Factors influencing growth and toxin production by cultures of the freshwater cyanobacterium Lyngbya wollei Farlow ex Gomont

Collections of Lyngbya wollei were taken from Guntersville Reservoir, Alabama, over a period of three years. Healthy filaments were isolated and transferred to agar plates of Z-8 and LM6E media. Unialgal isolates were cultured for the study of growth and paralytic shellfish poison (PSP) production. Filaments were extracted and the toxins were detected using high performance liquid chromatography (HPLC) with post column oxidation followed by fluorescence detection. HPLC profiles show that laboratory cultures of L. wollei produced decarbamoyl gonyautoxin 2 and 3, plus several other PSP like toxins whose structures are under investigation. At 26 °C and a light intensity of 11 or 22 μmol m-2 s-1 optimum production of both biomass and toxins occurred. A decrease or increase in temperature or light flux caused a reduction in dry weight or toxicity. Compared to control levels, lower PO4-P and NO3-N and higher calcium levels gave rise to higher biomass and toxicity. Lower calcium, calcium- or PO4-P deficient medium and high NO3-N or PO4-P caused a large decrease in dry weight and toxicity. This revised version was published online in August 2006 with corrections to the Cover Date.     

Morphological and genetic evidence that the cyanobacterium Lyngbya wollei (Farlow ex Gomont) Speziale and Dyck encompasses at least two species

Dense blooms of the cyanobacterium Lyngbya wollei are increasingly responsible for declining water quality and habitat degradation in numerous springs, rivers, and reservoirs. This research represents the first molecular phylogenetic analysis of L. wollei in comparison with the traditional morphological characterization of this species. Specimens were collected from several springs in Florida and a reservoir in North Carolina. Segments of the small-subunit (SSU) rRNA and nifH genes were PCR amplified, cloned, and sequenced. The phylogenetic analysis of the SSU rRNA gene revealed sequences that fell into three distinct subclusters, each with >97% sequence similarity. These were designated operational taxonomic unit 1 (OTU1), OTU2, and OTU3. Similarly, the nifH sequences fell into three distinct subclusters named S1, S2, and S3. When either bulk samples or individual filaments were analyzed, we recovered OTU1 with S1, OTU2 with S2, and OTU3 with S3. The coherence between the three SSU rRNA gene and nifH subclusters was consistent with genetically distinct strains or species. Cells associated with subclusters OTU3 and S3 were significantly wider and longer than those associated with other subclusters. The combined molecular and morphological data indicate that the species commonly identified as L. wollei in the literature represents two or possibly more species. Springs containing OTU3 and S3 demonstrated lower ion concentrations than other collection sites. Geographical locations of Lyngbya subclusters did not correlate with residual dissolved inorganic nitrogen or phosphorus concentrations. This study emphasizes the need to complement traditional identification with molecular characterization to more definitively detect and characterize harmful cyanobacterial species or strains.     

Nitrogen fixation by the benthic freshwater cyanobacterium Lyngbya wollei

The ability of the benthic cyanobacterium Lyngbya wollei to fix nitrogen was studied using field samples and axenic cultures. L. wollei was collected and isolated from Lake Okeechobee, Florida, where it forms extensive mats. Rates of acetylene reduction up to 39.1 nmol mg dry wt⁻¹ h⁻¹ were observed for field samples. The maximum observed rate of acetylene reduction in axenic laboratory cultures was 200 nmol mg dry wt⁻¹ h⁻¹. Aerobic conditions limited nitrogen fixation activity, but dark/light cycles promoted the development of activity. Reduced oxygen levels appeared to be required for the development of significant levels of nitrogenase activity. The level of irradiance also had a significant impact on the level of activity. The potential significance of nitrogen fixation to Lyngbya production is discussed.     

