Non-antibiotic antimicrobial agents for chronic rhinosinusitis: a narrative review.

OBJECTIVE: This narrative review explores alternative non-antibiotic antimicrobial agents for CRS management in adults. METHODS: Alternative antimicrobial agents using EPOS 2020 guidelines as reference were selected, and articles dated from 2003 to 2022 in English, Portuguese, or Spanish using PubMed and EMBASE databases. The parameters analyzed included study design, evidence level, population characteristics, CRS characteristics, interventions, outcomes, sample size, randomization, blinding, and side effects. Reviews, unrelated contexts,in vitro experiments, and duplicates were excluded. RESULTS: 148 articles were screened; 19 articles were selected for analysis. Randomized controlled trials and cohort studies assessing non-antibiotic antimicrobial treatments for CRS were included. Xylitol demonstrated effectiveness in reducing CRS symptoms, particularly SNOT-22 scores, surpassing saline irrigation benefits. Manuka honey showed potential microbiological benefits in recalcitrant CRS, but symptomatic and endoscopic improvements remained inconclusive. Baby shampoo irrigation improved nasal mucociliary clearance and postoperative outcomes. Colloidal silver nasal irrigation showed limited efficacy in reducing CRS symptoms or endoscopic scores. Povidone-Iodine (PI) nasal irrigation yielded mixed results, with varying effects on culture negativity and SNOT-20 scores. Bacteriophage treatment exhibited promise in decreasing specific bacterial strains and cytokine levels. CONCLUSION: Non-antibiotic antimicrobial therapies, including xylitol, manuka honey, baby shampoo, colloidal silver, PI, bacteriophages, lactoferrin, and carrageenan offer potential alternatives for CRS in adult patients. Xylitol, baby shampoo, and PI presented benefits in improving symptoms and nasal endoscopic scores, however, the number of studies is limited for conclusive recommendations and safety assessments. CRS management should adopt a comprehensive approach, particularly for non-infectious or immune-related cases, moving beyond antibiotics. Antibiotics should be reserved for confirmed bacterial infections. Overall, this review shows the importance of exploring non-antibiotic therapies to enhance the management of CRS.

Xylitol associated or not with fluoride: Is the action the same on de- and remineralization?

OBJECTIVES: This study evaluated the effect of xylitol combined or not with fluoride (F) on reduction of demineralization and increase of remineralization of shallow and deep artificial enamel lesions. METHODS: Bovine enamel samples were allocated to the following solutions groups: no xylitol (negative control), 5% xylitol, 10% xylitol, 20% xylitol, 500 ppm F (as NaF), 5% xylitol+F, 10% xylitol+F or 20% xylitol+F (n = 12-15). For the demin study, a pH-cycling model (demineralization-6 h, pH 4.7/remineralization 18 h, pH 7.0) was employed for 7 days. Treatments were applied 2 × 1 min. In the remin study, specimens were pre-demineralized for 2, 5 or 10 days. Afterwards, a pH-cycling protocol was conducted (2 h demineralizing and 22 h remineralizing solution/day for 8 days) and the same treatments were done. The response variables were percentage surface hardness loss (%SHL) and transverse microradiography. Data were analyzed by RM ANOVA/Tukey or Kruskal-Wallis/Dunn (p < 0.05) RESULTS: F and Xylitol combined with F reduced the %SHL (23-30%) compared to the negative control (61.5%). The integrated mineral loss and the lesion depth were not reduced by any treatment. Surface hardness recovery was seen only for shallow lesions in case of 20% xylitol+F compared to negative control. No lesion depth recovery, but significant mineral recovery was seen for F (2-days and 10-days lesion). CONCLUSIONS: All concentrations of xylitol+F reduced enamel surface demineralization, while only 20% xylitol+F improved surface remineralization of shallow lesions in vitro. CLINICAL SIGNIFICANCE: Our results suggest that while F or any concentration of xylitol + F reduces surface demineralization, only 20% xylitol+F improves surface remineralization of shallow lesions in vitro. Therefore, xylitol may be added into oral products, combined to F, to control dental caries.

Metabolic engineering of Saccharomyces cerevisiae for second-generation ethanol production from xylo-oligosaccharides and acetate.

