BackgroundBiofilm formation by Helicobacter pylori may be one of the factors influencing eradication outcome. However, genetic differences between good and poor biofilm forming strains have not been studied.Materials and MethodsBiofilm yield of 32 Helicobacter pylori strains (standard strain and 31 clinical strains) were determined by crystal-violet assay and grouped into poor, moderate and good biofilm forming groups. Whole genome sequencing of these 32 clinical strains was performed on the Illumina MiSeq platform. Annotation and comparison of the differences between the genomic sequences were carried out using RAST (Rapid Annotation using Subsystem Technology) and SEED viewer. Genes identified were confirmed using PCR.ResultsGenes identified to be associated with biofilm formation in H. pylori includes alpha (1,3)-fucosyltransferase, flagellar protein, 3 hypothetical proteins, outer membrane protein and a cag pathogenicity island protein. These genes play a role in bacterial motility, lipopolysaccharide (LPS) synthesis, Lewis antigen synthesis, adhesion and/or the type-IV secretion system (T4SS). Deletion of cagA and cagPAI confirmed that CagA and T4SS were involved in H. pylori biofilm formation.ConclusionsResults from this study suggest that biofilm formation in H. pylori might be genetically determined and might be influenced by multiple genes. Good, moderate and poor biofilm forming strain might differ during the initiation of biofilm formation.
The biofilm-forming-capability of Helicobacter pylori has been suggested to be among factors influencing treatment outcome. However, H. pylori exhibit strain-to-strain differences in biofilm-forming-capability. Metabolomics enables the inference of spatial and temporal changes of metabolic activities during biofilm formation. Our study seeks to examine the differences in metabolome of low and high biofilm-formers using the metabolomic approach. Eight H. pylori clinical strains with different biofilm-forming-capability were chosen for metabolomic analysis. Bacterial metabolites were extracted using Bligh and Dyer method and analyzed by Liquid Chromatography/Quadrupole Time-of-Flight mass spectrometry. The data was processed and analyzed using the MassHunter Qualitative Analysis and the Mass Profiler Professional programs. Based on global metabolomic profiles, low and high biofilm-formers presented as two distinctly different groups. Interestingly, low-biofilm-formers produced more metabolites than high-biofilm-formers. Further analysis was performed to identify metabolites that differed significantly (p-value < 0.005) between low and high biofilm-formers. These metabolites include major categories of lipids and metabolites involve in prostaglandin and folate metabolism. Our findings suggest that biofilm formation in H. pylori is complex and probably driven by the bacterium’ endogenous metabolism. Understanding the underlying metabolic differences between low and high biofilm-formers may enhance our current understanding of pathogenesis, extragastric survival and transmission of H. pylori infections.
Osmosonication represents a potential processing alternative for producing safe and high-quality concentrated fruit juice without applying thermal treatments. Findings reported in this article can also be applied by industries when concentrating juices by classical means at relatively low temperature. It provides industries with a mathematical model specific for blackberry juice, from which different combinations of sonication time and storage time of concentrate can be chosen to achieve safety and quality goals.
The effect of osmotic pressure alone or combined with the application of sonication on the reduction of Salmonella spp. in concentrated orange juice was evaluated. Frozen concentrated orange juice (12.6 MPa, pH = 3.2), a neutral sugar solution (9.2 MPa, pH = 6.6) and an acid sugar solution (8.8 MPa, pH = 3.2) were inoculated with Salmonella spp. (6-7 log cfu/mL). Reductions were measured after different storage times with or without previous sonication treatment of 1 h . No significant osmotic shock was observed. Reductions appeared to increase over storage time in high osmotic environments. Reductions were also significantly higher for sonicated samples when compared with nonsonicated samples. The highest reduction (7.21 log cfu/mL) was found for concentrated orange juice sonicated during 60 min and stored for 168 h. Combination of sonication and osmotic evaporation (osmosonication) represents a promising new technology that could be designed to athermally produce safe, concentrated fruit juices.
PRACTICAL APPLICATIONSThe results derived from this research indicate that combining sonication with osmotic pressure during storage of concentrated orange juice provides a * Corresponding
Ultrasound is a useful alternative to thermal processing that can be applied to many food products and juices to aid with enzymes and microorganism inactivation and to improve the efficiency of unit operations generally applied in the food industry. The aim of this study was to evaluate the effect of a high-intensity sonication treatment (frequency 20 kHz; intensity 39.4 W/cm2) applied for treatment times from 0 to 105 min on the content of polyphenols, vitamin C, organic acids, and carotenoids, and on the hydrophilic and lipophilic antioxidant capacity and color of orange juice. Treatments were performed in triplicate and data was statistically analyzed. Sonication time did not have a significant effect ( P > 0.05) on total polyphenols, total vitamin C, organic acid, and carotenoid contents, lipophilic antioxidant capacity, or juice color. The hydrophilic antioxidant activity and the lutein content increased significantly ( P < 0.05) with increased sonication time. These results may be useful as a baseline for the development of sonication treatments that could be used in combination with other traditional and emerging processing approaches to protect the most important bioactive compounds and quality properties of orange juice.
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