Category Archives: Shewanella

Research – Microbial community structure of plant-based meat alternatives.

Nature

A reduction in animal-based diets has driven market demand for alternative meat products, currently raising a new generation of plant-based meat alternatives (PBMAs). It remains unclear whether these substitutes are a short-lived trend or become established in the long term. Over the last few years, the trend of increasing sales and diversifying product range has continued, but publication activities in this field are currently limited mainly to market research and food technology topics. As their popularity increases, questions emerge about the safety and nutritional risks of these novel products. Even though all the examined products must be heated before consumption, consumers lack experience with this type of product and thus further research into product safety, is desirable. To consider these issues, we examined 32 PBMAs from Austrian supermarkets. Based on 16S rRNA gene amplicon sequencing, the majority of the products were dominated by lactic acid bacteria (either Leuconostoc or Latilactobacillus), and generally had low alpha diversity. Pseudomonadota (like Pseudomonas and Shewanella) dominated the other part of the products. In addition to LABs, a high diversity of different Bacillus, but also some Enterobacteriaceae and potentially pathogenic species were isolated with the culturing approach. We assume that especially the dominance of heterofermentative LABs has high relevance for the product stability and quality with the potential to increase shelf life of the products. The number of isolated Enterobacteriaceae and potential pathogens were low, but they still demonstrated that these products are suitable for their presence.

Research – Correlation of High Seawater Temperature with Vibrio and Shewanella Infections, Denmark, 2010–2018

CDC

Abstract

During 2010–2018 in Denmark, 638 patients had Vibrio infections diagnosed and 521 patients had Shewanella infections diagnosed. Most cases occurred in years with high seawater temperatures. The substantial increase in those infections, with some causing septicemia, calls for clinical awareness and mandatory notification policies.

Vibrio and Shewanella spp. bacteria cause a variety of human infections, including wound infections, ear infections, septicemia, and gastroenteritis (1). Domestically acquired Vibrio and Shewanella infections occur only sporadically in countries in northern Europe because the coastal seawater temperature tends to be too cold to support growth and high bacterial pathogen concentration levels (2,3). However, the warming of low-salinity coastal waters of the Baltic Sea has promoted the growth of Vibrio and Shewanella spp. and consequently increased the risk of disease for humans exposed to such seawater (4). In the unusually warm summer of 1994 in Denmark, several V. vulnificus and S. algae infections were seen among patients who reported bathing in seawater (5,6). Furthermore, during 2014–2018, more than 1,055 cases of vibriosis were reported in northern Europe countries, including Denmark (7).

Considering the annual increase in infections during recent summer seasons in Denmark and the recurring heatwaves across Europe, this emerging public health threat requires more investigation to provide decision-makers with evidence for action. The aim of our nationwide study was to describe the distribution of Vibrio and Shewanella infections in Denmark during 2010–2018 and investigate a possible correlation between infections and sea surface temperature.

Research – Characterization of Microbiological Quality of Whole and Gutted Baltic Herring

MDPI

There is growing interest in Baltic herring (Clupea harengus membras) and other undervalued, small-sized fish species for human consumption. Gutting or filleting of small-sized fish is impractical; hence, the aim of this study was to explore the suitability of the whole (ungutted) herring for food use. The microbiological quality of commercially fished whole and gutted herring was analysed with culture-dependent methods combined with identification of bacterial isolates with MALDI-TOF Mass Spectrometry and culture-independent 16S rRNA gene amplicon sequencing. Whole and gutted herring had between 2.8 and 5.3 log10 CFU g−1 aerobic mesophilic and psychrotrophic bacteria and between 2.2 and 5.6 log10 CFU g−1 H₂S-producing bacteria. Enterobacteria counts remained low in all the analysed herring batches. The herring microbiota largely comprised the phyla Proteobacteria, Firmicutes, and Actinobacteria (71.7% to 95.0%). ShewanellaPseudomonas, and Aeromonas were the most frequently isolated genera among the viable population; however, with the culture-independent approach, Shewanella followed by Psychrobacter were the most abundant genera. In some samples, a high relative abundance of the phylum Epsilonbacteraeota, represented by the genus Arcobacter, was detected. This study reports the bacterial diversity present in Baltic herring and shows that the microbiological quality was acceptable in all the analysed fish batches. View Full-Text

