Investigation of bacterial epiphytes of the agar-producing red seaweed Gracilaria gracilis (Stackhouse) Steentoft, Irvine et Farnham from Saldanha Bay, South Africa and Luderitz, Namibia

A large number of culturable bacterial epiphytes were isolated from the agarophyte Gracilaria gracilis (Stackhouse) Steentoft, Irvine et Farnham. Most of these bacteria were Gram negative, motile rods, and many were classified to genus level. Scanning electron microscopy confirmed that a large epiphytic population of coccoid and rod-shaped bacteria occur primarily on the main thalli of the plant. Of the total number of isolates examined, 34% were highly agarolytic. The agarolytic and proteolytic activity of these bacterial epiphytes suggests that they may be pathogenic to G. gracilis.