Diversity and frequency of yeasts from the dorsum of the tongue and necrotic root canals associated with primary apical periodontitis

Expression of Toll-like receptor 2, Dectin-1, and Osteopontin in murine model of pulpitis

OBJECTIVES

This in vivo animal study aimed to develop a murine model of pulpitis induced by pulp exposure with or without application of zymosan in Naval Medical Research Institute (NMRI) mice and observe expressions of Toll-like receptor (TLR)-2, TLR-4, Dectin-1, Osteopontin (OPN), tumor necrosis factor alpha (TNF-α), interleukin (IL)-6, and IL-1ß.

MATERIAL AND METHODS

A total of 168 NMRI mice were divided into two groups, i.e., group A (n = 84) (pulpitis induced by pulp exposure only) and group B (n = 84) (pulpitis induced by pulp exposure and zymosan application). Right maxillary molar pulps were exposed with ¼ round bur, and animals were sacrificed at 0, 6, 9, 12, 24, 48, and 72 h. The exposed teeth were obtained for real-time polymerase chain reaction (qRT-PCR) analysis and histological and immunohistochemistry (IHC) analysis.

RESULTS

Histological evaluation revealed a time-dependent steady increase in inflammation. Similar time-dependent increase in the expression of inflammatory cytokines was noted. Group A exhibited an increase in TLR-4, Dectin-1, and OPN at 6 h, while TLR-2 was expressed at 24 h. Group B expressed TLR-2, Dectin-1, and OPN at 9, 48, and 72 h, respectively (p ≤ 0.05). Expression of OPN and TNF-α exhibited a similar pattern in both groups. IHC also detected expression of TLR-2, Dectin-1, TLR4, and CD68 in some cells at 6 and 9 h.

CONCLUSIONS

NMRI mice provided for a stable pulp inflammation model. Zymosan may be used to develop pulp inflammation model and study inflammatory response towards fungal antigens. Dental pulp expressed Dectin-1 receptor. OPN and TNF-α exhibited a similar expression pattern.

CLINICAL RELEVANCE

Innate immunity of dental pulp is capable of detecting fungal pathogens.

Present status and future directions - microbiology of endodontic infections

Apical periodontitis has a microbial aetiology and is one of the most common inflammatory diseases that affect humans. Fungi, archaea and viruses have been found in association with apical periodontitis, but bacteria are by far the most prevalent and dominant microorganisms in endodontic infections. Bacterial infection of the root canal system only occurs when the pulp is necrotic or was removed for previous treatment. In some specific cases, including acute and chronic abscesses, the bacterial infection may reach the periradicular tissues. Intracanal bacteria are usually observed as sessile multispecies communities (biofilms) attached to the dentinal root canal walls. Infection in the main root canal lumen can spread to other areas of the root canal system. Although more than 500 bacterial species have been detected in endodontic infections, a selected group of 20 to 30 species are most frequently detected and may be considered as the core microbiome. There is a high interindividual variability in the endodontic microbiome in terms of species composition and relative abundance. Obligate anaerobic species are more abundant in the intraradicular bacterial communities of teeth with primary apical periodontitis, while both anaerobes and facultatives dominate the communities in post-treatment apical periodontitis. Bacterial interactions play an essential role in determining the overall virulence of the community, which has been regarded as the unit of pathogenicity of apical periodontitis. This article reviews the microbiologic aspects of endodontic infections and provides perspectives for future research and directions in the field.

Prevalence of Fungi in Primary Endodontic Infections of a Greek-living Population Through Real-time Polymerase Chain Reaction and Matrix-assisted Laser Desorption/Ionization Time-of-flight Mass Spectrometry

INTRODUCTION

Fungi are considered to be opportunistic pathogens that may play a significant role in the pathogenesis of endodontic infections. The main purpose of this study was to assess the prevalence of 2 selected genera of fungi, Candida albicans and Aspergillus spp., using real-time polymerase chain reaction (RT-PCR) and to compare the findings with the respective ones obtained by a culture-dependent approach, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-ToF MS). A secondary aim was to assess the presence of other bacteria growing under aerobic conditions.

