Research Publications (Food Safety)

Myxococcus xanthus displays several social behaviors involving cell–cell contacts. To understand the role of the lipopolysaccharide (LPS) in these behaviors, we identified key enzymes involved in O‐antigen and LPS biosynthesis: the polyisoprenyl‐phosphate hexose‐1‐phosphate transferase, responsible for priming O‐antigen synthesis and the O‐antigen ligase.

Vibrio cholerae mutants lacking lytic transglycosylases MltC and RlpA are defective for daughter cell separation. Our results suggest that lytic transglycosylases at the division septum serve as a back‐up mechanism to cleave peptidoglycan strands that cannot be cleared by highly‐regulated amidase activity, and to clear peptidoglycan debris that may block the completion of outer‐membrane invagination.

The bacterial pathogen Salmonella Typhimurium invades intestinal epithelial cells. Following invasion, the bacteria can either replicate within a membrane bound vacuole or escape into the cytosol. We show here that SipA, a secreted bacterial protein, facilitates the early survival and/or initiation of replication of cytosolic Salmonella. Summary Salmonella enterica serovar Typhimurium is a facultative intracellular pathogen that invades the intestinal epithelium.

SiiA is required for the function of the Salmonella SPI4‐encoded T1SS. Using structural and functional studies, we show that the periplasmic domain of SiiA displays a peptidoglycan (PG)‐binding OmpA‐like fold and that SiiA binds PG in vitro and in vivo, albeit at an acidic pH, only. SiiA in complex with SiiB translocates protons across the inner membrane; however, further studies are needed to understand how SiiA uses the proton motif force to support the T1SS.

The interactions between plant roots and soil are an area of active research, particularly in terms of water and nutrient uptake. Since non‐invasive, in vivo studies are required, tomographic imaging appears an obvious method to use, but no one imaging modality is well suited to capture the complete system.

Different antibiotic‐based drugs are being used for the treatment of Aeromonas hydrophila infection in rainbow trout, and several studies emphasize the use of medicinal plants as immunostimulants for prophylactic measure against Aeromoniasis disease. However, therapeutic effects of aqueous methanolic extracts of tetra (Cotinus coggygria) against A. hydrophila in rainbow trout were not investigated.

ABSTRACT Aims:  Microbiological and molecular analysis of antibiotic resistance in Gram‐positive cocci derived from the Italian PDO dairy food product Mozzarella di Bufala Campana (MBC). Methods and Results:  177 coccal colonies were assigned to Enterococcus faecalis, Lactococcus lactis and Streptococcus bovis genera by ARDRA analysis. Among them, 16 Ent. faecalis, 26 L. lactis and 39 Strep. bovis displayed high MIC values for tetracycline, while 17 L.

Aims:  To assess norovirus (NoV) contamination in aquatic ecosystems in the city of Florianópolis, in Southern Brazil, in order to provide epidemiological data that can support actions for environmental contamination control. Methods and Results:  An adsorption‐elution method, followed by ultrafiltration, was performed to concentrate the viruses. NoV were detected using semi‐nested PCR and quantified by real‐time PCR.

ABSTRACT Aim:  To identify a DNA sequence specific to a bacterium found in poultry litter that was indicative of faecal contamination by poultry sources. Methods and Results:  Faecally‐contaminated poultry litter and soils were used as source material for development of a quantitative polymerase chain reaction (qPCR) method targeting the 16S rRNA gene of a Brevibacterium sp. The identified sequence had 98% nucleotide identity to the 16S rRNA gene of B. avium.

Aims:  This study aimed to compare the efficacy of different disinfection methods in eliminating Salmonella contamination from turkey houses. Methods and results:  Fifty depopulated turkey houses which had all housed Salmonella‐positive flocks were visited after cleaning and disinfection. A minimum of 45 swab samples from different surfaces were taken per house and analysed for the presence of Salmonella.

Aims:  To develop simple and rapid PCR‐fingerprinting methods for Vibrio cholerae O1 (El Tor and classical biotypes) and O139 serogroup strains which cause major cholera epidemics, on the basis of the diversity of superintegron (SI) carried by these strains. Methods and Results:  PCR‐restriction fragment length polymorphism (PCR‐RFLP) assay was developed targeting region between integrase gene in the SI and its nearby ORF, followed by BglI digestion. Besides, a V.

Acinetobacter baumannii causes several nosocomial infections and poses major threat when it is multidrug resistant. Even pan drug‐resistant strains have been reported in some countries. The intensive care unit (ICU) mortality rate ranged from 45.6% to 60.9% and it is as high as 84.3% when ventilator‐associated pneumonia was caused by XDR (extensively drug resistant) A. baumannii.

