BACTERIA INDUCED POLYMORPHISM IN AN AXENIC LABORATORY STRAIN OF ULVA LACTUCA (CHLOROPHYCEAE)¹

Abstract

A laboratory culture of Ulva lactuca L. purified with antibiotics in 1958 can assume different morphologies. In synthetic media of the ASP type it grows as a pin‐cushion composed of uniseriate branching filaments. Only occasionally some finger‐like germlings appear which, after a few millimeters growth, disintegrate and originate the branched uniseriate filaments. Many strains of marine bacteria, isolated from Ulva and other seaweeds collected in nature or from laboratory cultures, when grown together with this axenic Ulva, induced growth of long thin Enteromorpha‐like tubes (active bacteria). Other bacterial strains have no visible morphological effect on the Ulva (inactive). Combinations of several active and inactive bacterial strains result in flat ribbons which can be wide or narrow and with distromatic portions intercalated between tubular portions. No combination has so far induced the axenic Ulva to produce the typical expanded foliose thallus. Bacterial filtrates are inactive; syntrophic growth seems indispensable. The bacterial strains lose the ability to induce morphogenic effects on the axenic Ulva when grown for several transfers in organic marine media and regain it by growing with Ulva for several transfers in synthetic mineral media. Each partner appears therefore to be dependent on the metabolites produced by the other. The perpetuation of a wide morphological versatility of this laboratory strain of Ulva after 15 yr maintenance under under artificial conditions emphasizes the phylogenetic importance of this versatility.

A bacterial sulfonolipid triggers multicellular development in the closest living relatives of animals

“…Although Bacteroidetes bacteria regulate morphogenetic processes in such diverse lineages as animals, red algae, and green algae (Provasoli and Pintner 1980; Matsuo et al 2005; Mazmanian et al 2005), the bacterially produced chemical cues that regulate most of these partnerships remain obscure. The limited phylogenetic distribution of bacteria capable of inducing rosette colony development suggested that A. machipongonensis and its close relatives may produce a characteristic molecule that could be identified biochemically.…”

Molecular and Ecological Evidence for Species Specificity and Coevolution in a Group of Marine Algal-Bacterial Symbioses

“…Bacterial interactions with algae in nature remain virtually unstudied, despite evidence from a number of laboratories that bacteria can have important consequences for algal growth and morphogenesis in culture (22,23,36,(39)(40)(41)45). Axenic cultures of marine macroalgae do not grow normally, a condition which can be alleviated by the readdition of any number of uncharacterized bacterial epiphytes or the maintenance of appropriate ratios of phytohormones (36,(39)(40)(41)45).…”

“…Axenic cultures of marine macroalgae do not grow normally, a condition which can be alleviated by the readdition of any number of uncharacterized bacterial epiphytes or the maintenance of appropriate ratios of phytohormones (36,(39)(40)(41)45).…”

Variability and abundance of the epiphytic bacterial community associated with a green marine Ulvacean alga

“…By using CARD-FISH analysis we found that bacteria accounted for more than 90% of the cells in the microbial community over all four seasons. This is relatively high in comparison to the average of 56% determined in a review of FISH studies in aquatic environments (Bouvier and del Giorgio, 2003) and could be a reflection of the importance of bacteria for the normal morphological growth of Ulva (Provasoli and Pintner, 1980;Nakanishi et al, 1996;Matsuo et al, 2003). The larger non-hybridized cells observed frequently on the surface of U. australis are possibly diatoms and microalgae, which is in agreement with scanning electron micrographs-based observations of microfouling of small diatoms and blue-green algae on seaweed surfaces (Sieburth, 1975;Provasoli and Pintner, 1980;Dobretsov and Qian, 2002).…”