Simultaneous intracellular depolymerization of xylo-oligosaccharides (XOS) and acetate fermentation by engineered Saccharomyces cerevisiae offers significant potential for more cost-effective second-generation (2G) ethanol production. In the present work, the previously engineered S. cerevisiae strain, SR8A6S3, expressing enzymes for xylose assimilation along with an optimized route for acetate reduction, was used as the host for expressing two ß-xylosidases, GH43-2 and GH43-7, and a xylodextrin transporter, CDT-2, from Neurospora crassa, yielding the engineered SR8A6S3-CDT-2-GH34-2/7 strain. Both ß-xylosidases and the transporter were introduced by replacing two endogenous genes, GRE3 and SOR1, that encode aldose reductase and sorbitol (xylitol) dehydrogenase, respectively, and catalyse steps in xylitol production. The engineered strain, SR8A6S3-CDT-2-GH34-2/7 (sor1Δ gre3Δ), produced ethanol through simultaneous XOS, xylose, and acetate co-utilization. The mutant strain produced 60% more ethanol and 12% less xylitol than the control strain when a hemicellulosic hydrolysate was used as a mono- and oligosaccharide source. Similarly, the ethanol yield was 84% higher for the engineered strain using hydrolysed xylan, compared with the parental strain. Xylan, a common polysaccharide in lignocellulosic residues, enables recombinant strains to outcompete contaminants in fermentation tanks, as XOS transport and breakdown occur intracellularly. Furthermore, acetic acid is a ubiquitous toxic component in lignocellulosic hydrolysates, deriving from hemicellulose and lignin breakdown. Therefore, the consumption of XOS, xylose, and acetate expands the capabilities of S. cerevisiae for utilization of all of the carbohydrate in lignocellulose, potentially increasing the efficiency of 2G biofuel production.

Avaliação antimicrobiana de uma resina Bulk Fill Fluida com inserção do xilitol / Antimicrobial evaluation of a Fluid Bulk Fill resin with xylitol insertion

Introdução: As resinas Bulk Fill apresentam uma boa procura pelos profissionais, pois o seu uso diminui o tempo clínico, como também a melhora qualidade das restaurações, porém não possuem atividade antibacteriana, sendo um dos fatores que ainda causam impacto negativo na vida das pessoas. A biomodificação com o xilitol tem o sentido de produzir ação microbiana e com isso aperfeiçoar as suas características clínicas. Objetivo: Avaliar a ação antimicrobiana de uma resina Bulk Fill flow após a inserção do xilitol. Metodologia: A resina Tetric® N-Flow Bulk Fill foi misturada às concentrações de xilitol (0% [Controle], 2,5% e 5% p/p). Amostras cilíndricas (n=5 do grupo controle e n=3 dos demais grupos experimentais) foram confeccionadas em moldes acrílicos de diâmetro de 2mm espessura, fotoativadas por 10s e armazenadas a 37ºC por 24h. Os espécimes foram esterilizados por luz ultravioleta por 20 minutos antes de serem acomodadas em uma placa de 48 poços estéril, sendo adicionado em cada poço 0,5mL de caldo Mueller Hinton. Então, adicionou-se 50µL do inóculo de S. mutans nos poços correspondentes. A placa foi incubada a 37 ± 1 ˚C durante 48 horas. Após o período de incubação, os espécimes foram gentilmente removidos e o crescimento microbiano foi indicado pela adição de 100µL da solução aquosa de resazurina (SigmaAldrich) a 0,01% com a posterior incubação a 37 ± 1 ˚C por duas horas. Micro-organismos viáveis reduzem o corante mudando sua coloração azul para rosa e a CIM foi definida como a menor concentração da substância que inibiu a mudança de coloração da resazurina. Em um poço contendo o grupo controle foi acrescentado clorexidina a 0,12% com o intuito de comparar o resultado gerado dos grupos testes. Resultado: Não houve inibição do crescimento bacteriano nos poços com inóculos que continham S. mutans e corpo de prova de resina acrescida de xilitol. Conclusão: Esse estudo mostrou que o acréscimo de 2,5% e 5% de Xilitol à resina Tetric® N-Flow Bulk Fill não apresentou inibição do crescimento bacteriano (AU).

Introduction: Bulk Fill resins are in good demand among professionals, as their use reduces clinical time and improves the quality of restorations, but they do not have antibacterial activity, which is one of the factors that still hurt people's lives. Biomodification with xylitol aims to improve its clinical characteristics. Objective: To evaluate the antimicrobial action of a Bulk Fill flow resin after inserting xylitol. Methodology: Tetric® N-Flow Bulk Fill resin was mixed with xylitol concentrations (0% [Control], 2.5% and 5% w/w). Cylindrical samples (n=5 from the control group and n=3 from the other groups) were made in acrylic molds with a diameter of 2 mm thick, light-cured for 10 s and stored at 37ºC for 24h. The specimens were sterilized by ultraviolet light for 20 minutes before being placed in a sterile 48-well plate, with 0.5 mL of Mueller Hinton broth added to each well. The plate was incubated at 37 ± 1 ˚C for 48 hours. After the incubation period, the specimens were gently removed, and microbial growth was indicated by adding 100 µL of 0.01% resazurin aqueous solution with subsequent incubation at 37 ± 1 ˚C for two hours. Viable microorganisms reduce the dye, changing its color from blue to pink. The MIC was defined as the lowest concentration of the substance that inhibited the color change of resazurin. In 0.12%, chlorhexidine was added to a well containing the control group to compare the results generated from the test groups. Result: There was no inhibition of bacterial growth in the wells with inocula containing S. mutans and the resin specimen with xylitol added. Conclusion: This study showed that adding 2.5% and 5% Xylitol to the Tetric® N-Flow Bulk Fill resin did not inhibit bacterial growth (AU).

