Re-identification of five strains of Rhizopus arrhizus from tempeh based on ITS regions of rDNA sequence data

摘要

The Rhizopus strains in the Universitas Indonesia Culture Collection (UICC) were isolated from tempeh. Five strains of Rhizopus (UICC 26, UICC 36, UICC 39, UICC 55, UICC 121) were identified as R. arrhizus based on morphological and physiological characters. In the current taxonomy of Rhizopus, R. arrhizus is synonym of R. oryzae. The aim of this study was to re-identify five R. arrhizus strains by molecular approach based on internal transcribed spacers (ITS) regions of ribosomal DNA sequence data. The sequence homology search showed that strains UICC 36 and UICC 55 have very high homology (99.8%) to R. oryzae CBS 112.07~T type strain, however the other three strains (UICC 26, UICC 39, and UICC 121) showed a lower homology (99.0-99.2%) to R. oryzae CBS 112.07~T type strain. The phylogenetic tree showed that strains UICC 36 and UICC 55 were placed in a monophyletic group with R. oryzae CBS 112.07~T type strain. The tree revealed that three strains (UICC 26, UICC 39, and UICC 121) were placed in a monophyletic group with R. delemar CBS 120.12~T type strain. The phylogenetic tree showed that the group of R. delemar was phylogenetically very closely related with the group of R. oryzae. In this study, two strains (UICC 36 and UICC 55) were re-identified as R. oyzae (UICC 36 and UICC 55), and three strains (UICC 26, UICC 39, UICC 121) were re-identified as R. delemar. Morphological observation of all strains showed the characters corresponded to R. oryzae.