Research – Antimicrobial activity and mechanism of oregano essential oil against Shewanella putrefaciens

Wiley Online

The aim of the present study was to investigate the antimicrobial mechanism of oregano essential oil (OEO) against Shewanella putrefaciens. Antimicrobial activity of OEO against Shewanella putrefaciens was investigated by the agar disc diffusion method. The change of growth curve, electric conductivity, the integrity of cell membrane, alkaline phosphatase (AKP), and lactate dehydrogenase (LDH) activity were measured to evaluate its antibacterial mechanism. The morphology of bacterial cells was observed by scanning electron microscopy (SEM). The interaction between OEO and Shewanella putrefaciens genomic DNA was measured by ultraviolet–visible (UV–Vis) spectroscopy, and DNA ethidium bromide adduct was analyzed by fluorescence. The results showed that the minimum inhibitory concentration of OEO against Shewanella putrefaciens was 0.09% (v/v), and OEO could inhibit the growth of Shewanella putrefacien with a dose-dependent manner. The cell membrane and cell wall of Shewanella putrefaciens were destroyed by OEO, which led to the leakage of nucleic acid, protein, and the release of AKP and LDH. The results of SEM confirmed the damaging effect of OEO on the bacterial morphology. The results of UV–Vis and fluorescence titration indicated that binding of the complexes to DNA was an intercalative mode.

Research – Antimicrobial Efficacy and Spectrum of Phosphorous-Fluorine Co-Doped TiO2 Nanoparticles on the Foodborne Pathogenic Bacteria Campylobacter jejuni, Salmonella Typhimurium, Enterohaemorrhagic E. coli, Yersinia enterocolitica, Shewanella putrefaciens, Listeria monocytogenes and Staphylococcus aureus

MDPI

Contamination of meats and meat products with foodborne pathogenic bacteria raises serious safety issues in the food industry. The antibacterial activities of phosphorous-fluorine co-doped TiO2 nanoparticles (PF-TiO2) were investigated against seven foodborne pathogenic bacteria: Campylobacter jejuniSalmonella Typhimurium, Enterohaemorrhagic E. coliYersinia enterocoliticaShewanella putrefaciensListeria monocytogenes and Staphylococcus aureus. PF-TiO2 NPs were synthesized hydrothermally at 250 °C for 1, 3, 6 or 12 h, and then tested at three different concentrations (500 μg/mL, 100 μg/mL, 20 μg/mL) for the inactivation of foodborne bacteria under UVA irradiation, daylight exposure or dark conditions. The antibacterial efficacies were compared after 30 min of exposure to light. Distinct differences in the antibacterial activities of the PF-TiO2 NPs, and the susceptibilities of tested foodborne pathogenic bacterium species were found. PF-TiO2/3 h and PF-TiO2/6 h showed the highest antibacterial activity by decreasing the living bacterial cell number from ~106 by ~5 log (L. monocytogenes), ~4 log (EHEC), ~3 log (Y. enterolcolitcaS. putrefaciens) and ~2.5 log (S. aureus), along with complete eradication of C. jejuni and S. Typhimurium. Efficacy of PF-TiO2/1 h and PF-TiO2/12 h NPs was lower, typically causing a ~2–4 log decrease in colony forming units depending on the tested bacterium while the effect of PF-TiO2/0 h was comparable to P25 TiO2, a commercial TiO2 with high photocatalytic activity. Our results show that PF-co-doping of TiO2 NPs enhanced the antibacterial action against foodborne pathogenic bacteria and are potential candidates for use in the food industry as active surface components, potentially contributing to the production of meats that are safe for consumption. View Full-Text

Research – Antimicrobial Efficacy and Spectrum of Phosphorous-Fluorine Co-Doped TiO2 Nanoparticles on the Foodborne Pathogenic Bacteria Campylobacter jejuni, Salmonella Typhimurium, Enterohaemorrhagic E. coli, Yersinia enterocolitica, Shewanella putrefaciens, Listeria monocytogenes and Staphylococcus aureus

