title: Food preparation with mucoralean fungi: A potential biosafety issue?
abstract: Mucorales have been used for production of fermented food in Asia and Africa since time immemorial. Particularly Rhizopus species are rapidly growing, active producers of lipases and proteases and occur naturally during the first stages of soybean fermentation. Two biosafety issues have been raised in recent literature: (1) pathogenicity, Rhizopus species being prevalent opportunists causing erosive infections in severely compromised patients, and (2) toxicity, strains harbouring endosymbiotic Burkholderia producing toxic secondary metabolites. At the molecular level, based on different gene markers, species identity was found between strains used for food processing and clinical strains. In this study, we screened for bacterial symbionts in 64 Rhizopus strains by light microscopy, 16S rRNA sequencing, and HPLC. Seven strains (11 %) carried bacteria identified as Burkholderia rhizoxinica and Burkholderia endofungorum, and an unknown Burkholderia species. The Burkholderia isolates proved to be able to produce toxic rhizoxins. Strains with endosymbionts originated from food, soil, and a clinical source, and thus their presence could not be linked to particular habitats. The presence of Burkholderia in Rhizopus producing toxins could not be excluded as a potential risk for human health. In contrast, given the type of diseases caused by Rhizopus species, we regard the practical risk of infection via the food industry as negligible.
authors.affiliation: CBS-KNAW Fungal Biodiversity Centre, Utrecht, The Netherlands; Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Amsterdam, The Netherlands; Cellular and Molecular Research Center, Sabzevar University of Medical Sciences, Sabzevar, Iran. Electronic address: S.dolat@cbs.knaw.nl.
authors.forename: Somayeh
authors.initials: S
authors.lastname: Dolatabadi
authors.affiliation: Leibniz Institute for Natural Product Research and Infection Biology, Hans Knöll Institute (HKI), Jena, Germany.
authors.forename: Kirstin
authors.initials: K
authors.lastname: Scherlach
authors.affiliation: CBS-KNAW Fungal Biodiversity Centre, Utrecht, The Netherlands.
authors.forename: Marian
authors.initials: M
authors.lastname: Figge
authors.affiliation: Leibniz Institute for Natural Product Research and Infection Biology, Hans Knöll Institute (HKI), Jena, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Hertweck
authors.affiliation: CBS-KNAW Fungal Biodiversity Centre, Utrecht, The Netherlands.
authors.forename: Jan
authors.initials: J
authors.lastname: Dijksterhuis
authors.affiliation: Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Amsterdam, The Netherlands.
authors.forename: Steph B J
authors.initials: SB
authors.lastname: Menken
authors.affiliation: CBS-KNAW Fungal Biodiversity Centre, Utrecht, The Netherlands; Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Amsterdam, The Netherlands; Peking University Health Science Center, Research Center for Medical Mycology, Beijing, China; Chang Zheng Hospital, Second Military Medical University, Shanghai, China; Basic Pathology Department, Federal University of Paraná State, Curitiba, Paraná, Brazil; King Abdulaziz University, Jeddah, Saudi Arabia.
authors.forename: G Sybren
authors.initials: GS
authors.lastname: de Hoog
mesh_terms: D042521:Burkholderiaceae / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D002851:Chromatography, High Pressure Liquid; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D005511:Food Handling / Q000379:methods*; D005516:Food Microbiology; D059022:Food Safety; D008853:Microscopy; D009090:Mucorales / Q000302:isolation & purification / Q000378:metabolism*; D009091:Mucormycosis / Q000382:microbiology; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D012988:Soil Microbiology; D013559:Symbiosis
chemical_list: D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D012336:RNA, Ribosomal, 16S
keywords: Burkholderia; Endosymbiosis; Mycotoxin; Rhizopus; Rhizoxin; β-Proteobacterium