Evaluation of Solutions Containing Fluoride, Sodium Trimetaphosphate, Xylitol, and Erythritol, Alone or in Different Associations, on Dual-Species Biofilms.

Although the association of polyols/polyphosphates/fluoride has been demonstrated to promote remarkable effects on dental enamel, little is known on their combined effects on biofilms. This study assessed the effects of solutions containing fluoride/sodium trimetaphosphate (TMP)/xylitol/erythritol on dual-species biofilms of Streptococcus mutans and Candida albicans. Biofilms were grown in the continuous presence of these actives alone or in different associations. Quantification of viable plate counts, metabolic activity, biofilm biomass, and extracellular matrix components were evaluated. Overall, fluoride and TMP were the main actives that significantly influenced most of the variables analyzed, with a synergistic effect between them for S. mutans CFUs, biofilm biomass, and protein content of the extracellular matrix (p < 0.05). A similar trend was observed for biofilm metabolic activity and carbohydrate concentrations of the extracellular matrix, although without statistical significance. Regarding the polyols, despite their modest effects on most of the parameters analyzed when administered alone, their co-administration with fluoride and TMP led to a greater reduction in S. mutans CFUs and biofilm biomass compared with fluoride alone at the same concentration. It can be concluded that fluoride and TMP act synergistically on important biofilm parameters, and their co-administration with xylitol/erythritol significantly impacts S. mutans CFUs and biomass reduction.

Efeito da incorporação de xilitol na dureza de superfície de um compósito bulk fill fluido / Efeito da incorporação de xilitol na dureza de superfície de um compósito bulk fill fluido

Introdução: Frente à necessidade de maior longevidade das restaurações, o desenvolvimento de resinas antimicrobianas vem sendo necessário. O xilitol, um composto antimicrobiano natural e biocompatível, pode ser um aditivo em potencial para incluir esta propriedade em uma resina bulk fill fluida sem comprometer sua integridade. Objetivo: Avaliar a microdureza de superfície de uma resina antimicrobiana desenvolvida a partir da adição de xilitol (0% ou controle; 2,5%; 5%) em resina bulk fill fluida comercial (Tetric N-Flow Bulk Fill, Ivoclar Vivadent, Schaan, Liechtenstein). Metodologia: 3 grupos (n=12) foram obtidos através da variação da concentração de xilitol (0% ou controle; 2,5%; 5%). Para obter as resinas experimentais, xilitol em pó foi incorporado à resina fluida por espatulação manual por 1 min em uma câmara escura. A partir de um molde de acrílico, discos de 5 mm de diâmetro foram confeccionados através da fotoativação de um incremento único com um aparelho de LED de irradiância 1400 mW/cm² (Bluephase, Ivoclar Vivadent) por 10 s. Os discos foram submetidos à análise de microdureza Vickers (HMV-2, Shimadzu, Tokyo, Japan) na face superior, com uma carga estática de 300g e em um tempo de 10 s, obtendo uma média após três indentações por amostra. A análise estatística foi realizada através da variância ANOVA a um fator e teste de Tukey para a comparação entre os grupos (p < 0,05). Resultados: O grupo xilitol 5% mostrou a menor média de microdureza de superfície quando comparado aos grupos 0% e 2,5%. Conclusão: O xilitol afetou negativamente à dureza da restauração, principalmente quando foi utilizada uma concentração de 5% (AU).

Introduction: In view of the need for improved longevity of restorations, the development of antimicrobial resins has become necessary. Xylitol, a natural and biocompatible antimicrobial compound, may be a potential additive to include this property in a flowable bulk fill resin without compromising its integrity. Objective: To evaluate the surface microhardness of an antimicrobial resin developed by adding xylitol (0% or control; 2.5%; 5%) to a commercial flowable bulk fill resin (Tetric N-Flow Bulk Fill, Ivoclar Vivadent, Schaan, Liechtenstein). Methodology: 3 groups (n=12) were obtained by changing the xylitol concentration (0% or control; 2.5%; 5%). To obtain the experimental resins, xylitol powder was incorporated into the flowable resin by manual spatulation for 1 min in a darkroom. Based on an acrylic mold, 5 mm diameter disks were made by curing of a single increment with a 1400 mW/cm² irradiance LED device (Bluephase, Ivoclar Vivadent) for 10s. The disks were subjected to Vickers microhardness analysis (HMV-2, Shimadzu, Tokyo, Japan) on the upper face, with a static load of 300g and in a time of 10 s, obtaining an mean after three indentations for sample. Statistical analysis was performed using one-way ANOVA and Tukey's test for comparison between groups (p < 0.05). Results: The 5% xylitol group showed lower mean surface microhardness when compared to the 0% and 2.5% groups. Conclusion: Xylitol negatively affected restoration hardness mainly when a 5% concentration was used (p < 0.01) (AU).