First evidence for the production of cylindrospermopsin and deoxy-cylindrospermopsin by the freshwater benthic cyanobacterium, Lyngbya wollei (Farlow ex Gomont) Speziale and Dyck

Lyngbya wollei (Farlow ex Gomont) Speziale and Dyck is a common mat-forming benthic cyanobacterium from freshwater habitats. We found that two populations from southeast Queensland (Australia) produce the potent cyanotoxin cylindrospermopsin (CYN) and its analogue, deoxy-cylindrospermopsin (deoxy-CYN). The highest concentrations in environmental samples were 20 and 550 μg g⁻¹ dry weight for CYN and deoxy-CYN, respectively. A sub-sample maintained in culture for over 16 months yielded concentrations of 33 and 308 μg g⁻¹ dry weight for CYN and deoxy-CYN, respectively. The concentration of deoxy-CYN in L. wollei was 10–300 times higher than CYN, suggesting that, unlike many other CYN-producing cyanobacteria, the primary compound produced by L. wollei is deoxy-CYN. The production of CYN and deoxy-CYN by L. wollei represents a potential human health risk and an additional source of these toxins in freshwaters. This is the first report of the production of CYN and deoxy-CYN by L. wollei or any species of the Oscillatoriales.     

Lyngbyaureidamides A and B,two anabaenopeptins from the cultured freshwater cyanobacterium Lyngbya sp. (SAG 36.91)

Two anabaenopeptin-type peptides, lyngbyaureidamides A and B, together with two previously reported peptides lyngbyazothrins C and D, were isolated from the cultured freshwater cyanobacterium Lyngbya sp. (SAG 36.91). Their structures were determined by spectroscopic and chemical methods. Lyngbyazothrins C and D were also able to inhibit the 20S proteasome with IC₅₀ values of 7.1 μM and 19.2 μM, respectively, while lyngbyaureidamides A and B were not active at 50 μM.     

potamolejeunea Holtii (Spruce) nov.comb.

Abstract

Bryophytes usually have anti-feeding properties to defend against microbial and herbivore attack; however, the consumption of Haplocladium microphyllum (Hedw.) Broth. capsules by Agrotis sp. larvae is rather common in Shanghai in the spring. To test whether H. microphyllum is the only moss eaten, and why the gametophytes of H. microphyllum are not eaten, a series of quantitative experiments were carried out to understand the feeding habits of Agrotis larvae on the given moss materials at three growth stages of larval life. The results show that the larvae can feed on the capsules of six moss species to different degrees: Funaria hygrometrica Hedw., H. microphyllum, Physcomitrium sphaericum (C.F.Ludw. ex Schkuhr) Brid., Trematodon longicollis Michx., Ditrichum pallidum (Hedw.) Hampe, and Pogonatum inflexum (Lindb.) Sande Lac. The capsules of the first four species were grazed heavily by the larvae, compared with limited consumption of the latter two (D. pallidum and P. inflexum), which even induced a high mortality rate among the larvae. With the growth of the larval instar, the daily demand for moss capsules by the larvae increases gradually. The lipid content of the capsules may play an important role when the larva selects its feeding target.     

Determination of paralytic shellfish poisoning (PSP) toxins in UK shellfish

A study was conducted to aid the interpretation of data generated by parallel testing of the qualitative Jellett Rapid Test (JRT) and the mouse bioassay (MBA) for detection of paralytic shellfish poisoning (PSP) toxins within the UK statutory shellfish biotoxin monitoring programme. A selection of stored sample extracts subjected to testing by MBA and/or JRT were further analysed by liquid chromatography with fluorescence detection (LC–FLD) to provide additional information on the concentrations of PSP toxins and toxin profiles.Results, from this study, demonstrate the potential of the JRT to effectively screen out PSP toxin negative shellfish samples and samples containing low concentrations of toxins from UK monitoring programmes. Additionally, data generated using LC–FLD highlights the potential of introducing alternative analytical techniques to completely replace the requirement for the MBA.     

Evidence for production of paralytic shellfish toxins by bacteria associated with Alexandrium spp. (Dinophyta) in culture.

A substantial proportion of bacteria from five Alexandrium cultures originally isolated from various countries produced sodium channel blocking (SCB) toxins, as ascertained by mouse neuroblastoma assay. The quantities of SCB toxins produced by bacteria and dinoflagellates were noted, and the limitations in comparing the toxicities of these two organisms are discussed. The chemical nature of the SCB toxins in selected bacterial isolates was determined as paralytic shellfish toxins by pre- and postcolumn high-performance liquid chromatography, capillary electrophoresis-mass spectrometry, and enzyme immunoassay.     

