A photocarotenogenic Rhodococcus sp. isolated from the sym- biotic fern Azolla

An aerobic, heterotrophic bacterium, termed strain APG1, was isolated from surfacesterilized fronds of Azolla pinnata, a water fern having symbiotic leaf cavities. Based on its fatty acid profile, morphology and biochemical characteristics, strain APG1 was assigned to the genus Rhodococcus. Exposure to light caused colonies to yellow due to accumulation of a s-carotene-like pigment. We suggest that photocarotenogenesis and other traits of strain APG1 could facilitate the survival of the bacterium in planta.