METHODS

Microbial samples were obtained from the root canals of 60 teeth associated with pulp necrosis and apical periodontitis. DNA was extracted, and RT-PCR was applied for the detection of C. albicans and Aspergillus spp. pathogenic subtypes. In addition, MALDI-ToF MS was performed to identify microorganisms grown under aerobic conditions.

RESULTS

Based on RT-PCR, Aspergillus was detected in 8 cases, whereas C. albicans was detected in 4 cases. Using MALDI-ToF MS, no trace of Aspergillus was detected, whereas C. albicans was identified in 2 cases. Significant differences were revealed in the detection potential for Aspergillus spp. between MALDI-ToF MS and RT-PCR (P = .01); conversely, this was not the case for C. albicans (P = .50). After MALDI-ToF MS, 35 samples showed evidence of bacterial growth. The vast majority was colonized by Achromobacter xylosoxidans followed by Lactobacillus spp., Methylobacterium spp., and Enterococcus faecalis.

CONCLUSIONS

The findings confirm the presence of fungi in primarily infected canals with apical periodontitis as well as some rarely inspected aerobic bacterial species. A. xylosoxidans was prevalent; however, the clinical relevance of its presence needs to be investigated further.

Fungal species in endodontic infections: A systematic review and meta-analysis

Fungal infections are common on oral mucosae, but their role in other oral sites is ill defined. Over the last few decades, numerous studies have reported the presence of fungi, particularly Candida species in endodontic infections, albeit in relatively small numbers in comparison to its predominant anaerobic bacteriome. Here, we review the fungal biome of primary and secondary endodontic infections, with particular reference to the prevalence and behavior of Candida species. Meta-analysis of the available data from a total of 39 studies fitting the inclusion criteria, indicate the overall weighted mean prevalence (WMP) of fungal species in endodontic infections to be 9.11% (from a cumulative total of 2003 samples), with 9.0% in primary (n = 1341), and 9.3% in secondary infections (n = 662). Nevertheless, WMP for fungi in primary and secondary infections which were 6.3% and 7.5% for culture-based studies, increased to 12.5% and 16.0% in molecular studies, respectively. The most prevalent fungal species was Candida spp. The high heterogeneity in the reported fungal prevalence suggests the need for standardized sampling, and speciation methods. The advent of the new molecular biological analytical platforms, such as the next generation sequencing (NGS), and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF), that enables identification and quantitation of a broad spectrum of hitherto unknown organisms in endodontic infections should radically alter our understanding of the endodontic mycobiome in the future. Candida spp. appear to be co-pathogens with bacteria in approximately one in ten patients with endodontic infections. Hence, clinicians should comprehend the importance and the role of fungi in endodontic infections and be cognizant of the need to eradicate both bacteria and fungi for successful therapy.

Adhesive protein-mediated cross-talk between Candida albicans and Porphyromonas gingivalis in dual species biofilm protects the anaerobic bacterium in unfavorable oxic environment

The oral cavity contains different types of microbial species that colonize human host via extensive cell-to-cell interactions and biofilm formation. Candida albicans-a yeast-like fungus that inhabits mucosal surfaces-is also a significant colonizer of subgingival sites in patients with chronic periodontitis. It is notable however that one of the main infectious agents that causes periodontal disease is an anaerobic bacterium-Porphyromonas gingivalis. In our study, we evaluated the different strategies of both pathogens in the mutual colonization of an artificial surface and confirmed that a protective environment existed for P. gingivalis within developed fungal biofilm formed under oxic conditions where fungal cells grow mainly in their filamentous form i.e. hyphae. A direct physical contact between fungi and P. gingivalis was initiated via a modulation of gene expression for the major fungal cell surface adhesin Als3 and the aspartic proteases Sap6 and Sap9. Proteomic identification of the fungal surfaceome suggested also an involvement of the Mp65 adhesin and a "moonlighting" protein, enolase, as partners for the interaction with P. gingivalis. Using mutant strains of these bacteria that are defective in the production of the gingipains-the proteolytic enzymes that also harbor hemagglutinin domains-significant roles of these proteins in the formation of bacteria-protecting biofilm were clearly demonstrated.

