Dynamics of starter, adjunct non-starter lactic acid bacteria and propionic acid bacteria in low-fat and full-fat Dutch-type cheese

Cotter

et al. 2015

Appl Environ Microbiol

We sought to determine if the time, within a production day, that a cheese is manufactured has an influence on the microbial community present within that cheese. To facilitate this, 16S rRNA amplicon sequencing was used to elucidate the microbial community dynamics of brine-salted continental-type cheese in cheeses produced early and late in the production day. Differences in the microbial composition of the core and rind of the cheese were also investigated. Throughout ripening, it was apparent that cheeses produced late in the day had a more diverse microbial population than their early equivalents. Spatial variation between the cheese core and rind was also noted in that cheese rinds were initially found to have a more diverse microbial population but thereafter the opposite was the case. Interestingly, the genera Thermus, Pseudoalteromonas, and Bifidobacterium, not routinely associated with a continental-type cheese produced from pasteurized milk, were detected. The significance, if any, of the presence of these genera will require further attention. Ultimately, the use of high-throughput sequencing has facilitated a novel and detailed analysis of the temporal and spatial distribution of microbes in this complex cheese system and established that the period during a production cycle at which a cheese is manufactured can influence its microbial composition.

Section: Figmentioning

confidence: 99%

Temporal and Spatial Differences in Microbial Composition during the Manufacture of a Continental-Type Cheese

Cotter

et al. 2015

Appl Environ Microbiol

“…The gel cassette was run at 120 V, Current 50 mA, Power 5 W, Time 16 h. When the gel run was finished the gel was stained in a solution of 250 ml of 1xTAE (Tris-acetate-EDTA) buffer + 25 μl ethidium bromide, placed on a shaker for approximately 30 min and visualization was made in the BioRad Gel Doc (Bio-Rad Laboratories, Hercules, CA, USA. DGGE bands of interest were excised with a sterile scalpel blade, transferred to a sterile Eppendorf tube, and DNA was eluted by 50 μl of 0.1xTAE buffer and kept overnight at 4°C (Porcellato et al 2013). A mixture of 5 μl purified PCR product and 5 μl primers were sent to GATC (Biotech AG, Cologne, Germany) for genome sequencing.…”

Section: Preparation Of the Gel Cassette And Gel Analysismentioning

confidence: 99%

Biochemical and molecular identification and characterization of lactic acid bacteria and yeasts isolated from Ethiopian naturally fermented buttermilk

2015

Lactic acid bacteria (LAB) and yeasts were enumerated and identified from naturally fermented buttermilk. Isolates were first subjected to chemical tests and then to molecular characterization. Molecular identification involved pure sequencing of 16s rRNA (LAB) and 18s rRNA (yeast) genes. Polymerase Chain Reaction-Denaturing Gradient Gel Electrophoresis (DGGE) was used for detection of microbiota composition. Eighty-five LAB and 26 yeast isolates obtained from 16 small-scale dairy farms were isolated and identified. The microbial composition was dominated by strains of Lactococcus lactis ssp. lactis, Lactobacillus plantarum and Saccharomyces cerevisiae. Molecular techniques enabled not only genetic confirmation but also detection of some uncultivated strains. The presence of diverse strains of LAB and yeasts in NFB indicated a potential for development of different starter cultures to make new dairy products.

“…are not believed to have a significant effect in the acidification process in the early stages of cheese making (Ardö and Varming, 2010 ). However, leuconostocs have been shown to dominate the cheese microbiota in the later stages of ripening with added propionic acid bacteria (Porcellato et al, 2013 ; Østlie et al, 2016 ). The genus Leuconostoc is comprised of 13 species, with the species Leuconostoc mesenteroides divided into subspecies mesenteroides, dextranicum, cremoris , and suionicum (Hemme and Foucaud-Scheunemann, 2004 ; Gu et al, 2012 ).…”

Section: Introductionmentioning

confidence: 99%

Genomic Characterization of Dairy Associated Leuconostoc Species and Diversity of Leuconostocs in Undefined Mixed Mesophilic Starter Cultures

et al. 2017

Self Cite

Undefined mesophilic mixed (DL-type) starter cultures are composed of predominantly Lactococcus lactis subspecies and 1–10% Leuconostoc spp. The composition of the Leuconostoc population in the starter culture ultimately affects the characteristics and the quality of the final product. The scientific basis for the taxonomy of dairy relevant leuconostocs can be traced back 50 years, and no documentation on the genomic diversity of leuconostocs in starter cultures exists. We present data on the Leuconostoc population in five DL-type starter cultures commonly used by the dairy industry. The analyses were performed using traditional cultivation methods, and further augmented by next-generation DNA sequencing methods. Bacterial counts for starter cultures cultivated on two different media, MRS and MPCA, revealed large differences in the relative abundance of leuconostocs. Most of the leuconostocs in two of the starter cultures were unable to grow on MRS, emphasizing the limitations of culture-based methods and the importance of careful media selection or use of culture independent methods. Pan-genomic analysis of 59 Leuconostoc genomes enabled differentiation into twelve robust lineages. The genomic analyses show that the dairy-associated leuconostocs are highly adapted to their environment, characterized by the acquisition of genotype traits, such as the ability to metabolize citrate. In particular, Leuconostoc mesenteroides subsp. cremoris display telltale signs of a degenerative evolution, likely resulting from a long period of growth in milk in association with lactococci. Great differences in the metabolic potential between Leuconostoc species and subspecies were revealed. Using targeted amplicon sequencing, the composition of the Leuconostoc population in the five commercial starter cultures was shown to be significantly different. Three of the cultures were dominated by Ln. mesenteroides subspecies cremoris. Leuconostoc pseudomesenteroides dominated in two of the cultures while Leuconostoc lactis, reported to be a major constituent in fermented dairy products, was only present in low amounts in one of the cultures. This is the first in-depth study of Leuconostoc genomics and diversity in dairy starter cultures. The results and the techniques presented may be of great value for the dairy industry.