Quantification and differentiation of Bacillus cereus group species in spices and herbs by real-time PCR

Frentzel, Hendrik; Thanh, Mai Dinh; Krause, Gladys; Appel, Bernd; Mader, Anneluise

doi:10.1016/j.foodcont.2016.11.028

Cited by 14 publications

(14 citation statements)

References 25 publications

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“…group strains isolated from dried spices and herbs in Germany [5]. In that investigation 94.9% of strains possessed the hbl gene, while the nhe gene and the cytK genes were present in 96.6 and 50.8% of strains, respectively [5]. Other reports have also shown that the nhe gene sequence is detected at high frequency [27, 28].…”

Section: Discussionmentioning

confidence: 98%

“…This was slightly lower than reported for Bacillus cereus s.l. group strains isolated from dried spices and herbs in Germany [5]. In that investigation 94.9% of strains possessed the hbl gene, while the nhe gene and the cytK genes were present in 96.6 and 50.8% of strains, respectively [5].…”

Section: Discussionmentioning

confidence: 99%

“…Bacillus cereus group species are readily isolated from food crops and food plants [2–4]. Significant numbers of bacteria belonging to the B. cereus group have been shown to occur in dried spices and herbs, but also in fresh herbs and vegetables (carrots, leaf lettuce, cucumbers and mixed salad leaves) in Germany [2, 5, 6]. The presence of both vegetative cells and spores in food commodities has been reported and their role in food safety and food spoilage is well known [7].…”

Section: Introductionmentioning

confidence: 99%

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Antibiotics resistance and toxin profiles of Bacillus cereus-group isolates from fresh vegetables from German retail markets

et al. 2019

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BackgroundThis study aimed to evaluate the safety of raw vegetable products present on the German market regarding toxin-producing Bacillus cereus sensu lato (s.l.) group bacteria.ResultsA total of 147 B. cereus s.l. group strains isolated from cucumbers, carrots, herbs, salad leaves and ready-to-eat mixed salad leaves were analyzed. Their toxinogenic potential was assessed by multiplex PCR targeting the hemolysin BL (hbl) component D (hblD), non-hemolytic enterotoxin (nhe) component A (nheA), cytotoxin K-2 (cytK-2) and the cereulide (ces) toxin genes. In addition, a serological test was used to detect Hbl and Nhe toxins. On the basis of PCR and serological results, none of the strains were positive for the cereulide protein/genes, while 91.2, 83.0 and 37.4% were positive for the Hbl, Nhe and CytK toxins or their genes, respectively. Numerous strains produced multiple toxins. Generally, strains showed resistance against the β-lactam antibiotics such as penicillin G and cefotaxim (100%), as well as amoxicillin/clavulanic acid combination and ampicillin (99.3%). Most strains were susceptible to ciprofloxacin (99.3%), chloramphenicol (98.6%), amikacin (98.0%), imipenem (93.9%), erythromycin (91.8%), gentamicin (88.4%), tetracycline (76.2%) and trimethoprim/sulfamethoxazole combination (52.4%). The genomes of eight selected strains were sequenced. The toxin gene profiles detected by PCR and serological test mostly agreed with those from whole-genome sequence data.ConclusionsOur study showed that B. cereus s.l. strains encoding toxin genes occur in products sold on the German market and that these may pose a health risk to the consumer if present at elevated levels. Furthermore, a small percentage of these strains harbor antibiotic resistance genes. The presence of these bacteria in fresh produce should, therefore, be monitored to guarantee their safety.

