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ARS Home » Northeast Area » Wyndmoor, Pennsylvania » Eastern Regional Research Center » Characterization and Interventions for Foodborne Pathogens » Research » Publications at this Location » Publication #392805

Research Project: Development of Innovative Technologies and Strategies to Mitigate Biological, Chemical, Physical, and Environmental Threats to Food Safety

Location: Characterization and Interventions for Foodborne Pathogens

Title: Sporobolomyces lactucae sp. nov. (Pucciniomycotina,microbotryomycetes, Sporidiobolales): An Abundant Component of romaine lettuce phylloplanes

item FATEMI, SAMIRA - Purdue University
item HAELEWATERS, DANNY - Purdue University
item URBINA, HECTOR - Purdue University
item BROWN, SAMUEL - Purdue University
item HOUSTON, MAKENNA - Purdue University
item AIME, M - Purdue University

Submitted to: The Journal of Fungi
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/7/2022
Publication Date: 3/16/2022
Citation: Fatemi, S., Haelewaters, D., Urbina, H., Brown, S., Houston, M.L., Aime, M.C. 2022. Sporobolomyces lactucae sp. nov. (Pucciniomycotina,microbotryomycetes, Sporidiobolales): An abundant component of romaine lettuce phylloplanes. The Journal of Fungi. 8(3):302.

Interpretive Summary: Romaine lettuce is an important staple of American agriculture. As is true for all plants, lettuce leaves are inhabited by microorganisms when they grow, most of which are harmless or beneficial to the plants. However, because lettuce is typically consumed raw, it is important to understand what microbes inhabit the lettuce leaves. In this study, we describe the most commonly isolated yeast found on lettuce as a new species. This species was recovered from all purchased Romain lettuce samples. It was also recovered from environmental isolates from the lettuce-growing region of California, and DNA sequences of microorganisms reveal its presence in other food sources grown in Mediterranean climates. Results show how that even commonly consumed vegetables harbor undescribed microbial species, and that food supply chains may inadvertently serve as a source for spreading microbes to new regions.

Technical Abstract: Shifts in food microbiomes may impact the establishment of human pathogens, such as virulent lineages of Escherichia coli, and thus are important to investigate. Foods that are often consumed raw, such as lettuce, are particularly susceptible to such outbreaks. We have previously found that an undescribed Sporobolomyces yeast is an abundant component of the mycobiome of commercial romaine lettuce (Lactuca sativa). Here, we formally describe this species as Sporobolomyces lactucae sp. nov. (Pucciniomycotina, Microbotryomycetes, and Sporidiobolales). We isolated multiple strains of this yeast from commercial romaine lettuce purchased from supermarkets in Illinois and Indiana; additional isolates were obtained from various plant phylloplanes in California. S. lactucae is a red-pigmented species that is similar in appearance to other members of the genus Sporobolomyces. However, it can be differentiated by its ability to assimilate glucuronate and D-glucosamine. Gene genealogical concordance supports S. lactucae as a new species. The phylogenetic reconstruction of a four-locus dataset, comprising the internal transcribed spacer and large ribosomal subunit D1/D2 domain of the ribosomal RNA gene, translation elongation factor 1-a, and cytochrome B, places S. lactucae as a sister to the S. roseus clade. Sporobolomyces lactucae is one of the most common fungi in the lettuce microbiome.