Effects of Cold Smoking on the Microbiological Characteristics and Volatile Compounds of a Formaella-Type Hard Ewe’s Milk Cheese

Polyphasic study of microbial communities of two Spanish farmhouse goats' milk cheeses from Sierra de Aracena

Development of a functional Greek sheep yogurt incorporating a probiotic Lacticaseibacillus rhamnosus wild-type strain as adjunct starter culture

Significance of low molecular weight nitrogen constituents in cheese milk and of proteinase-negative variants of a Lactococcus lactis subsp. cremoris strain on the production and maturation of Danbo cheese

The aim of this study was to identify and characterize the lactic acid bacteria (LAB) of artisanal Golija raw and cooked cows? milk cheeses traditionally manufactured without the addition of starter culture. A total of 188 Gram-positive and catalase-negative isolates of Golija cheeses were obtained from seven samples of different ripening time. Phenotypebased assays as well as rep-PCR and 16S rDNA sequence analysis were undertaken for all 188 Lstrains. The most diverse species were isolated from 20-day-old BGGO8 cheese (Lactobacillus fermentum, Lactobacillus plantarum, Lactobacillus casei/paracasei, Lactobacillus sucicola, Lactococcus lactis subsp. lactis, Lactococcus lactis subsp. lactis bv. diacetylactis, Enterococcus faecium, Enterococcus durans and Leuconostoc mesenteroides). In other Golija cheeses Lactobacillus reuteri, Lactobacillus curvatus, Lactobacillus rhamnosus, Lactococcus lactis subsp. cremoris, Lactococcus garvieae, Streptococcus thermophilus and Leuconostoc pseudomesenteroides were found. Pronounced antimicrobial properties showed enterococci (13/42) and lactococci (12/31), while the good proteolytic activity demonstrated lactococci (13/31) and lactobacilli (10/29).

This study aimed to evaluate the microbiome, resistome and virulome of two types of Portuguese cheese using high throughput sequencing (HTS). Culture-dependent chromogenic methods were also used for certain groups/microorganisms. Eight samples of raw ewe’s milk cheese were obtained from four producers: two producers with cheeses with a PDO (Protected Designation of Origin) label and the other two producers with cheeses without a PDO label. Agar-based culture methods were used to quantify total mesophiles, Enterobacteriaceae, Escherichia coli, Staphylococcus, Enterococcus and lactic acid bacteria. The presence of Listeria monocytogenes and Salmonella was also investigated. The selected isolates were identified by 16S rRNA gene sequencing and evaluated to determine antibiotic resistance and the presence of virulence genes. The eight cheese samples analyzed broadly complied with EC regulations in terms of the microbiological safety criteria. The HTS results demonstrated that Leuconostoc mesenteroides, Lactococcus lactis, Lactobacillus plantarum, Lacticaseibacillus rhamnosus, Enterococcus durans and Lactobacillus coryniformis were the most prevalent bacterial species in cheeses. The composition of the bacterial community varied, not only between PDO and non-PDO cheeses, but also between producers, particularly between the two non-PDO cheeses. Alpha-diversity analyses showed that PDO cheeses had greater bacterial diversity than non-PDO cheeses, demonstrating that the diversity of spontaneously fermented foods is significantly higher in cheeses produced without the addition of food preservatives and dairy ferments. Despite complying with microbiological regulations, both PDO and non-PDO cheeses harbored potential virulence genes as well as antibiotic resistance genes. However, PDO cheeses exhibited fewer of these virulence and antibiotic resistance genes compared to non-PDO cheeses. Therefore, the combination of conventional microbiological methods and the metagenomic approach could contribute to improving the attribution of the PDO label to this type of cheese.