Prevalence of Candida Species in Endodontic Infections: Systematic Review and Meta-analysis

INTRODUCTION

Candida in endodontic infections has been investigated in a large number of studies, but its role as an endodontic pathogen is still debatable. The aim of this study was to systematically review the literature on the prevalence of Candida species in root canal infections.

METHODS

Extensive literature research was performed in the most important electronic biomedical databases, and additional studies have been identified from references from relevant articles. Studies were critically appraised using a modified version of the Joanna Briggs Institute Critical Appraisal Checklist.

RESULTS

From 2225 unique records, 2118 were excluded on the basis of title and abstract. Of the remaining 107 studies, 50 were excluded after full-text review, and 57 were included for qualitative and quantitative analysis. The overall prevalence of Candida spp. in root canal infections was 8.20% (95% confidence interval, 5.56%-11.21%). Candida albicans was the most frequently isolated species. Significant heterogeneity among studies was observed (P < .001, I² = 86.07%). Subgroup analyses revealed a higher prevalence of Candida spp. from African samples. All studies considered, a high or unclear risk of bias was prevalent regarding 6 out of the 8 items considered in the critical appraisal.

CONCLUSIONS

Candida spp. occurred in a small proportion of root canal infections. Further and better designed research is needed to investigate the real contribution of Candida spp. to the microbial ecology in infected root canals.

Endodontic Microbiology and Pathobiology: Current State of Knowledge

Newer research tools and basic science knowledge base have allowed the exploration of endodontic diseases in the pulp and periapical tissues in novel ways. The use of next generation sequencing, bioinformatics analyses, genome-wide association studies, to name just a few of these innovations, has allowed the identification of hundreds of microorganisms and of host response factors. This review addresses recent advances in endodontic microbiology and the host response and discusses the potential for future innovations in this area.

Forgotten fungi-the gut mycobiome in human health and disease

The human body is home to a complex and diverse microbial ecosystem that plays a central role in host health. This includes a diversity of fungal species that is collectively referred to as our 'mycobiome'. Although research into the mycobiome is still in its infancy, its potential role in human disease is increasingly recognised. Here we review the existing literature available on the human mycobiota with an emphasis on the gut mycobiome, including how fungi interact with the human host and other microbes. In doing so, we provide a comprehensive critique of the methodologies available to research the human mycobiota as well as highlighting the latest research findings from mycological surveys of different groups of interest including infants, obese and inflammatory bowel disease cohorts. This in turn provides new insights and directions for future studies in this burgeoning research area.

Prevalence and nature of fungi in root canal infections: a systematic review and meta-analysis

The role of bacteria in causing apical periodontitis has been widely established, whilst the role of other microorganisms is studied less thoroughly. This systematic review and meta-analysis reviewed the literature for the prevalence and diversity of fungi in root canal infections. An extensive literature search was carried out in the Cochrane databases, EMBASE, MEDLINE, LILACS, SciELO and Web of Science. Additional studies were identified from six endodontic journals, four main endodontic textbooks and references of relevant papers. Selected clinical studies included sampling of necrotic pulps in permanent teeth and microbial analysis of these samples. Studies were critically appraised using the Joanna Briggs Institute Prevalence Critical Appraisal Checklist. Meta-analysis was performed using MetaXL. The screening of 1041 titles and abstracts and full-text reading yielded 54 studies. The overall prevalence of fungi in root canal infections was 7.5% (CI 95%: 3.6-11.8%) in the inverse variance fixed effect heterogeneity model. Candida albicans was the most frequently isolated species. Significant heterogeneity was observed (P < 0.001, I²  = 85.04%). Subgroup analyses based on geographical location, period of publication, type of infection, state of general health, communication with the oral cavity, type of sample and identification method revealed no factor influencing the prevalence. Better standardized techniques and a comprehensive analysis will reveal a more detailed and accurate representation of the prevalence and nature of fungi in root canal infections.

