سامانه همایش های موسسه پژوهشی علوم و صنایع غذایی

صفحه اصلی / سومین همایش ملی پژوهش های کاربردی امنیت غذایی: فرآوری، ایمنی و سلامت

Tuf gene-based qPCR method for quality control and quantification of Lactobacillus acidophilus LA-5 in probiotic dairy products

نویسندگان :

Salman Odooli¹

1- دانشگاه آزاد اسلامی واحد شیراز

کلمات کلیدی :

Lactobacillus acidophilus LA-5،qPCR،tuf،Shelf-life،Quality control

چکیده :

A minimal concentration of 106 cell/g (mL) is required for probiotic bacteria to exert their intended beneficial effects. Given the increasing development of commercial probiotic products, establishing sensitive, specific, and rapid methods for quantitative monitoring and quality control of bacteria in probiotic products seems essential. Due to the limitations and disadvantages of traditional culture-dependent methods, some quantitative Real-Time PCR (qPCR) procedures based on the 16S rRNA gene have been described. However, since the 16S rRNA genes exist in multiple copies in the bacterial genome, the quantitative data are ambiguous. In this study, the single-copy tuf gene sequence was used to design a primer set for Lactobacillus acidophilus LA-5. The specificity of designed primer was evaluated against prevalent probiotic Bifidobacterial and Lactobacilli strains presented in commercial probiotic yoghurts. Afterwards, a new tuf gene-based qPCR was developed for the quantification of L. acidophilus LA-5 in commercial probiotic yoghurts during shelf life. The PCR assays confirmed the specificity of tuf gene-based primer set for L. acidophilus LA-5. The obtained standard curve of tuf gene-based qPCR reactions from 104-109 cell/mL was linear (R2=0.98) with the efficiency of 90.4%. The enumeration results with qPCR and selective plate count did not show any significant difference. Despite the gradual decrease in the L. acidophilus LA-5 count during shelf-life, it was according to the CODEX standard [106 cell/g (mL)] on the day of the expiration date. In conclusion, the tuf gene-based qPCR procedure developed here could serve as a powerful and rapid method (3 hours) for counting L. acidophilus LA-5 in commercial probiotic yoghurts, compared to culture methods (3 days).