allisonella allisonella allisonella is a gram-negative, ovoid-shaped, histamine-producing and non-motile genus of bacteria from the family of veillonellaceae with one known species (allisonella histaminiformans). allisonella is named after the american microbiologist m. j. allison. allisonella scientific classification domain: bacteria phylum: bacillota class: negativicutes order: veillonellales family: veillonellaceae genus: allisonellagarner et al. 2003 type species allisonella histaminiformans species a. histaminiformans