Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 33
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Int J Food Microbiol ; 341: 109059, 2021 Mar 02.
Artigo em Inglês | MEDLINE | ID: mdl-33508581

RESUMO

The microbial community of ungerminated and germinated barley grains from three different cultivars grown at four different locations in Norway was investigated by culture dependent and culture independent methods. Lactic acid bacteria (LAB) was focused in this study and was isolated from germinated barley. The number of LAB ranged between 2.8 and 4.6 log cfu/g in ungerminated grains and between 4.9 and 6.3 log cfu/g in germinated grains. In total 66 out of 190 isolates were Gram+, catalase-negative and presumptive LAB. The LAB isolates were by 16S rRNA sequencing identified to be Carnobacterium maltaromaticum (6), Lactococcus lactis (2), Enterococcus sp. (1) and Leuconostoc sp. (57). Germination significantly influenced the bacterial composition. Regarding the different cultivars and growth places no significant difference in bacterial composition was seen. The most abundant bacterial genus was Pantoea (18.5% of the total sequences), followed by Rhizobium (10.1%) and Sphingomonas (9.9%). Fungal composition was significantly influenced by the germination process and the cultivation place, but no significant difference in fungal composition was detected between the 3 cultivars. The most abundant fungal genera were Cryptococcus (43.8% of all the sequences), Cladosporium (8.2%), Pyrenophora (7.4%) and Vagicola (6.3%). This study revealed knowledge of barley grain associated microbes of Norwegian barley that can be useful to control the malt quality. Germination affected both bacterial and fungal microbiota composition. No difference in bacterial microbiota composition was seen regarding cultivars and cultivation place, however, the fungal microbiota composition was significantly influenced by the cultivation place. Differences in fungal community of ungerminated and germinated barley samples of different geographical locations were more pronounced than differences in bacterial communities.


Assuntos
Carnobacterium/isolamento & purificação , Enterococcus/isolamento & purificação , Fungos/isolamento & purificação , Hordeum/microbiologia , Lactococcus lactis/isolamento & purificação , Leuconostoc/isolamento & purificação , Carnobacterium/classificação , Carnobacterium/genética , Enterococcus/classificação , Enterococcus/genética , Fungos/classificação , Fungos/genética , Germinação/fisiologia , Lactococcus lactis/classificação , Lactococcus lactis/genética , Leuconostoc/classificação , Leuconostoc/genética , Microbiota , Noruega , RNA Ribossômico 16S/genética
2.
Appl Environ Microbiol ; 85(20)2019 10 15.
Artigo em Inglês | MEDLINE | ID: mdl-31399404

RESUMO

Carnobacterium maltaromaticum and Carnobacterium divergens are often predominant in the microbiota of vacuum-packaged (VP) meats after prolonged storage at chiller temperatures, and more so in recent studies. We investigated the antibacterial activities of C. maltaromaticum and C. divergens (n = 31) from VP meats by phenotypic characterization and genomic analysis. Five strains showed antibacterial activities against Gram-positive bacteria in a spot-lawn assay, with C. maltaromaticum strains having an intergeneric and C. divergens strains an intrageneric inhibition spectrum. This inhibitory activity is correlated with the production of predicted bacteriocins, including carnobacteriocin B2 and carnolysin for C. maltaromaticum and divergicin A for C. divergens The supernatants of both species cultured in meat juice medium under anaerobic conditions retarded the growth of most Gram-positive and Gram-negative bacteria in broth assay in a strain-dependent manner. C. maltaromaticum and C. divergens produced formate and acetate but not lactate under VP meat-relevant conditions. The relative inhibitory activity by Carnobacterium strains was significantly correlated (P < 0.05) to the production of both acids. Genomic analysis revealed the presence of genes required for respiration in both species. In addition, two clusters of C. divergens have an average nucleotide identity below the cutoff value for species delineation and thus should be considered to be two subspecies. In conclusion, both bacteriocins and organic acids are factors contributing significantly to the antibacterial activity of C. maltaromaticum and C. divergens under VP meat-relevant conditions. A few Carnobacterium strains can be explored as protective cultures to extend the shelf life and improve the safety of VP meats.IMPORTANCE The results of this study demonstrated that both bacteriocins and organic acids are important factors contributing to the antibacterial activities of Carnobacterium from vacuum-packaged (VP) meats. This study demonstrated that formate and acetate are the key organic acids produced by Carnobacterium and demonstrated their association with the inhibitory activity of carnobacteria under VP meat-relevant storage conditions. The role of lactate, on the other hand, may not be as important as previously believed in the antimicrobial activities of Carnobacterium spp. on chilled VP meats. These findings advance our understanding of the physiology of Carnobacterium spp. to better explore their biopreservative properties for chilled VP meats.