Kefir is a high nutritional fermented dairy beverage associated with a wide range of health benefits. It constitutes a unique symbiotic association, comprising mainly lactic acid bacteria, yeasts, and occasionally acetic acid bacteria, which is strongly influenced by the geographical origin of the grains, the type of milk used, and the manufacture technology applied. Until recently, kefir microbiota has been almost exclusively studied by culture-dependent techniques. However, high-throughput sequencing, alongside omics approaches, has revolutionized the study of food microbial communities. In the present study, the bacterial, and yeast/fungal microbiota of four home-made samples (both grains and drinks), deriving from well spread geographical regions of Greece, and four industrial beverages, was elucidated by culture-dependent and -independent analyses. In all samples, classical microbiological analysis revealed varying populations of LAB and yeasts, ranging from 5.32 to 9.60 log CFU mL–1 or g–1, and 2.49 to 7.80 log CFU mL–1 or g–1, respectively, while in two industrial samples no yeasts were detected. Listeria monocytogenes, Salmonella spp. and Staphylococcus spp. were absent from all the samples analyzed, whereas Enterobacteriaceae were detected in one of them. From a total of 123 isolates, including 91 bacteria and 32 yeasts, Lentilactobacillus kefiri, Leuconostoc mesenteroides, and Lactococcus lactis as well as Kluvyeromyces marxianus and Saccharomyces cerevisiae were the mostly identified bacterial and yeast species, respectively, in the home-made samples. On the contrary, Streptococcus thermophilus, Lactobacillus delbrueckii subsp. bulgaricus, and Lacticaseibacillus rhamnosus along with Debaryomyces hansenii and K. marxianus were the main bacterial and yeast species, respectively, isolated from the industrial beverages. In agreement with the identification results obtained from the culture-dependent approaches, amplicon-based metagenomics analysis revealed that the most abundant bacterial genera in almost all home-made samples (both grains and drinks) were Lactobacillus and Lactococcus, while Saccharomyces, Kazachstania, and Kluvyeromyces were the predominant yeasts/fungi. On the other hand, Streptococcus, Lactobacillus, and Lactococcus as well as Kluvyeromyces and Debaryomyces dominated the bacterial and yeast/fungal microbiota, respectively, in the industrial beverages. This is the first report on the microbiota of kefir produced in Greece by a holistic approach combining classical microbiological, molecular, and amplicon-based metagenomics analyses.

Effect of indigenous cheese isolates via co-culture fermentation models on metabolic and lipidomic interactions of dairy cream.

“Nostrano-cheeses” are traditional alpine cheeses made from raw cow's milk in Trentino-Alto Adige, Italy. This study identified lactic acid bacteria (LAB) developing during maturation of “Nostrano-cheeses” and evaluated their potential to produce γ-aminobutyric acid (GABA), an immunologically active compound and neurotransmitter. Cheese samples were collected on six cheese-making days, in three dairy factories located in different areas of Trentino and at different stages of cheese ripening (24 h, 15 days, and 1, 2, 3, 6, and 8 months). A total of 1,059 LAB isolates were screened using Random Amplified Polymorphic DNA-PCR (RAPD-PCR) and differentiated into 583 clusters. LAB strains from dominant clusters (n = 97) were genetically identified to species level by partial 16S rRNA gene sequencing. LAB species most frequently isolated were Lactobacillus paracasei, Streptococcus thermophilus, and Leuconostoc mesenteroides. The 97 dominant clusters were also characterized for their ability in producing GABA by high-performance liquid chromatography (HPLC). About 71% of the dominant bacteria clusters evolving during cheeses ripening were able to produce GABA. Most GABA producers were Lactobacillus paracasei but other GABA producing species included Lactococcus lactis, Lactobacillus plantarum, Lactobacillus rhamnosus, Pediococcus pentosaceus, and Streptococcus thermophilus. No Enterococcus faecalis or Sc. macedonicus isolates produced GABA. The isolate producing the highest amount of GABA (80.0±2.7 mg/kg) was a Sc. thermophilus.

Campylobacter and Salmonella are the two most prominent foodborne zoonotic pathogens reported in the European Union. As poultry is one of the major sources of these pathogens, it is imperative to mitigate the colonization of these pathogens in poultry. Many strains of lactic acid bacteria (LAB) have demonstrated anti-Salmonella and anti-Campylobacter characteristics to varying degrees and spectrums which are attributed to the production of various metabolites. However, the production of these compounds and consequent antimicrobial properties are highly strain dependent. Therefore, the current study was performed to select a potent LAB and determine its causal attribute in inhibiting Salmonella enterica and Campylobacter jejuni, in-vitro. Six LAB (Lactiplantibacillus plantarum (LP), Lacticaseibacillus casei (LC), Limosilactobacillus reuteri (LR), Lacticaseibacillus rhamnosus (LRh), Leuconostoc mesenteroides (LM) and Pediococcus pentosaceus (PP)) and three serovars of Salmonella enterica (Typhimurium, Enterica and Braenderup) and Campylobacter jejuni were used in the current study. Spot overlays, well diffusion, co-culture and co-aggregation assays against Salmonella and well diffusion assays against Campylobacter jejuni were performed. Organic acid profiling of culture supernatants was performed using HPLC. The results indicated that LRh, LM and PP had the most significant anti-Salmonella effects while LP, LC, LM and PP displayed the most significant anti-Campylobacter effects. Lactic acid and formic acid detected in the culture supernatants seem the most likely source of the anti-Salmonella and anti-Campylobacter effects exhibited by these LAB. In conclusion, Leuconostoc mesenteroides displayed the most significant overall anti-pathogenic effects when compared to the other LAB strains studied, indicating its potential application in-vivo.

