title: Microbial diversity and dynamics throughout manufacturing and ripening of surface ripened semi-hard Danish Danbo cheeses investigated by culture-independent techniques.
abstract: Microbial successions on the surface and in the interior of surface ripened semi-hard Danish Danbo cheeses were investigated by culture-dependent and -independent techniques. Culture-independent detection of microorganisms was obtained by denaturing gradient gel electrophoresis (DGGE) and pyrosequencing, using amplicons of 16S and 26S rRNA genes for prokaryotes and eukaryotes, respectively. With minor exceptions, the results from the culture-independent analyses correlated to the culture-dependent plating results. Even though the predominant microorganisms detected with the two culture-independent techniques correlated, a higher number of genera were detected by pyrosequencing compared to DGGE. Additionally, minor parts of the microbiota, i.e. comprising <10.0% of the operational taxonomic units (OTUs), were detected by pyrosequencing, resulting in more detailed information on the microbial succession. As expected, microbial profiles of the surface and the interior of the cheeses diverged. During cheese production pyrosequencing determined Lactococcus as the dominating genus on cheese surfaces, representing on average 94.7%±2.1% of the OTUs. At day 6 Lactococcus spp. declined to 10.0% of the OTUs, whereas Staphylococcus spp. went from 0.0% during cheese production to 75.5% of the OTUs at smearing. During ripening, i.e. from 4 to 18 weeks, Corynebacterium was the dominant genus on the cheese surface (55.1%±9.8% of the OTUs), with Staphylococcus (17.9%±11.2% of the OTUs) and Brevibacterium (10.4%±8.3% of the OTUs) being the second and third most abundant genera. Other detected bacterial genera included Clostridiisalibacter (5.0%±4.0% of the OTUs), as well as Pseudoclavibacter, Alkalibacterium and Marinilactibacillus, which represented <2% of the OTUs. At smearing, yeast counts were low with Debaryomyces being the dominant genus accounting for 46.5% of the OTUs. During ripening the yeast counts increased significantly with Debaryomyces being the predominant genus, on average accounting for 96.7%±4.1% of the OTUs. The interior of the cheeses was dominated by Lactococcus spp. comprising on average 93.9%±7.8% of the OTUs throughout the cheese processing. The microbial dynamics described at genus level in this study add to a comprehensive understanding of the complex microbiota existing especially on surface ripened semi-hard cheeses.
authors.affiliation: Department of Food Science, University of Copenhagen, Rolighedsvej 26, DK-1958 Frederiksberg C, Denmark.
authors.forename: Mia
authors.initials: M
authors.lastname: Ryssel
authors.affiliation: Department of Food Science, University of Copenhagen, Rolighedsvej 26, DK-1958 Frederiksberg C, Denmark. Electronic address: pernillejohansen@food.ku.dk.
authors.forename: Pernille
authors.initials: P
authors.lastname: Johansen
authors.affiliation: Department of Biology, University of Copenhagen, Universitetsparken 15, DK-2100 København Ø, Denmark.
authors.forename: Waleed Abu
authors.initials: WA
authors.lastname: Al-Soud
authors.affiliation: Department of Biology, University of Copenhagen, Universitetsparken 15, DK-2100 København Ø, Denmark.
authors.forename: Søren
authors.initials: S
authors.lastname: Sørensen
authors.affiliation: Department of Food Science, University of Copenhagen, Rolighedsvej 26, DK-1958 Frederiksberg C, Denmark.
authors.forename: Nils
authors.initials: N
authors.lastname: Arneborg
authors.affiliation: Department of Food Science, University of Copenhagen, Rolighedsvej 26, DK-1958 Frederiksberg C, Denmark.
authors.forename: Lene
authors.initials: L
authors.lastname: Jespersen
mesh_terms: D015373:Bacterial Typing Techniques; D001483:Base Sequence; D002611:Cheese / Q000382:microbiology*; D004269:DNA, Bacterial / Q000235:genetics; D004271:DNA, Fungal / Q000235:genetics; D058645:Denaturing Gradient Gel Electrophoresis; D017045:Lactococcus / Q000145:classification / Q000235:genetics / Q000302:isolation & purification; D064307:Microbiota; D016533:Mycological Typing Techniques; D012335:RNA, Ribosomal / Q000235:genetics; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D004718:Saccharomycetales / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification; D017422:Sequence Analysis, DNA; D013210:Staphylococcus / Q000145:classification / Q000235:genetics / Q000302:isolation & purification
chemical_list: D004269:DNA, Bacterial; D004271:DNA, Fungal; D012335:RNA, Ribosomal; D012336:RNA, Ribosomal, 16S; C065096:RNA, ribosomal, 26S
keywords: Cheese; DGGE; Microbial dynamics; Pyrosequencing