Detection of viable Lacticaseibacillus paracasei in fermented milk using propidium monoazide combined with quantitative loop-mediated isothermal amplification.
FEMS Microbiol Lett
; 368(20)2021 12 07.
Article
em En
| MEDLINE
| ID: mdl-34849766
ABSTRACT
To quantify viable probiotic Lacticaseibacillus paracasei (L. paracasei) in fermented milk accurately and quickly, propidium monoazide combined with quantitative loop-mediated isothermal amplification (PMA-qLAMP) was applied. The optimal PMA treatment conditions for treating a L. paracasei suspension were determined using an orthogonal test to eliminate the DNA amplification of 108 CFU/mL of dead L. paracasei. Primers were designed based on the species-specific gyrB gene of L. paracasei. A phylogenetic tree based on the gyrB gene showed that L. paracasei clustered on the same branch with 91% support. Compared with the 16 strains commonly found in fermented milk, three strains of L. paracasei showed positive PMA-qLAMP results, and the melting temperature was approximately 82.4°C. There was a linear relationship (R2 = 0.9983) between the Ct values and the logarithm of the concentration of viable bacteria. The PMA-qLAMP detection limit for the L. paracasei artificially added to fermented milk was 7.3 × 102 CFU/mL. There was no significant difference between the logarithm values of the concentration of viable L. paracasei of 50 fermented milk samples within shelf life using the PMA-qLAMP and plate count methods (P > 0.01). PMA-qLAMP is specific and accurate for obtaining reliable results faster than when using plate counts.
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Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Propídio
/
Azidas
/
Técnicas de Amplificação de Ácido Nucleico
/
Técnicas de Diagnóstico Molecular
/
Produtos Fermentados do Leite
/
Leite
/
Viabilidade Microbiana
/
Lacticaseibacillus paracasei
Tipo de estudo:
Diagnostic_studies
Limite:
Animals
Idioma:
En
Revista:
FEMS Microbiol Lett
Ano de publicação:
2021
Tipo de documento:
Article
País de afiliação:
China