자작나무 수액을 이용한 유산균 발효에 적합한 균주의 선발 실험을 통하여 선발된 Lactobacillus균을 이용하여 발효시킨 수액을 실온에서 2주일 이상의 장시간 동안 저장한 결과 10? cfu/mL 이상의 유산균수를 유지하며, 유기산의 생성으로 pH 4.0 이하를 유지하였고 일반세균은 검출되지 않았다. 또, 여과하여 제균을 실시할 시의 미네랄성분의 변화와 유산균에 의한 미네랄의 변화를 분석한 결과 손실량이 극히 적은 것으로 나왔다. 이것으로 보아 유산균 발효에 의한 저장성 증진의 효능이 입증되었다.

Diversity of lactic acid bacteria associated with traditional fermented dairy products in Mongolia

Characterization of lactic acid bacteria isolated from artisanal Travnik young cheeses, sweet creams and sweet kajmaks over four seasons

Assessment of Abilities of Conjugal Transfer and Stability of pAMβ1 in Dairy Lactobacilli with Emphasis on Thermophilic and Nonstarter Lactobacilli

Tempoyak as local wisdom and national culture is poorly documented. Therefore, it is important to explore the preferences of the millennial generation regarding the organoleptic qualities of Tempoyak. The research design is a one-shot case study. The variables tested were the diversity of microflora in tempoyak, and its influence on the level of organoleptic quality and the level of preference of the millennial generation. Identification of isolates using API-50CHL, biochemical tests and physiological tests. Organoleptic quality uses the hedonic scale test. The research panelists were 120 people from the Dayak, Madura, Jawa and Banjar tribes. Data analysis uses one way Anava analysis. 15 isolates of microflora were found in Tempoyak which affected its taste and organoleptics, 8 isolates including lactic acid bacteria, including Pediococcus acidilactici, Lactobacillus curvatus, Leuconostoc mesenteroides, Lactobacillus plantarum, Streptococcus thermophiles, Lactobacillus pentosus, Enterococcus faecium, and Weissella paramesenteroides. 1 isolate of non-lactic acid bacteria that is Micrococcus varians. 2 isolates from the yeast group consisted of Saccharomyces cereviciae and Kluyveromyces marxianus, and 4 isolates included Rhizopus, Monilia sitophila, and Mucor roxii. All microflora found were capable of producing lactic acid, except Aspergillus repens. The statistical test results show the significance of its influence on the organoleptic quality of all sub-variables, including color, taste, aroma and texture of Tempoyak. The exploration results in this research indicate opportunities for Tempoyak to be more developed, innovative and contemporary, so that it is preferred by the millennial generation.

The free fatty acid (FFA) profile of high pressure treated ewes' milk cheeses were studied to assess the effect of pressure treatment on cheese lipolysis. Cheeses were treated at 200, 300, 400 or 500 MPa (2P to 5P) at two stages of ripening (after 1 and 15 days of manufacturing; P1 and P15) and FFA were assayed at 1, 15 and 60 d ripening. On the first day of ripening, 3P1-cheeses showed levels of FFA twice that of the control cheeses. However, no significant differences were found between 3P1 and control cheeses at 60 d ripening. On the contrary, 4P1 and 5P1-cheeses had the lowest total FFA levels. The point at which pressure treatment was applied influenced the FFA profile of cheeses; cheeses pressurized at pressures<400 MPa on the first day of ripening were more similar to untreated cheeses than their homologues treated at 15 d.