Assuntos
Ácidos/farmacologia , Antibacterianos/farmacologia , Bacteriocinas/farmacologia , Carnobacterium/metabolismo , Carne/microbiologia , Acetatos/metabolismo , Antibacterianos/metabolismo , Bacteriocinas/metabolismo , Carnobacterium/classificação , Carnobacterium/genética , Microbiologia de Alimentos , Embalagem de Alimentos , Formiatos/metabolismo , Genoma Bacteriano , Bactérias Gram-Negativas/efeitos dos fármacos , Bactérias Gram-Positivas/efeitos dos fármacos , Ácido Láctico/metabolismo , Testes de Sensibilidade Microbiana , Filogenia , Vácuo
3.
Int J Food Microbiol ; 300: 14-21, 2019 Jul 02.
Artigo em Inglês | MEDLINE | ID: mdl-30991234

RESUMO

It is well established, that certain bacteria within the Brochothrix, Carnobacterium, Lactobacillus, Lactococcus, and Leuconostoc genera have an important role in the spoilage of chill stored poultry meat packaged in modified atmosphere. However, little is known about the role of microorganisms that are difficult to culture and the microbiota during poultry spoilage. We combined traditional cultivation and culture-independent 16S rRNA amplicon sequencing to investigate the microbiota encompassing putative bacteria of whole broiler meat, packaged in modified atmosphere, during and exceeding shelf-life. Samples were taken from 6 flocks during independent slaughter days. Additional samples were analysed from the production line. There was a significant difference in the microbial community structure of 80%O2/20%CO2 retail packaged broiler meat during different times of shelf-life, mainly due to an increase of species within the Brochothrix, Carnobacterium, Vagococcus, and Janthinobacterium genera. These genera were already detected four to eight days after slaughter. However, no significant difference between flocks with respect to the microbiota encompassing putative spoilage bacteria was observed when examined in retail packaged broilers, slaughtered at the same abattoir on different days. Our study also showed that lactic acid bacteria within the Vagococcus genus can constitute a dominating part of the later shelf-life microbiota in fresh whole broiler meat packaged in 80%O2/20%CO2 modified atmosphere. A single operational taxonomic unit (OTU) assigned as Janthinobacterium lividum, an occasional spoiler of meat products, was identified as a major part of the microbiota in late shelf life broiler meat and swab samples in the cooling facility at the slaughter house production line. The combination of traditional cultivation and culture-independent methods provided a great insight into the microbiota of broiler meat during shelf-life and identified a potential point of contamination in the production line for cold tolerant Janthinobacterium.


Assuntos
Fenômenos Fisiológicos Bacterianos , Galinhas/microbiologia , Microbiologia de Alimentos , Carne/microbiologia , Microbiota/fisiologia , Matadouros , Animais , Bactérias/genética , Bactérias/crescimento & desenvolvimento , Carnobacterium/genética , Carnobacterium/fisiologia , Galinhas/genética , Embalagem de Alimentos , Microbiota/genética , RNA Ribossômico 16S/genética
4.
Int J Food Microbiol ; 293: 102-113, 2019 Mar 16.
Artigo em Inglês | MEDLINE | ID: mdl-30677559

RESUMO

Thawed hake (Merluccius capensis and M. paradoxus) and plaice (Pleuronectes platessa) fillets were used as a model to evaluate the effect of storage temperature (0 or 10 °C) and biological variability (fish species, lot to lot) on bacterial growth kinetics and microbial successions. Both culture dependent methods (plate counts on non-selective and selective media) and culture independent methods (qPCR and 16S rRNA gene metabarcoding) were used. Bacterial counts exceeded 107 cfu/g within 2-3 days at 10 °C and 7-8 days at 0 °C. Plate counts on three media (Plate Count Agar +0.5% NaCl, Iron Agar Lyngby and Pseudomonas Selective medium) and 16S rRNA gene counts estimated by qPCR were highly correlated. Growth was modelled using the D-model and specific growth rate ranged between 0.97 and 1.24 d-1 and 3.54 and 5.90 d-1 at 0 and 10 °C, respectively. The initial composition of the microbiota showed lot-to-lot variation, but significant differences between the two fish species were detected. Alpha diversity significantly decreased during storage. When bacterial counts exceeded 107 cfu/g, the microbiota was dominated by members of the genera Pseudomonas, Psychrobacter, Acinetobacter, Serratia, Flavobacterium, Acinetobacter, Carnobacterium, Brochothrix and Vagococcus. However, Photobacterium and Shewanella, two genera frequently associated with fish spoilage, were either absent or minor components of the microbiota. As expected, storage temperature significantly affected the abundance of several species. The inference of microbial association networks with three different approaches (an ensemble approach using the CoNet app, Sparse Correlations for Compositional data, and SParse InversE Covariance Estimation for Ecological Association Inference) allowed the detection of both a core microbiota, which was present throughout storage, and a number of taxa, which became dominant at the end of spoilage and were characterized by a disproportionate amount of negative interactions.


