Bacterial induction and inhibition of a fast necrotic response in Gracilaria conferta (Rhodophyta)

Weinberger, Florian, Hoppe, Hans-Georg and Friedlander, Michael (1997) Bacterial induction and inhibition of a fast necrotic response in Gracilaria conferta (Rhodophyta) Journal of Applied Phycology, 9 (3). pp. 277-285. DOI 10.1023/A:1007990712925.

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Of 45 bacterial isolates from healthy tips of Gracilaria conferta (Schousboe ex Montagne) J. et G. Feldmann, 29% were identified as 'conditional inducers' of an apical necrosis. That is, the isolates induced necrotic tips in G. conferta within 16 h after elimination of most of the resident microflora from the alga. Several disinfectants and antibiotics were screened for their ability to induce algal susceptibility to the bacteria and to suppress uncontrolled appearance of tip necrosis. Treatment with 100 mg L-1 Cefotaxim + 100 mg L-1 Vancomycin over three days was the least damaging and most efficient. Tip necrosis was related to isolates of the Corynebacterium-Arthrobacter-group and to the Flavobacterium-Cytophaga-group. The damaging effect occurred due to the bacterial excretion of active agents and was not correlated with a capability to degrade agar. The damaging influence of four Cytophaga-like strains was inhibited by 20 of 40 isolates. This protective effect was caused by very different organisms. In five of six cases examined further, the effect was not cellbound, but due to the excretion of agents. These were not antimicrobially active, but inactivated necrosis-inducing excretions. These results indicate that epiphytic bacterial degradation or inactivation of damaging agents is a protecting factor in Gracilaria, which prevents the alga from being harmed by epiphytes.

Document Type: Article
Keywords: cefotaxim; epiphytic bacteria; Gracilaria; seaweed-microbe interactions; seaweed pathology; Vancomycin
Research affiliation: OceanRep > GEOMAR > FB3 Marine Ecology > FB3-MI Marine Microbiology
Refereed: Yes
DOI etc.: 10.1023/A:1007990712925
ISSN: 0921-8971
Date Deposited: 29 Jan 2014 13:01
Last Modified: 25 Jan 2017 14:12

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