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Section: Discussionmentioning

confidence: 98%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Antibiotics resistance and toxin profiles of Bacillus cereus-group isolates from fresh vegetables from German retail markets

et al. 2019

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“…Primers used in this study for pathogen detection are listed in Table 1 [19][20][21][22][23][24]. Amplification of the lettuce samples was carried out in a total volume of 50 μl as follows: 1 μl of extracted DNA template (32.3-119.5 ng), 1 μl of (0.2 μM) primers, 5 μl of dNTP (0.2 mM), 5 μl of 10× nTaq Buffer, 1 μl of nTaq DNA Polymerase (Enzynomics, Korea), and 36 μl of distilled water.…”

Section: Pcr For Specific Bacterial Detectionmentioning

confidence: 99%

Analysis of the Microbiota on Lettuce (Lactuca sativa L.) Cultivated in South Korea to Identify Foodborne Pathogens

Yu¹,

Yum²,

Jeon³

et al. 2018

Journal of Microbiology and Biotechnology

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Lettuce (Lactuca sativa L.) is a major ingredient used in many food recipes in South Korea. Lettuce samples were collected during their maximum production period between April and July in order to investigate the microbiota of lettuce during different seasons. 16S rRNA gene-based sequencing was conducted using Illumina MiSeq, and real-time PCR was performed for quantification. The number of total bacterial was greater in lettuce collected in July than in that collected in April, albeit with reduced diversity. The bacterial compositions varied according to the site and season of sample collection. Potential pathogenic species such as Bacillus spp., Enterococcus casseliflavus, Klebsiella pneumoniae, and Pseudomonas aeruginosa showed season-specific differences. Results of the network cooccurrence analysis with core genera correlations showed characteristics of bacterial species in lettuce, and provided clues regarding the role of different microbes, including potential pathogens, in this microbiota. Although further studies are needed to determine the specific effects of regional and seasonal characteristics on the lettuce microbiota, our results imply that the 16S rRNA gene-based sequencing approach can be used to detect pathogenic bacteria in lettuce.

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“…To provide more detailed information of commercial probiotic products to consumers, identifying and quantifying bacteria strains in food products is important. However, in this study, since quantification was performed on the DNA isolated from a culture, the concentration of Bifidobacterium may be underestimated when applied to a food matrix, as reported in previous studies ( Kralik and Ricchi, 2017 ; Frentzel et al, 2018 ). Our real-time PCR assay can be used to differentiate and quantify multiple Bifidobacterium subspecies in food sample.…”

Section: Discussionmentioning

confidence: 79%

Development of Real-Time PCR Assay to Specifically Detect 22 Bifidobacterium Species and Subspecies Using Comparative Genomics

Kim

Yang

et al. 2020

Front. Microbiol.

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Bifidobacterium species are used as probiotics to provide beneficial effects to humans. These effects are specific to some species or subspecies of Bifidobacterium. However, some Bifidobacterium species or subspecies are not distinguished because similarity of 16S rRNA and housekeeping gene sequences within Bifidobacterium species is very high. In this study, we developed a real-time polymerase chain reaction (PCR) assay to rapidly and accurately detect 22 Bifidobacterium species by selecting genetic markers using comparative genomic analysis. A total of 210 Bifidobacterium genome sequences were compared to select species-or subspecies-specific genetic markers. A phylogenetic tree based on pan-genomes generated clusters according to Bifidobacterium species or subspecies except that two strains were not grouped with their subspecies. Based on pan-genomes constructed, species-or subspecies-specific genetic markers were selected. The specificity of these markers was confirmed by aligning these genes against 210 genome sequences. Real-time PCR could detect 22 Bifidobacterium specifically. We constructed the criterion for quantification by standard curves. To further test the developed assay for commercial food products, we monitored 26 probiotic products and 7 dairy products. Real-time PCR results and labeling data were then compared. Most of these products (21/33, 63.6%) were consistent with their label claims. Some products labeled at species level only can be detected up to subspecies level through our developed assay.

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Quantification and differentiation of Bacillus cereus group species in spices and herbs by real-time PCR

Cited by 14 publications

References 25 publications

Antibiotics resistance and toxin profiles of Bacillus cereus-group isolates from fresh vegetables from German retail markets

Antibiotics resistance and toxin profiles of Bacillus cereus-group isolates from fresh vegetables from German retail markets

Analysis of the Microbiota on Lettuce (Lactuca sativa L.) Cultivated in South Korea to Identify Foodborne Pathogens

Development of Real-Time PCR Assay to Specifically Detect 22 Bifidobacterium Species and Subspecies Using Comparative Genomics

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