Associations between microbes and macroalgae: Host, epiphyte and environmental effects

The present work was carried out in order to contribute towards our understanding on alga-bacteria relationships. Different macroalgae in the same habitat may all exert the same important ecological role as primary producers, but in terms of interactions every single species represents a completely different microenvironment occupied by rich and diverse microbial communities. The present study covered potential effects from the host, season and epibiota in regulating the associated microbial communities. It also covered pathogenic relationships and possible specific associations

Maullinia braseltonii sp. nov. (Rhizaria, Phytomyxea, Phagomyxida) : A Cyst-forming Parasite of the Bull Kelp Durvillaea spp. (Stramenopila, Phaeophyceae, Fucales)

Help in biomass collection by David J. Patiño (UACh), Liliana A. Muñoz (University of Aberdeen (UoA)) and Alexandra Mystikou (South Atlantic Environmental Research Institute & UoA), and in conducting electron microscopy by Gillian Milne (Aberdeen Microscopy Facility) is acknowledged. Thanks are due to the three anonymous reviewers, whose comments helped to improve the earlier version of this manuscript. PM was funded by Conicyt (BecasChile N° 72130422) for PhD studies at the University of Aberdeen, and by the NERC IOF Pump-priming (scheme NE/L013223/1) for activities at the Scottish Association for Marine Sciences. RW thanks financial support from Gobierno Regional de Los Lagos (projects FIC 2012 E7259-2 and FIC 2013 BIP30234872-0) and Fondef, Conicyt (HUAM AQ12I0010), which allows the sampling expeditions at Chiloe Island by David J. Patiño, Liliana Muñoz and PM. SN was funded by the Austrian Science Fund (FWF): grant J3175-B20 (Erwin Schrödinger Fellowship) and grant Y801-B16 (START-grant). PvW is supported by the UoA, BBSRC and NERC. Also, the MASTS pooling initiative (Marine Alliance for Science and Technology for Scotland, funded by the Scottish Funding Council and contributing institutions; grant reference HR09011) is gratefully acknowledged for its support to FCK. Finally, we would like to thank the UoA, Shackleton Fund (FCK) and the John Cheek Fund (FCK) for supporting the expeditions of Alexandra Mystikou, PvW and FCK to the Falkland Islands.Peer reviewedPublisher PD

Cultivar development of kelps for commercial cultivation - Past lessons and future prospects

Cultivated kelps and other macroalgae have great potential in future provision of food, feed, bioenergy, fertilizer, and raw material for a range of chemical products including pharmaceuticals, food and feed additives, and cosmetics. Only a few species are currently cultivated, almost exclusively in Asia. There is a range of species that could be utilized in different parts of the world, providing that protocols for reproduction, propagation, and cultivation are developed. Domestication of species involves selection of traits that are desirable in cultivation and in the utilization of the harvested biomass. Genetic improvement of cultivated species through recombination of alleles and selection (breeding) has ensured high productivity and product quality in both agri- and aquaculture and will likely do so for macroalgae cultivation and use as well. According to the published literature, genetic improvement of kelps in Asia has so far largely relied on utilization of heterosis expressed in certain combinations of parental material, sometimes species hybrids. Here, we explore and evaluate the various methods that could be used in kelp breeding and propose an initial simple and low-cost breeding strategy based on recurrent mixed hybridization and phenotypic selection within local populations. We also discuss the genetic diversity in wild populations, and how this diversity can be protected against genetic pollution, either by breeding and cultivating local populations, or by developing cultivars that are not able to establish in, or hybridize with, wild populations.publishedVersio

Observación de bacterias sobre la superficie de oogonios liberados de Fucus vesiculosus L. (Phaeophyceae)

Pese al enorme número de bacterias que se encuentran normalmente en la columna de agua, se registra por primera vez su presencia sobre oogonios del alga Fucus vesiculosus. En cortes transversales, sin embargo, los oogonios se encontraban libres de epibiosis. Las algas fucoides son fundamentales en ciertos ambientes costeros, mas el impacto microbiano sobre su ciclo de vida y colonización es completamente desconocido.Pese al enorme número de bacterias que se encuentran normalmente en la columna de agua, se registra por primera vez su presencia sobre oogonios del alga Fucus vesiculosus. En cortes transversales, sin embargo, los oogonios se encontraban libres de epibiosis. Las algas fucoides son fundamentales en ciertos ambientes costeros, mas el impacto microbiano sobre su ciclo de vida y colonización es completamente desconocido

