Symbiotic relations between bacteria and the domoic acid producing diatom Pseudo-nitzschia multiseries and the capacity of these bacteria for gluconic acid/gluconolactone formation

Abstract

ABSTRACT. Bacteria isolated from cultures of 4 different strains of the diatom Pseudo-nitzschia multiseries following numerous transfers in a defined medium were identified as mainly Moraxella and Alteromonas sp. These bacteria apparently form a characteristic suite of microorganisms living in a symbiotic relationship with the diatom. The bacterial isolates from each of the P. multiseries strains divided metabolically into 2 groups; those that produced significant amounts of acid from carbohydrates and those that grew readily at the expense of amino acids. The specific acid forming bacteria isolated from each diatom species grown in the presence of glucose produced gluconic acid/gluconolactone in quantity and released it to the surrounding medium. For growth of the diatom a salinity of 33 ppt was more favorable than 26 or 38 ppt; sorbitol varied with the salinity and thus might be an osmolyte. Glucose was present in s~gnificant quantities In the diatom grown at all 3 salinities Nonaxenic growth of the diatom was stimulated considerably by the presence of proline alone and to approximately the same level when it was combined with glucose or sodium acetate, but not when glycine was substituted for the proline. Stimulation of the growth of the diatom by the presence of proline was considered to be a function of the associated bacteria. Glycine combined with sodium acetate was slightly inhibitory to the growth of the diatom but both glycine plus sodium acetate and glycine plus glucose combinations were markedly inhibitory to the growth of the associated bacteria. The possible role of all of these features in the initiation of a bloom of Pseudo-nitzschia rnultiseries, espec.idlly in an inshore environment enriched by organic nitrogen, and the consequent production of domolc acid is discussed.

Bacterial community composition differs with species and toxigenicity of the diatom Pseudo-nitzschia

“…Our findings therefore build upon prior work that characterized bacteria in P. multiseries cultures (Bates et al 1995, Stewart et al 1997, Kobayashi et al 2003, Kaczmarska et al 2005. The high-throughput fingerprinting technique ARISA allowed for rapid comparison of bacterial community composition among multiple cultures.…”

“…The taxonomic identifications of the bacteria in Pseudo-nitzschia cultures revealed members of the Roseobacter clade, Flavobacteria, and Gammaproteobacteria, all frequently found with other phytoplankton cultures (Stewart et al 1997, Alavi et al 2001, Hold et al 2001, Schäfer et al 2002, Kobayashi et al 2003, Fandino et al 2005, Grossart et al 2005, Jasti et al 2005, Kaczmarska et al 2005, Sapp et al 2007a. However, the level of intraspecific diversity was unexpected; 9 of 10 ARISA peaks sequenced in replicate contained multiple nonidentical 16S rDNA sequences, suggesting that multiple strains of the same bacterial species (> 99% 16S rDNA identity; Acinas et al 2004) coexisted in Pseudo-nitzschia cultures.…”

“…Although the nature of interactions between Pseudonitzschia and bacteria has not been determined, bacteria in some Pseudo-nitzschia multiseries cultures have been identified as taxa commonly detected with other phytoplankton, including members of the Roseobacter clade and other rhodobacters, alteromonads and other Gammaproteobacteria, and a member of the Bacteroidetes (Stewart et al 1997, Kobayashi et al 2003, Kaczmarska et al 2005. Some of these bacteria may occur intracellularly (Kobayashi et al 2003), and these same bacterial taxa often co-occur among other diatom and dino flagellate cultures (Alavi et al 2001, Hold et al 2001, Schäfer et al 2002, Fandino et al 2005, Grossart et al 2005, Jasti et al 2005, Sapp et al 2007a).…”

Iron and copper limitations differently affect growth rates and photosynthetic and physiological parameters of the marine diatom Pseudo‐nitzschia delicatissima

“…Another hypothesis regarding DA production may also be postulated: If DA-acquired Cu is used to access Fe complexed by siderophores (Wells et al 2005), DA production may be triggered not only by Cu or Fe limitation but also by a threshold concentration of siderophores in the medium. It has already been postulated that DA production could be triggered by gluconolactonegluconic acid, produced by some bacteria as a metal chelator (Stewart et al 1997). Cultures of Pseudo-nitzschia grown without bacteria do, indeed, lose their toxicity (Douglas et al 1993).…”

Gluconic acid/gluconolactone: physiological influences on domoic acid production by bacteria associated with Pseudo-nitzschia multiseries

“…In a separate study (Stewart et al 1997, in this issue), one was identified as an Alteromonas sp. which produced gluconic acid/gluconolactone from glucose and the other as a Moraxella sp.…”