thermoanaerobacter kivui thermoanaerobacter kivui thermoanaerobacter kivui (formerly acetogenium kivui) is a thermophilic, anaerobic, nonspore-forming species of bacteria. thermoanaerobacter kivui scientific classification domain: bacteria phylum: bacillota class: clostridia order: thermoanaerobacterales family: thermoanaerobacteraceae genus: thermoanaerobacter species: t. kivui binomial name thermoanaerobacter kivui(leigh and wolfe 1983) collins et al. 1994 t. kivui was originally isolated from lake kivu in africa. the growth range for the organism is 50 to 72°c at ph 5.3-7.3, with optimal growth conditions at 66°c and ph 6.4. although the organism stains gram-negative, it shows a gram-positive cell structure. the original genus acetogenium was named because this organism principally produces acetic acid from substrates. t. kivui was originally named acetogenium kivui, which was the only species within a new genus. however, further 16s ribosomal rna studies put this bacterium into genus thermoanaerobacter and the previous genus was no longer necessary.