MISIDENTIFIKASI FENOTIPIK KHAMIR AMILOLITIK DARI TAPE SINGKONG YANG TERUNGKAP MELALUI SEKUENSING ITS rDNA

Phenotypic Misidentification Of Amilolytic Yeast From Cassava Tape Revealed Through ITS rDNA Sequencing

Abstract

Accurate yeast identification was very important for studying microbial diversity and optimizing traditional food fermentation processes. The production of cassava tapai depended on specific yeasts capable of hydrolyzing starch and fermenting sugars. However, many studies still relied on phenotypic identification methods, which could lead to taxonomic inaccuracies. This study aimed to explore the reliability of phenotypic identification using the API 20C AUX Kit compared with molecular identification through rDNA sequencing of the internal transcribed spacer region. Four groups of indigenous amylolytic yeasts isolated from cassava tapai were characterized using the API 20C AUX carbohydrate assimilation profile and were phenotypically identified as Candida guilliermondii, Trichosporon mucoides, Cryptococcus humicola, and Candida utilis. Molecular identification was performed through PCR amplification of the ITS region using ITS1 and ITS4 primers, followed by DNA sequencing, and the results were analyzed using the BLAST method. The molecular results revealed discrepancies between phenotypic and genotypic identification. Isolate C, which was initially identified as Cryptococcus humicola, showed 100% sequence identity with Saccharomycopsis fibuligera. Isolate D, previously identified as Candida utilis, was reclassified as Candida tropicalis with 100% identity. These findings indicated phenotypic misidentification when relying solely on biochemical assimilation profiles.