Culture studies of Acrochaete leptochaete comb. nov. and A. wittrockii comb. nov. (Chaetophoraceae, Chlorophyceae)

A culture study of the plants known as Phaeophila leptochaete (Huber) Nielsen and P. wittrockii (Wille) Nielsen proved that these are distinct species. Both have the Acrochaete type of hairs, and therefore, the new combinations Acrochaete leptochaete and A. wittrockii are introduced. Several isolates of both species were started from plants collected at different places in Europe.
A. leptochaete in culture was mainly characterised by having two or more (up to six) pyrenoids in many of its cells, while in A. wittrockii there invariably was only one. The swarmers formed by A. leptochaete had two or four flagella. Several hairs from one basal swelling were sometimes observed in one of the isolates. Another isolate often formed a hair on the germinated zoospore. The isolates of A. wittrockii had a variable morphology, from unicellular plants to large pseudoparenchymatous cell masses. Different kinds of swarmers were observed; zoospores with three flagella seemed typical, but ones with two or four flagella were also observed. Small, pale biflagellate swarmers were assumed to be gametes. One of the isolates of A. wittrockii differed from the rest as the only swarmer type observed was zoospores with two flagella. Chlorophilum ephemerum is considered identical to A. wittrockii. Observations on hair formation in A. repens suggested that the hair structure represents a separate cell.     

Systematic study of the genus Acetobacter with descriptions of Acetobacter indonesiensis sp. nov., Acetobacter tropicalis sp. nov., Acetobacter orleanensis (Henneberg 1906) comb. nov., Acetobacter lovaniensis (Frateur 1950) comb. nov., and Acetobacter estunensis (Carr 1958) comb. nov

Thirty-one Acetobacter strains obtained from culture collections and 45 Acetobacter strains isolated from Indonesian sources were investigated for their phenotypic characteristics, ubiquinone systems, DNA base compositions, and levels of DNA-DNA relatedness. Of 31 reference strains, six showed the presence of ubiquinone 10 (Q-10). These strains were eliminated from the genus Acetobacter. The other 25 reference strains and 45 Indonesian isolates were subjected to a systematic study and separated into 8 distinct groups on the basis of DNA-DNA relatedness. The known species, Acetobacter aceti, A. pasteurianus, and A. peroxydans are retained for three of these groups. New combinations, A. orleanensis (Henneberg 1906) comb. nov., A. lovaniensis (Frateur 1950) comb. nov., and A. estunensis (Carr 1958) comb. nov. are proposed for three other groups. Two new species, A. indonesiensis sp. nov. and A. tropicalis sp. nov. are proposed for the remaining two. No Indonesian isolates were identified as A. aceti, A. estunensis, and A. peroxydans. Phylogenetic analysis on the basis of 16S rDNA sequences was carried out for representative strains from each of the groups. This supported that the eight species belonged to the genus Acetobacter. Several strains previously assigned to the species of A. aceti and A. pasteurianus were scattered over the different species. It is evident that the value of DNA-DNA relatedness between strains comprising a new species should be determined for the establishment of the species. Thus current bacterial species without data of DNA-DNA relatedness should be reexamined for the stability of bacterial nomenclature.     

Ptilagrostis milleri comb. nov. (Poaceae: Stipeae)

Based on a comparison of the macro‐morphology and lemma micro‐morphology, Stipa milleri Noltie is transferred to Ptilagrostis Griseb. as P. milleri (Noltie) M. Nobis & A. Nobis. Lemma epidermal patterns in the examined species are presented and discussed.     

Parietochloris incisa comb. nov. (Trebouxiophyceae, Chlorophyta)

A coccoid green alga, Myrmecia incisa Reisigl, was isolated from the soil of Mt Tateyama, Japan. Electronmicroscopy revealed that the organism has pyrenoids sparsely covered with starch segments and traversed by many parallel thylakoid membranes, and zoo-spores with counterclockwise basal body orientation. Due to the presence of these features, we have proposed a reclassification of M. incisa into the genus Parietochloris, Trebouxiophyceae.     

Cyclosorus procerus comb. nov. (Thelypteridaceae) from Thailand

Following a discussion of the complex nomenclature of a species of Thai Thelypteridaceae the new combination Cyclosorus procerus (D. Don) S. Linds. & D. J. Middleton is made.     