Mining the oral mycobiome: Methods, components, and meaning

Research on oral fungi has centered on Candida. However, recent internal transcribed spacer (ITS)-based studies revealed a vast number of fungal taxa as potential oral residents. We review DNA-based studies of the oral mycobiome and contrast them with cultivation-based surveys, showing that most genera encountered by cultivation have also been detected molecularly. Some taxa such as Malassezia, however, appear in high prevalence and abundance in molecular studies but have not been cultivated. Important technical and bioinformatic challenges to ITS-based oral mycobiome studies are discussed. These include optimization of sample lysis, variability in length of ITS amplicons, high intra-species ITS sequence variability, high inter-species variability in ITS copy number and challenges in nomenclature and maintenance of curated reference databases. Molecular surveys are powerful first steps to characterize the oral mycobiome but further research is needed to unravel which fungi detected by DNA are true oral residents and what role they play in oral homeostasis.

An in vitro Comparison of Antimicrobial Activity of Three Endodontic Sealers with Different Composition

AIMS

The aim of the study was to compare the antimicrobial property of newly introduced EndoSequence BC sealer with commonly used zinc oxide-eugenol-based sealer (Zical) and epoxy resin-based sealer (MM-Seal) against Candida albicans, Lactobacillus, Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa.

MATERIALS AND METHODS

The agar diffusion test was done to measure the antimicrobial activity of sealers. The sealers were put in the 4 mm wells prepared in the inoculated agar plates. The agar plates were incubated at 37°C for 24 hours and the zones of inhibition that appeared was measured. Chi-square test was done to evaluate intraobserver bias for all study samples. Intergroup comparison was done for all five parameters using Pearson correlation statistical analysis.

RESULTS

EndoSequence BC sealer showed maximum mean of diameter of zones of inhibition against all the microorganisms but with no statistically significant difference with other sealers. Zical did not show any zone of inhibition against the P. aeruginosa. MM-Seal did not show any inhibitory activity against the P. aeruginosa and C. albicans.

CONCLUSION

EndoSequence BC sealer showed antimicrobial activity against all the microorganisms and proved to be a better choice when compared with other two sealers.

CLINICAL SIGNIFICANCE

Antimicrobial properties of endodontic sealers are important to prevent the persistent infection of the complex root canals. EndoSequence BC sealer has been proved to be a better sealer in this aspect.

Differential Proteinase Patterns among Candida albicans Strains Isolated from Root Canal and Lingual Dorsum: Possible Roles in Periapical Disease

INTRODUCTION

Proteinases play pivotal roles in Candida albicans infections. Although the yeast can colonize the pulpal environment, there is no information about the enzymatic profile of this organism. This in vitro study aimed to determine the proteolysis levels and to investigate differences in the expression of aspartyl proteinase genes (Sap 1, Sap 2, and Sap 4) among various root canal strains and clinical isolates from the lingual dorsum.

METHODS

The extracellular proteinase activity of 104 C. albicans samples isolated from the lingual dorsum and from necrotic root canals was measured with respect to bovine serum albumin degradation after 5 days of incubation at 37°C. We used reverse-transcription polymerase chain reaction, a highly sensitive method, to detect messenger RNA transcripts of aspartyl proteinase genes (Sap 1, Sap 2, and Sap 4). The C. albicans strain SC 5314 was used as a positive control for both experiments because it is recognized as being highly proteolytic. All tests were performed in triplicate.

