Relevance of an integrative approach for taxonomic revision in sponge taxa: case study of the shallow-water Atlanto-Mediterranean Hexadella species (Porifera, Ianthellidae, Verongida)

The identification of sponges lacking mineral skeleton is always highly challenging, especially for Hexadella species which are also fiberless. Recently, the yellow species Hexadella pruvoti Topsent was identified as a cryptic species complex while the pink colored Hexadella racovitzai Topsent showed two highly divergent lineages. We performed a COI phylogenetic reconstruction using 27 new Mediterranean Hexadella samples in order to confirm the presence of divergent lineages within both shallow-water species. Specimens were described with an integrative approach combining morphological and cytological investigations, biochemical profiling and assessment of natural toxicity in order to identify diagnostic characters for each taxon. H. topsenti sp. nov. is distinguished from H. racovitzai by its color, its surface network shape, divergent secondary metabolite patterns and toxicity values. H. crypta sp. nov. differs from H. pruvoti by a different encrusting growth form when alive, and by distinctively coloring the ethanol fixative solution. In addition, H. pruvoti and H. crypta show different types of cells with inclusions as well as distinct metabolic fingerprints. Natural toxicity values however, do not permit to separate H. pruvoti and H. crypta. Our work shows that only the use of a combination of complementary tools can provide relevant descriptions for some problematic taxa

Life history determinants of the susceptibility of the blood alga Haematococcus to infection by Paraphysoderma sedebokerense (Blastocladiomycota)

Haematococcus pluvialis is currently cultivated at large scale for its ability to produce high amounts of the high value keto-carotenoid astaxanthin when encysted. Mass cultivation of this species is threatened by the destructive blastocladialean fungus, Paraphysoderma sedebokerense Boussiba, Zarka and James, responsible for the fast collapse of Haematococcus populations. Given the difficulty of maintaining pathogen-free production systems and the lack of treatment options, the selection and development of resistant Haematococcus strains could potentially present an effective and efficient method to control infection. In the present work, we examined the host specificity of P. sedebokerense (strain PS1) through quantitative phenotyping of 44 Haematococcus strains in a laboratory-controlled infectivity assay. We determined the growth and photosynthetic activity of strains in the presence and absence of PS1 over time (using Chl a in vivo fluorescence) and quantified the degree of infection through the intensity of fluorescence after staining with Wheat Germ Agglutinin (WGA)-Fluorescein, which labels PS1 without interfering with Haematococcus. The measurements were converted into three infectivity proxies, allowing comparisons amongst strains. Eventually, microscopy was performed to check the life stage of Haematococcus upon infection. Strains of Haematococcus clearly exhibited different levels of susceptibility against PS1 as determined by the three proxies. These were not related to phylogenetic background, nor the sampling origin of the strains. Amongst ten strains with low susceptibility, five occurred as flagellated state cultures, while others were palmelloid and/or aplanospore dominated. In addition, in a long-term selection experiment, we showed that susceptibility to PS1 of a highly sensitive H. pluvialis strain decreased through the dominance of flagellated phenotypes over several generations of infection. While providing considerable expansion of the relation between PS1 and Haematococcus our study opens the possibility for selection and development of resistant strains

Species diversity in European Haematococcus pluvialis (Chlorophyceae, Volvocales)

Haematococcus pluvialis has received much interest because it can accumulate large quantities of the pigment astaxanthin. While different isolates of H. pluvialis seem to differ considerably in their physiology, their phylogenetic diversity has not yet been thoroughly studied. We studied the species diversity in a set of temperate European strains of H. pluvialis based on internal transcribed spacer (ITS) rDNA and rbcL molecular phylogenies and determined their congruence with morphology and temperature preferences. The ITS rDNA phylogeny resolved three lineages with the European strains. Three additional lineages were not represented by our European strains. Both statistical parsimony network analysis and the general mixed Yule coalescent recovered these six lineages as different species. An ITS1 structure analysis revealed up to three compensatory base changes (CBCs) between each of the three European lineages, while one CBC was found between lineages in the ITS2 secondary structure. Yet the CBCs were not always present in all strains of each lineage. The rbcL was much less variable and separated only two of the three ITS lineages. We propose an epitype for H. pluvialis and describe the two lineages containing European strains as new species, Haematococcus rubicundus and Haematococcus rubens. Although there is broad morphological overlap, strains of H. pluvialis and H. rubens have, on average, more elongated cells, more noticeable cytoplasmic strands and a more (extreme) pear-shaped protoplast apex than H. rubicundus. Optimal temperatures for growth were similar for the three species and varied between 17 degrees C and 23 degrees C, which is lower than reported earlier from other strains. This study provides a robust phylogenetic framework for further ecophysiological study of Haematococcus

Sustainable production of biologically active molecules of marine based origin

The marine environment offers both economic and scientific potential which are relatively untapped from a biotechnological point of view. These environments whilst harsh are ironically fragile and dependent on a harmonious life form balance. Exploitation of natural resources by exhaustive wild harvesting has obvious negative environmental consequences. From a European industry perspective marine organisms are a largely underutilised resource. This is not due to lack of interest but due to a lack of choice the industry faces for cost competitive, sustainable and environmentally conscientious product alternatives. Knowledge of the biotechnological potential of marine organisms together with the development of sustainable systems for their cultivation, processing and utilisation are essential. In 2010, the European Commission recognised this need and funded a collaborative RTD/SME project under the Framework 7-Knowledge Based Bio-Economy (KBBE) Theme 2 Programme 'Sustainable culture of marine microorganisms, algae and/or invertebrates for high value added products'. The scope of that project entitled 'Sustainable Production of Biologically Active Molecules of Marine Based Origin' (BAMMBO) is outlined. Although the Union is a global leader in many technologies, it faces increasing competition from traditional rivals and emerging economies alike and must therefore improve its innovation performance. For this reason innovation is placed at the heart of a European Horizon 2020 Strategy wherein the challenge is to connect economic performance to eco performance. This article provides a synopsis of the research activities of the BAMMBO project as they fit within the wider scope of sustainable environmentally conscientious marine resource exploitation for high-value biomolecules. © 2013 Elsevier B.V. All rights reserved