Assuntos
Contaminação de Alimentos/análise , Armazenamento de Alimentos , RNA Ribossômico 16S/isolamento & purificação , Alimentos Marinhos/microbiologia , Acinetobacter/genética , Acinetobacter/isolamento & purificação , Animais , Carga Bacteriana , Brochothrix/genética , Brochothrix/isolamento & purificação , Carnobacterium/genética , Carnobacterium/isolamento & purificação , Temperatura Baixa , Contagem de Colônia Microbiana , DNA Bacteriano/genética , DNA Bacteriano/isolamento & purificação , Peixes , Microbiologia de Alimentos , Consórcios Microbianos , Photobacterium/genética , Photobacterium/isolamento & purificação , Pseudomonas/genética , Pseudomonas/isolamento & purificação , Psychrobacter/genética , Psychrobacter/isolamento & purificação , RNA Ribossômico 16S/genética , Shewanella/genética , Shewanella/isolamento & purificação
5.
J Appl Microbiol ; 126(2): 377-387, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30307684

RESUMO

AIMS: Carnobacterium maltaromaticum is a lactic acid bacterium of technological interest in the field of dairy ripening and food bioprotection and is generally recognized as safe in the United States. As it is associated with fish infections, the European Food Safety Agency did not include this species in the qualified presumption safety list of micro-organisms. This implies that the risk assessment for the species has to be performed at the strain level. METHODS AND RESULTS: Multilocus sequence typing (MLST) is a tool that (i) potentially allows to discriminate strains isolated from diseased fish from apathogenic strains and (ii) to assess the genetic relatedness between both groups of strains. In this study, we characterized by MLST 21 C. maltaromaticum strains including 16 strains isolated from diseased fish and 5 apathogenic dairy strains isolated from cheese. The resulting population structure was investigated by integrating these new data to the previously published population structure (available at http://pubmlst.org), which represents an overall of 71 strains. CONCLUSIONS: This analysis revealed that none of the strains isolated from diseased fish is assigned to a clonal complex containing cheese isolates, and that 11 strains exhibit singleton genotypes suggesting that the population of diseased fish isolates is not clonal. SIGNIFICANCE AND IMPACT OF THE STUDY: This study thus provides a population structure of C. maltaromaticum that could serve in the future as a reference that could contribute to the risk assessment of C. maltaromaticum strains intended to be used in the food chain.


Assuntos
Carnobacterium/classificação , Queijo/microbiologia , Doenças dos Peixes/microbiologia , Infecções por Bactérias Gram-Positivas/veterinária , Animais , Carnobacterium/genética , Carnobacterium/isolamento & purificação , Peixes , Genótipo , Infecções por Bactérias Gram-Positivas/microbiologia , Tipagem de Sequências Multilocus
6.
Int J Food Microbiol ; 286: 120-127, 2018 Dec 02.
Artigo em Inglês | MEDLINE | ID: mdl-30081251

RESUMO

Carnobacterium spp. are frequently isolated from vacuum-packaged (VP) meat. Specific strains of Carnobacterium and their growth characteristics may be associated with the storage life of such products. This study investigated the growth of 44 Carnobacterium isolates obtained from VP meat cuts produced at three Canadian abattoirs (A, B and C) under the following conditions: pH 5.4, 6.2 and 7.4; lactic acid at 60 and 90 mM; acetic acid at 33.6 mM. Whole genome sequencing was performed for all 44 isolates and a core genome phylogenetic tree was created to identify strain variability among isolates from different abattoirs. The isolates were clustered into 11 groups. All isolates from abattoirs B and C were identified as C. divergens, while the isolates from abattoir A included both C. maltaromaticum and C. divergens at equal proportions. C. divergens isolates from abattoir A belonged to two phylogenetic groups and none of them was found in the phylogenetic groups containing isolates from abattoirs B or C. Whole genome sequencing revealed that identical strains were isolated from different samples obtained at the same abattoir. The mean growth rate and maximum population density of the C. maltaromaticum isolates were lower than those of the C. divergens isolates. C. divergens isolates from abattoir A had higher growth rates and maximum population density than those from abattoirs B and C. In conclusion, growth characteristic and whole genome analysis both demonstrated strain variability of Carnobacterium among abattoirs, which could be a result of the difference in the antimicrobial interventions used for carcasses at different abattoirs, and may be associated with different storage lives of VP meats produced from different abattoirs.


