Bates S S, Douglas D J, Doucette G J, Léger C
Department of Fisheries and Oceans, Gulf Fisheries Centre, Moncton, New Brunswick, Canada.
Nat Toxins. 1995;3(6):428-35. doi: 10.1002/nt.2620030605.
Axenic cultures of Pseudo-nitzschia multiseries (formerly Pseudonitzschia pungens f. multiseries) produce less domoic acid (DA) than the original bacteria-containing cultures. Bacterial strains isolated from two nonaxenic P. multiseries clones were reintroduced individually into cultures of three axenic P. multiseries strains. The bacteria did not substantially affect division rates or cell yields. However, they did cause a 2- to 95-fold enhancement of DA production (per cell basis) relative to the axenic culture, depending on the P. multiseries and bacterial strain used. Bacteria isolated from a nontoxic Chaetoceros sp. culture also enhanced DA per cell (by 115-fold), showing that it is not necessary for the bacteria to be isolated from a toxic culture in order to enhance toxin production. There was no evidence of intracellular bacteria in disrupted P. multiseries cells obtained from axenic cultures. Our results demonstrate an important, but nonessential, role of extracellular bacterial in DA production. Characterization of the bacterial strains using morphology, substrate utilization, and restriction fragment length polymorphism (RFLP) analyses clearly showed that we had isolated different species of bacteria from the various nonaxenic cultures. We conclude that not one but several bacterial species enhance DA production by P. multiseries.
多列拟菱形藻（以前的尖刺拟菱形藻多列变种）的无菌培养物产生的软骨藻酸（DA）比原始含细菌培养物少。从两个非无菌的多列拟菱形藻克隆中分离出的细菌菌株分别重新引入到三个多列拟菱形藻无菌菌株的培养物中。这些细菌对分裂速率或细胞产量没有实质性影响。然而，根据所用的多列拟菱形藻和细菌菌株，它们确实导致（以每个细胞为基础）DA产量相对于无菌培养物提高了2至95倍。从无毒的角毛藻属培养物中分离出的细菌也提高了每个细胞的DA产量（提高了115倍），这表明为了提高毒素产量，细菌并非必须从有毒培养物中分离出来。从无菌培养物获得的破碎多列拟菱形藻细胞中没有细胞内细菌的证据。我们的结果证明了细胞外细菌在DA产生中起重要但非必要的作用。使用形态学、底物利用和限制性片段长度多态性（RFLP）分析对细菌菌株进行表征清楚地表明，我们从各种非无菌培养物中分离出了不同种类的细菌。我们得出结论，不是一种而是几种细菌物种提高了多列拟菱形藻的DA产量。
