades. In Malaysia, plant species have been used as alternatives to the conventional antimicrobial therapy. Several Malaysian plant species are known to control biofilm infection by inhibition of quorum sensing pathway, disruption of EPS matrix, alteration of cell permeability and reduction in cell surface hydrophobicity. This review demonstrates that Malaysian plant species may become excellent therapeutic agents in combating the biofilm infection.

Matched MeSH terms: Biofilms
Fulltext Assessing biofilm formation by Listeria monocytogenes

Fouladynezhad, N., Afsah-Hejri, L., Rukayadi, Y., Abdulkarim, S.M., Son, R., Marian, M.N.

International Food Research Journal, 2013;20(2):987-990.
MyJurnal

Listeria monocytogenes (L. monocytogenes) is a serious food-borne pathogen for immunocompromised individuals. L. monocytogenes is capable of producing biofilm on the surface of food processing lines and instruments. The biofilm transfers contamination to food products and impose risk to public health. Transfers contamination to food products, and impose risk hazard to public health. The aim of this study was to investigate biofilm producing ability of L. monocytogenes isolates. Microtitre assay was used to measure the amount of biofilm production by ten L. monocytogenes isolates from minced chicken / meat, sausages and burgers. Results showed that all 10 L. monocytogenes isolates were able to form biofilm after 24 h at 20˚C on polystyrene surface (the common surface in food industries). Some strains were capable of forming biofilm more than the others. All strains showed a slight raise in the quantities of attached cells over 48 and 72 h. L. monocytogenes strains isolated from minced chicken, minced meat and burgers were better biofilm-producers comparing to the strains isolated from sausages.

Matched MeSH terms: Biofilms
Fulltext Natural Therapeutic Options in Endodontics - A Review

Venkateshbabu N, Anand S, Abarajithan M, Sheriff SO, Jacob PS, Sonia N

Open Dent J, 2016;10:214-26.
PMID: 27386007 DOI: 10.2174/1874210601610010214

Complete eradication of microbial biofilms and elimination of the smear layer are the key factors during endodontic treatment. Various chemical irrigants have been proposed in the literature for the same. The major setback with these chemical irrigants is that they are not bio-friendly to the dental and peri-radicular tissues. In the recent years, research to use natural products for root canal disinfection has gained importance. The aim of this article is to compile various herbal products that have been used as an irrigants and intracanal medicaments in the field of Endodontics to eradicate the biofilm and remove smear layer.

Matched MeSH terms: Biofilms
Microbiome involved in microbial electrochemical systems (MESs): A review

Saratale RG, Saratale GD, Pugazhendhi A, Zhen G, Kumar G, Kadier A, et al.

Chemosphere, 2017 Mar 09;177:176-188.
PMID: 28288426 DOI: 10.1016/j.chemosphere.2017.02.143

Microbial electrochemical systems (MESs) are an attracting technology for the disposal of wastewater treatment and simultaneous energy production. In MESs, at the anode microorganisms through the catalytic activity generates electrons that can be converted into electricity or other valuable chemical compounds. Microorganisms those having ability to donate and accept electrons to and from anode and cathode electrodes, respectively are recognized as 'exoelectrogens'. In the MESs, it renders an important function for its performance. In the present mini-review, we have discussed the role of microbiome including pure culture, enriched culture and mixed culture in different BESs application. The effects of operational and biological factors on microbiome development have been discussed. Further discussion about the molecular techniques for the evaluation of microbial community analysis is addressed. In addition different electrochemical techniques for extracellular electron transfer (EET) mechanism of electroactive biofilms have been discussed. This review highlights the importance of microbiome in the development of MESs, effective operational factors for exo-electrogens activities as well their key challenges and future technological aspects are also briefly discussed.

Matched MeSH terms: Biofilms
Fulltext Antimicrorobial evaluation of sodium hypochlorite and ozonated water on E. faecalis biofilm

Ibrahim, N.Z., Abdullah, M.