RESULTS

Regardless of the isolation site, all C. albicans strains produced an opaque precipitation halo around the colonies, indicating some proteinase activity. However, the production of proteinase on the plates was significantly greater (P < .05) by the endodontic samples. Sap 2 was the most commonly expressed gene in all samples. Among the root canal samples, the detection of Sap 1 transcripts was always associated with the expression of Sap 2 and Sap 4. Sap 4 gene expression was detected in all root canal samples. The simultaneous expression of the 3 investigated Sap genes (Sap 1, Sap 2, and Sap 4) was more common in strains isolated from the lingual dorsum (50%) than in those isolated from root canals (29.4%).

CONCLUSIONS

The increased proteolytic activity as well as the distinct pattern of Sap expression observed among the root canal samples may suggest a pathogenic role for C. albicans in endodontic infections.

Molecular epidemiology, phylogeny and evolution of Candida albicans

A small number of Candida species form part of the normal microbial flora of mucosal surfaces in humans and may give rise to opportunistic infections when host defences are impaired. Candida albicans is by far the most prevalent commensal and pathogenic Candida species. Several different molecular typing approaches including multilocus sequence typing, multilocus microsatellite typing and DNA fingerprinting using C. albicans-specific repetitive sequence-containing DNA probes have yielded a wealth of information regarding the epidemiology and population structure of this species. Such studies revealed that the C. albicans population structure consists of multiple major and minor clades, some of which exhibit geographical or phenotypic enrichment and that C. albicans reproduction is predominantly clonal. Despite this, losses of heterozygosity by recombination, the existence of a parasexual cycle, toleration of a wide range of aneuploidies and the recent description of viable haploid strains have all demonstrated the extensive plasticity of the C. albicans genome. Recombination and gross chromosomal rearrangements are more common under stressful environmental conditions, and have played a significant role in the evolution of this opportunistic pathogen. Surprisingly, Candida dubliniensis, the closest relative of C. albicans exhibits more karyotype variability than C. albicans, but is significantly less adaptable to unfavourable environments. This disparity most likely reflects the evolutionary processes that occurred during or soon after the divergence of both species from their common ancestor. Whilst C. dubliniensis underwent significant gene loss and pseudogenisation, C. albicans expanded gene families considered to be important in virulence. It is likely that technological developments in whole genome sequencing and data analysis in coming years will facilitate its routine use for population structure, epidemiological investigations, and phylogenetic analyses of Candida species. These are likely to reveal more minor C. albicans clades and to enhance our understanding of the population biology of this versatile organism.

Recent mouse and rat methods for the study of experimental oral candidiasis

The Candida genus expresses virulence factors that, when combined with immunosuppression and other risk factors, can cause different manifestations of oral candidiasis. The treatment of mucosal infections caused by Candida and the elucidation of the disease process have proven challenging. Therefore, the study of experimentally induced oral candidiasis in rats and mice is useful to clarify the etiopathology of this condition, improve diagnosis, and search for new therapeutic options because the disease process in these animals is similar to that of human candidiasis lesions. Here, we describe and discuss new studies involving rat and mouse models of oral candidiasis with respect to methods for inducing experimental infection, methods for evaluating the development of experimental candidiasis, and new treatment strategies for oral candidiasis.

Characterization of the oral fungal microbiota in smokers and non-smokers

This study aimed to assess the effect of smoking on the biodiversity of the oral fungal microbiota of healthy young subjects, using an improved culture method that assesses both total and pathogenic viable fungi. Forty individuals (20 smokers and 20 non-smokers) were selected. All individuals presented fungal growth (100% for molds and 92.5% for yeasts), a prevalence higher than previously reported. The most commonly occurring molds were Penicillium sp., Aspergillus sp., and Cladosporium sp. Smokers presented significantly higher levels of yeasts and pathogenic molds than did non-smokers. No differences in fungal prevalence and diversity were observed in smokers and non-smokers following a 30-wk observation period. In conclusion, tobacco smoking may alter the oral mycobiota and facilitate colonization of the oral cavity with yeasts and pathogenic molds. The effect of chronic fungal colonization on the oral health of tobacco smokers cannot be neglected.

