|Li, Xin Liang|
Submitted to: Mycological Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/9/2009
Publication Date: 10/1/2009
Citation: Manitchotpisit, P., Leathers, T.D., Peterson, S.W., Kurtzman, C.P., Li, X., Eveleigh, D.E., Lotrakul, P., Prasongsuk, S., Dunlap, C.A., Vermillion, K., Punnapayak, H. 2009. Multilocus Phylogenetic Analyses, Pullulan Production and Xylanase Activity of Tropical Isolates of Aureobasidium pullulans. Mycological Research. 113:1107-1120.
Interpretive Summary: Improved microbial germplasm is needed to enhance bioconversions of agricultural materials to high-value bioproducts. Microbial germplasm from unique environments in Thailand were surveyed and molecular tools were used for the first time to identify classes of organisms having high-level production of valuable polysaccharides and enzymes. This work will be of interest to researchers developing new uses and value-added products from agricultural commodities and byproducts.
Technical Abstract: Aureobasidium pullulans is the source of the commercial polysaccharide, pullulan, and the enzyme, xylanase (EC 18.104.22.168). Isolates are typically off-white to black on solid media, while some tropical isolates have been described as "color variants" with bright pigments of red, yellow, or purple. In spite of the phenotypic diversity of this commercially important organism, a molecular phylogenetic taxonomy has not been reported. In this study, 5 loci (internal transcribed spacer, intergenic spacer 1, translation elongation factor-1 alpha, beta tubulin, and RNA polymerase II) were sequenced from 46 new tropical isolates (Thailand), 1 new isolate from the U.S., and 7 comparative strains. Phenotypic characteristics were determined for all isolates, including colony characteristics, pullulan production, and xylanase activity. Based on the phylogenetic analyses, isolates were classified into 12 clades. Each clade showed different colors on different culture media, and some clades exhibited high levels of pullulan production or xylanase activity. Moreover, we found two new isolates that were identified as a distinct species closely related to A. pullulans. This study will be beneficial for the identification and selection of new commercial strains producing high amounts of pullulan and xylanase.