Ann Dent, 2008;15(1):20-26.
MyJurnal

This study aim to evaluate antimicrobial efficacy of sodium hypochlorite (NaOCl) and ozonated water against Enterococci faecalis biofilm. The bacterial biofilm was exposed to 2.62%, 1.31% NaOCl and 0.1 ppm ozonated water over a range of time periods. The presence of viable cells was determined by enumeration of colony forming units (CFU). All experiments were repeated four times (n=4). The effectiveness of the agents was compared using nonparametric Kruskal- Wallis test. The result revealed that 2.62% of NaOCl can completely kill E. faecalis biofilm in 15 minutes whereas 1.31 % NaOCl required a longer time to produce such effect. 0.1 ppm ozonated, however, did not exhibit any antimicrobial effect within the period of time tested. From this study, it can be concluded that 0.1 ppm ozonated water was not comparable with 2.62% and 1.31% NaOCl in antimicrobial efficacy against E. faecalis biofilm.

Matched MeSH terms: Biofilms
Fulltext Biofilm forming ability and time course study of growth of Salmonella Typhi on fresh produce surfaces

Tang, P.L., Pui, C.F., Wong, W.C., Noorlis, A., Son, R.

International Food Research Journal, 2012;19(1):71-76.
MyJurnal

This study aimed to determine the biofilm formation ability by Salmonella Typhi on cucumber, mango and guava surface, as well as to determine the relationship between time contact and biofilm formation. Crystal violet assay was performed to quantify the biofilm formation based on the value of optical density at 570 nm of the destaining crystal violet at the specific interval time. The result showed that the attachment of the bacterial cells on the fresh produce surface increased with the contact time. The readings of OD570at time 12 h for cucumber, mango and guava surfaces were 0.824, 0.683 and 0.598, respectively, indicating that the biofilm formation by Salmonella Typhi on different fresh produce surface varied with time. Since the result showed that Salmonella Typhi formed biofilm on fresh produce surfaces, hygienic practice from farm to fork including handling, processing, distribution and storage of the fresh produce should be of concern.

Matched MeSH terms: Biofilms
Fulltext Cloning and Characterization of the Autoinducer Synthase Gene from Lipid-Degrading Bacterium Cedecea neteri

Tan KH, How KY, Tan JY, Yin WF, Chan KG

Front Microbiol, 2017;8:72.
PMID: 28197135 DOI: 10.3389/fmicb.2017.00072

The process of intercellular communication among bacteria, termed quorum sensing (QS), is mediated by small diffusible molecules known as the autoinducers. QS allows the population to react to the change of cell density in unison, in processes such as biofilm formation, plasmid conjugation, virulence, motility and root nodulation. In Gram-negative proteobacteria, N-acyl homoserine lactone (AHL) is the common "language" to coordinate gene expression. This signaling molecule is usually synthesized by LuxI-type proteins. We have previously discovered that a rare bacterium, Cedecea neteri, exhibits AHL-type QS activity. With information generated from genome sequencing, we have identified the luxIR gene pair responsible for AHL-type QS and named it cneIR. In this study, we have cloned and expressed the 636 bp luxI homolog in an Escherichia coli host for further characterization. Our findings show that E. coli harboring cneI produced the same AHL profile as the wild type C. neteri, with the synthesis of AHL known as N-butyryl-homoserine lactone. This 25 kDa LuxI homolog shares high similarity with other AHL synthases from closely related species. This work is the first documentation of molecular cloning and characterization of luxI homolog from C. neteri.

Matched MeSH terms: Biofilms
Fulltext Application of Zwitterions in Forward Osmosis: A Short Review

Chiao YH, Sengupta A, Ang MBMY, Chen ST, Haan TY, Almodovar J, et al.

Polymers (Basel), 2021 Feb 15;13(4).
PMID: 33672026 DOI: 10.3390/polym13040583

Forward osmosis (FO) is an important desalination method to produce potable water. It was also used to treat different wastewater streams, including industrial as well as municipal wastewater. Though FO is environmentally benign, energy intensive, and highly efficient; it still suffers from four types of fouling namely: organic fouling, inorganic scaling, biofouling and colloidal fouling or a combination of these types of fouling. Membrane fouling may require simple shear force and physical cleaning for sufficient recovery of membrane performance. Severe fouling may need chemical cleaning, especially when a slimy biofilm or severe microbial colony is formed. Modification of FO membrane through introducing zwitterionic moieties on the membrane surface has been proven to enhance antifouling property. In addition, it could also significantly improve the separation efficiency and longevity of the membrane. Zwitterion moieties can also incorporate in draw solution as electrolytes in FO process. It could be in a form of a monomer or a polymer. Hence, this review comprehensively discussed several methods of inclusion of zwitterionic moieties in FO membrane. These methods include atom transfer radical polymerization (ATRP); second interfacial polymerization (SIP); coating and in situ formation. Furthermore, an attempt was made to understand the mechanism of improvement in FO performance by zwitterionic moieties. Finally, the future prospective of the application of zwitterions in FO has been discussed.

