Exploring the genealogy and phenomic divergences of indigenous domesticated yeasts cultivated by six ethnic communities of Assam, India

Abstract

Background and Objective: Wild and spontaneous fermentation are popular practice among home brewers representing indigenous communities of the world. Assam, a biodiversity rich region is a treasure house of traditional knowledge and multiple ethnicities which has not been properly documented. Household fermentation is highly rampant amongs’t different races who follow their own inherited system, extricably linked to social, cultural, environmental and institutional contexts. In this study, ‘Starter materials' from six ethnic communities were collected to enumerate and comprehend the assortment of yeasts that are fundamental to ethnic fermentation. Methodology: Starter materials from six ethnic communities were collected and yeasts were isolated in yeast extract-peptone-dextrose (YPD). These were identified on the basis of morphology, comparative physiology, biochemical responses and ultra miscoscopy. Establishment of molecular identity were done through 18S ribosomal DNA analysis using inter transcribed sequence (ITS1 and ITS4) primers for amplifying D1/D2 regions of yeast DNA. Phylogenetic relationships were established through maximum parsimony and Unweighted Pair Group Method with Arithmetic mean (UPGMA) methods. Interrelationships among yeasts representing interspecies and intercommunity variations were sorted out using five point summary plot analysis. Results: A total of 64 isolates were identified on the basis of morphological, physiological and biochemical differences that represented 31 variants. The 31 variants could be categorized further into 7 different genera representing 9 different species viz., Candida tropicalis, Pichia anomala, Saccharomyces cerevisiae, Wickerhamomyces anomalus, Candida glabrata, Pichia burtonii, Saccharomycopsis fibuligera, Meyerozyma caribbica and Rhodotorula taiwanensis based on molecular analysis. Wickerhamomyces anomalus dominated the entire spectrum of starter cultures except Ahom starters, where Candida isolates appeared predominant. Conclusion: Study indicated that starters used by the communities originate from one place which eventually underwent a parallel segregation and perpetuated in different regions exposed to varied stress and diverse maintenance processes practiced by individual communities. This domestication and human selection through continuous breeding led to the development of cultivated variants that thrive in man shaped environments and behave sub-optimally in nature which corroborate further to consider the fact that the originality of a common starter culture cannot be denied. It is apparent that subtle differences in yeasts fundamentally originated from different lineages in the wild.