Provolone del Monaco PDO cheese: Lactic microflora, biogenic amines and volatilome characterization.

One commercial production run of Provolone del Monaco - a long-ripened pasta filata cheese - was followed up to the end of ripening for a total of 20 samples. 371 LAB isolates were subject to genetic characterization followed by 16S rRNA gene sequencing. The dominant species were Lacticaseibacillus casei/paracasei (19.

Diversity of the Microbiota of Traditional Izmir Tulum and Izmir Brined Tulum Cheeses and Selection of Potential Probiotics.

High-throughput DNA sequencing (HTS) was used to study the microbial diversity of commercial traditional Izmir Tulum (IT) and Izmir Brined Tulum (IBT) cheeses from Izmir, Türkiye. Simultaneously, cultivation-dependent methods were used to isolate, identify and characterize bacterial strains displaying probiotic potential. At the phylum level, dominated the microbiota of both cheese types comprising >98% of the population.

Modification of fast-slow differential agar medium for selective isolation of potential starter lactic acid bacteria from cheese.

Starter Lactic Acid Bacteria (LAB) are responsible for converting lactose to lactic acid during cheese manufacturing and, as a result, play a critical role in defining the attributes of the final product. There is great interest in isolating novel starter LAB strains to provide alternatives to existing industry cultures or to help enhance the quality and safety of cheeses traditionally made without starter cultures addition [1]. The Fast-Slow Differential Agar (FSDA) medium was developed in 1984 and still remains the standard to rapidly differentiate fast and slow milk-coagulating lactic streptococci and thus avoid screening a large number of isolates for acid production capacity [2].

Viability droplet digital polymerase chain reaction accurately enumerates probiotics and provides insight into damage experienced during storage.

Probiotics are typically enumerated by agar plate counting (PC) techniques. PC has several limitations including poor specificity, high variability, inability to enumerate dead cells, viable but non-culturable cells and cells in complex matrices. Viability droplet digital polymerase chain reaction (v-ddPCR) is an emerging enumeration technique with improved specificity, precision, and the ability to enumerate cells in varying states of culturability or in complex matrices.

Identification of Streptococcus infantarius subsp. infantarius as the species primarily responsible for acid production in Izmir Brined Tulum Cheese from the Aegean Region of Türkiye.

Izmir Brined Tulum (IBT) Cheese is a traditional semi hard cheese produced in the Aegean region of Türkiye. Lactic acid bacteria (LAB) isolates from IBT cheese samples taken during manufacture and from mature IBT cheeses were investigated for their acid producing capability with the aim of detecting LAB strains responsible for acid production in IBT cheese. Forty two out of 216 isolates decreased the pH of milk to 5.

Novel microaerobic agar plate method delivers highly selective and accurate enumeration of probiotic lactobacilli in freeze-dried blends containing bifidobacteria.

The enumeration of viable bacteria is an essential metric in the dietary supplement and food industry to ensure quality of probiotic products. However, selective enumeration of lactobacilli in probiotic freeze-dried blends containing bifidobacteria is difficult to achieve with current Lactobacillus-specific agars (i.e.

Optimization of Viability Treatment Essential for Accurate Droplet Digital PCR Enumeration of Probiotics.

Improvements offered by viability droplet digital PCR (v-ddPCR) include increased precision, specificity and decreased time to results making for an attractive alternative method to traditional plate count enumeration of probiotic products. A major hurdle faced in v-ddPCR, however, is distinguishing between live and dead cells. The objective of this study was to evaluate a combination of PMA and EMA (PE51) for viability treatment of freeze-dried probiotic powders.

Next-generation multiparameter flow cytometry assay improves the assessment of oxidative stress in probiotics.

Stability of probiotic products' potency throughout shelf life is essential to ensure systematic delivery of the dosages required to provide clinically-proven health benefits. Due to the oxygen sensitivity of gut-derived microorganisms, methods for the rapid and accurate monitoring of oxidative stress in probiotics are greatly needed as they can be instrumental to both bioprocess optimization and quality control. This study introduces a next-generation flow cytometry method multiplexing the CellROX® Green and Propidium Iodide probes for the simultaneous measurement of free total reactive oxygen species (ROS) and membrane integrity, respectively.

Insights into the Mode of Action of the Sactibiotic Thuricin CD.

Thuricin CD is a two-component bacteriocin, consisting of the peptides Trnα and Trnβ, and belongs to the newly designated sactibiotic subclass of bacteriocins. While it is clear from studies conducted thus far that it is a narrow-spectrum bacteriocin, requiring the synergistic activity of the two peptides, the precise mechanism of action of thuricin CD has not been elucidated. This study used a combination of flow cytometry and traditional culture-dependent assays to ascertain the effects of the thuricin CD peptides on the morphology, physiology and viability of sensitive DPC6349 cells.

High-throughput DNA sequencing to survey bacterial histidine and tyrosine decarboxylases in raw milk cheeses.

Background: The aim of this study was to employ high-throughput DNA sequencing to assess the incidence of bacteria with biogenic amine (BA; histamine and tyramine) producing potential from among 10 different cheeses varieties. To facilitate this, a diagnostic approach using degenerate PCR primer pairs that were previously designed to amplify segments of the histidine (hdc) and tyrosine (tdc) decarboxylase gene clusters were employed. In contrast to previous studies in which the decarboxylase genes of specific isolates were studied, in this instance amplifications were performed using total metagenomic DNA extracts.

Genetic response to bacteriophage infection in Lactococcus lactis reveals a four-strand approach involving induction of membrane stress proteins, D-alanylation of the cell wall, maintenance of proton motive force, and energy conservation.

In this study, whole-genome microarrays were used to gain insights into the global molecular response of Lactococcus lactis subsp. lactis IL1403 at an early stage of infection with the lytic phage c2. The bacterium differentially regulated the expression of 61 genes belonging to 14 functional categories, including cell envelope processes (12 genes), regulatory functions (11 genes), and carbohydrate metabolism (7 genes).

Plasmids of raw milk cheese isolate Lactococcus lactis subsp. lactis biovar diacetylactis DPC3901 suggest a plant-based origin for the strain.

The four-plasmid complement of the raw milk cheese isolate Lactococcus lactis subsp. lactis biovar diacetylactis DPC3901 was sequenced, and some genetic features were functionally analyzed. The complete sequences of pVF18 (18,977 bp), pVF21 (21,739 bp), pVF22 (22,166 bp), and pVF50 (53,876 bp) were obtained.

The presence of pMRC01 promotes greater cell permeability and autolysis in lactococcal starter cultures.

Conjugative transfer of plasmid-associated properties is routinely used to generate food-grade derivatives of lactococcal starter strains with improved technological traits. However, the introduction of one or more plasmids in a single strain is likely to impose a burden on regular cell metabolism and may affect the growth characteristics of the transconjugant culture. The aim of this study was to evaluate the impact of the 60.