Microbial diversity and stability during primary cultivation and subcultivation processes of Tibetan kefir

Abstract

In this study, we have investigated the microbial diversity and stability in the Tibetan kefir during the primary cultivation and subcultivation processes via a combination of culture-independent and culturedependent methods. According to the culture-independent methods, the profiles of PCR-DGGE (polymerase chain reaction-denaturing gradient gel electrophoresis) indicated that nine microbial species were predominant at different cultivation stages; seventy four isolates of seven predominant species were obtained and identified via the culture-dependent methods. PCR-DGGE further confirmed that Lactobacillus kefiranofaciens, Lactobacillus kefiri, Lactobacillus paracasei, Streptococcus thermophilus, Kazachstania unispora and Saccharomyces cerevisiae were the most dominant species in the Tibetan kefir during the process of primary cultivation, among which Lb. kefiri, Lb. paracasei and K. unispora showed relative strong stability during both the processes of primary cultivation and subcultivation. These findings suggested that some isolates of the three species possessed the potentiality of being used in the development of direct vat set (DVS) starters for the production of Tibetan kefir and the related products.

Genotypic diversity of bacteria and yeasts isolated from Tibetan kefir

“…The final quality of fermented food relies heavily on the technology characteristics of microbial strains in the starter cultures (Zeng et al ., ; Guarrasi et al ., ). Application of the (GTG) 5 ‐REP‐PCR technology in this study enabled the microbial isolates from Tibetan kefir classified to species level (Gao et al ., ) could be further classified to strain level for genotype distinguishment, which is not only the necessary grouping procedure for the selection of strain with outstanding technology characteristic from the strains of each genotype in our further next study, but also is the precondition for strains of all different genotypes can be included in the ‘direct vat set starter of Tibetan kefir’ in our further ultimate application study.…”

“…The final quality of fermented food relies heavily on the technology characteristics of microbial strains in the starter cultures (Zeng et al, 2016;Guarrasi et al, 2017). Application of the (GTG) 5 -REP-PCR technology in this study enabled the microbial isolates from Tibetan kefir classified to species level (Gao et al, 2015) could be further classified to strain level for genotype distinguishment, which is not only the necessary grouping procedure for the selection of I 2 III 19 3566 , 3291, 3230, 2657, 3291, 3230, , 2188, 3291, 3230, , 1904, 3291, 3230, , 1551, 3291, 3230, , 1485, 3291, 3230, , 1377 II IV 17 3566, 3291, 3230, 2657, 2188, 1904, 1551, 1485, 1377ZLGX15-17 III V 16 3230, 2657, 1904, 1551, 1485, 1377ZLGX20-24, 30-31 IV VI 12 3566, 3291, 3230, 2657, 2188, 1904, 1551, 1485 International Journal of Food Science and Technology 2018 strain with outstanding technology characteristic from the strains of each genotype in our further next study, but also is the precondition for strains of all different genotypes can be included in the 'direct vat set starter of Tibetan kefir' in our further ultimate application study.…”

“…Seventy-one microbial isolates (six species) originated from Tibetan kefir were obtained from our previous research (Gao et al, 2015). Forty-nine bacterial and twenty-two yeast isolates were identified to species level via the 16S rDNA and 26S rDNA-D1/D2 gene sequencing technology, respectively (Gao et al, 2015). The bacterial isolates were activated in LB medium (Hai Bo, Qingdao, China), and the yeast isolates were activated in PDA medium (Hai Bo, Qingdao, China).…”

Potential contribution of beneficial microbes to face the COVID-19 pandemic

“…For example, kefir microbiota is dependent on its origin (Gao & Li, 2016). In addition, the microbiota of kefir changes along the successive subcultivations of the kefir grains used to produce this fermented food (Gao et al, 2015). Then, technically products with undefined microbiota such as kefir, sauerkraut or kombucha, do not qualify as probiotics (Reid et al, 2019), however these fermented foods can have potential beneficial effects due to their content of viable microorganisms (Rosa et al, 2017).…”

Monitoring of the bacterial communities of bamboo shoots (Dendrocalamus latiflorus) during pickling process

“…Recently, culture-independent methods such as polymerase chain reaction denaturing gradient gel electrophoresis (PCR-DGGE) and quantitative real-time polymerase chain reaction (qRT-PCR) have been proven to be powerful tools for studying the microorganisms in food samples (Ishikawa et al, 2009;Xu et al, 2011;Leite et al, 2012;Achilleos & Berthier, 2013;Gao et al, 2015). However, few studies have employed culture-independent approaches to investigate the microbial communities involved in bamboo shoots.…”