Matched MeSH terms: Biofilms
In situ functionalizing calcium phosphate biomaterials with curcumin for the prevention of bacterial biofilm infections

Lee WH, Rohanizadeh R, Loo CY

Colloids Surf B Biointerfaces, 2021 Oct;206:111938.
PMID: 34198233 DOI: 10.1016/j.colsurfb.2021.111938

This study developed a novel bioactive bone substitute (hydroxyapatite, HA) with improved anti-biofilm activity by functionalizing with curcumin (anti-biofilm compound) which provide sufficient flux of curcumin concentration for 14 days. The released curcumin acts to inhibit biofilm formation and control the number of viable planktonic cells simultaneously. To prepare curcumin-functionalized HA, different concentrations of curcumin (up to 3% w/v) were added simultaneously during the precipitation process of HA. The highest loading (50 mg/g HA) of curcumin onto HA was achieved with 2% w/v of curcumin. Physicochemical characterizations of curcumin-functionalized HA composites revealed that curcumin was successfully incorporated onto HA. Curcumin was sustainably released over 14 days, while higher curcumin release was observed in acidic condition (pH 4.4) compared to physiological (pH 7.4). The cytotoxicity assays revealed that no significant difference on bone cells growth on curcumin-functionalized HA and non-functionalized HA. Curcumin-functionalized HA was effective to inhibit bacterial cell attachment and subsequent biofilm maturation stages. The anti-biofilm effect was stronger against Staphylococcus aureus compared to Pseudomonas aeruginosa. The curcumin-functionalized HA composite significantly delayed the maturation of S. aureus compared to non-functionalized HA in which microcolonies of cells only begin to appear at 96 h. Up to 3.0 log reduction in colony forming unit (CFU)/mL of planktonic cells was noted at 24 h of incubation for both microorganisms. Thus, in this study we have suggested that curcumin loaded HA could be an alternative antimicrobial agent to control the risk of infections in post-surgical implants.

Matched MeSH terms: Biofilms
Fulltext Advances in pulmonary drug delivery targeting microbial biofilms in respiratory diseases

Sharma A, Kumar D, Dahiya K, Hawthorne S, Jha SK, Jha NK, et al.

Nanomedicine (Lond), 2021 09;16(21):1905-1923.
PMID: 34348474 DOI: 10.2217/nnm-2021-0057

The increasing burden of respiratory diseases caused by microbial infections poses an immense threat to global health. This review focuses on the various types of biofilms that affect the respiratory system and cause pulmonary infections, specifically bacterial biofilms. The article also sheds light on the current strategies employed for the treatment of such pulmonary infection-causing biofilms. The potential of nanocarriers as an effective treatment modality for pulmonary infections is discussed, along with the challenges faced during treatment and the measures that may be implemented to overcome these. Understanding the primary approaches of treatment against biofilm infection and applications of drug-delivery systems that employ nanoparticle-based approaches in the disruption of biofilms are of utmost interest which may guide scientists to explore the vistas of biofilm research while determining suitable treatment modalities for pulmonary respiratory infections.

Matched MeSH terms: Biofilms
Fulltext Biofilm formation following chitosan-based varnish or chlorhexidine-fluoride varnish application in patients undergoing fixed orthodontic treatment: a double blinded randomised controlled trial

Poornima P, Krithikadatta J, Ponraj RR, Velmurugan N, Kishen A

BMC Oral Health, 2021 09 23;21(1):465.
PMID: 34556107 DOI: 10.1186/s12903-021-01805-8

