97 Sensitivity of cyanobacteria to a potential biological control agent, bacterium SG-3

Cyanobacteria cause many problems in freshwater ecosystems. For example, the production of off-flavor compounds by cyanobacteria causes serious problems in catfish aquaculture. Control of cyanobacteria is generally limited to treatment with copper compounds, which are non-selective and sometimes ineffective at controlling certain species of cyanobacteria. Biological control could provide selective management by removing unwanted species while leaving desirable algae species. A bacterium (SG-3) (NRRL B-30043) lyses a number of planktonic species of cyanobacteria including bloom-forming species of Anabaena and Oscillatoria . We tested SG-3 for activity against 10 isolates, representing seven species, of mat-forming cyanobacteria within the genera Oscillatoria, Lyngbya , and Phormidium . Plugs (0.5 cm diameter) were cut from mats of the cyanobacterium, inoculated with liquid cultures of SG-3, and incubated as static cultures. The reduction in dry weights ranged from –0.5% to 90% compared to the untreated controls and appeared to be species specific. For example, dry weight reductions of Oscillatoria deflexoides and O. amoena ranged from 80 to 90% whereas the reduction of O. limosa tended to be lower at 36 to 72%. Although results varied among and within species, they indicate that this bacterium could have potential for use as a biological control for mat-forming cyanobacteria. Light microscopic observations indicate the bacteria do not penetrate the cyanobacteria cells. Currently, we are studying the possible causes of the observed cell lysis.     

Differences of the primer-independent phosphorylase isozyme in thermophilic and mesophilic algae

Kinetic studies of the primer-independent, aa phosphorylaseisozyme of two thermophilic algae, Cyanidium caldarium and Oscillatoriaprinceps, and two mesophilic algae, Spirogyra setiformis andChlorella pyrenoidosa, indicate that the isozyme of thermophilicspecies is more resistant to denaturation by heat, and has lessaffinity for the glucose-1-phosphate substrate than the sameisozyme of mesophilic algae. This points out the possibilitythat this enzyme's structure is more rigid in thermophiles andmay lack the flexible conformation found in the mesophilic isozyme.The evolutionary significance of thermophily as a primitivecharacter rather than an adaptive trait is discussed in thelight of studies with a low temperature variant strain of thethermophilic alga, Oscillatoria princeps, LTV. (Received November 15, 1972; )     

Electrophoresis of algal glucans

The ability of reactive dyes based on chloro-s-triazine to reactwith the primary and secondary hydroxyl groups of glucose, formingcovalent bonds, has been used to dye the storage polyglucosidesof the algae, Cytmidium caldarium, Oscillatoria princeps, Rhodymeniapertusa and Spirogyra setiformis, prior to electrophoresis oncellulose polyacetate strips in borate buffer. The techniqueresolves mixtures of glucans and defines some of the parametersof the internal structure of these glucans. The similarity ofthe glucans from Cyanidium caldarium and Oscillatoria princepsis evident using this method. The two components of the "starch"from Spirogyra setiformis have been studied and identified bytheir reactions with the dye and the mobilities of the dyedcomponents during electrophoresis. Inferences as to the biphyleticevolutionary pathways leading from the Cyanophyceae to the Rhodophyceaeand the Chlorophyceae can be made based on the data. (Received June 27, 1973; )     

The Effect of pH on Copper Toxicity to Blue-Green Algae

The effect of pH on copper toxicity to two planktonic blue-green algae, Aphanizomenon gracile and Oscillatoria redekei, was investigated. Growth rates of the algae without copper treatment decrease with pH, Aphanizomenon is earlier and more affected than Oscillatoria. On the other hand, pH-lowering leads sooner to a toxicity enhancement in Oscillatoria. In the acid range, toxicity retardation occurs in Aphanizomenon. At pH 5.1, shortening of the interval between copper toxicity and copper stimulus is characteristic for both species.     

Response of Cyanobacteria and Algae from Antarctic Wetland Habitats to Freezing and Desiccation Stress

Antarctic wetlands are characterized by the presence of liquid water during short austral summer. Filamentous cyanobacteria are often dominant there and are exposed to severe conditions, of which the changes in the desiccation–rehydration and freeze–thaw cycles are two of the most stressful. Vigor, after freezing and desiccation, was laboratory tested in cyanobacterial and algal strains from wetland habitats collected in maritime and continental Antarctica. Whereas minor sub-zero temperatures (−4°C), demonstrating summer diurnal freeze–thaws did not cause significant damage on either cyanobacteria or algae, low sub-zero temperatures (−40, −100, −196°C), demonstrating annual winter freeze, caused little harm to cyanobacteria, but was fatal for more than 50% of the population of algae. Freezing and desiccation tolerance of these strains was compared using multiregression methods: cyanobacteria from continental Antarctica were significantly more tolerant to low sub-zero temperatures than similar strains from maritime Antarctica (P = 0.026; F = 3.66); and cyanobacteria from seepages habitat were less tolerant to freezing and desiccation than cyanobacteria from other wetlands (P = 0.002; F = 5.69).     