Minireview: algal natural compounds and extracts as antifoulants

Marine biofouling is a paramount phenomenon in the marine environment and causes serious problems to maritime industries worldwide. Marine algae are known to produce a wide variety of chemical compounds with antibacterial, antifungal, antialgal, and anti-macrofouling properties, inhibiting the settlement and growth of other marine fouling organisms. Significant investigations and progress have been made in this field in the last two decades and several antifouling extracts and compounds have been isolated from micro- and macroalgae. In this minireview, we have summarized and evaluated antifouling compounds isolated and identified from macroalgae and microalgae between January 2010 and June 2016. Future directions for their commercialization through metabolic engineering and industrial scale up have been discussed. Upon comparing biogeographical regions, investigations from Southeast Asian waters were found to be rather scarce. Thus, we have also discussed the need to conduct more chemical ecology based research in relatively less explored areas with high algal biodiversity like Southeast Asia

A Novel Phytomyxean Parasite Associated with Galls on the Bull-Kelp Durvillaea antarctica (Chamisso) Hariot

Durvillaea antarctica (Fucales, Phaeophyceae) is a large kelp of high ecological and economic significance in the Southern Hemisphere. In natural beds along the central coast of Chile (Pacific Ocean), abnormal growth characterized by evident gall development and discolorations of the fronds/thallus was observed. Analysing these galls by light microscopy and scanning electron microscopy revealed the presence of endophytic eukaryotes showing typical characteristics for phytomyxean parasites. The parasite developed within enlarged cells of the subcortical tissue of the host. Multinucleate plasmodia developed into many, single resting spores. The affiliation of this parasite to the Phytomyxea (Rhizaria) was supported by 18S rDNA data, placing it within the Phagomyxida. Similar microorganisms were already reported once 23 years ago, indicating that these parasites are persistent and widespread in D. antarctica beds for long times. The symptoms caused by this parasite are discussed along with the ecological and economic consequences. Phytomyxean parasites may play an important role in the marine ecosystem, but they remain understudied in this environment. Our results demonstrate for the first time the presence of resting spores in Phagomyxida, an order in which resting spores were thought to be absent making this the first record of a phagomyxean parasite with a complete life cycle so far, challenging the existing taxonomic concepts within the Phytomyxea. The importance of the here described resting spores for the survival and ecology of the phagomyxid parasite will be discussed together with the impact this parasite may have on 'the strongest seaweed of the world', which is an important habitat forming and economic resource from the Southern Hemisphere

Observation of bacteria over the surface of released oogonia from Fucus vesiculosus L (Phaeophyceae)

Pese al enorme número de bacterias que se encuentran normalmente en la columna de agua, se registra por primera vez su presencia sobre oogonios del alga Fucus vesiculosus. En cortes transversales, sin embargo, los oogonios se encontraban libres de epibiosis. Las algas fucoides son fundamentales en ciertos ambientes costeros, mas el impacto microbiano sobre su ciclo de vida y colonización es completamente desconocido

Effects of Anisotropy in (2+1)-dimensional QED

We summarize our results for the impact of anisotropic fermionic velocities in (2+1)-dimensional QED on the critical number of fermion flavors, N^c_f, and dynamical mass generation. We apply different approximation schemes for the gauge boson vacuum polarization and the fermion-boson vertex to analyze the according Dyson-Schwinger equations in a finite volume. Our results point towards large variations of N^c_f away from the isotropic point in agreement with other approaches.Comment: 7 pages, 4 figures, contribution to the proceedings of the International School of Nuclear Physics, Erice 201

Antimicrobial Activities of Bacteria Associated with the Brown Alga Padina pavonica

General rights It is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulations If you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: https://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. Macroalgae belonging to the genus Padina are known to produce antibacterial compounds that may inhibit growth of human-and animal pathogens. Hitherto, it was unclear whether this antibacterial activity is produced by the macroalga itself or by secondary metabolite producing epiphytic bacteria. Here we report antibacterial activities of epiphytic bacteria isolated from Padina pavonica (Peacocks tail) located on northern coast of Tunisia. Eighteen isolates were obtained in pure culture and tested for antimicrobial activities. Based on the 16S rRNA gene sequences the isolates were closely related to Proteobacteria (12 isolates; 2 Alpha-and 10 Gammaproteobacteria), Firmicutes (4 isolates) and Actinobacteria (2 isolates). The antimicrobial activity was assessed as inhibition of growth of 12 species of pathogenic bacteria (Aeromonas salmonicida, A. hydrophila, Enterobacter xiangfangensis, Enterococcus faecium, Escherichia coli, Micrococcus sp., Salmonella typhimurium, Staphylococcus aureus, Streptococcus sp., Vibrio alginoliticus, V. proteolyticus, V. vulnificus) and one pathogenic yeast (Candida albicans). Among the Firmicutes, isolate P8, which is closely related to Bacillus pumilus, displayed the largest spectrum of growth inhibition of the pathogenic bacteria tested. The results emphasize the potential use of P. pavonica associated antagonistic bacteria as producers of novel antibacterial compounds