The host-range ofParaphysoderma sedebokerensis, a chytrid that infectsHaematococcus pluvialis

Abstract

A parasitic chytrid that attacks the green alga Haematococcus pluvialis was recently isolated in our laboratory and identified as a novel species from the phylum Blastocladiomycota, named herein Paraphysoderma sedebokerensis (nom. prov.). A method for early and precise detection of chytrid infections was developed using the fluorescent dye, Nile red, which stained the chytrids' sporangia. Using this technique we determined the specificity of Paraphysoderma sedebokerensis for 13 algal species belonging to the Chlorophyta. Algal species tested including: Chlamydomonas nivalis, Chlorella emersonii, Chlorella vulgaris, Chlorococcum sp., Chlorogonium elongatum, Monoraphidium braunii, Muriella zofigiensis, Scenedesmus obliquus, Scenedesmus vacuolatus (two strains), and Scotiellopsis oocystiformis were either resistant to infection, or only experienced slight levels of infection during exponential growth. During exponential growth phase 100% Chlorella zofigiensis Donz cells were infected, but none developed any infection during resting stage. Only in cultures of H. pluvialis did infections develop rapidly (3-4 days) and intensively (100% cells infected) during both the logarithmic and stationary stages of growth. We suggest that the newly isolated chytrid, Paraphysoderma sedebokerensis (nom. prov.), is highly specific for H. pluvialis, but has a limited capacity to infect other green algae.

Fungi and Algae Co-Occur in Snow: An Issue of Shared Habitat or Algal Facilitation of Heterotrophs?

“…It is tempting to speculate on whether these chytrids parasitize or prey on snow algae (Naff et al, 2013) as such associations are common in algae-dominated freshwater systems (Hoffman et al, 2008;Gutman et al, 2009;Rasconi et al, 2011). Snow chytrids may also act as facultative mutualists or have obligate syntrophic relationships; there is a precedence of such relationships in other aquatic systems (Picard et al, 2013).…”

Astaxanthin in microalgae: pathways, functions and biotechnological implications

“…Mass culture of Haematococcus can be contaminated by fungal parasites and zooplanktonic predators (e.g., amoebas, ciliates, and rotifers), as well as other microalgae and cyanobacteria, resulting in reduced biomass yield and quality, and sometimes loss of culture all together. A parasitic blastoclad fungus identified as Paraphysoderma sedebokerensis is the most devastating disease responsible for reduced astaxanthin productivity and frequent culture collapses (Hoffman et al 2008, Gutman et al 2009). Hoffman et al (2008) made detailed observations on the infection of Haematococcus culture by the parasite P. sedebokerensis (Hoffman et al 2008).…”

Hidden diversity among aquatic heterotrophic flagellates: ecological potentials of zoosporic fungi

“…Amoebophrya species are mainly known as marine endoparasites in red-tide dinoflagellate blooms (Coats et al, 1996), and were intensively studied in oceans where they display a worldwide distribution (Park et al, 2004). In freshwater ecosystems, saprotrophs and parasites also include zoosporic fungi and some of them are host-specific to various phytoplankton species (Barr & Hickman, 1967;Gutman et al, 2009;Rasconi et al, 2009). …”