MDPI

Yersinia p

Contamination of meats and meat products with foodborne pathogenic bacteria raises serious safety issues in the food industry. The antibacterial activities of phosphorous-fluorine co-doped TiO2 nanoparticles (PF-TiO2) were investigated against seven foodborne pathogenic bacteria: Campylobacter jejuniSalmonella Typhimurium, Enterohaemorrhagic E. coliYersinia enterocoliticaShewanella putrefaciens, Listeria monocytogenes and Staphylococcus aureus. PF-TiO2 NPs were synthesized hydrothermally at 250 °C for 1, 3, 6 or 12 h, and then tested at three different concentrations (500 μg/mL, 100 μg/mL, 20 μg/mL) for the inactivation of foodborne bacteria under UVA irradiation, daylight exposure or dark conditions. The antibacterial efficacies were compared after 30 min of exposure to light. Distinct differences in the antibacterial activities of the PF-TiO2 NPs, and the susceptibilities of tested foodborne pathogenic bacterium species were found. PF-TiO2/3 h and PF-TiO2/6 h showed the highest antibacterial activity by decreasing the living bacterial cell number from ~106 by ~5 log (L. monocytogenes), ~4 log (EHEC), ~3 log (Y. enterolcolitca, S. putrefaciens) and ~2.5 log (S. aureus), along with complete eradication of C. jejuni and S. Typhimurium. Efficacy of PF-TiO2/1 h and PF-TiO2/12 h NPs was lower, typically causing a ~2–4 log decrease in colony forming units depending on the tested bacterium while the effect of PF-TiO2/0 h was comparable to P25 TiO2, a commercial TiO2 with high photocatalytic activity. Our results show that PF-co-doping of TiO2 NPs enhanced the antibacterial action against foodborne pathogenic bacteria and are potential candidates for use in the food industry as active surface components, potentially contributing to the production of meats that are safe for consumption.

Research – Evaluation of weakly acidic electrolyzed water and modified atmosphere packaging on the shelf life and quality of farmed puffer fish (Takifugu obscurus ) during cold storage

Wiley Online

The combined effect of weakly acidic electrolyzed water (WAEW) and modified atmosphere packaging (MAP) treatments on the quality of puffer fish (Takifugu obscurus ) during cold storage was studied on aspects of microbiological activity, texture, total volatile basic nitrogen (TVB‐N), trimethylamine (TMA), free amino acids (FAAs), thiobarbituric acid reactive substance (TBARS), ATP‐related compounds and value, volatile organic compounds (VOCs), and organoleptic properties. As a result, significantly ( < .05) higher inhibitory effects on total viable counts (TVC), H2S‐producing bacteria (including Shewanella putrefaciens ), Pseudomonas spp., and lactic acid bacteria (LAB) were observed in WAEW‐treated puffer fish packaged in 60%CO2/5%O2/35%N2 atmosphere than that in air package and vacuum package with/without WAEW‐treated samples. In addition, chemical results showed that WAEW together with MAP treatments were highly efficient in maintaining lower TVB‐N, TMA, and TBARS values in refrigerated puffer fish. Moreover, the presence of WAEW combined with MAP treatments showed positive effects on retarding the relative content of fishy flavor compounds, such as 1‐octen‐3‐ol, 1‐penten‐3‐ol, hexanal, heptanal, nonanal, decanal, ()‐2‐octenal, and 2,3‐butanedione. As a whole, the combined effect of WAEW and MAP on refrigerated puffer fish is advisable to maintain better quality and extend the shelf life.

Norway -Vibrio and Shewanella: Norway health officials warn of swimming in the warm waters

Outbreak News Today 

CDC Vibrio

Image CDC Enter a caption

Norwegian health authorities are warning people who are particularly vulnerable to Vibrio infections to take precautions while swimming as a number of serious bacterial infections ave been recorded.

This summer, six people have been severely ill with wound infection due to bacteria in seawater (five Vibrio and one Shewanella). The infection has occurred after swimming in the Oslo Fjord.

All adults over the age of 50 who have had a sore wound or have suffered sores during bathing in the Oslo Fjord in five different municipalities, Bærum, Oslo, Moss, Vestby and Fredrikstad.

In addition to the serious cases we know from earlier, there have been reports of 20 people who have had mild Vibrio infections on August 8th. These are sore infections and ear infections that often do not require treatment.