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Two cyanobacterial strains, one collected from an epidermal mat present on a dead bottlenose dolphin and the other as a bioaerosol 457 m (1500 ft) above the river, were recently analysed from the St. Johns River, Jacksonville, Florida, USA. Both samples had major phenotypic plasticity which confused morphological identification. Amplicon sequencing of the 16S rRNA gene from the isolates revealed that both samples were closely aligned (branch bootstrap support = 100%) with the recently erected genus Komarekiella. Whole genome sequencing and phylogenetic construction also supported the isolation of a new species of cyanobacteria branching from the Nostoc clade. A total evidence approach of molecular, genetic, and ecological examination of these strains supported the erection of a new species, Komarekiella delphini-convector. A prior study determined that the dolphin with the epidermal mat had low levels of microcystins/nodularins (MCs/NODs) in the hepatic tissue. To investigate whether these toxins originated from the epidermal mat, immunoassay (ELISA) and 2-methyl-3-methoxy-4-phenylbutyric acid (MMPB) techniques were conducted on the original mat and subsequent culture samples. The results from both analyses were not conclusive. Genome mining was conducted and revealed diverse biosynthetic capabilities of this species but could not support toxin-producing potential. Further analytical work is required to determine the pathogenic capacity of this epizoic species.

© 2014 Elsevier B.V. Species of the genus Gambierdiscus are epiphytic dinoflagellates well known from tropical coral reef areas at water temperatures from 24 to 29°C. Gambierdiscus spp. are able to produce ciguatoxins (CTXs) known to bioaccumulate in fish, and the ingestion of tropical fish that accumulated CTXs and possibly also maitotoxins (MTXs) can cause ciguatera fish poisoning (CFP) in humans. In Australia, ciguatera poisonings have been reported in tropical parts of Queensland and the Northern Territory. Here, we report for the first time the seasonal abundance (April-May 2012/13) of Gambierdiscus spp. (up to 6565-8255cellsg-1 wet weight algae) from Merimbula and Wagonga Inlets in temperate southern New South Wales, Australia (37°S) at water temperatures of 16.5-17°C. These are popular shellfish aquaculture and recreational fisheries areas with no reports of ciguatera poisoning. Sequencing of a region of the 28S rRNA gene led to the conclusive identification of Gambierdiscus carpenteri. The cells differed however from the Belize type description, including the absence of a thecal groove, dorsal rostrum and variable hatchet- to rectangular-shaped 2' plate, and were morphologically more similar to Gambierdiscus toxicus. To study the dinoflagellate community structure in detail, a pyrosequencing approach based on the 18S rRNA gene was applied, which confirmed the presence of a single Gambierdiscus species only. Neither CTXs nor MTXs were detected in natural bloom material by LC-MS/MS; however, the extracts were found to be toxic via mouse-bioassay, with symptoms suggestive of poisoning by MTX-like compounds. Understanding the abundance of Gambierdiscus populations in areas with no apparent human health impacts is important towards defining the alternate conditions where sparse populations can create ciguatera problems.

The role of ciguatoxins (CTX) in Ciguatera fish poisoning (CFP) has been investigated previously, but little is known about Maitotoxin (MTX) and whether it plays a significant role in causing human illness. The MTXs are known to have slightly higher potency than CTXs when administered intraperitoneally in mice, but are less potent when administered orally, due to their water solubility. It is not known whether MTXs accumulate in carnivorous fish tissues, and to investigate this further fish feeding trials with snapper (Pagrus auratus) were undertaken. Replicate P. auratus were fed with juvenile mullet (Aldrichetta forsteri) injected with a pellet of a known quantity of Gambierdiscus australes, which is a known producer of MTX. The levels of MTX in different fish tissues were determined using two newly developed sensitive LC-MS/MS assays for MTX that monitor either a specific cleavage fragment (generated from micro-scale oxidation of the intact toxin) or the intact toxin itself. The investigations revealed the presence of MTX in P. auratus viscera, liver and muscle samples. The presence of Gambierdiscus-related genes in P. auratus digestive organs was confirmed using DNA amplification technology. © 2014 Elsevier B.V.

