Category Archives: Microorganism DNA

Research – Isolation of Listeria monocytogenes from poultry red mite (Dermanyssus gallinae) infesting a backyard chicken farm in Greece

Nature.com

The poultry red mite (PRM), Dermanyssus gallinae, is arguably the most harmful, ubiquitous haematophagous ectoparasite infesting egg-laying hens. PRM is a vector of various microorganisms, with some being important for food microbiology and public health. The present study aimed to investigate the presence of specific pathogens, including Escherichia coliSalmonella spp. and Listeria spp., carried by PRM infesting a chicken farm in Greece. Mites were caught using cardboard traps (Avivet), and 100 unwashed PRM were homogenized and used for microbiological cultures. Microbiological cultures were carried out on general and selective substrates to detect the above-mentioned bacteria. Specifically for Listeria spp., DNA was extracted from bacteria grown in Tryptone Soya Yeast Extract Agar using a commercial kit. The hly gene encoding the Listeriolysin O protein was amplified by PCR. Mites were identified as D. gallinae using morphological keys as well as by COI DNA barcoding. Microbiological cultures and PCR assays were positive for Listeria monocytogenes. No other bacteria were detected. The current study constitutes the first molecular isolation of L. monocytogenes from Dgallinae, confirming that PRM can carry this food-borne pathogen. PRM control measures and hygiene practices should be applied to minimize any possible contamination risk of poultry products with L. monocytogenes and safeguard public health.

Research – Microbial Consortium Associated with Crustacean Shells Composting

MDPI

Soil microbes play an essential role in the biodegradation of crustacean shells, which is the process of sustainable bioconversion to chitin derivatives ultimately resulting in the promotion of plant growth properties. While a number of microorganisms with chitinolytic properties have been characterized, little is known about the microbial taxa that participate in this process either by active chitin degradation or by facilitation of this activity through nutritional cooperation and composting with the chitinolytic microorganisms. In this study, we evaluated the transformation of the soil microbiome triggered by close approximation to the green crab shell surface. Our data indicate that the microbial community associated with green crab shell matter undergoes significant specialized changes, which was reflected in a decreased fungal and bacterial Shannon diversity and evenness and in a dramatic alteration in the community composition. The relative abundance of several bacterial and fungal genera including bacteria FlavobacteriumClostridiumPseudomonas, and Sanguibacter and fungi MortierellaMycochlamys, and Talaromyces were increased with approximation to the shell surface. Association with the shell triggered significant changes in microbial cooperation that incorporate microorganisms that were previously reported to be involved in chitin degradation as well as ones with no reported chitinolytic activity. Our study indicates that the biodegradation of crab shells in soil incorporates a consortium of microorganisms that might provide a more efficient way for bioconversion. View Full-Text

Research – High-pressure processing: food safety without compromising quality

EFSA

High-pressure processing (HPP) of food is effective at destroying harmful microorganisms and poses no more food safety concerns than other treatments. These are two of the conclusions of a scientific opinion published by EFSA today.

EFSA experts assessed the safety and efficacy of HPP of food and, more specifically, whether it can be used to control Listeria monocytogenes in ready-to-eat (RTE) foods and as an alternative to thermal pasteurisation of raw milk.

HPP is a non-thermal food preservation technique that kills microorganisms that can cause diseases or spoil food. It uses intense pressure for a certain time and has minimal effects on taste, texture, appearance, or nutritional values.

HPP can be used at different steps of the food chain, usually on pre-packed products. It can be applied to raw materials such as milk, fruit juices, and smoothies but also to products that have already been processed, such as sliced cooked meat products and RTE meals. In the latter case, it reduces the contamination originating from the manufacturing environment, for example during slicing and manipulation of the products.

This processing method reduces levels of Listeria monocytogenes in RTE meat products, at specific time-pressure combinations defined in the scientific opinion. In general, the longer the duration and intensity of the pressure, the more reduction is achieved. This is an important finding because L. monocytogenes contamination of RTE foods is a public health concern in the EU. HPP also proved to be effective at decreasing the levels of other pathogens, such as Salmonella and E. coli.

For raw milk, experts identified the time-pressure combinations that can be considered to have the same effect as thermal pasteurisation. These vary depending on the pathogen considered.

HPP is not specifically regulated at EU level and EFSA’s advice will inform the possible decisions of risk managers in this field.

RASFF Alert – unauthorised genetically modified micro-organism DNA in food enzymes

RASFF-Logo

RASFF – unauthorised genetically modified micro-organism DNA in food enzymes from Belgium, with raw material from Germany in Germany