May be involved in H(2) production during fermentative growth (PubMed:24025676). Involved in the export and assembly of a fimbrial subunit across the outer membrane (Probable). Loss of H(2) production on minimal glucose and complex glucose but not on complex formate medium. Alters production of organic acids when grown on minimal glucose medium. This phenotype was complemented by reintroduction of the ygiG gene. Belongs to the fimbrial export usher family. Could be the product of a pseudogene. It is missing about 10 N-terminal amino acids compared to orthologs.