Diversity of Yeasts Microbiota in Iranian Doogh and Influence of Kluyveromyces Marxianus on its Protein profiles

Abstract

Background and Objective: Iranian drinking yogurt (Doogh) is one of the traditional beverages commercially produced and widely consumed. Mostly the spoilage of dairy products including Doogh is caused by a wide diversity of yeasts. In the present study, the swollen packages of pasteurized Doogh were investigated for yeast diversity and also the effect of predominant yeast on the proteins and peptides profiling of Doogh. Material and Methods: The swollen packages of pasteurized Doogh were collected from a local dairy plant for one year. Isolation and identification were done using morphological, biochemical and molecular techniques. Afterward, the protein and peptide profiles of inoculated Doogh sample with high proteolytic activity yeast in comparison with Control sample were evaluated by SDS-PAGE and consequently MALDI-TOF-MS techniques. Results and Conclusion: In total, 13 isolates belong to two genuse namely; Kluyveromyces and Candida were identified. According to 18S rRNA gene sequencing, the 8 isolates were identified as Kluyveromyces marxianus; 4 isolates matched with Kluyveromyces lactis, and 1 isolate was identified as Candida kefyr. Also, o-phthaldialdehyde test (OPA) showed that K. marxianus contain the highest proteolytic activity compare to other tested species. The results showed that the K. marxianus enzyme conducted protein profiles to β-lactoglubolin and α-lactalbumin isoforms and several peptides with molecular weight less than 10 KDa.

Keywords

• ▪ genotypic identification ▪ iranian drinking yogurt ▪ phenotypic ▪ proteolysis ▪ proteomics techniques ▪ yeast diversity