Research Publications (Food Safety)

Lysozyme is an important component of the innate immune system. It functions by hydrolysing the peptidoglycan (PG) layer of bacteria. The human pathogen Listeria monocytogenes is intrinsically lysozyme resistant. The peptidoglycan N-deacetylase PgdA and O-acetyltransferase OatA are two known factors contributing to its lysozyme resistance. Furthermore, it was shown that the absence of components of an ABC transporter, here referred to as EslABC, leads to reduced lysozyme resistance.

Persistence of Listeria monocytogenes in retail deli environments is a serious food safety issue, potentially leading to cross-contamination of ready-to-eat foods such as deli meats, salads, and cheeses. We previously discovered strong evidence of L. monocytogenes persistence in delis across multiple states. We hypothesized that this was correlated with isolates' innate characteristics, such as biofilm-forming capacity or gene differences.

Glucose oxidase (GOx) with high enzyme activity at low temperature (4°C) is potentially useful for food preservation, especially for aquatic products preservation. A cold-active GOx with approximately 83% similarity to known protein sequences, was isolated from Penicillium sp. MX3343 and expressed in Pichia pastoris X33. Through high cell density fermentation, the yield of recombinant enzyme (named GOxP5) reached 458.6 U/mL.

Central nervous system (CNS) infections continue to be associated with significant neurological morbidity and mortality despite various existing therapies. Adjunctive steroid therapy has been employed clinically to reduce inflammation in the treatment of CNS infections across various causative pathogens.

Antibiotic resistance is an important issue affecting humans and livestock. Antimicrobial peptides are promising alternatives to antibiotics. In this study, the antimicrobial peptide Css54, isolated from the venom of C. suffuses, was found to exhibit antimicrobial activity against bacteria such as Listeria monocytogenes, Streptococcus suis, Campylobacter jejuni, and Salmonella typhimurium that cause zoonotic diseases.

The scattering experiment is shown in Figure 1. The aptamer of Listeria monocytogenes is fixed on the bare electrode surface and its complementary DNA sequence (DNA1) labeled with bipyridyl ruthenium is self‐assembled to the electrode surface through base complementary pairing, which keeps the strongest electrochemical luminescence signal.

Research suggests that small and independent delis are less likely to follow proper sanitation procedures, including slicer inspection, which could lead to a higher likelihood of these delis being a reservoir for Listeria monocytogenes growth and cross-contamination.    This study was undertaken to determine the incidence of L. monocytogenes in counter-sliced turkey deli meat obtained from independent delis in an urban city.

Lactic acid bacteria (LAB) have been isolated from fermented foodstuff and pre‐identified using API 50 CHL and confirmed by polymerase chain reaction method to investigate the protective properties against important food‐borne pathogens of their cell free supernatants (CFS) and neutralized cell free supernatants (NCFS). The antimicrobial activity of CFS and NCFS was determined using agar well diffusion assay.

Aims This study evaluated the microbiological quality and safety of minimally processed parsley sold in southeastern Brazilian food markets. Methods and Results One hundred samples were submitted to the enumeration of Enterobacteriaceae by plating on MacConkey agar. Colonies of Enterobacteriaceae were randomly selected and identified by MALDI‐TOF MS. Samples were also tested for Listeria monocytogenes and Salmonella spp.

This study evaluated the effects of low doses of gamma radiation (up to 2.0 kGy) on the survival and growth of Listeria monocytogenes and on technological characteristics of RTE cooked hams, formulated without and with 50 and 150 mg kg‐1 of sodium nitrite, after 30 days of cold (4 °C) storage. The radiation reduced from 0.33 kGy in uncured and RTE50 to 0.25 kGy in RTE150 and after storage, a reduction (P > 0.05) in the Listeria growth in the cured samples.

The present study aimed to examine the efficiency of ethanolic extract of Capsicum annuum L (CAE) in improving the shelf life and quality of fresh‐cut C. annuum (FCCa). The uniformly sliced FCCa were prewashed with sodium hypochlorite solution (NaOCl) and then treated with 10% of CAE. The foodborne pathogens of Listeria monocytogenes and Salmonella enterica were patched on the surface of FCCa and stored at 15°C and 4°C for 12 days.

