Mete Yilmaz

University of Florida, Gainesville, FL, United States

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Publications (7)16.22 Total impact

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    ABSTRACT: Lyngbya wollei, a commonly observed cyanobacterium in Florida's spring fed systems, is considered a nuisance organism due to its formation of large benthic and floating mats. Standing crops and mats of Lyngbya from two Florida springs, Silver Glen Springs (Ocala National Forest) and Blue Hole Spring (Ichetucknee Springs State Park), were sampled and characterized via microscopy. A near full-length 16S rRNA gene sequence recovered from genomic DNA preparation of a filament collected from Silver Glen Natural Well was 99% identical to another L. wollei sequence. Paralytic shellfish toxin (PST) biosynthesis genes sxtA and sxtG were also detected in the filament DNA and were 97% and 98% identical in sequence, respectively, to those of L. wollei. PSTs were characterized utilizing High Performance Liquid Chromatography (HPLC) coupled with Mass Spectrometry (MS). Analysis of extracted algal material with LC/MS/MS verified that PSTs decarbamoylgonyautoxin 2&3 (dcGTX2&3) and decarbamoylsaxitoxin (dcSTX) were present in L. wollei mats in Florida springs and provided evidence supporting the presence of all L. wollei toxins (LWT 1-6). Levels of quantifiable toxins (dcGTX2&3 & dcSTX) ranged from 19 to 73 μg STX-eq (g dry weight)−1. Although L. wollei toxins 1–6 could not be quantified due to a lack of available standards, their presence indicates samples may be higher in toxicity. This is the first detailed study confirming PST presence in L. wollei dominated mats in Florida spring systems.
    No preview · Article · Apr 2012 · Harmful Algae
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    ABSTRACT: The St. Lucie Estuary, located on the southeast coast of Florida, provides an example of a subtropical ecosystem where seasonal changes in temperature are modest, but summer storms alter rainfall regimes and external inputs to the estuary from the watershed and Atlantic Ocean. The focus of this study was the response of the phytoplankton community to spatial and temporal shifts in salinity, nutrient concentration, watershed discharges, and water residence times, within the context of temporal patterns in rainfall. From a temporal perspective, both drought and flood conditions negatively impacted phytoplankton biomass potential. Prolonged drought periods were associated with reduced nutrient loads and phytoplankton inputs from the watershed and increased influence of water exchange with the Atlantic Ocean, all of which restrict biomass potential. Conversely, under flood conditions, nutrient loads were elevated, but high freshwater flushing rates in the estuary diminished water residence times and increase salinity variation, thereby restricting the buildup of phytoplankton biomass. An exception to the latter pattern was a large incursion of a cyanobacteria bloom from Lake Okeechobee via the St. Lucie Canal observed in the summer of 2005. From a spatial perspective, regional differences in water residence times, sources of watershed inputs, and the proximity to the Atlantic Ocean influenced the composition and biomass of the phytoplankton community. Long water residence times in the North Fork region of the St. Lucie Estuary provided an environment conducive to the development of blooms of autochthonous origin. Conversely, shorter residence times in the mid-estuary limit autochthonous increases in biomass, but allochthonous sources of biomass can result in bloom concentrations of phytoplankton. KeywordsRainfall–Waster residence time–Harmful algal blooms– Microcystis aeruginosa – Akashiwo sanguinea – Skeletonema costatum
    Full-text · Article · Jan 2012 · Estuaries and Coasts
  • Mete Yilmaz · Edward J. Phlips
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    ABSTRACT: Cylindrospermopsis raciborskii is a potentially toxic cyanobacterium which has become increasingly prominent in algal blooms throughout the USA. Twenty strains of C. raciborskii isolated from Florida, and one strain from Indiana (USA), were tested for the ability to produce three toxins, cylindrospermopsin, microcystin and saxitoxin using newly developed Polymerase Chain Reaction (PCR) primers and Enzyme Linked Immunosorbent Assays (ELISA). None of these strains demonstrated the ability to produce any of the three toxins. Phylogenetic analyses of 16S rRNA gene sequences, a common genetic marker used in taxonomic differentiation, did not delineate these isolates from other C. raciborskii strains. However, Rubisco Large Subunit gene sequences, a less commonly used but useful genetic marker, provided better resolution of differences between Florida strains of C. raciborskii and those from Australia, which are known to be toxic. There may be toxic strains of C. raciborskii in the USA, but none were found among the Florida and Indiana strains examined, suggesting that strains of C. raciborskii in Florida lakes, and perhaps other regions of North America, may not be toxic. The potential management implications of this observation warrant further exploration of the toxicity of this species in the Americas.
    No preview · Article · Sep 2011 · Lake and reservoir management
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    Mete Yilmaz · Edward J Phlips