BACKGROUND: Orthodontic treatment poses an increased risk of plaque accumulation and demineralisation of enamel leading to white spot lesion around the brackets. This parallel arm trial aims to assess the degree of bacterial plaque formation adjacent to orthodontic brackets, following the application of a chitosan-based varnish or chlorhexidene-fluoride varnish.
METHODS: A total of 200 teeth from 20 patients undergoing fixed orthodontic therapy were assessed and biofilm formation around the brackets were recorded using the Bonded Bracket Index (Plaque index) at baseline and weekly for 6 weeks. The bacterial count and plaque pH at corresponding weekly intervals were also recorded. Following bracket bonding, the patients were cluster randomised to receive chitosan-based varnish-CHS (UNO Gel Bioschell, Germiphene corp., Brantford, Canada) or chlorhexidine-fluoride varnish-CFV (Cervitec F, Ivoclar Vivadent, Schaan, Liechtenstein) every week on the representative teeth respectively. BBI proportions were compared between groups at all time intervals using Chi square test. Mean plaque bacterial count and plaque pH were compared using Mann Whitney U test and Tukey's HSD test respectively.
RESULTS: Baseline characteristics were similar between the groups: Mean age was CHS = 23 and CFV = 21; male to female ratio was CHS = 5/5, CFV = 7/3. At the end of 6 weeks, chitosan-based varnish performed equal to chlorhexidine-fluoride varnish (P > 0.05) with 98% and 95% of teeth with acceptable scores respectively. The plaque bacterial count significantly reduced at 6 weeks for both varnish compared to the baseline; The value for CHS was 0.43 ± 0.4 × 104 and CFV was 0.77 ± 0.64 × 104 CFU (P

Matched MeSH terms: Biofilms
Fulltext Characterisation of Bacterial Isolates from Infected Post-Operative Patients in a Malaysian Tertiary Heart Care Centre

Yong YK, Wen NCM, Yeo GEC, Chew ZX, Chan LL, Md Zain NZ, et al.

Int J Environ Res Public Health, 2021 09 17;18(18).
PMID: 34574752 DOI: 10.3390/ijerph18189828

Several bacterial species cause post-operative infections, which has been a critical health concern among hospital patients. Our study in this direction is a much-needed exploratory study that was carried out at the National Heart Institute (IJN) of Malaysia to examine the virulence properties of causative bacteria obtained from postoperative patients. The bacterial isolates and data were provided by the IJN. Antibiotic resistance gene patterns, and the ability to form biofilm were investigated for 127 isolates. Klebsiella pneumoniae (36.2%) was the most common isolate collected, which was followed by Pseudomonas aeruginosa (26%), Staphylococcus aureus (23.6%), Streptococcus spp. (8.7%) and Acinetobacter baumannii (5.5%). There were 49 isolates that showed the presence of multidrug resistance genes. The mecA gene was surprisingly found in methicillin-susceptible S. aureus (MSSA), which also carried the ermA gene from those erythromycin-susceptible strains. The phenotypic antibiotic resistance profiles varied greatly between isolates. Findings from the biofilm assay revealed that 44 of the 127 isolates demonstrated the ability to produce biofilms. Our findings provide insights into the possibility of some of these bacteria surviving under antibiotic stress, and some antibiotic resistance genes being silenced.

Matched MeSH terms: Biofilms
Fulltext Elucidation of Gram-Positive Bacterial Iron(III) Reduction for Kaolinite Clay Refinement

Jing H, Liu Z, Kuan SH, Chieng S, Ho CL

Molecules, 2021 May 21;26(11).
PMID: 34064160 DOI: 10.3390/molecules26113084

Recently, microbial-based iron reduction has been considered as a viable alternative to typical chemical-based treatments. The iron reduction is an important process in kaolin refining, where iron-bearing impurities in kaolin clay affects the whiteness, refractory properties, and its commercial value. In recent years, Gram-negative bacteria has been in the center stage of iron reduction research, whereas little is known about the potential use of Gram-positive bacteria to refine kaolin clay. In this study, we investigated the ferric reducing capabilities of five microbes by manipulating the microbial growth conditions. Out of the five, we discovered that Bacillus cereus and Staphylococcus aureus outperformed the other microbes under nitrogen-rich media. Through the biochemical changes and the microbial behavior, we mapped the hypothetical pathway leading to the iron reduction cellular properties, and found that the iron reduction properties of these Gram-positive bacteria rely heavily on the media composition. The media composition results in increased basification of the media that is a prerequisite for the cellular reduction of ferric ions. Further, these changes impact the formation of biofilm, suggesting that the cellular interaction for the iron(III)oxide reduction is not solely reliant on the formation of biofilms. This article reveals the potential development of Gram-positive microbes in facilitating the microbial-based removal of metal contaminants from clays or ores. Further studies to elucidate the corresponding pathways would be crucial for the further development of the field.

Matched MeSH terms: Biofilms

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