Community Composition of Bacteria Isolated from Swiss Banknotes Varies Depending on Collection Environment

Humans interact constantly with surfaces and associated microbial communities in the environment. The factors shaping the composition of these communities are poorly understood: some proposed explanations emphasize the influence of local habitat conditions (niche-based explanations), while others point to geographic structure and the distance among sampled locations (dispersal-based explanations). However, the relative roles of these different drivers for microbial community assembly on human-associated surfaces are not clear. Here, we used a combination of sampling, sequencing (16S rRNA) and culturing to show that the composition of banknote-associated bacterial communities varies depending on the local collection environment. Using banknotes collected from various locations and types of shops across Switzerland, we found taxonomic diversity dominated by families such as Pseudomonadaceae, Staphylococcaceae and Streptococcaceae, but with banknote samples from particular types of shops (especially butcher shops) having distinct community structure. By contrast, we found no evidence of geographic structure: similarity of community composition did not decrease with increasing distance among sampled locations. These results show that microbial communities associated with banknotes, one of the most commonly encountered and exchanged human-associated surfaces, can reflect the local environmental conditions (in this case, the type of shop), and the signal for this type of variation was stronger than that for geographic structure among the locations sampled here.

Basic Geometric Constructions

Basic geometric constructions, including tubing, boundary twisting, pushing down intersections, and contraction followed by push-off are presented. These moves are used repeatedly later in the proof. New, detailed pictures illustrating these constructions are provided. The Clifford torus at an intersection point between two surfaces in 4-dimensional space is described. The chapter closes with an important application of some of these moves called the Geometric Casson Lemma. This lemma upgrades algebraically dual spheres to geometrically dual spheres, at the cost of introducing more self-intersections. It is also shown that an immersed Whitney move is a regular homotopy of the associated surfaces.

Persistence of Listeria monocytogenes in food commodities: foodborne pathogenesis, virulence factors, and implications for public health

Listeria monocytogenes is a ubiquitous pathogen found commonly in vast environment conditions and most commonly found in fresh-cut salads, raw fruits raw vegetables, sausages, cured meat, shellfish, refrigerated ready to eat food, soft cheeses, raw and under pasteurized milk. L. monocytogenes is a member of genus Listeria, along with five other members, such as L. innocua, L. ivanovii, L. seeligeri, L. grayi and L. murrayi. However, L. monocytogenes is the widely known species found in human cases, although a few cases with L. ivanovii have also reported. The infection caused by L. monocytogenes is known as listeriosis, and most affected populations are neonates, pregnant women, immune-suppressed and older people. Listeriosis is a severe condition with a higher level of hospitalization (94%) and around 16% fatality. Listeria can tolerate wide ranges of temperature, pH values, ions including Chlorides and Nitrites, different Oxygen levels. Therefore, L. monocytogenes is widely identified and survived easily on harsh environmental conditions. The ability of biofilm formation makes Listeria even harder to eliminate through food processing and associated surfaces. Although outbreaks are not very common, several large outbreaks have been documented in the literature. The extensive incubation period of this pathogen makes it challenging to identify the cause in most of the outbreaks, and most of the Listeria associated cases found to be sporadic. L. monocytogenes can cause substantial economic and public health impacts due to its effect on humans. Once contaminated, Listeria is hard to eliminate due to widespread presence in the environment, intrinsic physiological resistance, ability to adapt to external stresses, and the ability to grow at a wide range of temperatures. The objective of this review was to understand foodborne Listeria infections in humans and animals, the occurrence of infections and outbreaks, the growth and survival of L. monocytogenes in food-related industries, and risk reduction strategies.

Draft Genome Sequences of Six Strains Isolated from the InSight Spacecraft and Associated Surfaces Using Oxford Nanopore- and Illumina-Based Sequencing

ABSTRACT Whole-genome sequencing and annotation have allowed planetary protection engineers to assess the functional capabilities of microorganisms isolated from spacecraft hardware and associated surfaces. Here, we report draft genomes of six strains isolated from the InSight mission, determined using Oxford Nanopore- and Illumina-based sequencing.