Assuntos
Ácidos/metabolismo , Carnobacterium/classificação , Carnobacterium/crescimento & desenvolvimento , Embalagem de Alimentos/métodos , Carne Vermelha/microbiologia , Matadouros , Animais , Canadá , Carnobacterium/genética , Carnobacterium/isolamento & purificação , Filogenia , Vácuo , Sequenciamento Completo do Genoma
7.
Int J Syst Evol Microbiol ; 68(5): 1672-1677, 2018 May.
Artigo em Inglês | MEDLINE | ID: mdl-29616891

RESUMO

A novel, alkaliphilic, psychrotolerant, facultative anaerobe, designated CP1T, was isolated from sandy soil near the Davis Station in Antarctica. The short-rod-shaped cells displayed Gram-positive staining and did not form spores. Strain CP1T was able to grow at temperatures between 4 and 36 °C, pH 6.0-9.5, and in the presence of up to 5.0 % (w/v) NaCl. 16S rRNA gene and multilocus (pheS, rpoA, and atpA) sequence analysis revealed Carnobacterium mobile DSM 4848T and Carnobacterium iners LMG 26642T as the closest relatives (97.4 and 97.1 % 16S rRNA gene sequence similarity, respectively). The genomic G+C content was 38.1 mol%, and DNA-DNA hybridization with DSM 4848T revealed 32.4±3.4 % similarity. The major fatty acid components were C14 : 0 and C16 : 1ω9c. The cell wall contained meso-diaminopimelic acid and was of peptidoglycan type A1γ. Based on physiological, genotypic and biochemical characteristics, strain CP1T represents a novel species of the genus Carnobacterium for which the name Carnobacterium antarcticum sp. nov. is proposed. The type strain is CP1T (=DSM 103363T=CGMCC 1.15643T).


Assuntos
Carnobacterium/classificação , Filogenia , Microbiologia do Solo , Regiões Antárticas , Técnicas de Tipagem Bacteriana , Composição de Bases , Carnobacterium/genética , Carnobacterium/isolamento & purificação , DNA Bacteriano/genética , Ácido Diaminopimélico/química , Ácidos Graxos/química , Hibridização de Ácido Nucleico , Peptidoglicano/química , RNA Ribossômico 16S/genética , Análise de Sequência de DNA
8.
Food Microbiol ; 65: 236-243, 2017 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-28400008

RESUMO

Pork-based cooked products, such as cooked hams, are economically valuable foods that are vulnerable to bacterial spoilage, even when applying cooling and modified atmosphere packaging (MAP). Besides a common presence of Brochothrix thermosphacta, their microbiota are usually dominated by lactic acid bacteria (LAB). Yet, the exact LAB species diversity can differ considerably among products. In this study, 42 sliced cooked pork samples were acquired from three different Belgian supermarkets to map their bacterial heterogeneity. The community compositions of the dominant bacterial species were established by analysing a total of 702 isolates from selective agar media by (GTG)5-PCR fingerprinting followed by gene sequencing. Most of the isolates belonged to the genera Carnobacterium, Lactobacillus, and Leuconostoc, with Leuconostoc carnosum and Leuconostoc gelidum subsp. gelidum being the most dominant members. The diversity of the dominant bacterial species varied when comparing samples from different production facilities and, in some cases, even within the same product types. Although LAB consistently dominated the microbiota of sliced cooked pork products in the Belgian market, results indicated that bacterial diversity needs to be addressed on the level of product composition and batch variation. Dedicated studies will be needed to substantiate potential links between such variability and microbial composition. For instance, the fact that higher levels of lactobacilli were associated with the presence of potassium lactate (E326) may be suggestive of selective pressure but needs to be validated, as this finding referred to a single product only.


Assuntos
Biodiversidade , Carnobacterium/isolamento & purificação , Culinária , Embalagem de Alimentos , Lactobacillaceae/isolamento & purificação , Leuconostoc/isolamento & purificação , Produtos da Carne/microbiologia , Carne Vermelha/microbiologia , Animais , Atmosfera , Bélgica , Carnobacterium/efeitos dos fármacos , Carnobacterium/genética , Contagem de Colônia Microbiana , Microbiologia de Alimentos , Embalagem de Alimentos/normas , Conservação de Alimentos , Lactatos/farmacologia , Lactobacillaceae/efeitos dos fármacos , Lactobacillaceae/genética , Leuconostoc/efeitos dos fármacos , Leuconostoc/genética , Microbiota/efeitos dos fármacos , Reação em Cadeia da Polimerase , Suínos
9.
Food Microbiol ; 62: 147-152, 2017 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-27889141

RESUMO

Understanding the factors influencing meat bacterial communities is important as these communities are largely responsible for meat spoilage. The composition and structure of a bacterial community on a high-O2 modified-atmosphere packaged beef product were examined after packaging, on the use-by date and two days after, to determine whether the communities at each stage were similar to those in samples taken from different production lots. Furthermore, we examined whether the taxa associated with product spoilage were distributed across production lots. Results from 16S rRNA amplicon sequencing showed that while the early samples harbored distinct bacterial communities, after 8-12 days storage at 6 °C the communities were similar to those in samples from different lots, comprising mainly of common meat spoilage bacteria Carnobacterium spp., Brochothrix spp., Leuconostoc spp. and Lactococcus spp. Interestingly, abundant operational taxonomic units associated with product spoilage were shared between the production lots, suggesting that the bacteria enable to spoil the product were constant contaminants in the production chain. A characteristic succession pattern and the distribution of common spoilage bacteria between lots suggest that both the packaging type and the initial community structure influenced the development of the spoilage bacterial community.


