rubrobacter xylanophilus rubrobacter xylanophilus rubrobacter xylanophilus is a thermophilic species of bacteria. it is slightly halotolerant, short rod- and coccus-shaped and gram-positive, with type strain prd-1t. it is the only true radiation resistant thermophile. it can degrade xylan and hemicellulose. the first strain of the genus rubrobacter was isolated from gamma-irradiated hot spring water samples by yoshinaka. this organism was found to be extremely gamma-radiation resistant, with a higher shoulder dose than the canonical radiation resistant species of the genus deinococcus. the organism stained gram-positive and was slightly thermophilic with an optimum growth temperature of about 60 °c. rubrobacter xylanophilus scientific classification domain: bacteria phylum: actinomycetota class: rubrobacteria order: rubrobacterales family: rubrobacteraceae genus: rubrobacter species: r. xylanophilus binomial name rubrobacter xylanophiluscarreto et al. 1996