Comparison of In-house and Commercial Real-time PCR Systems for the Detection of Enterobacteriaceae and their Evaluation Within an Interlaboratory Study Using Infant Formula Samples

A Comprehensive Evaluation of Enterobacteriaceae Primer Sets for Analysis of Host-Associated Microbiota

Enterobacteriaceae is one of the most important bacterial groups within the Proteobacteria phylum. This bacterial group includes pathogens, commensal and beneficial populations. Numerous 16S rRNA gene PCR-based assays have been designed to analyze Enterobacteriaceae diversity and relative abundance, and, to the best of our knowledge, 16 primer pairs have been validated, published and used since 2003. Nonetheless, a comprehensive performance analysis of these primer sets has not yet been carried out. This information is of particular importance due to the recent taxonomic restructuration of Enterobacteriaceae into seven bacterial families. To overcome this lack of information, the identified collection of primer pairs (n = 16) was subjected to primer performance analysis using multiple bioinformatics tools. Herein it was revealed that, based on specificity and coverage of the 16S rRNA gene, these 16 primer sets could be divided into different categories: Enterobacterales-, multi-family-, multi-genus- and Enterobacteriaceae-specific primers. These results highlight the impact of taxonomy changes on performance of molecular assays and data interpretation. Moreover, they underline the urgent need to revise and update the molecular tools used for molecular microbial analyses.

Preliminary study on alleviation of heat-induced intestinal inflammation through compensatory effects of glucose oxidase

1. The influence of glucose oxidase (GOD) supplementation on growth, gut inflammation and its compensatory effects in broilers was investigated before and after heat stress.2. Before heat stress, one-day-old broilers were divided into two groups: the control (CON) and GOD (100 g/t complete feed) groups. On d 21, the CON group was equally divided into CON1 and CON2 groups, and heat stress (35°C) was applied to the CON2 and GOD groups for 8 h/day to the end of the study, d 27 of age. The chickens were either killed before heat stress and 2 d after heat stress for the determination of cytokines in the liver and ileum, serum antioxidant enzymes and ileal microbiota. Growth performance was determined before and 7 d after heat stress.3. The GOD decreased Clostridiales and Enterobacteriaceae families of bacteria and increased ileal nuclear factor-κB, interleukin-1β, and interferon-γ (P < 0.05) before heat stress. The broilers exhibited compensatory effects, including increases in ileal sirtuin-1, heat shock protein 70 expression, liver nuclear factor erythroid 2-related factor 2 content, serum total antioxidant capacity and glutathione peroxidase level (P < 0.05). At 2 d after heat stress, inflammatory factors were increased in both the CON2 and GOD groups, but the levels were lower in the GOD than CON2 (P < 0.05). On d 7 after heat stress, GOS alleviated heat stress induced growth retardation (P < 0.05).4. These data suggested that GOD supplementation in broiler diets before heat stress stimulated intestinal oxidative stress and produced a compensatory response, which prevented a rapid increase in intestinal inflammatory factors and helped to maintain growth performance under heat stress.

Application of Real Time PCR for the Detection and Enumeration of Vibrio parahaemolyticus from Seafood in Sarawak (Malaysia)

Vibrio parahaemolyticus has been associated as the major cause of food poisoning and gastroenteritis in manycountries including Southeast Asia. Their human infection is regularly associated with the consumption of rawor undercooked seafood and contaminated water supplies. A rapid method of detection is important to monitorthe occurrence of V. parahaemolyticus in both food and environment samples especially in Malaysia. Thus, theaim of this study was to detect and enumerate V. parahaemolyticus from seafood by using the real-time PCRbased on the SYBR green assay. targeting the thermolabile (tl) gene. The assay was applied on 24 seafoodsamples comprised of 6 cockles, 6 prawns, 6 squids and 6 fishes. In this study, all of the six cockles and prawnswere positive for the presence of V. parahaemolyticus while fish samples have only 2 positive isolates.However, this study recorded no presence of V. parahaemolyticus in squids. Overall, the real-time PCR assaywas proven to be highly specific, and is sensitive in detecting and enumerating V. parahaemolyticus in theseafood samples. In addition, this study has proven that seafood (especially cockles and prawns) are potentialsources for V. parahaemolyticus.