Determination of volatile aroma composition of some hazelnut varieties grown in Akçakoca conditions.

Türkiye is leading country for hazelnut production and hazelnut orchards are widely established in Black Sea belt. Akçakoca district belongs to Duzce province is accepted as one of the most important production areas. In this research, volatile aroma components in nuts (kernels) of Çakildak, Kara, Sari (Mincane), Tombul and Yomra hazelnut varieties grown in Akçakoca district were determined by SPME/GC-MS. The analysis revealed the presence a total of 55 different volatile aroma components. These analyzes identified the presence of 39 descriptive volatile aroma compounds with significant differences between varieties. Çakildak variety differed from the other varieties in terms of Isopentyl alcohol and Ethyl acetate components. At the same time, some volatile aroma compounds are commonly detected among the all varieties. This study has shown that the climate and soil conditions of Akçakoca cause the emergence of unique taste profiles through the effect of hazelnut varieties on volatile aroma components. The findings emphasize that regional diversity and local ecosystem factors play a critical role in determining flavor in hazelnut kernels. This study also emphasizes that variety selection is a critical factor in ensuring sustainability in hazelnut cultivation and that determining volatile aroma components is an important indicator in this selection.

Metabolic profiles of Weissella spp. postbiotics with anti-microbial and anti-oxidant effects.

INTRODUCTION: This present study aimed to isolate beneficial bacteria from honey bee pollen microbiota and to investigate the metabolite profiles of postbiotics exhibiting anti-microbial and anti-oxidant properties. METHODOLOGY: Pour plate technique was used to isolate bacteria from honey bee (Apis mellifera L.) pollen samples. Different colonies grown on agar plates were selected and screened for their anti-microbial activity against important pathogens using agar well diffusion assay. The isolates that exhibited remarkable inhibitory effects against all tested pathogens were identified by 16S rRNA sequence analysis. DPPH (2, 2-diphenyl-1-picrylhydrazil) free radical scavenging assays were used to assess the antioxidant capacity of their postbiotics. Besides, the total phenolic and total flavonoid compounds in postbiotics were determined as gallic acid and quercetin equivalents, respectively. The valuable metabolites in postbiotics were also profiled using chromatographic tools and Mass Spectrophotometry (MS) analysis. RESULTS: Twenty-seven strains were isolated from different honey bee pollen samples. 16 out of the 27 strains exhibited antagonistic activity against at least one reference strain of pathogens, tested. The most effective strains belonging to the genus Weissella were identified as W. cibaria and W. confusa. Postbiotics above 10 mg/mL exhibited higher radical scavenging activity and high total phenolic and total flavonoid contents. MS analysis demonstrated that metabolites in postbiotics derived from Weissella spp. were found very similar to the metabolites found in honeybee pollen. CONCLUSIONS: The outcomes of this study revealed that honey bee pollen could be considered a potential source for the bacteria which produce anti-microbial and anti-oxidant agents. The similarity with the nutritional dynamics of honey bee pollen also indicated that postbiotics could also be used as novel and sustainable food supplements.

Analysis of Chemical Structure and Antibiofilm Properties of Exopolysaccharides from Lactiplantibacillus plantarum EIR/IF-1 Postbiotics.

