ABSTRACT
Aims@#This study aimed to evaluate the effect of electroporation on the growth characteristics and antimicrobial activity of lactic acid bacteria (LAB) including Bifidobacterium longum ATCC 15707, Lactobacillus acidophilus ATCC 314, Lactobacillus casei ATCC 393 and Lactobacillus fermentum ATCC 14931.@*Methodology and results@# Electroporation with the strength of electric field at 1.0–3.0 kV/cm for 2-4 millisecond were applied on the bacterial cultures. All bacterial cultures showed significant (P<0.05) increased in cell viability (40%-325%) upon electroporation. Such treatment also increased the acidity of the cell where the pH of cells decreased upon treatment. In tandem with the increased viability, electroporated bacterial cultures also showed higher proteolytic activity compared to the control (P<0.05). The electroporation treatment also increased (P<0.05) the bacteriocin activity of treated cells compared to the control. However, the molecular weight of bacteriocins produced were not affected by electroporation. Treated cells also possessed better antimicrobial activity. According to the results collected, all treated LAB strains showed 11.5%-113.8% higher (P<0.05) inhibitory activity compared to untreated control against tested pathogenic bacteria, Escherichia coli and Listeria monocytogenes that commonly associated with food contamination. Microarray data analysis showed that electroporation regulated the entities encoding for surface protein and transporter.@*Conclusion, significance and impact of study@#The results from this study suggested that electroporation could enhance the growth characteristics and antimicrobial activity of LAB by modifying the surface regions of the cells. This result may serve as the reference for food manufacturers to opt for effective biopreservation method and produce food with extended shelf life.
Subject(s)
Electroporation , LactobacillalesABSTRACT
Aims@#Up to date, there is limited heat-treated non-dairy probiotic food products in the market. Therefore, this study aims to develop a new functional cracker containing microencapsulated pumpkin-probiotics with acceptable sensory characteristics. @*Methodology and results@#The sample crackers (crackers with beads containing pumpkin and probiotic) have achieved a minimum required viable count of 6.26 ± 0.05 Log10 CFU/g and showed significantly (p<0.05) lower viability loss compared to control crackers (crackers with beads containing probiotic only). Sample crackers were perceived as acceptable (score 6.61) by 93 untrained panelists when tested using 9-point hedonic test. The ash content of sample pumpkin crackers was significantly higher (p<0.05) than the control. Both sample and control pumpkin crackers exhibit high level of total dietary fiber (>6%). @*Conclusion, significance and impact of study@#In summary, development of pumpkin crackers with microencapsulated L. acidophilus could be an alternative healthy option cracker for consumers. In addition, the results also suggested a new technique to deliver live culture in baked goods.
ABSTRACT
Introduction: Acute respiratory tract infections (ARTIs) are a major cause of morbidity and mortality in paediatric patients. Therefore, early detection of the viral aetiologies of ARTIs is essential for patient management and infection control. In this study, we evaluated the performance of a new multiplex polymerase chain reaction (PCR) assay (xTAG Respiratory Viral Panel [RVP] Fast v2) in the detection of respiratory viruses by comparing it with that of viral culture and direct immunofluorescence (IF) staining. Methods: Nasopharyngeal swab and aspirate samples were collected prospectively from 199 patients who presented with ARTIs at the University Malaya Medical Centre (UMMC) in Kuala Lumpur, Malaysia during a 10-month period. The PCR assay was conducted in parallel with conventional culture and direct IF staining methods. Results: The positive rate of the xTAG RVP Fast v2 assay (78.4%) in detecting respiratory viruses was higher than that of the viral isolation (7.5%) and direct IF (23.1%) methods. Using the xTAG RVP Fast v2 assay, human enterovirus/human rhinovirus (HEV/HRV) was the most frequently detected (46.2%). The xTAG RVP Fast v2 assay revealed mixed infection caused by two or three respiratory viruses in 40 specimens, and these were undetected by the viral isolation and direct IF methods. Conclusion: The xTAG RVP Fast v2 assay was superior to conventional methods in the identification of common respiratory viruses, with higher sensitivity and shorter turnaround times for laboratory results.