Exploring resource competition by protective lactic acid bacteria cultures to control in food: an Achilles' heel to target?

is a pathogenic bacterium, being the second most commonly reported foodborne pathogen in Europe, due to the ability of its different serovars to contaminate a wide variety of foods, with differences among countries. Common chemical or physical control methods are not always effective, eco-sustainable and adapted to the diversity of serovars. Thus, great attention is given to developing complementary or alternative control methods that can be tailor made for specific situations.

Phages Shape Microbial Dynamics and Metabolism of a Model Community Mimicking Cider, a Fermented Beverage.

Model microbial communities are often studied to better understand interactions and fluxes during fermentation processes. However, models that take into account the potential impact of bacteriophages (phages), which are recognized as drivers of microbial communities, are scarce, especially in fermented foods. This study aimed at investigating the behavior of a cider model microbial community, which was subjected to disturbance in the presence or absence of phages and at two different temperatures (25 °C and 15 °C).

Contribution of omics to biopreservation: Toward food microbiome engineering.

Biopreservation is a sustainable approach to improve food safety and maintain or extend food shelf life by using beneficial microorganisms or their metabolites. Over the past 20 years, omics techniques have revolutionised food microbiology including biopreservation. A range of methods including genomics, transcriptomics, proteomics, metabolomics and meta-omics derivatives have highlighted the potential of biopreservation to improve the microbial safety of various foods.

Molecular approaches to uncover phage-lactic acid bacteria interactions in a model community simulating fermented beverages.

Food microbial diversity and fluxes during the fermentation processes are well studied whereas phages-bacteria interactions are still poorly described in the literature. This is especially true in fermented beverages, and especially in cider, which is an alcoholic fermented apple beverage. The transcriptomic and proteomic responses of the lactic acid bacterium (LAB) Liquorilactobacillus mali UCMA 16447 to a lytic infection by phage UCMA 21115, both isolated from cider, were investigated, in order to get a better understanding of phages-bacteria interactions in such fermented beverage.

Investigation of the Phageome and Prophages in French Cider, a Fermented Beverage.

Phageomes are known to play a key role in the functioning of their associated microbial communities. The phageomes of fermented foods have not been studied thoroughly in fermented foods yet, and even less in fermented beverages. Two approaches were employed to investigate the presence of phages in cider, a fermented beverage made from apple, during a fermentation process of two cider tanks, one from an industrial producer and one from a hand-crafted producer.

Pseudomonas crudilactis sp. nov., isolated from raw milk in France.

Strains belonging to the Pseudomonas genus have been isolated worldwide from various biotic (humans, animals and plant tissues) and abiotic (food, soil, water and air) environments. Raw milk provides a favorable environment for the growth of a broad spectrum of microorganisms, including Pseudomonas. Here we present the description of Pseudomonas sp.

Corrigendum: Characterization of Milkisin, a Novel Lipopeptide With Antimicrobial Properties Produced By sp. UCMA 17988 Isolated From Bovine Raw Milk.

[This corrects the article DOI: 10.3389/fmicb.2018.

Phage community involvement in fermented beverages: an open door to technological advances?

Bacteriophages (phages) are considered the most abundant biological entities on Earth. An increasing interest in understanding phage communities, also called viromes or phageomes, has arisen over the past decade especially thanks to the development and the accessibility of Next Generation Sequencing techniques. Despite the increasing amount of available metagenomic data on microbial communities in various habitats, viromes remain poorly described in the scientific literature particularly when it comes to fermented food and beverages such as wine and cider.

Purification, Characterization and Thermodynamic Assessment of an Alkaline Protease by of Dairy Origin.

Background: Alkaline proteases is the important group of enzymes having numerous industrial applications including dairy food formulations.

Objectives: The current study deals with the purification and characterization of an alkaline serine protease produced by QAUGC01, isolated from indigenous fermented milk product, Dahi.

Material And Methods: In total twelve strains were screened for their proteolytic activity by using standard protease assay.

Safety assessment of Gram-negative bacteria associated with traditional French cheeses.

Twenty Gram-negative bacterial (GNB) strains were selected based on the biodiversity previously observed in French traditional cheeses and their safety was assessed considering various safety criteria. For the majority of tested GNB strains, only gastric stress at pH 2 (vs pH 4) resulted in low survival and no regrowth after an additional simulated gastro-intestinal stress. Presence of milk was shown to be rarely protective.

Phages for biocontrol in foods: What opportunities for Salmonella sp. control along the dairy food chain?

Controlling the presence of pathogenic bacteria, such as Salmonella sp., in dairy products production is a burning issue since contamination with Salmonella can occur at any stage of the production chain. The use of Salmonella-phages applied as control agents has gained considerable interest.

Characterization of Milkisin, a Novel Lipopeptide With Antimicrobial Properties Produced By sp. UCMA 17988 Isolated From Bovine Raw Milk.

Biosurfactants such as lipopeptides are amphiphilic compounds produced by microorganisms such as bacteria of the genera of and . Some of these molecules proved to have interesting antimicrobial, antiviral, insecticide, and/or tensioactive properties that are potentially useful for the agricultural, chemical, food, and pharmaceutical industries. Raw milk provides a physicochemical environment that is favorable to the multiplication of a broad spectrum of microorganisms.

Draft Genome Sequence of Enterococcus mundtii QAUEM2808, Isolated from Dahi, a Fermented Milk Product.