Effect of experimental toothpaste containing hydroxyapatite nanoparticles and propolis, with and without fluoride, on the microcosm biofilm and enamel demineralization.

This study evaluated the antimicrobial and anticaries effects of toothpaste containing hydroxyapatite nanoparticles (nanoHAP - 5 or 10%), xylitol (2 or 3%) and propolis (1 or 2%), associated or not with 1500 ppm fluoride (F). An in vitro model was used with microcosm biofilm produced from a pool of human saliva and McBain saliva (1:50) in the first 8 h of culture on 162 bovine enamel specimens. At the end of the experimental period, analyses of metabolic activity, colony forming units (CFU) and transverse microradiography (TMR) were performed. This study showed a possible decrease in demineralization and increase in remineralization by the commercial toothpaste (1500 ppm F) and for the experimental toothpaste containing the highest concentration of all agents, combined with F. In addition, a reduction in antimicrobial activity possibly caused by propolis and xylitol, mainly in relation to cariogenic bacteria, was observed.

Rheological parameters of mixed Brazilian Cerrado fruits sugar-free preserves: the effect of body agents.

The aim of this study was to evaluate the effect of the bodying agents (erythritol, sorbitol, xylitol, and polydextrose) and their mixtures on the preparation of mixed Brazilian Cerrado fruit preserves (marolo, soursop, and sweet passion fruit). Mixture design was used for product optimization and the preserves were evaluated by texture profile, stress relaxation test, and uniaxial compression test. The research data were analyzed using regression equations on SAS software. The results indicated that the rheological parameters were affected by the body agents. Erythritol should not be used as an isolated component because it provoked changes in the properties of the final product (harder and brittle preserves); xylitol and sorbitol made preserves more elastic, cohesive, and more fragile; and polydextrose showed a synergistic effect with erythritol for rupture deformation and lesser effects for hardness, adhesiveness, and gumminess.

Relation of xylitol formation and lignocellulose degradation in yeast.

One of the critical steps of the biotechnological production of xylitol from lignocellulosic biomass is the deconstruction of the plant cell wall. This step is crucial to the bioprocess once the solubilization of xylose from hemicellulose is allowed, which can be easily converted to xylitol by pentose-assimilating yeasts in a microaerobic environment. However, lignocellulosic toxic compounds formed/released during plant cell wall pretreatment, such as aliphatic acids, furans, and phenolic compounds, inhibit xylitol production during fermentation, reducing the fermentative performance of yeasts and impairing the bioprocess productivity. Although the toxicity of lignocellulosic inhibitors is one of the biggest bottlenecks of the biotechnological production of xylitol, most of the studies focus on how much xylitol production is inhibited but not how and where cells are affected. Understanding this mechanism is important in order to develop strategies to overcome lignocellulosic inhibitor toxicity. In this mini-review, we addressed how these inhibitors affect both yeast physiology and metabolism and consequently xylose-to-xylitol bioconversion. In addition, this work also addresses about cellular adaptation, one of the most relevant strategies to overcome lignocellulosic inhibitors toxicity, once it allows the development of robust and tolerant strains, contributing to the improvement of the microbial performance against hemicellulosic hydrolysates toxicity. KEY POINTS: • Impact of lignocellulosic inhibitors on the xylitol production by yeasts • Physiological and metabolic alterations provoked by lignocellulosic inhibitors • Cell adaptation as an efficient strategy to improve yeast's robustness.

In vitro effect of low-fluoride toothpaste supplemented with sodium trimetaphosphate, xylitol, and erythritol on enamel demineralization.

OBJECTIVE: Regular use of toothpaste with fluoride (F) concentrations of ≥ 1000 ppm has been shown to contribute to reducing caries increment. However, when used by children during the period of dental development, it can lead to dental fluorosis. In this study, we aimed to evaluate the in vitro effect of a toothpaste formulation with reduced fluoride (F) concentration (200 ppm) supplemented with sodium trimetaphosphate (TMP: 0.2%), Xylitol (X:16%), and Erythritol (E: 4%) on dental enamel demineralization. METHODOLOGY: Bovine enamel blocks were selected according to initial surface hardness (SHi) and then divided into seven experimental toothpaste groups (n=12). These groups included 1) no F-TMP-X-E (Placebo); 2) 16% Xylitol and 4% Erythritol (X-E); 3) 16% Xylitol, 4% Erythritol and 0.2%TMP (X-E-TMP); 4) 200 ppm F (no X-E-TMP: (200F)); 5) 200 ppm F and 0.2% TMP (200F-TMP); 200 ppm F, 16% Xylitol, 4% Erythritol, and 0.2% TMP (200F-X-E-TMP); and 7) 1,100 ppm F (1100F). Blocks were individually treated 2×/day with slurries of toothpastes and subjected to a pH cycling regimen for five days (DES: 6 hours and RE: 18 hours). Then, the percentage of surface hardness loss (%SH), integrated loss of subsurface hardness (ΔKHN), fluoride (F), calcium (Ca), and phosphorus (P) in enamel were determined. The data were analyzed by ANOVA (1-criterion) and the Student-Newman-Keuls test (p<0.001). RESULTS: We found that the 200F-X-E-TMP treatment reduced %SH by 43% compared to the 1100F treatments (p<0.001). The ΔKHN was ~ 65% higher with 200F-X-E-TMP compared to 1100F (p<0.001). The highest concentration of F in enamel was observed on the 1100F treatment (p<0.001). The 200F-X-E-TMP treatment promote higher increase of Ca and P concentration in the enamel (p<0.001). CONCLUSION: The association of 200F-X-E-TMP led to a significant increase of the protective effect on enamel demineralization compared to the 1100F toothpaste.