Assuntos
Embalagem de Alimentos , Armazenamento de Alimentos/normas , Microbiota , Carne Vermelha/microbiologia , Animais , Carga Bacteriana , Brochothrix/genética , Brochothrix/isolamento & purificação , Carnobacterium/genética , Carnobacterium/isolamento & purificação , Bovinos , DNA Bacteriano , Microbiologia de Alimentos , Lactococcus/genética , Lactococcus/isolamento & purificação , Leuconostoc/genética , Leuconostoc/isolamento & purificação , Microbiota/genética , Microbiota/fisiologia , RNA Ribossômico 16S/genética
10.
J Dairy Res ; 83(3): 383-6, 2016 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-27600975

RESUMO

During the last years the interest in donkey milk has increased significantly mainly because of its compelling functional elements. Even if the composition and nutritional properties of donkey milk are known, its microbiota is less studied. This Research Communication aimed to provide a comprehensive characterisation of the lactic acid bacteria in raw donkey milk. RAPD-PCR assay combined with 16S rDNA sequencing analysis were used to describe the microbial diversity of several donkey farms in the North West part of Italy. The more frequently detected species were: Lactobacillus paracasei, Lactococcus lactis and Carnobacterium maltaromaticum. Less abundant genera were Leuconostoc, Enterococcus and Streptococcus. The yeast Kluyveromyces marxianus was also isolated. The bacterial and biotype distribution notably diverged among the farms. Several of the found species, not previously detected in donkey milk, could have an important probiotic activity and biotechnological potential. This study represents an important insight to the ample diversity of the microorganisms present in the highly selective ecosystem of raw donkey milk.


Assuntos
Equidae/microbiologia , Lactobacillaceae/classificação , Lactobacillaceae/isolamento & purificação , Leite/microbiologia , Animais , Biodiversidade , Carnobacterium/genética , Carnobacterium/isolamento & purificação , DNA Bacteriano/análise , Ecossistema , Itália , Kluyveromyces/isolamento & purificação , Lactobacillaceae/genética , Lactobacillus/genética , Lactobacillus/isolamento & purificação , Lactococcus lactis/genética , Lactococcus lactis/isolamento & purificação , Probióticos , RNA Ribossômico 16S/genética , Técnica de Amplificação ao Acaso de DNA Polimórfico/veterinária
11.
Food Microbiol ; 58: 79-86, 2016 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-27217362

RESUMO

The dairy population of Carnobacterium maltaromaticum is characterized by a high diversity suggesting a high diversity of the genetic traits linked to the dairy process. As lactose is the main carbon source in milk, the genetics of lactose metabolism was investigated in this LAB. Comparative genomic analysis revealed that the species C. maltaromaticum exhibits genes related to the Leloir and the tagatose-6-phosphate (Tagatose-6P) pathways. More precisely, strains can bear genes related to one or both pathways and several strains apparently do not contain homologs related to these pathways. Analysis at the population scale revealed that the Tagatose-6P and the Leloir encoding genes are disseminated in multiple phylogenetic lineages of C. maltaromaticum: genes of the Tagatose-6P pathway are present in the lineages I, II and III, and genes of the Leloir pathway are present in the lineages I, III and IV. These data suggest that these genes evolved thanks to horizontal transfer, genetic duplication and translocation. We hypothesize that the lac and gal genes evolved in C. maltaromaticum according to a complex scenario that mirrors the high population diversity.


Assuntos
Carnobacterium/genética , Galactose/metabolismo , Variação Genética , Genômica , Lactose/metabolismo , Leite/metabolismo , Animais , Carnobacterium/metabolismo , Hexosefosfatos , Filogenia , Análise de Sequência de DNA , Sintenia
12.
Int J Food Microbiol ; 226: 1-4, 2016 Jun 02.
Artigo em Inglês | MEDLINE | ID: mdl-26998709

RESUMO

Carnobacterium maltaromaticum is a Lactic Acid Bacterium (LAB) of technological interest for the food industry, especially the dairy as bioprotection and ripening flora. The industrial use of this LAB requires accurate and resolutive typing tools. A new typing method for C. maltaromaticum inspired from MLVA analysis and called Repeat-based Sequence Typing (RST) is described. Rather than electrophoresis analysis, our RST method is based on sequence analysis of multiple loci containing Variable-Number Tandem-Repeats (VNTRs). The method described here for C. maltaromaticum relies on the analysis of three VNTR loci, and was applied to a collection of 24 strains. For each strain, a PCR product corresponding to the amplification of each VNTR loci was sequenced. Sequence analysis allowed delineating 11, 11, and 12 alleles for loci VNTR-A, VNTR-B, and VNTR-C, respectively. Considering the allele combination exhibited by each strain allowed defining 15 genotypes, ending in a discriminatory index of 0.94. Comparison with MLST revealed that both methods were complementary for strain typing in C. maltaromaticum.


