Utilization of Macroalgal Carbohydrates By The Marine Amoeba Trichosphaerium Sieboldi

Abstract

^University Marine Biological Station Millport, Isle of Cumbrae, Scotland, KA28 OEG Trichosphaerium sieboldi is a marine amoeba with a cosmopolitan distribution. The ability of three strains, from different geographical regions, to digest a range of macroalgae was investigated. Prior to these experiments, methods were developed for the axenic cultivation of T. sieboldi. Algae included Fucus vesiculosus, F. spiralis, Laminaria digitata, L. saccharina, Mastocarpus stellatus, Palmaria palmata, Porhyra sp., and Ulva sp. Allwere degraded with equivalent ease; typically 50% of the tissue biomass was removed within seven days. The wall of this amoeba was studied to obtain clues on how a protist could be digesting macroalgal tissue. The fibrous nature of the outer cell wall presumably allows the wall to part and remesh during consumption of large particles. It is suggested that during digestion of macroalgae, the wall is parted to enable digestive enzymes to be localized along the surface of the seaweed wall, effectively forming an 'enzyme pocket'. Trichosphaerium has both polysaccharidases and glycosidases, notably glucosidase, cellobiosidase, mannosidase and fucosidase. These enzymes work in concert to facilitate the breakdown of the complex polysaccharides found across the range of seaweeds used. These studies suggest that T. sieboldi could be a primary invader of seaweeds in the field. They also suggest that some protistan groups may be important in the degradation and recycling of algal material in coastal waters.

High Numbers of Naked Amoebae in the Planktonic Waters of a Mangrove Stand in Southern Florida, USA

“…In so doing, they are exploiting a unique niche. Moreover, at least one marine amoeba has been shown to be capable of directly digesting particulate carbon (Rogerson et al 1998). The large numbers of surface‐associated naked amoebae in mangroves, the wealth of new species, and the importance of mangroves in the cycling of coastal carbon and nutrients, all indicate that the ecological role of mangrove protozoa, and amoebae in particular, deserves further consideration.…”

“…Out of all the heterotrophic protists, amoebae are unique in that they are intimately associated with surfaces and may graze niches spatially unavailable to other microconsumers. Moreover, there is some evidence that amoebae have unusual enzymes that enable them to digest a wide range of microbial prey and even macroalgal carbon (Rogerson et al 1998). The ecological implications of these grazing protozoans are yet to be appreciated but their seemingly ubiquitous distribution indicates that they are a largely overlooked group of protozoa deserving of further attention.…”

Utilisation of seaweed carbon by three surface-associated heterotrophic protists, Stereomyxa ramosa, Nitzschia alba and Labyrinthula sp.

“…For example, Sherr (1988) demonstrated that some estuarine flagellates can use high molecular weight polysaccharides found in surface waters, and one amoeba, Tnchosphaerium sieboldi, has been shown to be capable of digesting intact seaweeds (Polne-Fuller et al 1990, Rogerson et al 1998.…”

Omics of an Enigmatic Marine Amoeba Uncovers Unprecedented Gene Trafficking from Giant Viruses and Provides Insights into Its Complex Life Cycle

“…Its members are primarily described from marine environments. They are among algae eating protists playing an important ecological role in the marine environment [ 15 , 16 ]. The taxonomy of Trichosphaerium is poorly understood mainly due to the dramatic morphological transformations it undergoes during its life cycle.…”