Strategy to reduce acetic acid in sugarcane bagasse hemicellulose hydrolysate concomitantly with xylitol production by the promising yeast Cyberlindnera xylosilytica in a bioreactor.

The yeast Cyberlindnera xylosilytica UFMG-CM-Y309 has been identified as a promising new xylitol producer from sugarcane bagasse hemicellulosic hydrolysate (SCHH). However, SCHH pretreatment process generates byproducts, which are toxic to cell metabolism, including furans, phenolic compounds, and carboxylic acids, such as acetic acid, typically released at high concentrations. This research aims to reduce acetic acid in sugarcane hemicellulose hydrolysate concomitantly with xylitol production by yeast strain Cy. xylosilytica UFMG-CM-Y309 in a bioreactor by strategically evaluating the influence of volumetric oxygen transfer coefficient (kLa) (21 and 35 h-1). Experiments were conducted on a bench bioreactor (2 L volumetric capacity) at different initial kLa values (21 and 35 h-1). SCHH medium was supplemented with rice bran extract (10 g L-1) and yeast extract (1 g L-1). Cy. xylosilytica showed high xylitol production performance (19.56 g L-1), xylitol yield (0.56 g g-1) and, maximum xylitol-specific production rate (µpmáx 0.20 gxylitol·g-1 h-1) at kLa value of 21 h-1, concomitantly slowing the rate of acetic acid consumption. A faster acetic acid consumption (100%) by Cy. xylosilytica was observed at kLa of 35 h-1, concomitantly with an increase in maximum cellular growth (14.60 g L-1) and reduction in maximum xylitol production (14.56 g L-1 and Yp/s 0.34 g g-1). This study contributes to pioneering research regarding this yeast performance in bioreactors, emphasizing culture medium detoxification and xylitol production.

The effect of toothpaste with reduced concentration of fluoride-containing sodium trimetaphosphate and polyols on initial enamel erosion.

OBJECTIVES: This in vitro study evaluated the efficacy of toothpaste containing fluoride (F), sodium trimetaphosphate (TMP), and xylitol and erythritol (XE) to inhibit or repair initial enamel erosion lesions. MATERIALS AND METHODS: Bovine enamel blocks (n = 120) were selected according to surface hardness (SH) and randomly divided into 5 experimental groups (n = 24 blocks/group): Placebo (no F, TMP, XE); 1100 ppm F; 16% xylitol + 4% erythritol (XE); 200 ppm F + 0.2% TMP (200 ppm F/TMP); and 200 ppm F + 0.2% TMP + 16% xylitol + 4% erythritol (200 ppm F/TMP/XE). The sound and softened blocks were immersed in toothpaste slurry in human saliva for 2 min. The blocks were then submitted to 4 erosive challenges in citric acid (0.75%, pH 3.5), each challenge for 1 min, with stirring. The SH of the blocks was determined after treatment (t) and after the 4 erosive challenges. In addition, the precipitates were analyzed by scanning electron microscopy (SEM). Variables were submitted to a two-way repeated-measures analysis of variance followed by a Student-Newman-Keuls test (p < 0.05). RESULTS: Toothpaste containing 200 ppm F/TMP/XE led to the highest protective and repair effect compared to the other groups (p < 0.001). The protective and repair effect was XE > 200 ppm F/TMP > 1100 ppm F > placebo (p < 0.001). All groups produced precipitates with a thicker layer for XE and TMP groups. CONCLUSIONS: Toothpaste containing 200 ppm F, TMP, and polyols demonstrated a superior protective and repair effect in initial enamel erosive lesions in vitro. CLINICAL RELEVANCE: Toothpaste containing F and polyols could be an advantage in patients affected by dental erosion, due to its higher preventive potential, mainly in individuals who frequently drink acidic beverages. However, future studies are needed to confirm these results.

Fermentation performance of a Mexican native Clavispora lusitaniae strain for xylitol and ethanol production from xylose, glucose and cellobiose.