Impact of cleaning and disinfection procedures on microbial ecology and Salmonella antimicrobial resistance in a pig slaughterhouse

To guarantee food safety, a better deciphering of ecology and adaptation strategies of bacterial pathogens such as Salmonella in food environments is crucial. The role of food processing conditions such as cleaning and disinfection procedures on antimicrobial resistance emergence should especially be investigated. In this work, the prevalence and antimicrobial resistance of Salmonella and the microbial ecology of associated surfaces communities were investigated in a pig slaughterhouse before and after cleaning and disinfection procedures. Salmonella were detected in 67% of samples and isolates characterization revealed the presence of 15 PFGE-patterns belonging to five serotypes: S.4,5,12:i:-, Rissen, Typhimurium, Infantis and Derby. Resistance to ampicillin, sulfamethoxazole, tetracycline and/or chloramphenicol was detected depending on serotypes. 16S rRNA-based bacterial diversity analyses showed that Salmonella surface associated communities were highly dominated by the Moraxellaceae family with a clear site-specific composition suggesting a persistent colonization of the pig slaughterhouse. Cleaning and disinfection procedures did not lead to a modification of Salmonella susceptibility to antimicrobials in this short-term study but they tended to significantly reduce bacterial diversity and favored some genera such as Rothia and Psychrobacter. Such data participate to the construction of a comprehensive view of Salmonella ecology and antimicrobial resistance emergence in food environments in relation with cleaning and disinfection procedures.

Draft Genome Sequences of Acinetobacter and Bacillus Strains Isolated from Spacecraft-Associated Surfaces

ABSTRACT We report here the draft genome sequences of four strains isolated from spacecraft-associated surfaces exhibiting increased resistance to stressors such as UV radiation and exposure to H2O2. The draft genomes of strains 1P01SCT, FO-92T, 50v1, and 2P01AA had sizes of 5,500,894 bp, 4,699,376 bp, 3,174,402 bp, and 4,328,804 bp, respectively.

Transfer of Campylobacter and Salmonella from Poultry Meat onto Poultry Preparation Surfaces

ABSTRACT Thermophilic Campylobacter and Salmonella enterica are major causes of gastrointestinal foodborne infection. Survival of these pathogens on food-associated surfaces is a risk contributing to their spread through the food system. This study examined the transfer of two strains each of C. jejuni, C. coli, Salmonella Enteritidis, and Salmonella Typhimurium from chicken meat to a knife or scissors used on either a plastic or wooden cutting board. Each strain of Campylobacter and Salmonella at ∼108 CFU mL−1 was inoculated (5 mL) onto 25 g of chicken meat with skin and allowed to attach (for 10 min). The meat was then cut (20 times per implement) into 1-cm2 pieces with either a knife or scissors on either a plastic or wooden cutting board. The numbers of pathogens transferred from meat onto cutting implements and cutting board surfaces were enumerated. The surfaces were subsequently either rinsed with water or rinsed with water and wiped with a kitchen towel to mimic commonly used superficial cleaning practices for these implements, and the numbers of pathogens were enumerated again. The bacterial numbers for both pathogens were determined on thin-layer agar. The attachment of the Salmonella strains to chicken meat (∼7.0 to 7.8 log CFU cm−2) was higher than the attachment of the Campylobacter strains (∼4.6 to 6.6 log CFU cm−2). All four Salmonella strains transferred in higher numbers (∼1.9 to 6.3 log CFU cm−2) to all surfaces than did the Campylobacter strains (∼1.1 to 3.9 log CFU cm−2). The transfer rates of both pathogens from the chicken meat to all the surfaces examined varied substantially between ∼0 and 21.1%. The highest rate of transfer (∼21.1%) observed was for C. coli 2875 when transferred from the chicken meat to the scissors. Most cleaning treatments reduced the numbers of both pathogens (∼0.3 to 4.1 log CFU cm−2) transferred to all the surfaces. Our study gives insights into the risks associated with the transfer of Campylobacter and Salmonella from poultry to the surfaces used in poultry preparation.