MALDI-TOF MS profiling of non-starter lactic acid bacteria from artisanal cheeses of the Greek island of Naxos

Gantzias, Charalampos; Lappa, Iliada K.; Aerts, Maarten; Georgalaki, Marina; Manolopoulou, Eugenia; Papadimitriou, Κonstantina; Brandt, Evie De; Tsakalidou, Effie; Vandamme, Peter

doi:10.1016/j.ijfoodmicro.2020.108586

Cited by 40 publications

(28 citation statements)

References 32 publications

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“…Several other studies have shown that score values and identification accuracy can be significantly improved by using in-house-built reference database containing several MALDI-TOF MS spectra of reference strains and own isolates of interest, depending on the sample composition and scope of the analyses, and by using a more advanced analysis of the spectra ( Singhal et al, 2015 ; Nacef et al, 2017 ; Gantzias et al, 2020 ; Jarocki et al, 2020 ). However, it should be kept in mind that, in this study, we intentionally used only the commercially available Biotyper library to demonstrate whether the MALDI-TOF MS approach is widely applicable in high-throughput routine laboratories for the control of probiotic products, without extensive expertise in this methodology.…”

Section: Discussionmentioning

confidence: 99%

“…This method has already been recognised as an attractive tool for clinical isolate identification, microbial diversity studies, and other applications. With the improved databases, it is now increasingly used also for the analysis of milk and dairy products ( Angelakis et al, 2011 ; Duskova et al, 2012 ; Nacef et al, 2017 ; Gantzias et al, 2020 ) but has not been widely used for the quality control of dietary supplements with added live beneficial bacteria (probiotic products) ( Singhal et al, 2015 ; Čanžek Majhenič et al, 2018 ). A few reports on the use of MALDI-TOF MS for the analysis of dietary supplements include the identification of bifidobacteria, lactic acid bacteria (LAB), Bacillus species, and Saccharomyces boulardii in various products available on the EU market and in the United States ( Bunesova et al, 2014 ; Vecchione et al, 2018 ; Ansari et al, 2019 ; Celandroni et al, 2019 ).…”

Section: Introductionmentioning

confidence: 99%

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Evaluation of Dietary Supplements Containing Viable Bacteria by Cultivation/MALDI-TOF Mass Spectrometry and PCR Identification

Lorbeg

Golob

Kramer³

et al. 2021

Front. Microbiol.

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The insufficient quality of products containing beneficial live bacteria in terms of content and viability of labelled microorganisms is an often-reported problem. The aim of this work was to evaluate the quality of dietary supplements containing viable bacteria available in Slovenian pharmacies using plate counting, matrix-assisted laser desorption ionisation time-of-flight mass spectrometry (MALDI-TOF MS) and species- or subspecies-specific PCR with DNA isolated from consortia of viable bacteria, from individual isolates, or directly from the products. Twelve percent of the products (3 of 26) contained insufficient numbers of viable bacteria. Eighty-three of the labelled species (111 in total) were confirmed by PCR with DNA from the product; 74% of these were confirmed by PCR with DNA from viable consortium, and 65% of these were confirmed by MALDI-TOF MS analysis of colonies. Certain species in multi-strain products were confirmed by PCR with DNA from viable consortia but not by MALDI-TOF MS, suggesting that the number of isolates examined (three per labelled strain) was too low. With the exception of Lacticaseibacillus casei and closely related species (Lacticaseibacillus rhamnosus and Lacticaseibacillus zeae), PCR and MALDI-TOF identification results agreed for 99% of the isolates examined, although several MALDI-TOF results had lower score values (1.700–1.999), indicating that the species identification was not reliable. The species L. zeae, which appeared in 20 matches of the Biotyper analysis, was identified as L. rhamnosus by PCR. The MALDI-TOF MS analysis was also unsuccessful in detecting Lactobacillus acidophilus La-5 and Bacillus coagulans due to missing peaks and unreliable identification, respectively. Mislabelling was detected by both methods for two putative L. casei strains that turned out to belong to the species Lacticaseibacillus paracasei. PCR remains more successful in subspecies-level identification as long as the database of MALDI-TOF MS spectra is not expanded by building in-house databases. The lack of positive PCR results with viable consortia or colonies, but positive PCR results with DNA isolated directly from the products observed in 10% (11/112) of the labelled strains, suggests the presence of non-culturable bacteria in the products. MALDI-TOF MS is a faster and simpler alternative to PCR identification, provided that a sufficient number of colonies are examined. Generation of in-house library may further improve the identification accuracy at the species and sub-species level.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Evaluation of Dietary Supplements Containing Viable Bacteria by Cultivation/MALDI-TOF Mass Spectrometry and PCR Identification

Lorbeg

Golob

Kramer³

et al. 2021

Front. Microbiol.