Lignocellulose hydrolysates are rich in fermentable sugars such as xylose, cellobiose and glucose, with high potential in the biotechnology industry to obtain bioproducts of higher economic value. Thus, it is important to search for and study new yeast strains that co-consume these sugars to achieve better yields and productivity in the processes. The yeast Clavispora lusitaniae CDBB-L-2031, a native strain isolated from mezcal must, was studied under various culture conditions to potentially produce ethanol and xylitol due to its ability to assimilate xylose, cellobiose and glucose. This yeast produced ethanol under microaerobic conditions with yields of 0.451 gethanol/gglucose and 0.344 gethanol/gcellobiose, when grown on 1% glucose or cellobiose, respectively. In mixtures (0.5% each) of glucose:xylose and glucose:xylose:cellobiose the yields were 0.367 gethanol/gGX and 0. 380 gethanol/gGXC, respectively. Likewise, in identical conditions, C. lusitaniae produced xylitol from xylose with a yield of 0.421 gxylitol/gxylose. In 5% glucose or xylose, this yeast had better ethanol and xylitol titers and yields, respectively. However, glucose negatively affected xylitol production in the mixture of both sugars (3% each), producing only ethanol. Xylose reductase (XR) and xylitol dehydrogenase (XDH) activities were evaluated in cultures growing on xylose or glucose, obtaining the highest values in cultures on xylose at 8 h (25.9 and 6.22 mU/mg, respectively). While in glucose cultures, XR and XDH activities were detected once this substrate was consumed (4.06 and 3.32 mU/mg, respectively). Finally, the XYL1 and XYL2 genes encoding xylose reductase and xylitol dehydrogenase, respectively, were up-regulated by xylose, whereas glucose down-regulated their expression.

Integrated bioinformatics, modelling, and gene expression analysis of the putative pentose transporter from Candida tropicalis during xylose fermentation with and without glucose addition.

The transport of substrates across the cell membrane plays an essential role in nutrient assimilation by yeasts. The establishment of an efficient microbial cell factory, based on the maximum use of available carbon sources, can generate new technologies that allow the full use of lignocellulosic constituents. These technologies are of interest because they could promote the formation of added-value products with economic feasibility. In silico analyses were performed to investigate gene sequences capable of encoding xylose transporter proteins in the Candida tropicalis genome. The current study identified 11 putative transport proteins that have not yet been functionally characterized. A phylogenetic tree highlighted the potential C. tropicalis xylose-transporter proteins CtXUT1, CtXUT4, CtSTL1, CtSTL2, and CtGXT2, which were homologous to previously characterized and reported xylose transporters. Their expression was quantified through real-time qPCR at defined times, determined through a kinetic analysis of the microbial growth curve in the absence/presence of glucose supplemented with xylose as the main carbon source. The results indicated different mRNA expression levels for each gene. CtXUT1 mRNA expression was only found in the absence of glucose in the medium. Maximum CtXUT1 expression was observed in intervals of the highest xylose consumption (21 to 36 h) that corresponded to consumption rates of 1.02 and 0.82 g/L/h in the formulated media, with xylose as the only carbon source and with glucose addition. These observations indicate that CtXUT1 is an important xylose transporter in C. tropicalis. KEY POINTS: • Putative xylose transporter proteins were identified in Candida tropicalis; • The glucose concentration in the cultivation medium plays a key role in xylose transporter regulation; • The transporter gene CtXUT1 has an important role in xylose consumption by Candida tropicalis.

Effect of humectants and Zygosaccharomyces bailii inoculation on the physical stability of oil-in-water emulsions modeling salad dressings.

BACKGROUND: Salad dressing formulations include a pH within 3.2-4.1, salt and other solutes to depress water activity. The interaction between hydrocolloids and other components such as humectants determines their physical and microbiological stability. To our knowledge, the effect of commonly used solutes on physical stability and rheological characteristics of oil-in-water emulsions stabilized by xanthan gum has not been reported, and neither has the effect of a spoilage yeast on physical stability been evaluated. RESULTS: The effect of different humectants (sodium chloride, glucose and xylitol) and Zygosaccharomyces bailii inoculation on the stability of oil-in-water emulsions containing different levels of xanthan gum to emulate different types of salad dressings was investigated by means of droplet size, zeta potential, rheological measurements and confocal laser scanning microscopy (CLSM). Generally, the addition of humectants strengthened the weak or strong emulsion structure, especially xylitol. Glucose or xylitol acted as stabilizers since they decreased Sauter and De Broucker diameter. On the contrary, NaCl destabilized the emulsions since it increased droplet size and exhibited the lowest absolute values of zeta potential. Inoculation with Z. bailii destabilized some emulsions since it increased Sauter and De Broucker diameter. Emulsion droplet size, polydispersity, and xanthan gum and yeast location were confirmed by CLSM imaging. CONCLUSION: This study highlights the key role of humectants and xanthan gum level on physical characteristics and stability of oil-in-water emulsions. Addition of xylitol leads to an enhancement in emulsion rheology and physical stability, suggesting that it is a potential low-calorie multifunctional additive for salad dressings. © 2022 Society of Chemical Industry.

