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236 results on '"Björkroth, Johanna"'

10. The Family Leuconostocaceae

Author

Nieminen, Timo T., Säde, Elina, Endo, Akihito, Johansson, Per, Björkroth, Johanna, Rosenberg, Eugene, editor, DeLong, Edward F., editor, Lory, Stephen, editor, Stackebrandt, Erko, editor, and Thompson, Fabiano, editor

Published
2014
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16. Comparative genomics of 40 Weissella paramesenteroides strains.

Author

Xing Wan, Takala, Timo M., Huynh, Vy A., Ahonen, Susanna L., Paulin, Lars, Björkroth, Johanna, Sironen, Tarja, Kant, Ravi, and Saris, Per

Subjects
COMPARATIVE genomics, GENOMICS, NUTRITIONAL value, FOOD fermentation, FERMENTED foods, METABOLITES
Abstract

Weissella strains are often detected in spontaneously fermented foods. Because of their abilities to produce lactic acid and functional exopolysaccharides as well as their probiotic traits, Weissella spp. improve not only the sensorial properties but also nutritional values of the fermented food products. However, some Weissella species have been associated with human and animal diseases. In the era of vast genomic sequencing, new genomic/genome data are becoming available to the public on daily pace. Detailed genomic analyses are due to provide a full understanding of individual Weissella species. In this study, the genomes of six Weissella paramesenteroides strains were de novo sequenced. The genomes of 42 W. paramesenteroides strains were compared to discover their metabolic and functional potentials in food fermentation. Comparative genomics and metabolic pathway reconstructions revealed that W. paramesenteroides is a compact group of heterofermentative bacteria with good capacity of producing secondary metabolites and vitamin Bs. Since the strains rarely harbored plasmid DNA, they did not commonly possess the genes associated with bacteriocin production. All 42 strains were shown to bear vanT gene from the glycopeptide resistance gene cluster vanG. Yet none of the strains carried virulence genes. [ABSTRACT FROM AUTHOR]

Published
2023
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20. The genus Leuconostoc

Author

Björkroth, Johanna, primary, Dicks, Leon M.T., additional, Endo, Akihito, additional, and H.Holzapfel, Wilhelm, additional

Published
2014
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23. Microbiomes in the Context of Refrigerated Raw Meat Spoilage

Author

Johansson, Per, Jääskeläinen, Elina, Nieminen, Timo, Auvinen, Petri, Björkroth, Johanna, Food Hygiene and Environmental Health, Microbial ecology of food spoilage, Department of Food and Nutrition, Staff Services, Institute of Biotechnology, Biosciences, DNA Sequencing and Genomics, Helsinki One Health (HOH), and Johanna Björkroth / Principal Investigator

Subjects
416 Food Science, education
Published
2020

32. Prevalence and genotype diversity of Campylobacter jejuniin hunted reared pheasants (Phasianus colchicus) in Finland

Author

Kivistö, Rauni, Sauvala, Mikaela, Fredriksson-Ahomaa, Maria, and Björkroth, Johanna

Abstract

Campylobacterspp., especially C. jejuni, is the most common zoonotic pathogen in humans worldwide. In Nordic countries, the prevalence of C. jejuniin broilers, which is an important reservoir of human infections, is generally low. Thus, other sources of domestically acquired infections besides chicken meat need to be considered. Game birds are known to carry a variety of zoonotic agents, including Campylobacter. The aim of this study was to investigate Campylobacterspp. carriage in a flock of reared pheasants at hunting in two successive samplings to better understand the dynamics of Campylobacterinfections in pheasants. Overall, 72% of the intestinal samples were positive for Campylobacterspp. by direct culture on mCCDA. C. jejuniwas the only species identified. The isolates were genotyped using whole genome sequencing (WGS), multilocus sequence typing (MLST), and ad hocwhole genome MLST (wgMLST). Two distinct C. jejuniclones were identified among the 18 isolates studied, representing MLST sequence types (STs) ST-45 and ST-699. The ST-45 isolates were closely related to previous human clinical isolates using core genome MLST (cgMLST). In contrast, the ST-699 isolates forming the dominant clone in the latter sampling were quite distinct from previously described cgMLST profiles from different hosts and sources worldwide. In conclusion, the intestine of reared pheasants is commonly colonized by C. jejuniand may carry genotypes relevant to infections in livestock and humans. Hygienic measures are needed to limit the spread of infection in reared flocks. Especially farmers and hunters having direct contact with pheasant offal need to be aware of the associated zoonosis risk to protect themselves and their working dogs alike. Biosecurity measures to improve the safety and reduce the zoonosis risk associated with pheasant farming should be further investigated.

