Atf1 gene studies for aroma and flavour of brewing yeasts of north western Himalayas

Twenty-four yeast strains isolated from alcoholic beverages in the North-Western Himalayas were systematically screened for their brewing characteristics. Among these, four strains—designated ABB, GP4, CH1, and PH1—demonstrated remarkable alcohol production, exceeding 11% v/v, with strains ABB, GP4, SC02, and SM2 exhibiting the highest alcohol tolerance above 14% v/v. Additionally, significant attenuation rates greater than 90% w/v were recorded for ABB, CH1, GP4, and PH1. DNA barcoding confirmed the identification of all yeast strains as Saccharomyces cerevisiae, except for one strain, classified as Pichia membranifaciens (SMLC). Based on the observed variations in brewing traits, fifteen strains were selected for further investigation of the ATF1 gene. Sequencing revealed a coding sequence of 1578 base pairs in the open reading frame (ORF), encoding a protein of 525 amino acids. Multiple sequence alignment against the Saccharomyces genomic database (SGD) identified 108 nucleotide substitutions within the coding region. Notably, twelve strains exhibited variations in their amino acid sequences, with strain ABB showing the greatest variation of four amino acids, while a minimum of one amino acid substitution—specifically asparagine (N) to lysine (K)—was noted in seven strains. These significant differences in the ATF1 gene correlate with variations in the aroma and flavour profiles of the fermented products, suggesting that ATF1 expression plays a critical role in shaping the sensory characteristics of brewing products. This study highlights the potential of these indigenous yeast strains to enhance the quality and distinctiveness of fermented beverages.