Enrichment of multilocus sequence typing clade 1 with oral Candida albicans isolates in patients with untreated periodontitis

This study investigated the prevalence and cell density of Candida species in periodontal pockets, healthy subgingival sites, and oral rinse samples of patients with untreated periodontitis. Twenty-one periodontitis patients underwent sampling at two periodontitis sites, and 19/21 of these patients underwent sampling at one periodontally healthy site. Both paper point and curette sampling techniques were employed. The periodontitis patients and 50 healthy subjects were also sampled by oral rinse. Candida isolates were recovered on CHROMagar Candida medium, and representative isolates were identified. Candida spp. were recovered from 10/21 (46.7%) periodontitis patients and from 16/50 (32%) healthy subjects. C. albicans predominated in both groups and was recovered from all Candida-positive subjects. Candida-positive periodontitis patients yielded Candida from periodontal pockets with average densities of 3,528 and 3,910 CFU/sample from curette and paper point samples, respectively, and 1,536 CFU/ml from oral rinse samples. The majority (18/19) of the healthy sites sampled from periodontitis patients were Candida negative. The 16 Candida-positive healthy subjects yielded an average of 279 CFU/ml from oral rinse samples. C. albicans isolates were investigated by multilocus sequence typing (MLST) to determine if specific clonal groups were associated with periodontitis. MLST analysis of 31 C. albicans isolates from periodontitis patients yielded 19 sequence types (STs), 13 of which were novel. Eleven STs belonged to MLST clade 1. In contrast, 16 C. albicans isolates from separate healthy subjects belonged to 16 STs, with 4 isolates belonging to clade 1. The distributions of STs between both groups were significantly different (P = 0.04) and indicated an enrichment of C. albicans isolates in periodontal pockets, which warrants a larger study.

Microbiologic profile of endodontic infections from HIV- and HIV+ patients using multiple-displacement amplification and checkerboard DNA-DNA hybridization

OBJECTIVE

To compare the microbiota of endodontic infections in necrotic pulp from HIV-negative and HIV-positive subjects.

MATERIALS AND METHODS

Root canal samples from necrotic pulp were collected from 40 HIV- and 20 HIV+ subjects. Pulps were amplified using multiple displacement amplification (MDA). Then, checkerboard DNA-DNA hybridization was employed to assess the levels of 107 microbial taxa. The percentage of DNA probe count and the percentage of teeth colonized by each test species were investigated. Significant differences between groups regarding proportions of taxa and prevalence of the test species were sought using the Mann-Whitney test and the Chi-square analysis, respectively.

RESULTS

The most prevalent taxa detected were Dialister pneumosintes, Stenotrophomonas maltophilia, Streptococcus sobrinus, Corynebacterium diphteriae, and Helicobacter pylori among HIV- subjects and D. pneumosintes, Prevotella tannerae, Porphyromonas gingivalis, Parvimonas micra, Prevotella nigrescens, and Corynebacterium diphtheriae among HIV+ individuals. D. pneumosintes, C. diphtheria, and C. albicans were the most abundant species in the HIV- group, whereas the predominant taxa in HIV+ samples were P. tannerae, D. pneumosintes and Olsenella uli. P. tannerae, O. uli, Veilonella dispar, Bacteroides fragilis, and Actinomyces meyeri were significantly more abundant in HIV+ samples.

CONCLUSIONS

There were significant differences in the prevalence and proportions of specific microbial taxa between HIV- and HIV+ individuals. The root canal microbiota may represent a reservoir of important oral and medical pathogens, mainly in HIV+ individuals.

