@article {471,
	title = {Interaction between bacteria and the domoic-acid-producing diatom Pseudo-nitzschia multiseries (Hasle) Hasle; can bacteria produce domoic acid autonomously?},
	journal = {Harmful Algae},
	volume = {3},
	number = {1},
	year = {2004},
	note = {812USTimes Cited:11Cited References Count:52},
	month = {Jan},
	pages = {11-20},
	abstract = {The interaction between bacteria and phytoplankton is increasingly becoming recognised as an important factor in the physiology of toxin production and the dynamics of harmful algal blooms (HABs). Bacteria can play a direct or indirect role in the production of biotoxins once solely attributed to microalgae. Evidence implicating bacteria as an autonomous source paralytic shellfish poisoning biotoxins raises the question of autonomous bacterial toxigenesis of the neurotoxin domoic acid (DA), the cause of amnesic shellfish poisoning. Here, we examine whether the previously observed bacterial enhancement of DA production by Pseudo-nitzschia multiseries (Hasle) Hasle may be attributable to independent biotoxin production by the extra-cellular bacteria associated with this diatom. The growth and toxicity of six cultures of xenic P. multiseries clone CLN-1 were followed for 24 days. Up to day 14 (mid-stationary phase), DA production was not statistically different among culture flasks. On day 14, R multiseries cells were removed by gentle filtration from a set of triplicate flasks, leaving the bacteria in the filtrate. Following the removal of the algal cells, DA in the filtrate ceased to increase. Instead, DA levels continuously declined. A follow-up experiment determined that this was likely caused by photodegradation rather than by bacterial degradation. We conclude that after removing R multiseries cells, the extra-cellular bacteria remaining in the filtrate were incapable of autonomous DA toxigenesis, even in the presence of P multiseries exudates. However, scanning electron microscopy revealed that R multiseries cells harboured epiphytic bacteria, the importance of which can still not be ruled out in DA production. Crown Copyright (C) 2004 Published by Elsevier B.V. All rights reserved.},
	keywords = {alexandrium-catenella, Bacillariophyceae, bacteria-phytoplankton interactions, bloom, culture, dinoflagellate, domoic acid, epiphytic bacteria, growth, marine-bacteria, paralytic shellfish toxins, Pseudo-nitzschia multiseries, pungens, spp.},
	isbn = {1568-9883},
	url = {<Go to ISI>://000220865000002},
	author = {Bates, S. S. and Gaudet, J. and Kaczmarska, I. and Ehrman, J. M.}
}
@article {469,
	title = {Diversity and distribution of epibiotic bacteria on Pseudo-nitzschia multiseries (Bacillariophyceae) in culture, and comparison with those on diatoms in native seawater},
	journal = {Harmful Algae},
	volume = {4},
	number = {4},
	year = {2005},
	note = {930ZCTimes Cited:12Cited References Count:63},
	month = {Jun},
	pages = {725-741},
	abstract = {Previous studies on the interaction between bacteria and harmful algal bloom species have mostly considered the bacteria in the bulk solution. Here, we document the abundance and mode of attachment of bacteria growing on the cell surface of the domoic acid-producing diatom Pseudo-nitzschia multiseries (Hasle) Hasle in culture, compared with diatoms in field samples. The epiphytic bacteria were examined by scanning electron microscopy to visualize their morphology and mode of attachment. Two P. multiseries cultures were studied: clone CLN-1 and sub-clone CLN-1-NRC; the latter had been maintained in another laboratory for 2 years. Each of these P. multiseries cultures exhibited a clearly different assemblage of epibiotic bacteria, even though both originated from the same parent culture. The bacterial diversity was greater in clone CLN-1 (nine distinct morphotypes seen) than in sub-clone CLN-1-NRC (six morphotypes). The former clone also produced more domoic acid than the latter. There was a succession of bacterial morphotypes as well as an increase in the number of epiphytic bacteria per diatom cell during the progression from exponential to stationary phase. The most diverse and common morphotypes were rod-shaped cells (e.g. a Caulobacter-like bacterium attached by a discoid holdfast). Epibionts showed a preference for attachment at specific regions of the host diatom frustule, e.g. the raphe or cingulum, locations where organic matter may be extruding from the diatom cell. Most diatom cells carried only one to five bacteria, and up to ca. 60\% of the intact diatom cells (although intact cells themselves were infrequent) were still free of epibiotic bacteria at the end of the 31-day batch culture experiment. Sequencing of the SSU rRNA gene showed that five of the eight bacterial strains isolated from the P multiseries cultures were members of the Alphaproteobacteria, three of the Gammaproteobacteria and one of the Bacteroidetes. A morphologically diverse assemblage of epibiotic bacteria was also found on both centric and pennate planktonic diatoms in natural coastal waters. Of the eight morphotypes recorded, all but two were also found in the cultures. Relatively fewer wild diatom cells carried bacteria compared to cells in culture. We hypothesize that the diversity and abundance of epiphytic bacteria may explain some of the variability seen in the production of DA by different P. multiseries clones, and should be considered as another important and controllable variable that influences diatom cell physiology. (c) 2004 Elsevier B.V. All rights reserved.},
	keywords = {alexandrium spp., bacteria-phytoplankton interactions, domoic acid, domoic-acid, epiphytic bacteria, growth, gymnodinium, marine-bacteria, morphology, paralytic shellfish toxin, populations, Pseudo-nitzschia multiseries, skeletonema-costatum, Toxicity},
	isbn = {1568-9883},
	url = {<Go to ISI>://000229454600005},
	author = {Kaczmarska, I. and Ehrman, J. M. and Bates, S. S. and Green, D. H. and Leger, C. and Harris, J.}
}
