The investigation of bacterial pathogens of the red macroalga gracilaria gracilis and its response to bacterial infection

The red agar-containing macroalga G. gracilis (Stackhouse) Steentoft, Irvine et, Farnham has occurred in Saldanha Bay, South Africa for many years. However, in recent years a number of collapses in this G. gracilis population were recorded, in some instances almost erradicating the entire population. One of the causes of these collapses is thought to be bacterial disease about which there is very little known. The bacterial pathogens of this macroalga were thus investigated to determine the nature of disease occurrence and how G. gracilis responds to such infections. A large number of culturable bacterial epiphytes isolated from G. gracilis from Saldanha Bay, South Africa, and Luderitz, Namibia were characterised and compared. The number of culturable bacteria isolated from the seawater surrounding the macroalgae was significantly lower than that which occurred epiphytically on the macro algal thalli. Most of the bacteria isolated 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 occurs primarily on the main thalli of the rnacroalga and that significantly fewer (and often none) reside on the thallus growth tips.

Grantor dc:publisher.institution

Department of Molecular and Cell Biology

Year dc:date.issued

1998

Author dc:creator

• Jaffray, Ann Elizabeth

Advisor dc:contributor.advisor

• Coyne, Vernon

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/11427/9557

OAI identifier oai:identifier

oai:open.uct.ac.za:11427/9557