Use of bacteria in cancer therapy, despite being considered as a potent strategy, has not really picked up the way other methods of cancer therapies have evolved. However, in recent years, the interest on use of bacteria to kill cancer cells has renewed considerably. The standard and widely followed strategies of cancer treatment often fail either due to the complexity of tumour biology or because of the accompanying side effects.

Actinomycetes are a rich source for secondary metabolites with a diverse array of biological activities. Among the various genera of actinomycetes, the genus Saccharopolyspora has long been recognized as a potential source for antibiotics and other therapeutic leads that belong to diverse classes of natural products. Members of the genus Saccharopolyspora have been widely reported from several natural sources including both terrestrial and marine environments.

Aims First, two inactivation models were compared for different phenotypic profiles of Escherichia coli O26 using ultraviolet‐C light (UV‐C) and thermal treatment (T), by means of Central Composite Rotatable Design of Experiment (CCRD). Second, we aimed to evaluate the subsequent survival and persistence of cells in simulated gastric fluid (SGF). Methods and Results Two strains of E. coli O26, a wild‐type strain and a clinical ATCC strain were used in both steps.

Aims Suilysin (SLY), a crucial virulence‐related factor, has multiple cytotoxicities that are regarded as playing a key role in several diseases induced by Streptococcus suis. The aim of this study was to identify an effective inhibitor of SLY and to evaluate the potential inhibitory effect of the inhibitor against S. suis virulence.

Aim The increase in the number of fungal infections worldwide, coupled with the limitations of current antifungal chemotherapy, demand the development of safe and effective new antifungals. Here, we presented the synthesis of a novel acridone (M14) and its antifungal properties against Candida and dermatophytes species. Methods and Results A series of 17 acridones was designed, synthesized and tested for its antifungal activity.

Aims This study evaluated the efficacy of essential oil from Origanum vulgare L. (oregano; OVEO) and Rosmarinus officinalis L. (rosemary; ROEO) to inactivate sessile cells of Salmonella enterica serovar Enteritidis 86 (SE86) in young and mature biofilms formed on stainless steel.

Aims To investigate the effects of ohmic heating (OH) and water bath heating (WB) on the membrane permeability, membrane structure, intracellular organization and leakage of intracellular substances of Escherichia coli O157:H7 at the same inactivation level and at a heating temperature of 72°C. Methods and Results Flow cytometry analysis indicated that membrane permeability of E. coli O157:H7 by OH was comparable to WB at 72°C.

The production of livestock and poultry faces major challenges to meet the global demand for meat and dairy products and eggs due to a steady increase in the world’s population and the ban of antibiotics in animal production. This ban has forced animal nutritionists to seek for natural alternatives to antibiotics. In this context, the yeast Saccharomyces cerevisiae has received considerable attention in the last decade.

Aims Predicting bacterial resistance provides valuable information that can assist in clinical decisions. With recent advances in whole genome sequencing technology, the detection of antibiotic resistance (AR) proteins directly from genomic data is becoming feasible. AR genes/proteins can be identified using best‐hit methods that work by comparing candidate sequences with known AR genes in public databases.

Aims The aim of this study was to develop a rapid detection and differentiation method for pathogenic Listeria species in stone fruits. Methods and Results We utilized activated charcoal enrichment media (ACM) to induce overexpression and hypersecretion of pathogenic Listeria virulence proteins which can subsequently be detected via immunoblot analysis. Plum and nectarine slices spiked with either L. monocytogenes or L.

Aims To evaluate antibacterial properties of Methylsulfonylmethane (MSM) on Escherichia coli (MDRE21) and Salmonella enterica serovar Kinshasa (SK132). Methods and Results Bacterial proliferation analysis was measured spectrophotometrically during log phase growth with 0, 3, 5, 7, 10, 12 and 16% MSM. To assess the mechanism of inhibition, cultures were grown overnight with 0–16% MSM and enumerated on unmedicated Brain Heart Infusion Agar (BHIA) or BHIA with 0–16 % MSM.

Aims The purposes were to evaluate the detection of low levels of Campylobacter in water by dead‐end ultrafiltration (DEUF) to determine the sensitivity and suitability for use under field condition. Methods and Results The DEUF technique followed by detection according to ISO 10272 was tested on artificially and naturally contaminated water.

Aims The objective of this study was to assess the probiotic potential of genuine strains of Bifidobacterium longum 51A and Weissella paramesenteroides WpK4, in experimental giardiasis. Methods and Results The bacteria were administered orally to gerbils (Meriones unguiculatus) 10 days before oral infection with trophozoites of Giardia lamblia.