title: Yeast species associated with orange juice: evaluation of different identification methods.
abstract: Five different methods were used to identify yeast isolates from a variety of citrus juice sources. A total of 99 strains, including reference strains, were identified using a partial sequence of the 26S rRNA gene, restriction pattern analysis of the internal transcribed spacer region (5.8S-ITS), classical methodology, the RapID Yeast Plus system, and API 20C AUX. Twenty-three different species were identified representing 11 different genera. Distribution of the species was considerably different depending on the type of sample. Fourteen different species were identified from pasteurized single-strength orange juice that had been contaminated after pasteurization (PSOJ), while only six species were isolated from fresh-squeezed, unpasteurized orange juice (FSOJ). Among PSOJ isolates, Candida intermedia and Candida parapsilosis were the predominant species. Hanseniaspora occidentalis and Hanseniaspora uvarum represented up to 73% of total FSOJ isolates. Partial sequence of the 26S rRNA gene yielded the best results in terms of correct identification, followed by classical techniques and 5.8S-ITS analysis. The commercial identification kits RapID Yeast Plus system and API 20C AUX were able to correctly identify only 35 and 13% of the isolates, respectively. Six new 5.8S-ITS profiles were described, corresponding to Clavispora lusitaniae, Geotrichum citri-aurantii, H. occidentalis, H. vineae, Pichia fermentans, and Saccharomycopsis crataegensis. With the addition of these new profiles to the existing database, the use of 5.8S-ITS sequence became the best tool for rapid and accurate identification of yeast isolates from orange juice.
authors.affiliation: Citrus Research and Education Center, University of Florida, IFAS, Lake Alfred, Florida 33850, USA.
authors.forename: Covadonga R
authors.initials: CR
authors.lastname: Arias
authors.forename: Jacqueline K
authors.initials: JK
authors.lastname: Burns
authors.forename: Lorrie M
authors.initials: LM
authors.lastname: Friedrich
authors.forename: Renee M
authors.initials: RM
authors.lastname: Goodrich
authors.forename: Mickey E
authors.initials: ME
authors.lastname: Parish
mesh_terms: D001628:Beverages / Q000382:microbiology*; D002957:Citrus / Q000382:microbiology*; D021903:DNA, Ribosomal Spacer / Q000032:analysis; D008969:Molecular Sequence Data; D016533:Mycological Typing Techniques; D010641:Phenotype; D012335:RNA, Ribosomal / Q000235:genetics; D012340:RNA, Ribosomal, 5.8S / Q000235:genetics; D011933:Reagent Kits, Diagnostic; D017422:Sequence Analysis, DNA; D015003:Yeasts / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification*
chemical_list: D021903:DNA, Ribosomal Spacer; D012335:RNA, Ribosomal; D012340:RNA, Ribosomal, 5.8S; C065096:RNA, ribosomal, 26S; D011933:Reagent Kits, Diagnostic