In vitro susceptibility of oral Candida albicans strains to different pH levels and calcium hydroxide saturated aqueous solution

Candida albicans is present in the oral cavity and in the whole digestive tract of humans and other animals, being frequently related to endodontic treatment failure. The present study determined the incidence of C. albicans in the oral cavity and the susceptibility of isolates to different pH values and saturated calcium hydroxide aqueous solution at pH 12.5. Sixty-five patients attending the Endodontic Clinic at the Sagrado Coração University participated in the study. The collected samples were cultivated in selective media for C. albicans and the isolates were tested in terms of resistance to both alkaline pH and saturated aqueous solution of calcium hydroxide. In relation to time variables, yeast viability was assessed by the Sabouraud's agar culture and fluorescein diacetate and ethidium bromide fluorescent staining method. Results from the different pHs and experimental times, including those from different techniques measuring fungal viability, were compared using the chi-square and Fisher's exact tests (α=0.05). The yeasts became completely inviable after 48 h of contact with the calcium hydroxide solution. On the other hand, when exposed to the alkaline culture broth, the yeasts were found to be viable at pHs 9.5 and 10.5 for up to 7 days. In conclusion, C. albicans can only be completely inhibited by direct contact with saturated calcium hydroxide aqueous solution after 48 h of exposure.

In vitro adherence of Candida albicans isolated from patients with chronic periodontitis

Adherence is considered an extremely important virulence factor in yeast.

OBJECTIVE

The aim of this study was to analyze the adherence to epithelial cells of C. albicans isolated from patients with chronic periodontitis in comparison to healthy patients.

MATERIAL AND METHODS

Candida albicans cells isolated from individuals with chronic periodontitis (n=25) and healthy controls (n=25) were included in this study. Suspensions of C. albicans (10(6) cells/mL) and epithelial cells (10(5) cells/mL) were mixed and incubated at 37ºC for 1 h. The number of yeasts adhered to 25 epithelial cells was counted.

RESULTS

The number of C. albicans cells adhered to epithelial cells was statistically higher in the chronic periodontitis group than in the control group (Student's t-test, p=0.000).

CONCLUSION

The results of the present study suggest a higher Candida adherence of samples isolated from patients with chronic periodontitis.

Inhibition of Candida albicans CC biofilms formation in polystyrene plate surfaces by biosurfactant produced by Trichosporon montevideense CLOA72

This study evaluated the effects of glycolipid-type biosurfactant produced by Trichosporon montevideense CLOA72 in the formation of biofilms in polystyrene plate surfaces by Candida albicans CC isolated from the apical tooth canal. Biofilm formation was reduced up to 87.4% with use of biosurfactant at 16 mg/ml concentration. It has been suggested that the interaction with the cell or polystyrene plate surface could ultimately be responsible for these actions. Therefore, the interaction of C. albicans CC cells with the biosurfactant, as well as the corresponding thermodynamic parameters, have been determined by isothermal titration calorimetry and zeta potential measurements. This process is endothermic (((int)H°=+1284±5 cal/mg OD(600)) occurring with a high increase of entropy (T((int)S°=+10635 cal/mg OD(600)). The caloric energy rate data released during the titulation indicates saturation of the cell-biosurfactant at 1.28 mg/ml OD(600). Also, the zeta potential of the cell surface was monitored as a function of the biosurfactant concentration added to cell suspension showing partial neutralization of net surface charge, since the value of zeta potential ranged from -16 mV to -6 mV during the titration. The changes of cell surface characteristics can contribute to the inhibition of initial adherence of cells of C. albicans in surface. The CMC of the purified biosurfactant produced from T. montevideense CLOA72 is 2.2 mg/ml, as determined both by ITC dilution experiments and by surface tension measurements. This biomolecule did not presented any cytotoxic effect in HEK 293A cell line at concentrations of 0.25-1 mg/ml. This study suggests a possible application of the referred biosurfactant in inhibiting the formation of biofilms on plastic surfaces by C. albicans.