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    ABSTRACT: Aphanizomenon ovalisporum is the only confirmed cylindrospermopsin producer identified in the United States to date. On the other hand, Cylindrospermopsis raciborskii is a prominent feature of many lakes in Florida and other regions of the United States. To see the variation in cylindrospermopsin cyrB gene adenylation domain sequences and possibly discover new cylindrospermopsin producers, we collected water samples for a 3-year period from 17 different systems in Florida. Positive amplicons were cloned and sequenced, revealing that approximately 92% of sequences were A. ovalisporum-like (>99% identity). Interestingly, 6% of sequences were very similar (>99% identity) to cyrB sequences of C. raciborskii from Australia and of Aphanizomenon sp. from Germany. Neutrality tests suggest that A. ovalisporum-like cyrB adenylation domain sequences are under purifying selection, with abundant low-frequency polymorphisms within the population. On the other hand, when compared between species by codon-based methods, amino acids of CyrB also seem to be under purifying selection, in accordance with the one proposed amino acid thought to be activated by the CyrB adenylation domain.
    Full-text · Article · Feb 2011 · Applied and Environmental Microbiology
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    Ken Black · Mete Yilmaz · Edward J. Phlips
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    ABSTRACT: One of the most common and widespread bloom-forming cyanobacteria associated with toxin production is Microcystis aeruginosa (Kutzing) Lemmerman. While normally associated with fresh water environments, this toxigenic species has been observed at bloom concentrations in a number of major estuaries worldwide. This study examined the effect of salinity on growth and toxin production by M. aeruginosa strain PCC 7806 under controlled laboratory conditions. Salt concentrations above 12.6 ppt resulted in total cessation of growth. Toxin production was similarly affected, with cul-tures grown in salt concentrations of 4.6 ppt and above yielding less toxin than the control after 20 days of culture. Toxin concentrations after 20 days of culture were 40% of the control at 4.6 ppt. The relative proportion of extracellu-lar to intracellular toxin increased over time in cultures with salt concentrations greater than 4.6 ppt. Extracellular toxins persisted in the media long after the cessation of growth. The results suggest that the influence of M. aeruginosa and/or its toxins can extend well out into estuarine environments under the influence of significant freshwater inputs.
    Full-text · Article · Jan 2011 · Journal of Environmental Protection
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    Mete Yilmaz · Edward J. Phlips · Daniel Tillett
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    ABSTRACT: DNA isolated from environmental samples often contains enzyme inhibitors disruptive to downstream molecular applications. Most of the existing methods of cyanobacterial DNA isolation do not effectively eliminate these inhibitors from sediment samples or cells collected from freshwater ecosystems. We describe improved methods based on the xanthogenate-SDS nucleic acid isolation (XS) method of Tillett and Neilan (2000). Our improved methods provided high-quality cyanobacterial DNA that could be amplified in PCR and digested with a restriction enzyme. Results were superior to several commercial kits. The DNA yield was also similar to that obtained via the standard XS method. These methods should provide valuable new tools for the expanded application of molecular genetics to limnological and oceanographic research.
    Full-text · Article · Mar 2009 · Journal of Phycology
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    ABSTRACT: The toxin cylindrospermopsin (CYN) is produced by a variety of cyanobacterial genera. One of these, Cylindrospermopsis raciborskii, is generally assumed to be the source of CYN in lakes and rivers in Florida, USA. However, in this study, none of the eight Florida isolates of this species tested contained the genetic determinants involved in toxin production nor did they produce CYN. We show for the first time that Aphanizomenon ovalisporum isolated from a pond in this state has the genes putatively associated with CYN production. Analysis by liquid chromatography with mass spectrometric detection (LC/MS) revealed that it produced CYN in the range of 7.39-9.33 microg mg(-1) freeze-dried cells. 16S rDNA sequences of this strain showed 99.6% and 99.9% identity to published A. ovalisporum and Anabaena bergii 16S sequences, respectively. These results help to explain the general lack of a defined relationship between the abundance of C. raciborskii in freshwater ecosystems of Florida and observed concentrations of CYN. The latter observation raises the potential that previous reports of CYN may be coincidental with unrecorded presence of another CYN-producing species.
    No preview · Article · Feb 2008 · Toxicon

Publication Stats

150 Citations
16.22 Total Impact Points


  • 2008-2012
    • University of Florida
      • • Department of Fisheries and Aquatic Sciences
      • • School of Forest Resources and Conservation
      Gainesville, FL, United States
  • 2011
    • Ege University
      • Faculty of Fisheries
      Ismir, İzmir, Turkey