Molecular identification of yeast species associated with 'Hamei'--a traditional starter used for rice wine production in Manipur, India.

In Manipur state of North-Eastern India, wine from glutinous rice using traditional solid state starter called 'Hamei' is particularly interesting because of its unique flavour. A total of 163 yeast isolates were obtained from fifty four 'Hamei' samples collected from household rice wine preparations in tribal villages of Manipur. Molecular identification of yeast species was carried out by analysis of the restriction digestion pattern generated from PCR amplified internal transcribed spacer region along with 5.8S rRNA gene (ITS1-5.8S-ITS2). Seventeen different restriction profiles were obtained from the size of PCR products and the restriction analysis with three endonucleases (Hae III, Cfo I and Hinf I). Nine groups were identified as S. cerevisiae, Pichia anomala, Trichosporon sp., Candida tropicalis, Pichia guilliermondi, Candida parapsilosis, Torulaspora delbrueckii, Pichia fabianii and Candida montana by comparing this ITS-RFLP profile with type strains of common wine yeasts, published data and insilico analysis of ITS sequence data available in CBS yeast database. ITS-RFLP profile of eight groups was not matching with available database of 288 common wine yeast species. The most frequent yeast species associated with 'Hamei' were S. cerevisiae (32.5%), P. anomala (41.7%) and Trichosporon sp. (8%). The identity of major groups was confirmed by additional restriction digestion of ITS region with Hind III, EcoRI, Dde I and Msp I. The genetic diversity of industrially important S. cerevisiae group was investigated using Pulsed Field Gel Electrophoresis (PFGE). Although most of the 53 strains of S. cerevisiae examined were exhibited a common species specific pattern, a distinct degree of chromosomal length polymorphism and variable number of chromosomal DNA fragments were observed with in the species. Cluster analysis showed seven major karyotypes (K1-K7) with more than 83% similarity. The karyotype pattern K1 was the most frequent (67.9%) among the strains from different samples. Other karyotypes K2-K7 were very unique with less than 80% similarity. Finally using mitochondrial DNA restriction analysis (mt-DNA RFLP), S. cerevisiae strains belonging to the major karyotype K1 were distinctly differentiated with highly polymorphic bands by Hinf I and Hae III endonucleases.