Assuntos
Carnobacterium/classificação , Carnobacterium/genética , Microbiologia de Alimentos , Alelos , Variação Genética , Genótipo , Repetições Minissatélites/genética , Tipagem de Sequências Multilocus , Reação em Cadeia da Polimerase , Especificidade da Espécie
13.
Int J Food Microbiol ; 218: 86-95, 2016 Feb 02.
Artigo em Inglês | MEDLINE | ID: mdl-26623935

RESUMO

Accumulation of volatile organic compounds was monitored in association with sensory quality, bacterial concentrations and culture-independent microbial community analyses in raw pork loin and pork collar during storage under high-oxygen modified atmosphere at +4 °C. Of the 48 volatile compounds detected in the pork samples, the levels of acetoin, diacetyl and 3-methyl-1-butanol had the highest correlations with the sensory scores and bacterial concentrations. These compounds accumulated in all of the four monitored lots of non-sterile pork but not in the sterilized pork during chilled storage. According to the culture-dependent and culture-independent characterization of bacterial communities, Brochothrix thermosphacta, lactic acid bacteria (Carnobacterium, Lactobacillus, Lactococcus, Leuconostoc, Weissella) and Photobacterium spp. predominated in pork samples. Photobacterium spp., typically not associated with spoilage of meat, were detected also in 8 of the 11 retail packages of pork investigated subsequently. Eleven isolates from the pork samples were shown to belong to Photobacterium phosphoreum by phenotypic tests and sequencing of the 16S rRNA and gyrB gene fragments. Off-odors in pork samples with high proportion of Photobacterium spp. were associated with accumulation of acetoin, diacetyl and 3-methyl-1-butanol in meat, but these compounds did not explain all the off-odors reported in sensory analyses.


Assuntos
Embalagem de Alimentos , Odorantes/análise , Photobacterium/metabolismo , Carne Vermelha/microbiologia , Compostos Orgânicos Voláteis/análise , Acetoína/análise , Animais , Carnobacterium/genética , Carnobacterium/isolamento & purificação , DNA Girase/genética , Diacetil/análise , Microbiologia de Alimentos , Cromatografia Gasosa-Espectrometria de Massas , Lactococcus/genética , Lactococcus/isolamento & purificação , Leuconostoc/genética , Leuconostoc/isolamento & purificação , Pentanóis/análise , Photobacterium/isolamento & purificação , RNA Ribossômico 16S/genética , Suínos
14.
Int J Food Microbiol ; 213: 79-87, 2015 Nov 20.
Artigo em Inglês | MEDLINE | ID: mdl-26044337

RESUMO

Biopreservation is a natural technology of food preservation, which consists of inoculating food with microorganisms selected for their antibacterial properties. The objective of this study was to select lactic acid bacteria (LAB) to improve the quality of cold-smoked salmon (CSS). In this work, different strains representative of the 4 dominant species, identified in a previous study by pyrosequencing the 16S rRNA gene, were isolated and their spoiling potential in CSS blocks, sterilized by ionization, was assessed by twelve trained panelists along the vacuum storage at 8°C. Photobacterium phosphoreum, Brochothrix thermosphacta and Serratia proteamaculans released strong off-odors whereas the spoiling potential of Carnobacterium divergens was weaker. The spoiling capacity of Lactococcus piscium EU2241, Leuconostoc gelidum EU2247, Lactobacillus sakei EU2885, Staphylococcus equorum S030674 and 4 commercial starters was tested by the same method and 2 strains were eliminated due to off-odor production. The effect of the 6 selected LAB against the 4 specific spoiling organisms (SSOs) selected was tested by challenge tests in sterile CSS blocks. The protective effect of the LAB differed from one SSO to another and no correlation could be established between the sensory improvement, SSO inhibition, and the implantation or acidification of protective cultures (PCs). All the PCs except L. piscium reduced the off-odors released by P. phosphoreum although some of them had no effect on its growth. S. equorum, which did not grow in CSS, favored the implantation of P. phosphoreum but prevented its off-odor formation. L. piscium was the only strain that prevented the spoilage of B. thermosphacta and S. proteamaculans although it did not grow very well and did not acidify the product. L. gelidum EU2247 inhibited the growth of these 2 SSOs and lowered the pH but had no effect on the sensory quality. Finally, L. piscium was tested in 2 naturally contaminated products, with a positive effect on 1 batch. This effect was not correlated with the microbial ecosystem as determined by acultural and cultural techniques. Based on these results, the selection strategy is discussed.