Efectos de azúcares totales sustitutos de sacarosa en la salud bucal. Revisión bibliográfica / Effects of sucrose substitute total sugars on oral health. Bibliographic review

Se realizó una revisión bibliográfica sobre los efectos de azúcares totales sustitutos de sacarosa sobre el estado de salud bucal. Los artículos científicos fueron localizados en bases de datos científicas digitales: Scopus, PubMed, Web Of Science y Ovid. Las fuentes empleadas son de libre acceso, 49 de los manuscritos fueron descartados, quedando 23. El 43,5% de los artículos mostraban resultados de ensayos clínicos sobre las gomas de mascar con xilitol, el 39,1% acerca de otros compuestos (stevia, magnolia, eritritol, fostato de calcio), el 13% revisiones narrativas y el 4,4% metaanálisis. Las gomas de mascar hechas con sustitutos de sacarosa estimulan la producción salival, neutralizan y elevan su pH, reconociéndosele su función promotora de salud bucal en varias publicaciones científicas. Los efectos anticariogénicos del xilitol están establecidos en diversos estudios. No existen suficientes estudios sobre los efectos de las sustancias: stevia, d-tagatosa, magnolia, eritritol y fostato de calcio.

A bibliographic review was carried out on the effects of sucrose substitute total sugars on the state of oral health. The scientific articles were in the following digital scientific databases: Scopus, PubMed, Web of Science and Ovid. The sources used were freely accessible, 49 of the manuscripts gotten by the search were discarded and 23 were used. 43.5% of the articles inclu-ded showed results of clinical trials on chewing gums with xylitol, 39.1% about other com-pounds (stevia, magnolia, erythritol, calcium phosphate), 13% narrative reviews and the 4.4% meta-analysis. Chewing gums made with sucrose substitutes stimulate salivary production, neutralize and raise its pH. That is why, its role in promoting oral health is recognized in several scientific publications. The anticariogenic effects of xylitol were established in various studies. There were not enough studies on the effects of the substances: stevia, d-tagatose, magnolia, erythritol and calcium phosphate

Symptom assessment after nasal irrigation with xylitol in the postoperative period of endonasal endoscopic surgery / Avaliação dos sintomas após irrigação nasal com xilitol no período pós-operatório de cirurgias endoscópicas endonasais

Abstract Introduction: Chronic rhinosinusitis is an inflammatory condition of the nasal cavity and the paranasal sinuses that requires multifactorial treatment. Xylitol can be employed with nasal irrigation and can provide better control of the disease. Objective: To evaluate the association between the effects of nasal lavage with saline solution compared to nasal lavage with a xylitol solution. Methods: Fifty-two patients, divided into two groups (n = 26 in the "Xylitol" group and n = 26 in the "Saline solution" group) answered questionnaires validated in Portuguese (NOSE and SNOT-22) about their nasal symptoms and general symptoms, before and after endonasal endoscopic surgery and after a period of 30 days of nasal irrigation. Results: The "Xylitol" group showed significant improvement in pain relief and nasal symptom reduction after surgery and nasal irrigation with xylitol solution (p < 0.001). The "Saline solution" group also showed symptom improvement, but on a smaller scale. Conclusion: This study suggests that the xylitol solution can be useful in the postoperative period after endonasal endoscopic surgery, because it leads to a greater reduction in nasal symptoms.

Resumo Introdução: Rinossinusite crônica é um quadro de inflamação da cavidade nasal e dos seios paranasais que necessita de tratamento multifatorial. O xilitol pode ser associado às irrigações nasais e pode prover melhor controle da doença. Objetivo: Avaliar a relação entre os efeitos da lavagem nasal com solução fisiológica em comparação à lavagem nasal com solução de xilitol. Método: Divididos em dois grupos (n = 26 no grupo Xilitol e n = 26 no grupo Soro), 52 pacientes responderam à questionários validados em língua portuguesa (NOSE e SNOT-22) sobre seus sintomas nasais e sintomas gerais, antes e depois de cirurgia endoscópica endonasal e após um período de 30 dias de irrigação nasal. Resultados: O grupo Xilitol apresentou melhoria significativa dos sintomas de dor e sintomas nasais após a cirurgia e a irrigação nasal com solução de xilitol (p < 0,001). O grupo Soro também apresentou melhoria dos sintomas, porém em menor escala. Conclusão: Este estudo sugere que a solução de xilitol pode ser usada no período pós-operatório de cirurgia endoscópica endonasal por levar a uma maior redução nos sintomas nasais.

Antiplaque and antigingivitis efficacy of medicated and non-medicated sugar-free chewing gum as adjuncts to toothbrushing: systematic review and network meta-analysis.