Taxonomic revision of three diatoms found in Lake Malawi: Afrocymbella brunii (Fricke) comb. nov., Afrocymbella rossii (Kociolek & Stoermer) comb. nov., and Aulacoseira euareolata (O.Müller) comb. nov. et nom. nov

Based on epilithic diatom samples collected from the rocky littoral zone of Lake Malawi (102 diatom taxa belonging to 34 genera were listed in the Supporting Information) we proposed the transfer of three taxa to new genera. Afrocymbella brunii (Fricke) comb. nov. was transferred from Gomphonema because of its dorsiventral valve and its transapically elongated dorsal stigma. Afrocymbella rossii (Kociolek & Stoermer) comb. nov. was also transferred from Gomphocymbella, which is actually a synonym of Gomphonema. Aulacoseira euareolata (O.Müller) comb. nov. et nom. nov. was transferred from Melosira because of the presence of linking spines and mantle areolae, and its specific epithet was replaced because of homonymy with Aulacoseira areolata Moisseeva.     

Thladiantha tomentosa (Cucurbitaceae) comb. nov. from southwestern China

In this paper, we propose that Thladiantha cordifolia (Blume) Cogn. var. tomentosa A. M. Lu & Z. Y. Zhang should be recognized at species rank as Thladiantha tomentosa (A. M. Lu & Z. Y. Zhang) W. Jiang & H. Wang. This species is similar to T. cordifolia and T. angustisepala W. J. de Wilde & Duyfjes, from which it differs mainly by having ovate bracts, linear sepals, and ellipsoidal, rostrate, ribbed verrucose fruits.     

Proposal of Sphingomonas suberifaciens (van Bruggen, Jochimsen and Brown 1990) comb. nov., sphingomonas natatoria (Sly 1985) comb. nov., Sphingomonas ursincola (Yurkov et al. 1997) comb. nov., and emendation of the genus Sphingomonas.

Based on the results of a phylogenetic analysis of 16S rRNA and the presence of sphingoglycolipid in cellular lipids of the type strains, transfer of "Rhizomonas" suberifaciens, Blastomonas natatoria and Erythromonas ursincola to the genus Sphingomonas as Sphingomonas suberifaciens (van Bruggen et al 1990) comb. nov., Sphingomonas natatoria (Sly 1985) comb. nov., and Sphingomonas ursincola (Yurkov et al 1997) comb. nov. are herein proposed together with the emendation of genus Sphingomonas. The type strain of S. suberifaciens is van Bruggen Cal=ATCC 49382=NCPPB 3629=IFO 15211=JCM 8521, that of S. natatoria is ATCC 35951 =DSM 3183=NCIMB 12085=JCM10396, and that of S. ursincola is DSM 9006= KR-99.     

Observations on Bostrychia radicosa comb. nov. (Rhodomelaceae, Rhodophyta)

Only two genera in the Rhodomelaceae share the morphological character of transverse division of periaxial cells into two or more tier cells in which the pit connection is retained between the lower cell and the axial cell: Bostrychia and Rhodolachne. One species, Rhodolachne radicosa Itono, has been reported from mangroves, a common habitat for Bostrychia. Many collections of an entity similar to Rhodolachne radicosa have been made from localities around the Indo‐Pacific. Culture observations show a Polysiphonia‐type sexual life history in Malaysia and New Caledonia isolates that produce self‐compatible bisexual gametophytes. The New Caledonia isolate also has unisexual gametophytes. An isolate from New South Wales (Australia) reproduces asexually through successive generations of tetrasporophytes. The Thailand isolate has successive generations of mixed‐phase tetrasporophytes. The tetrasporangial stichidia also bear male spermatangial sectors, but female structures are lacking. Western Australia and Madagascar isolates do not reproduce in culture. Molecular evidence, based on sequencing of the rbcL and the large subunit ribosomal RNA genes, shows that these isolates belong to the genus Bostrychia. Low molecular weight carbohydrate analysis reveals high levels of digeneaside in all isolates. The sugar hexitol sorbitol, an osmolyte characteristic of Bostrychia, occurs in all isolates, whereas the Madagascar and New Caledonia isolates have very low levels of dulcitol. Molecular, low molecular weight carbohydrate and morphological evidence show that Rhodolachne radicosa belongs within the genus Bostrychia. We transfer Rhodolachne radicosa to Bostrychia radicosa (Itono) West, Zuccarello and Hommersand.