Stimulator of interferon genes (STING) acts as a cytoplasmic signaling hub of innate immunity that is activated by host-derived or bacterially derived cyclic dinucleotides. Listeria monocytogenes is a foodborne, facultative intracellular pathogen that secretes c-di-AMP and activates STING, yet the in vivo role of the STING pathway during bacterial pathogenesis remains unclear.

Author(s): Aida Pérez-Baltar, Alejandro Serrano, Margarita Medina, Raquel Montiel

The aim of this study was to develop a refrigerator performance assessment procedure based on the temperature (2 × 106 values) of ground beef stored in its bottom drawer set to Fresh Meat (0 °C). Effects analyzed were ambient temperature (LT, 21.1 °C/HT, 32.2 °C), food load (LL, 22.5 kg/HL, 39.0 kg), door openings, and refrigerator compressor mode (SS, single speed/VS, variable speed).

Acidity is one of the principal physicochemical factors that influence the behavior of microorganisms in any environment, and their response to it often determines their ability to grow and survive.

Microorganisms play a crucial and unique role in fish and fish product safety. The presence of human pathogens and the formation of histamine caused by spoilage bacteria make the control of both pathogenic and spoilage microorganisms critical for fish product safety.

This study aimed to investigate the inactivation effect of 150 KeV low-energy X-ray on Salmonella Typhimurium, Escherichia coli O157:H7, Staphylococcus aureus, and Listeria monocytogenes that were inoculated in dry cardamom. The D10 value for E. coli O157:H7 was 71.43 Gy and the tR values for S. Typhimurium, L. monocytogenes, and S. aureus were 53.57, 87.74, and 114.64 Gy, respectively.

Following two O121 STEC outbreaks linked to wheat flour, this study was conducted to gain baseline information on the occurrence of bacterial pathogens and levels of indicator organisms in wheat flour in Canada. A total of 347 pre-packaged wheat flour samples were analyzed for Salmonella spp., Shiga Toxin-Producing Escherichia coli (STEC), Listeria monocytogenes ( L. monocytogenes ) , aerobic colony count (ACC), total coliforms, and generic Escherichia coli ( E. coli ) .

ABSTRACT While high temperature heat treatments can efficiently reduce pathogen levels, they also affect the quality and nutritional profile of foods, as well as increase the cost of processing. The food additive butyl para-hydroxybenzoate (BPB) was investigated for its potential to synergistically enhance the thermal inactivation at mild heating temperatures (54 – 58 ºC).

Author(s): Brianmax A. Takundwa, Prashant Bhagwat, Santhosh Pillai, Oluwatosin A. Ijabadeniyi

The hydrolysis of bovine cheese whey (BCW) proteins was performed by the Alcalase immobilized on the support glyoxyl-corn-cob-powder (AGCCP). The whey protein hydrolysates (WPH) obtained with AGCPP were fractionated by RP-HPLC according to the hydrophilicity of the peptides (F1, hydrophilic; F2, intermediate hydrophilicity; and F3, hydrophobic). The fractions were analyzed by MALDI-TOF, and molecular weight peptides (< 1500 m/z) were identified.

Several genes of the eut, pdu, and cob/cbi operons are responsible for the metabolism of ethanolamine (EA) and 1,2-propanediol (PD) and are essential during the pathogenic lifecycles of various enteric pathogens. Studies concerning EA and PD metabolism have primarily focused on bacterial genera from the family Enterobacteriaceae, especially the genus Salmonella.

Author(s): Tareq M. Osaili, Fayeza Hasan, Dinesh Kumar Dhanasekaran, Reyad S. Obaid, Anas A. Al-Nabulsi, Mutamed Ayyash, Layal Karam, Ioannis N. Savvaidis, Richard Holley

Author(s): Veronica Martinez-Rios, Mikael Pedersen, Monica Pedrazzi, Elissavet Gkogka, Jørn Smedsgaard, Paw Dalgaard