Thraustochytrids, a Neglected Component of Organic Matter Decomposition and Food Webs in Marine Sediments

Abstract

Decomposition of organic matter in marine sediments is a critical step influencing oxygen and carbon fluxes. In addition to heterotrophic bacteria and fungi, osmoheterotrophic protists may contribute to this process, but the extent of their role as decomposers is still unknown. Among saprophytic protists, the thraustochytrids have been isolated from different habitats and substrates. Recently, they have been reported to be particularly abundant in marine sediments characterized by the presence of recalcitrant organic matter such as seagrass and mangrove detritus where they can reach biomass comparable to those of other protists and bacteria. In addition, their capacity to produce a wide spectrum of enzymes suggests a substantial role of thraustochytrids in sedimentary organic decomposition. Moreover, thraustochytrids may represent a food source for several benthic microorganisms and animals and may be involved in the upgrading of nutrient-poor organic detritus. This chapter presents an overview on studies of thraustochytrids in benthic ecosystems and discusses future prospectives and possible methods to quantify their role in benthic food webs.

Marine fungoid producers of DHA, EPA and carotenoids from central and southern Chilean marine ecosystems

“…The wide distribution of the marine fungoid studied here is consistent with what was described by Bongiorni et al (2004Bongiorni et al ( , 2012.…”

“…A surface network was also observed covering cells similar to those in Thraustochytrids termed an ectoplasmic network (Perkins 1972). The information obtained here raises the question of whether microorganisms quantified and isolated through the pollen bait technique are all Thraustochytrides or whether they belong to other uncharacterized fungoid protist families (Bongiorni 2012). …”

“…The pine pollen bait technique (Gaertner 1966) consists of directly isolating microorganisms from seawater that can be grown on pine pollen and that have morphology consistent with that of the Thraustochytrids group widely described through this technique (Bongiorni 2012). This technique was chosen because the microorganisms isolated with it are potential producers of substances of commercial interest such as DHA, EPA and carotenoids (Yamasaki et al 2006) and allowed for constructing the strain collection used to investigate the presence of such substances.…”

Eukaryotic microbes, principally fungi and labyrinthulomycetes, dominate biomass on bathypelagic marine snow

“…Eukaryotic microbes dominate biomass on bathypelagic marine snow AB Bochdansky et al of decomposers of coastal leaf litter and phytoplankton in sediments (Bongiorni, 2012). Because many are also parasitic or symbiotic (Damare and Raghukumar, 2010), thraustochytrids' ecological role cannot be inferred from the data at hand.…”

Microalgas como ingrediente e suplemento dietético para tilápia <i>Oreochromis niloticus</i>: valor biológico, desempenho e composição da carcaça

“…(Benedict, 1987, Mariotti et al, 2008, Lourenço et al, 2004, Templeton and Laurens, 2015, Angell et al, 2016. (Bongiorni, 2012, Hong et al, 2011, Yokoyama and Honda, 2007. Essa espécie de microalga foi reconhecida pelas indústrias por sua composição em ácidos graxos poli-insaturados da série n-3, mais especificadamente pelo ácido docosaexaenoico -(DHA; C22:6n-3), a presença de β-caroteno e também por sua alta produtividade em sistemas heterotróficos, algo em torno de 23 g L -1 em matéria seca (Hong et al, 2011, Yokoyama andHonda, 2007).…”