Published
2023
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33. Lactobacillus oligofermentans glucose, ribose and xylose transcriptomes show higher similarity between glucose and xylose catabolism-induced responses in the early exponential growth phase

Author

University of Helsinki, Institute of Biotechnology, University of Helsinki, Faculty of Veterinary Medicine, Andreevskaya, Margarita, Johansson, Per, Jääskeläinen, Elina, Rämö, Tanja, Ritari, Jarmo, Paulin, Lars, Björkroth, Johanna, Auvinen, Petri, University of Helsinki, Institute of Biotechnology, University of Helsinki, Faculty of Veterinary Medicine, Andreevskaya, Margarita, Johansson, Per, Jääskeläinen, Elina, Rämö, Tanja, Ritari, Jarmo, Paulin, Lars, Björkroth, Johanna, and Auvinen, Petri

Published
2016

41. Weissella

Author

Björkroth, Johanna, primary, Dicks, Leon M.T., additional, and Holzapfel, Wilhelm. H., additional

Published
2015
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45. Lactobacillus oligofermentans sp. nov. associated with spoilage of modified atmosphere packaged poultry products

Author

Koort, Joanna, Murros, Anna, Coenye, Tom, Eerola, Susanna, Vandamme, Peter, Sukura, Antti, Björkroth, Johanna, Department of Food and Environmental Hygiene, Elintarvike- ja ympäristöhygienian laitos, and Livsmedels- och miljöhygien, Institutionen för

Subjects
polyphasic taxonomy, food and beverages, Modified Atmosphere package (MAP), Lactic Acid Bacteria (LAB)
Abstract

Unidentified lactic acid bacterium (LAB) isolates which had mainly been detected in spoiled, marinated, modified atmosphere packaged (MAP) broiler meat products during two previous studies were identified and analyzed for their phenotypic properties and the capability to produce biogenic amines. To establish the taxonomic position of these isolates, 16S rRNA gene sequence analysis, numerical analysis of ribopatterns, and DNA-DNA hybridization experiments were done. Unexpectedly for a meat spoilage associated LAB, the strains utilized glucose very weakly. According to the API 50 CHL test, arabinose and xylose were the only carbohydrates strongly fermented. None of the six strains tested for production of histamine, tyramine, tryptamine, phenylethylamine, putrescine and cadaverine were able to produce these main meat-associated biogenic amines in vitro. Polyphasic taxonomy approach showed that these strains represent a new Lactobacillus species. The six isolates sequenced for the 16S rRNA encoding genes shared the highest similarity (95.0 to 96.3%) with the sequence of the Lactobacillus durianis type strain. In the phylogenetic tree, these isolates formed a distinct cluster within the Lactobacillus reuteri -group which also includes L. durianis. Numerical analyses of HindIII/EcoRI ribotypes placed all isolates together in a cluster with seven subclusters well-separated from the L. reuteri group reference strains. The DNA-DNA hybridization levels between Lactobacillus sp. nov. isolates varied from 67 to 96% and low hybridization levels (3-15%) were obtained with the L. durianis type strain confirming that these isolates belong to same species different from L. durianis. The name Lactobacillus oligofermentans sp. nov. is proposed, with strain LMG 22743T (=DSM 15707T =AMKR18 T) as the type strain. Academy of Finland (project 100479)

Published
2005

46. Microbial ecology of marinated meat products

Author

Björkroth, Johanna, Department of Food and Environmental Hygiene, Elintarvike- ja ympäristöhygienian laitos, and Livsmedels- och miljöhygien, Institutionen för

Subjects
safety, modified atmosphere packaging, quality, review, marinated broiler meat
Abstract

www.elsevier.com/locate/meatsci Marinated meat products are consumed increasingly because they are convenient in meal preparing. In addition to sensory effects, marinating has been considered to increase product safety and shelf life quality. There are variations in meat marinating technologies around the world. In Finland, marinades are complex sauces which have a great effect on product appearance and taste. They are water-oil emulsions typically containing salt, sugar and acids (acetic, citric), rheology-improving additives (like xanthan gum and guar gum), antimicrobial agents (like sorbate and benzoate) spices and aroma strengtheners. The pH of these marinades is usually acidic, less than 5, so sugar is used to cut the edge of the acidic taste. Marinated meat products are usually packaged under modified atmospheres to prevent the growth of aerobic spoilage organisms. This results in the growth of psychrotrophic, anaerobic bacteria and lactic acid bacteria (LAB) are the dominating spoilage organisms in these products. Marinating did not increase the shelf life of Finnish poultry products and it strongly selects certain spoilage-associated novel LAB species. Surprisingly, it did not have a strong inhibitory effect on Campylobacter. This may be due to the buffering capability of meat quickly neutralizing the pH of the acidic marinade. The change in the acidic pH towards neutrality also results in dissociation of the lipophilic acids making their antimicrobial effect nonexistent.

Published
2004

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