ena-STUDY-Department of Agriculture-25-07-2018-11:47:20:274-1093
Unveiling hákarl: study of the microbiota of the traditional Icelandic fermented fish
In the present study, a polyphasic approach based on both culture and DNA-based techniques was adopted to have an insight into the microbial species occurring in ready-to-eat hákarl. To this aim, samples of ready-to-eat hákarl were subjected to viable counting on different selective growth media. The DNA directly extracted from the samples was further subjected to PCR-DGGE and Illumina sequencing. Moreover, the presence of Coxiella burnetii, Shiga toxin-producing Escherichia coli (STEC), and Pseudomonas aeruginosa was assessed via qualitative real-time PCR assays. pH values measured in the analyzed samples ranged between 8.07±0.06 and 8.76±0.00. Viable counts revealed the presence of total mesophilic aerobes, lactic acid bacteria and Pseudomonadaceae. Regarding bacteria, PCR-DGGE analysis highlighted the dominance of closest relatives to Tissierella creatinophila, moreover, closest relatives to Anerosalibacter, Murdochiella massiliensis, Sporanaerobacter acetigenes and Pontibacillus marinus were also found. As for metagenomic sequencing, the main operational taxonomic units shared among the data set were Tissierella (78.6 % of the relative abundance), Pseudomonas (8.4 %), Abyssivirga (4.0 %), Oceanobacillus (6.7 %) and Lactococcus (0.2 %). Several minor OTUs (<1%) were also detected like Listeria, Staphylococcus, Photobacterium and Acinetobacter. Regarding eumycetes species detected through PCR-DGGE, the presence of closest relatives to Candida tropicalis, Candida glabrata, Candida parapsilosis, Candida zeylanoides, Debaryomyces, Saccharomyces cerevisiae, Torulaspora, Yamadazyma, Sporobolomyces, Alternaria, Cladosporium tenuissimum, Moristroma and to Didymellaceae was highlighted. Finally, qualitative real-time PCR assays revealed the absence of Coxiella burnetii, Shiga toxin-producing Escherichia coli (STEC), and Pseudomonas aeruginosa in all the analyzed samples
In the present study, a polyphasic approach based on both culture and DNA-based techniques was adopted to have an insight into the microbial species occurring in ready-to-eat hákarl. To this aim, samples of ready-to-eat hákarl were subjected to viable counting on different selective growth media. The DNA directly extracted from the samples was further subjected to PCR-DGGE and Illumina sequencing. Moreover, the presence of Coxiella burnetii, Shiga toxin-producing Escherichia coli (STEC), and Pseudomonas aeruginosa was assessed via qualitative real-time PCR assays. pH values measured in the analyzed samples ranged between 8.07±0.06 and 8.76±0.00. Viable counts revealed the presence of total mesophilic aerobes, lactic acid bacteria and Pseudomonadaceae. Regarding bacteria, PCR-DGGE analysis highlighted the dominance of closest relatives to Tissierella creatinophila, moreover, closest relatives to Anerosalibacter, Murdochiella massiliensis, Sporanaerobacter acetigenes and Pontibacillus marinus were also found. As for metagenomic sequencing, the main operational taxonomic units shared among the data set were Tissierella (78.6 % of the relative abundance), Pseudomonas (8.4 %), Abyssivirga (4.0 %), Oceanobacillus (6.7 %) and Lactococcus (0.2 %). Several minor OTUs (<1%) were also detected like Listeria, Staphylococcus, Photobacterium and Acinetobacter. Regarding eumycetes species detected through PCR-DGGE, the presence of closest relatives to Candida tropicalis, Candida glabrata, Candida parapsilosis, Candida zeylanoides, Debaryomyces, Saccharomyces cerevisiae, Torulaspora, Yamadazyma, Sporobolomyces, Alternaria, Cladosporium tenuissimum, Moristroma and to Didymellaceae was highlighted. Finally, qualitative real-time PCR assays revealed the absence of Coxiella burnetii, Shiga toxin-producing Escherichia coli (STEC), and Pseudomonas aeruginosa in all the analyzed samples