title: The oral immunogenicity of BioProtein, a bacterial single-cell protein, is affected by its particulate nature.
abstract: The bacterial single-cell protein BioProtein (BP; Norferm Danmark, Odense, Denmark), produced by fermentation of natural gas with methanotrophic bacteria, is a potential protein source for man and animals. For human consumption, removal of the nucleic acid is necessary. Preliminary studies have shown that ingested BP induces a specific immune response. The objective of the present study was to characterize the type of response, its development over time and product-related causative factors. Mice were fed with diets containing 60 g nucleic acid-reduced BP/kg, 240 g nucleic acid-reduced BP/kg, 240 g untreated BP (basic BP)/kg or 240 g casein/kg (control). In another study, mice were fed 240 g basic BP/kg, whole cell-free BP-culture homogenate or control diet. The immune response was monitored using an ELISA for BP-specific immunoglobulin in blood and BP-specific immunoglobulin A in blood and saliva. Ingested BP induced a steady specific mucosal and systemic immune response, characterized by a dose-dependent production of immunoglobulin and immunoglobulin A in blood and immunoglobulin A in saliva. Basic BP and nucleic acid-reduced BP induced identical responses. However, feeding mice BP-culture homogenate induced immunoglobulin A in saliva but there was no systemic response. The antibodies from BP-fed mice cross-reacted with BP-culture homogenate revealing the presence of the same antigenic components in the two products despite the different oral immunogenicity. Thus, ingestion of BP induces a persistent mucosal and systemic immune response of which the systemic response can be avoided by ingesting a BP preparation free of whole cells. This indicates the importance of the non-particulate constitution of single-cell protein products intended for human or animal consumption.
authors.affiliation: BioCentrum-DTU, Section for Biochemistry and Nutrition, Technical University of Denmark, DK-2800 Lyngby, Denmark. hrc@biocentrum.dtu.dk
authors.forename: Hanne R
authors.initials: HR
authors.lastname: Christensen
authors.forename: Linea C
authors.initials: LC
authors.lastname: Larsen
authors.forename: Hanne
authors.initials: H
authors.lastname: Frøkiaer
mesh_terms: D000284:Administration, Oral; D000818:Animals; D000907:Antibodies, Bacterial / Q000032:analysis / Q000097:blood; D001426:Bacterial Proteins / Q000008:administration & dosage / Q000276:immunology*; D002455:Cell Division; D003429:Cross Reactions; D004044:Dietary Proteins / Q000008:administration & dosage / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D005260:Female; D005502:Food; D018928:Immunity, Mucosal; D007070:Immunoglobulin A / Q000032:analysis / Q000097:blood; D051379:Mice; D008807:Mice, Inbred BALB C; D009696:Nucleic Acids; D011897:Random Allocation; D012463:Saliva / Q000276:immunology; D013154:Spleen / Q000166:cytology
chemical_list: D000907:Antibodies, Bacterial; D001426:Bacterial Proteins; C459479:BioProtein, Bacteria; D004044:Dietary Proteins; D007070:Immunoglobulin A; D009696:Nucleic Acids