OBJECTIVE: This network meta-analysis (NMA) assessed the antiplaque and anti-inflammatory efficacy of different sugar-free chewing gums (SFCG) as adjuncts to toothbrushing. MATERIAL AND METHODS: PubMed, Scopus, EMBASE, Web of Science, and CENTRAL databases were searched up to February 2021 to identify randomized controlled trials, involving adults, comparing antiplaque and anti-inflammatory effects of SFCG, with different active ingredients, as adjunctive to mechanical control of biofilm, with a minimum of 7-day of follow-up. Plaque and gingival indexes were assessed. The risk of bias assessment was performed with the RoB 2.0 tool. NMA, and pairwise meta-analyses were performed for both dental plaque and gingival indexes. RESULTS: Twelve studies were included, comprising 850 (antiplaque) and 1459 (gingival inflammation) subjects randomized into 9 interventions: (1) chlorhexidine; (2) chlorhexidine + xylitol (CHX+Xyl); (3) green tea + xylitol (GT+Xyl); (4) magnolia; (5) Lactobacillus reuteri; (6) vitamin C + xylitol; (7) vitamin + carbamide; (8) eucalyptus; and (9) negative control, sorbitol, gum base only, or no chewing gum. No statistically significant differences were detected among SFCG, with different active ingredients, for both antiplaque and anti-inflammatory efficacy (p > 0.05). However, SFCG with GT+XyL outperformed negative control gums regarding antiplaque efficacy (SMD, - 2.93; 95% CrI, - 0.45 to - 5.38). The SUCRA results showed that SFCG containing GT+Xyl was ranked first, for both antiplaque and anti-inflammatory outcomes. CONCLUSION: SFCG containing GT+Xyl showed better antiplaque effect over negative controls. However, cautious interpretation is required due to the low number of direct comparisons arms. These shortcomings underscore the need for RCTs with mostly head-to-head comparison that provide more conclusive evidence. CLINICAL RELEVANCE: There is no robust evidence for the clinical indications of sugar-free chewing gums as adjunct to toothbrushing for the control of biofilm or the treatment of gingivitis.

Analysis of glucose and xylose metabolism in new indigenous Meyerozyma caribbica strains isolated from corn residues.

Aiming to broaden the base of knowledge about wild yeasts, four new indigenous strains were isolated from corn residues, and phylogenetic-tree assemblings on ITS and LSU regions indicated they belong to Meyerozyma caribbica. Yeasts were cultivated under full- and micro-aerobiosis, starting with low or high cell-density inoculum, in synthetic medium or corn hydrolysate containing glucose and/or xylose. Cells were able to assimilate both monosaccharides, albeit by different metabolic routes (fermentative or respiratory). They grew faster in glucose, with lag phases ~ 10 h shorter than in xylose. The hexose exhaustion occurred between 24 and 34 h, while xylose was entirely consumed in the last few hours of cultivation (44-48 h). In batch fermentation in synthetic medium with high cell density, under full-aerobiosis, 18-20 g glucose l-1 were exhausted in 4-6 h, with a production of 6.5-7.0 g ethanol l-1. In the xylose medium, cells needed > 12 h to consume the carbohydrate, and instead of ethanol, cells released 4.4-6.4 g l-1 xylitol. Under micro-aerobiosis, yeasts were unable to assimilate xylose, and glucose was more slowly consumed, although the ethanol yield was the theoretical maximum. When inoculated into the hydrolysate, cells needed 4-6 h to deplete glucose, and xylose had a maximum consumption of 57%. Considering that the hydrolysate contained ~ 3 g l-1 acetic acid, it probably has impaired sugar metabolism. Thus, this study increases the fund of knowledge regarding indigenous yeasts and reveals the biotechnological potential of these strains.

Symptom assessment after nasal irrigation with xylitol in the postoperative period of endonasal endoscopic surgery.

INTRODUCTION: Chronic rhinosinusitis is an inflammatory condition of the nasal cavity and the paranasal sinuses that requires multifactorial treatment. Xylitol can be employed with nasal irrigation and can provide better control of the disease. OBJECTIVE: To evaluate the association between the effects of nasal lavage with saline solution compared to nasal lavage with a xylitol solution. METHODS: Fifty-two patients, divided into two groups (n = 26 in the "Xylitol" group and n = 26 in the "Saline solution" group) answered questionnaires validated in Portuguese (NOSE and SNOT-22) about their nasal symptoms and general symptoms, before and after endonasal endoscopic surgery and after a period of 30 days of nasal irrigation. RESULTS: The "Xylitol" group showed significant improvement in pain relief and nasal symptom reduction after surgery and nasal irrigation with xylitol solution (p < 0.001). The "Saline solution" group also showed symptom improvement, but on a smaller scale. CONCLUSION: This study suggests that the xylitol solution can be useful in the postoperative period after endonasal endoscopic surgery, because it leads to a greater reduction in nasal symptoms.