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“…A recent study used MALDI-TOF MS to identify non-starter lactic acid bacteria (NSLAB) isolates from four artisanal kinds of cheeses, namely Kefalotyri, Anthotyro, Xynotyri, and Touloumotyri, synthesized from raw goat and sheep milk. The identified lactic acid bacteria (LAB) species included Lactobacillus brevis, Lactobacillus rhamnosus, Lactobacillus plantarum, Lactobacillus paracasei, Leuconostoc mesenteroides, Enterococcus faecium, Lactococcus lactis, and Pediococcus pentosaceus [6]. Albesharat et al assessed the LAB strains in breast milk, feces of mothers and babies, and local foods (fermented) using genotypic tools such as 16S RNA gene sequencing, random amplified polymorphic DNA (RAPD) and MALDI-TOF [7].…”

Section: Introductionmentioning

confidence: 99%

Microbiota “Fingerprint” of Greek Feta Cheese through Ripening

et al. 2021

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Feta is a Greek protected designation of origin (PDO) brined curd white cheese made from small ruminants’ milk. In the present research, Greek Feta cheese bacterial diversity was evaluated via matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS). Analysis of 23 cheese samples, produced in different regions of the country, was performed in two ripening times (three or six months post-production). The identified microbiota were primarily constituted of lactic acid bacteria. A total of 13 different genera were obtained. The dominant species in both ripening times were Lactobacillus plantarum (100.0% and 87.0%, at three or six months post-production, respectively), Lactobacillus brevis (56.5% and 73.9%), Lactobacillus paracasei (56.5% and 39.1%), Lactobacillus rhamnosus (13.0% and 17.4%), Lactobacillus paraplantarum (4.3% and 26.1%), Lactobacillus curvatus (8.7% and 8.7%). Other species included Enterococcus faecalis (47.8% and 43.5%), Enterococcus faecium (34.8% and 17.4%), Enterococcus durans (13.0% and 17.4%), Enterococcus malodoratus (4.3% and 4.3%), and Streptococcus salivarius subsp. thermophilus (21.7% and 30.4%). The increased ripening time was found to be correlated to decreased total solids (r = 0.616; p = 0.002), protein (r = 0.683; p < 0.001), and PH (r = 0.780; p < 0.001). The results of this study contribute to a better understanding of the core microbiota of Feta cheese.

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“…The first two were the most predominant species. This type of cheese is obtained from raw sheep and goat milk without added starter cultures [34].…”

Section: Microbiota and Characteristics Of Traditionally Processed Cheesesmentioning

confidence: 99%

Microbial Diversity of Traditionally Processed Cheese from Northeastern Region of Transylvania (Romania)

György¹,

Laslo²

2021

Fermentation - Processes, Benefits and Risks

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The composition and production technology of the cheese are extremely diverse. There are a wide variety of microbial species on their surface, with a much smaller number inside of the product. The microbiota of the cheese may be composed of beneficial microorganisms, spoilage and foodborne pathogens. Identification and characterization of the microorganisms present in these products are important nutrition, food safety and technological aspects. During our work we evaluated the prevalence of allochthonous bacteria and microscopic fungi in traditionally processed cheeses from northeastern region of Transylvania, with classical microbiological culture methods. Based on the results the microbiota of the analysed cheeses was highly diversified. The identified bacteria with the highest prevalence from different selective media, were as follows: Escherichia coli, Enterococcus durans, Enterococcus faecalis, Shigella flexnerii, Proteus vulgaris, Stenotrophomonas maltophilia, Staphylococcus equorum subsp. equorum, Staphylococcus equorum subsp. linens, Halomonas alkaliphila, Kocuria rhizophila, Hafnia paralvei, Bacillus licheniformis and Klebsiella michiganensis.

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MALDI-TOF MS profiling of non-starter lactic acid bacteria from artisanal cheeses of the Greek island of Naxos

Cited by 40 publications

References 32 publications

Evaluation of Dietary Supplements Containing Viable Bacteria by Cultivation/MALDI-TOF Mass Spectrometry and PCR Identification

Evaluation of Dietary Supplements Containing Viable Bacteria by Cultivation/MALDI-TOF Mass Spectrometry and PCR Identification

Microbiota “Fingerprint” of Greek Feta Cheese through Ripening

Microbial Diversity of Traditionally Processed Cheese from Northeastern Region of Transylvania (Romania)

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