serratia symbiotica serratia symbiotica serratia symbiotica is a species of bacteria that lives as a symbiont of aphids. in the aphid cinara cedri, it coexists with buchnera aphidicola, given the latter cannot produce tryptophan. it is also known to habitate in aphis fabae. together with other endosymbionts, it provides aphids protection against parasitoids. serratia symbiotica scientific classification domain: bacteria phylum: pseudomonadota class: gammaproteobacteria order: enterobacterales family: yersiniaceae genus: serratia species: s. symbiotica binomial name serratia symbioticamoran et al., 2005