Assuntos
Antibiose , Produtos Pesqueiros/microbiologia , Microbiologia de Alimentos , Conservação de Alimentos/métodos , Lactobacillus/crescimento & desenvolvimento , Odorantes/análise , Salmão/microbiologia , Animais , Sequência de Bases , Brochothrix/metabolismo , Carnobacterium/genética , DNA Bacteriano/genética , Lactococcus/metabolismo , Leuconostoc/metabolismo , Photobacterium/metabolismo , RNA Ribossômico 16S/genética , Análise de Sequência de DNA , Serratia/metabolismo , Vácuo
16.
FEMS Microbiol Lett ; 362(10)2015 May.
Artigo em Inglês | MEDLINE | ID: mdl-25868912

RESUMO

Carnobacterium jeotgali strain MS3(T) was isolated from traditionally fermented Korean shrimp produced with bay salt. The bacterium belongs to the family Carnobacteriaceae, produces lactic acid and contains gene clusters involved in the production of lactate, butyrate, aromatic compounds and exopolysaccharides. Carnobacterium jeotgali strain MS3(T) was characterized through extensive comparison of the virulence potential, genomic relatedness and sequence similarities of its genome with the genomes of other Carnobacteria and lactic acid bacteria. In addition, links between predicted functions of genes and phenotypic characteristics, such as antibiotic resistance and lactate and butyrate production, were extensively evaluated. Genomic and phenotypic analyses of strain MS3(T) revealed promising features, including minimal virulence genes and lactate production, which make this bacterium a desirable candidate for exploitation by the fermented food industry.


Assuntos
Carnobacterium/genética , Carnobacterium/isolamento & purificação , Conservação de Alimentos/métodos , Penaeidae/microbiologia , Alimentos Marinhos/microbiologia , Animais , Butiratos/metabolismo , Carnobacterium/metabolismo , Carnobacterium/patogenicidade , Fermentação , Genoma Bacteriano , Ácido Láctico/metabolismo , Lactobacillaceae/genética , Dados de Sequência Molecular , Família Multigênica , Fenótipo , Alinhamento de Sequência , Análise de Sequência de DNA , Virulência/genética
17.
Microbiology (Reading) ; 160(Pt 8): 1670-1678, 2014 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-24858287

RESUMO

Piscicolin 126 is a class 2a bacteriocin produced by Carnobacterium maltaromaticum strains UAL26 and JG126. Whilst strain UAL26 shows temperature-dependent piscicolin 126 production, strain JG126 produces bacteriocin at any growth temperature. Several clones containing combinations of the ATP-binding cassette transporter (pisT) and transporter accessory (pisE) genes from JG126 and UAL26 were created and tested for bacteriocin production. Bacteriocin production at 25 °C was observed only for a clone containing both pisT and pisE from JG126 (U-T(J)E(J)) and a clone containing pisT from UAL26 and pisE from JG126 (U-BamT(U)E(J)). Therefore, the deletion of a single CG base pair located on pisE of UAL26 that results in a frameshift and truncation of PisE causes the temperature-dependent piscicolin 126 production. Bacteriocin production of UAL26 was induced at 25 °C by the addition of supernatant containing the autoinducer peptide (AIP); however, the antimicrobial activity was lost after two subsequent overnight cultivations due to the presumed lack of the AIP. Changes in membrane fluidity due to changes in temperature or the presence of 2-phenylethanol (PHE) affected bacteriocin production of UAL26, but not of clones U-T(J)E(J) or U-BamT(U)E(J). Similarly, increased membrane fluidity due to PHE addition reduced production of sakacin A in Lactobacillus sakei Lb706 and Lactobacillus curvatus LTH 1174. The mechanism involved in the temperature-dependent piscicolin 126 production was described. Due to the conformational change in PisE at 25 °C, the transport machinery was not able to translocate AIP. To the best of our knowledge, this is the first report that links membrane fluidity with the regulation of bacteriocin production.


Assuntos
Antibacterianos/biossíntese , Bacteriocinas/biossíntese , Carnobacterium/metabolismo , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Carnobacterium/genética , Regulação Bacteriana da Expressão Gênica , Lactobacillus/genética , Lactobacillus/metabolismo , Temperatura
18.
Appl Environ Microbiol ; 80(13): 3920-9, 2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-24747901