Previous studies have indicated that the exopolysaccharides of lactic acid bacteria exhibit antibiofilm activity against non-oral bacteria by preventing their initial adhesion to surfaces and by downregulating the expression of genes responsible for their biofilm formation. The aims of this study were to (1) characterize the exopolysaccharides (EPSs) of Lactobacillus plantarum EIR/IF-1 postbiotics, (2) test their antibiofilm effect on dual biofilms, and (3) evaluate their bacterial auto-aggregation, co-aggregation, and hydrocarbon-binding inhibitory activity. The EPSs were characterized by FTIR, HPLC, and thermogravimetric analysis. Bacterial auto- and co-aggregation were tested by Kolenbrander's method and hydrocarbon binding was tested by Rosenberg's method. Dual biofilms were formed by culturing Fusobacterium nucleatum ATCC 25586 with one of the following bacteria: Prevotella denticola ATCC 33185, P. denticola AHN 33266, Porphyromonas gingivalis ATCC 33277, P. gingivalis AHN 24155, and Filifactor alocis ATCC 35896. The EPSs contained fractions with different molecular weights (51 and 841 kDa) and monosaccharides of glucose, galactose, and fructose. The EPSs showed antibiofilm activity in all the biofilm models tested. The EPSs may have inhibited bacterial aggregation and binding to hydrocarbons by reducing bacterial hydrophobicity. In conclusion, the EPSs of L. plantarum EIR/IF-1, which consists of two major fractions, exhibited antibiofilm activity against oral bacteria, which can be explained by the inhibitory effect of EPSs on the auto-aggregation and co-aggregation of bacteria and their binding to hydrocarbons.

The role of microbiota-derived postbiotic mediators on biofilm formation and quorum sensing-mediated virulence of Streptococcus mutans: A perspective on preventing dental caries.

Dental caries is not only one of the most prevalent diseases worldwide, but also a public health problem, undoubtedly. Among the various species of cariogenic bacteria, Streptococcus mutans is considered to be the major etiological pathogen of dental caries. The present study aimed to assess the influence of microbiota-derived postbiotic mediators (PMs) on the pathogenesis of dental caries. Within this aim, the antibacterial (agar diffusion method) and antibiofilm (crystal violet assay) characteristics of PMs derived from Lactiplantibacillus plantarum EIR/IF-1, Lactiplantibacillus curvatus EIR/DG-1, and Lactiplantibacillus curvatus EIR/BG-2 were analyzed against S. mutans (ATCC 25175). According to the results, PMs of the strain EIR/IF-1, isolated from infant feces showed the highest inhibitory effect (pH-dependent). Besides, sub-MIC doses of all PMs eliminated the biofilm formation following the co-treatment and pre-treatment assays. The reduction of cell viability and notable changes in biofilm formation were also confirmed both on glass coverslips and ex vivo human tooth surfaces by confocal laser scanning microscopy and scanning electron microscopy. Moreover, sub-MIC values of PMs down-regulated the expression of gtfC, comA, and comX, without any significant growth inhibition. Organic acids, fatty acids, and vitamins in PMs were also reported. Overall, these findings indicated the possible preventive role of microbiota-derived PMs in the pathogenesis of dental caries.

Weissella cibaria EIR/P2-derived exopolysaccharide: A novel alternative to conventional biomaterials targeting periodontal regeneration.

Healing and regeneration of periodontium are considered as a complex physiological process. Therefore, treatments need to be addressed with highly effective components modulating the multiple pathways. In this study, exopolysaccharide (EPS) produced by Weissella cibaria EIR/P2, was partially purified from the culture supernatant and subjected to characterization within the aim of evaluating its potential for periodontal regeneration. High-Performance Liquid Chromatography analysis revealed a single-peak corresponding to the glucose which identified the EPS as dextran. Fourier transform-infrared spectra were also displayed characteristic peaks for polysaccharides. According to the results of gel permeation/size exclusion-chromatography, the molecular mass was determined to be 8 × 106 Da. To clarify its anti-bacterial activity on Streptococcus mutans, effects on viability and biofilm formation was evaluated. At 50 mg/mL, dextran exhibited a bactericidal effect with 70% inhibition on biofilm formation. Besides, dose-dependent antioxidant effects were also detected. The efficacy of dextran in enhancing the viability of human periodontal ligament fibroblast cells (hPDLFCs) was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium-bromide (MTT) assay, and an increase was observed in the viability of hPDLFCs. In conclusion, dextran derived from W. cibaria can be potentially used as a multi-functional bioactive polymer in the design of new therapeutic strategies to promote healing and regeneration of periodontium.