Dinoflagellates in marine benthic habitats living epiphytically on macroalgae are an important but highly understudied group of protists. Many produce toxins that can have severe economic impacts on marine-based economies, and improved monitoring tools are required to enhance the management of toxin-related hazards. We analysed the distribution and diversity of epibenthic dinoflagellates inhabiting eight sites in Cocos (Keeling) Islands, Papua New Guinea, and Broome and Exmouth, Western Australia. We used pyrosequencing approaches based on two DNA barcoding marker genes - 18S ribosomal RNA (rRNA) and mitochondrial cytochrome b (cob) - and compared these to an approach based on clone libraries (197 sequences) using the cob gene. Dinoflagellate sequences accounted for 133 [64 unique operational taxonomic units (OTU)] out of 10529 18S rRNA gene sequences obtained from all samples. However, using the dinoflagellate specific assay targeting the cob gene marker, we obtained 9748 (1217 unique OTU) dinoflagellate sequences from the same environmental samples, providing the largest, to date, set of dinoflagellate cob gene sequences and reliable estimates of total dinoflagellate richness within the samples and biogeographic comparisons between samples. This study also reports the presence of potentially toxic species of the genera Gambierdiscus, Ostreopsis, Coolia, Prorocentrum and Amphidinium from the above-mentioned geographical regions. © 2013 Society for Applied Microbiology and John Wiley & Sons Ltd.

Families of closely related chemical compounds, which are relatively resistant to degradation, are often used as biomarkers to help trace the evolutionary history of early groups of organisms and the environments in which they lived. Biomarkers derived from hopanoid variations are particularly useful in determining bacterial community compositions. 2-Methylhopananoids have been thought to be diagnostic for cyanobacteria, and 2-methylhopanes in the geological record are taken as evidence for the presence of cyanobacteria-containing communities at the time of sediment deposition. Recently, however, doubt has been cast on the validity of 2-methylhopanes as cyanobacterial biomarkers, since non-cyanobacterial species have been shown to produce significant amounts of 2-methylhopanoids. This study examines the diversity of hpnP, the hopanoid biosynthesis gene coding for the enzyme that methylates hopanoids at the C2 position. Genomic DNA isolated from stromatolite-associated pustular and smooth microbial mat samples from Shark Bay, Western Australia, was analysed for bacterial diversity, and used to construct an hpnP clone library. A total of 117 partial hpnP clones were sequenced, representing 12 operational taxonomic units (OTUs). Phylogenetic analysis showed that 11 of these OTUs, representing 115 sequences, cluster within the cyanobacterial clade. We conclude that the dominant types of microorganisms with the detected capability of producing 2-methylhopanoids within pustular and smooth microbial mats in Shark Bay are cyanobacteria. © 2012 Society for Applied Microbiology and Blackwell Publishing Ltd.

The recent identification of genes involved in the production of the potent neurotoxin and keystone metabolite saxitoxin (STX) in marine eukaryotic phytoplankton has allowed us for the first time to develop molecular genetic methods to investigate the chemical ecology of harmful algal blooms in situ. We present a novel method for detecting and quantifying the potential for STX production in marine environmental samples. Our assay detects a domain of the gene sxtA that encodes a unique enzyme putatively involved in the sxt pathway in marine dinoflagellates, sxtA4. A product of the correct size was recovered from nine strains of four species of STX-producing Alexandrium and Gymnodinium catenatum and was not detected in the non-STX-producing Alexandrium species, other dinoflagellate cultures, or an environmental sample that did not contain known STX-producing species. However, sxtA4 was also detected in the non-STX-producing strain of Alexandrium tamarense, Tasmanian ribotype. We investigated the copy number of sxtA4 in three strains of Alexandrium catenella and found it to be relatively constant among strains. Using our novel method, we detected and quantified sxtA4 in three environmental blooms of Alexandrium catenella that led to STX uptake in oysters. We conclude that this method shows promise as an accurate, fast, and cost-effective means of quantifying the potential for STX production in marine samples and will be useful for biological oceanographic research and harmful algal bloom monitoring. © 2011, American Society for Microbiology.

Chlorophylls are essential for light-harvesting and energy transduction in photosynthesis. Four chemically distinct varieties have been known for the past 60 years. Here we report isolation of a fifth, which we designate chlorophyll f. Its in vitro absorption (706 nanometers) and fluorescence (722 nanometers) maxima are red-shifted compared to all other chlorophylls from oxygenic phototrophs. On the basis of the optical, mass, and nuclear magnetic resonance spectra, we propose that chlorophyll f is [2-formyl]-chlorophyll a (C55H70O6N4Mg). This finding suggests that oxygenic photosynthesis can be extended further into the infrared region and may open associated bioenergy applications.