RESUMO

Dairy products are colonized with three main classes of lactic acid bacteria (LAB): opportunistic bacteria, traditional starters, and industrial starters. Most of the population structure studies were previously performed with LAB species belonging to these three classes and give interesting knowledge about the population structure of LAB at the stage where they are already industrialized. However, these studies give little information about the population structure of LAB prior their use as an industrial starter. Carnobacterium maltaromaticum is a LAB colonizing diverse environments, including dairy products. Since this bacterium was discovered relatively recently, it is not yet commercialized as an industrial starter, which makes C. maltaromaticum an interesting model for the study of unindustrialized LAB population structure in dairy products. A multilocus sequence typing scheme based on an analysis of fragments of the genes dapE, ddlA, glpQ, ilvE, pyc, pyrE, and leuS was applied to a collection of 47 strains, including 28 strains isolated from dairy products. The scheme allowed detecting 36 sequence types with a discriminatory index of 0.98. The whole population was clustered in four deeply branched lineages, in which the dairy strains were spread. Moreover, the dairy strains could exhibit a high diversity within these lineages, leading to an overall dairy population with a diversity level as high as that of the nondairy population. These results are in agreement with the hypothesis according to which the industrialization of LAB leads to a diversity reduction in dairy products.


Assuntos
Carnobacterium/classificação , Carnobacterium/genética , Laticínios/microbiologia , Variação Genética , DNA Bacteriano/química , DNA Bacteriano/genética , Genes Bacterianos , Dados de Sequência Molecular , Tipagem de Sequências Multilocus , Análise de Sequência de DNA
19.
Mol Biotechnol ; 56(3): 210-22, 2014 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-24037409

RESUMO

Eight putative consistently expressed genes in Carnobacterium maltaromaticum and Lactobacillus curvatus, and nine in Listeria innocua, were examined for their potential as references for the normalization of gene expression. Expression stability of candidate reference genes was evaluated under growth conditions of low (5 °C) and moderately high (40-42.5 °C) temperatures, and high salt (≥3 % NaCl) using the geNormplus and NormFinder algorithms. Under temperature stress, both algorithms ranked elongation factor Tu (Tuf) as the most stably expressed gene in C. maltaromaticum. In L. curvatus, at similar conditions, geNormplus identified Tuf and 6-phosphogluconate dehydrogenase (6PGDH) as suitable for normalization, while NormFinder identified phenylalanyl-tRNA synthase and recombinase A as the best pair. In L. innocua grown under the same temperatures, geNormplus ranked 6PGDH, glyceraldehyde-3-phosphate dehydrogenase (GAPDH), and Tuf as the top three most stable references, whereas NormFinder identified GAPDH and 6PGDH as suitable for normalization, with Tuf ranked as number six. There was less consistency between algorithms in the salt stress experiment. No gene was identified that exhibited such a constant level of expression as to outperform the other candidates under both experimental conditions. This study underlines the need for normalizing bacterial gene expression using multiple carefully selected references.


Assuntos
Proteínas de Bactérias/metabolismo , Carnobacterium/genética , Lactobacillus/genética , Listeria/genética , Algoritmos , Carnobacterium/classificação , Carnobacterium/fisiologia , Perfilação da Expressão Gênica , Regulação Bacteriana da Expressão Gênica , Genes Bacterianos , Lactobacillus/classificação , Lactobacillus/fisiologia , Listeria/classificação , Listeria/fisiologia , Estresse Fisiológico
20.
World J Microbiol Biotechnol ; 30(2): 399-406, 2014 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-23933805

RESUMO

Wilt disease of soybean caused by a very common soil-borne fungus, Fusarium oxysporum is one of the most destructive diseases of the crop. The aim of the present study was to characterize plant growth-promotion activities and induced resistance of a rhizobacterial strain for the soybean plant against F. oxysporum. Rhizobacterium strain SJ-5 exhibited plant growth-promotion characteristics and antagonistic activity against the test pathogen on dual plate assay. It was identified as a Carnobacterium sp. A 950 bp PCR product was amplified from Carnobacterium sp. strain SJ-5, using zwittermicin A self-resistance gene-specific primers (zmaR). The strain produced indole 3-acetic acid (19 µg/ml) in the presence of salt stress and exhibited growth in Dworkin and Foster salt medium amended with 1-aminocyclopropane-1-carboxylate (ACC) through ACC deaminase activity (277 nmol/mg/h) as compared to the control. Strain seeds treated with the strain significantly enhanced the quorum of healthy plants after challenge inoculation at 14 days after seeding. An increase in the activity of stress enzymes after challenge inoculation with the test pathogen is reported. Treatment with the bacterium resulted in an increase in the chlorophyll content in the leaves in comparison with challenge-inoculated plants.


Assuntos
Carnobacterium/fisiologia , Fusarium/crescimento & desenvolvimento , Doenças das Plantas/prevenção & controle , Soja/crescimento & desenvolvimento , Soja/microbiologia , Carnobacterium/genética , Carnobacterium/metabolismo , Clorofila/análise , Proteínas de Choque Térmico/biossíntese , Ácidos Indolacéticos/metabolismo , Reguladores de Crescimento de Planta/metabolismo , Folhas de Planta/química , Soja/enzimologia
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...