Enterococcus mundtii QAUEM2808 has been isolated from dahi, an indigenous fermented milk product of Pakistan. Here, we report the draft genome sequence for this strain, which consists of 160 contigs corresponding to 2,957,514 bp and a G+C content of 38.5%.

Traditional cheeses: rich and diverse microbiota with associated benefits.

The risks and benefits of traditional cheeses, mainly raw milk cheeses, are rarely set out objectively, whence the recurrent confused debate over their pros and cons. This review starts by emphasizing the particularities of the microbiota in traditional cheeses. It then describes the sensory, hygiene, and possible health benefits associated with traditional cheeses.

Biodiversity of the Surface Microbial Consortia from Limburger, Reblochon, Livarot, Tilsit, and Gubbeen Cheeses.

Comprehensive collaborative studies from our laboratories reveal the extensive biodiversity of the microflora of the surfaces of smear-ripened cheeses. Two thousand five hundred ninety-seven strains of bacteria and 2,446 strains of yeasts from the surface of the smear-ripened cheeses Limburger, Reblochon, Livarot, Tilsit, and Gubbeen, isolated at three or four times during ripening, were identified; 55 species of bacteria and 30 species of yeast were found. The microfloras of the five cheeses showed many similarities but also many differences and interbatch variation.

Reduced growth of Listeria monocytogenes in two model cheese microcosms is not associated with individual microbial strains.

Two model antilisterial microbial communities consisting of two yeasts, two Gram positive and two Gram negative bacteria, and originating from Livarot cheese smear were previously designed. They were used in the present study to analyse the impact of microbial population dynamics on growth of Listeria monocytogenes in cheese microcosm. Specific culture media and PCR primers were developed for simultaneous culture-dependent and real-time PCR quantification of strains belonging to Marinomonas sp.

Impact of Gram-negative bacteria in interaction with a complex microbial consortium on biogenic amine content and sensory characteristics of an uncooked pressed cheese.

The impact of Gram-negative bacteria on sensory characteristics and production of volatile compounds as well as biogenic amines (BA) in the core of an uncooked pressed type model cheese was investigated in the presence of a defined complex microbial consortium. Eleven strains of Gram-negative bacteria, selected on the basis of their biodiversity and in vitro BA-production ability, were individually tested in a model cheese. Four out of 6 strains of Enterobacteriaceae (Citrobacter freundii UCMA 4217, Klebsiella oxytoca 927, Hafnia alvei B16 and Proteus vulgaris UCMA 3780) reached counts close to 6 log CFU g⁻¹ in the model cheese.

Diversity and assessment of potential risk factors of Gram-negative isolates associated with French cheeses.

The goal of this study was to identify at the species level a large collection of Gram-negative dairy bacteria isolated from milks or semi-hard and soft, smear-ripened cheeses (cheese core or surface samples) from different regions of France. The isolates were then assessed for two risk factors, antibiotic resistance and volatile and non-volatile biogenic amine production in vitro. In total, 173 Gram-negative isolates were identified by rrs and/or rpoB gene sequencing.

From undefined red smear cheese consortia to minimal model communities both exhibiting similar anti-listerial activity on a cheese-like matrix.

Starting from one undefined cheese smear consortium exhibiting anti-listerial activity (signal) at 15 °C, 50 yeasts and 39 bacteria were identified by partial rDNA sequencing. Construction of microbial communities was done either by addition or by erosion approach with the aim to obtain minimal communities having similar signal to that of the initial smear. The signal of these microbial communities was monitored in cheese microcosm for 14 days under ripening conditions.

Development of primers for detecting dominant yeasts in smear-ripened cheeses.

PCR primers were developed for the specific detection of Clavispora lusitaniae, Debaryomyces hansenii var hansenii, Geotrichum candidum, Kluyveromyces lactis and K. marxianus and Yarrowia lipolytica, yeast species commonly found on the surface of smear cheese. Forty eight representative strains frequently found in smear cheeses or taxonomically related to the target yeasts were used as templates, to validate the designed primers.

Agrococcus casei sp. nov., isolated from the surfaces of smear-ripened cheeses.

Seven Gram-positive, coryneform bacteria with virtually identical whole-organism protein patterns were isolated from the surface of smear-ripened cheeses. Representatives of these strains were the subject of a polyphasic study designed to establish their taxonomic status. The organisms formed a distinct branch in the Microbacteriaceae 16S rRNA gene tree and were most closely related to members of the genus Agrococcus, sharing sequence similarities of 95.

Geotrichum candidum dominates in yeast population dynamics in Livarot, a French red-smear cheese.

The diversity and dynamics of yeast populations in four batches of Livarot cheese at three points of ripening were determined. Nine different species were identified by Fourier transform infrared spectroscopy and/or sequencing, and each batch had its own unique yeast community. A real-time PCR method was developed to quantify the four main yeast species: Debaryomyces hansenii, Geotrichum candidum, Kluyveromyces sp.

Resin straw as an alternative system to securely store frozen microorganisms.

Freezing of prokaryotic and eukaryotic microorganisms is the main interest in the study of cold stress responses of living organisms. In parallel, applications which arise from this approach are of two types: (i) optimization of the frozen starters used in food processing; and (ii) improvement of the ex situ preservation of microorganisms in collections. Currently, cryopreservation of microorganisms in collections is carried out in cryotubes, and bibliographical references related to freezing microorganisms packaged in straws are scarce.