Use of algal monocultures by larvae of Hydroptila waubesiana and Oxyethira pallida (Trichoptera: Hydroptilidae)

Larvae of the microcaddisflies Hydroptila waubesiana Betten and Oxyethira pallida (Banks) were given monocultures of eight genera of algae to test their suitability as food sources, and to investigate the degree of trophic specialization exhibited by these larvae. Only those larvae given green algae (Chlorophyta) survived and emerged as adults. Oxyethira pallida consumed Zygnema and Spirogyra, and exhibited the shortest larval-pupal period on Spirogyra (P < 0.05). Similarly, H. waubesiana consumed Zygnema and Cladophora, but exhibited the shortest larval-pupal period on Cladophora (P < 0.001). Diatoms and Hydrodictyon allowed H. waubesiana to attain partial growth only, while O. pallida did not consume either alga. Oscillatoria and Anabaena were not consumed by either species. The larvae of the two species tested appear to obtain adequate nourishment from only a narrow spectrum of algae, and one alga allowed significantly faster growth compared to the others tested in each case. This revised version was published online in July 2006 with corrections to the Cover Date.     

Multiple Forms of Polyglucoside-Branching Enzyme in the Algae

Three isozymes specifically concerned with the “branching” of linear polyglucosides have been delected in algae. These enzymes were detected using two-dimensional polyacrylamide gel electrophoresis, and were found to be present in blue-green, red and in green algae. Two isozynies were found in Oscillatoria princeps; three enzymes were present in Spirogyra setiformis, and two and three such enzymes were detected in red algae of the Rhodymenia type. The significance of the multiple forms of this branching enzyme was assessed in light of the type of storage poly-glucosides formed by these plants. The “degree of branching” of the storage sugar appeared to be related to the evolutionary status of these algae.     

The role of water retaining substrata on the photosynthetic response of three drought tolerant phototrophic micro-organisms isolated from a terrestrial habitat

The water prerequisites of two drought tolerant Oscillatoria type cyanobacteria and one green alga were estimated by their ability to accomplish photosynthesis (carbon dioxide fixation) at conditions of subsaturating water supply. Fixation was zero in desiccated samples. Equilibration with solely water-saturated air did not enable any photosynthesis. However, granted properties of the physical environment of the samples could re-establish photosynthesis activity. These properties were elected by chosing membrane filters with different water retention characteristics as supporting substrata for the test samples in the de-and rehydration steps. Rehydration enabled the recovery of photosynthesis of desiccated samples only on the filters with good water retention, the filters with bad water retention were found ineffective. The Oscillatoria strains showed photosynthesis instantaneously and revealed nearly 100% viability. In contrast, rewetted cells of the green alga showed only 35% viability and the recovery of photosynthesis occurred only after 5 h. These differences reflect the natural environmental conditions: cyanobacteria are the first colonizers in the barren sand, whereas green algae can only start to colonize after progressing improvement of the water retention properties brought about by the pioneering cyanobacteria. The results will be discussed in the light of different specific mechanisms available to organisms which endeavour osmotic and matric water stress.Abbreviations DCMU 3(3,4-dichlorophenyl)-1,1-dimethyl-urea - DMF dimethylformamide - PFD photon flux density - TAPS N-tris[hydroxymethyl]methyl-3-amino-propanesulfonic acid     

Allelopathic activity of Spirogyra sp.: stimulating bloom formation and toxin production by Oscillatoria agardhii in some irrigation canals, Egypt

It has often been observed that irrigation canals in Egypt thatcontain Spirogyra are covered with blooms of Oscillatoria duringthe summer season. These blooms do not occur in the canals notcontaining Spirogyra. Thus, two irrigation canals, one containingSpirogyra and another not containing Spirogyra, were chosento study the possible allelopathic activity of Spirogyra onthe growth of Oscillatoria agardhii. The growth of O. agardhiiand other associated cyanobacterial species was followed inthese two canals during the period May–September 2000.The results revealed that O. agardhii was dominant and formedblooms in the canals containing Spirogyra, while it had a moderate/rareoccurrence in those not containing Spirogyra. To confirm thestimulatory allelopathic activity of this green alga on thegrowth of and microcystin production by O. agardhii, a laboratoryexperiment was run by growing O. agardhii with different concentrationsof Spirogyra aqueous extract. The results showed that the growthof and microcystin production by O. agardhii increased withincreasing concentrations of Spirogyra aqueous extract. Thisfinding demonstrates the allelopathic activity of the greenalga Spirogyra stimulating the growth of and toxin productionby O. agardhii. Such a biotic factor should be taken into considerationwhen cyanobacterial blooms are monitored in freshwater bodies.     

Invasibility of a reservoir to exotic Daphnia lumholtzi: experimental assessment of diet selection and life history responses to cyanobacteria

SUMMARY 1. In reservoirs of the south-central United States, the exotic cladoceran Daphnia lumholtzi is common during warm midsummer conditions, when cyanobacteria are abundant and native Daphnia are rare. In the current study, we employed surveys, field experiments, and a life table experiment to investigate the role of food quality in explaining the distribution and phenology of D. lumholtzi , relative to two native species ( Daphnia parvula and Daphnia mendotae ).
2. During May–September 2000 in eutrophic McDaniel Lake, Missouri U.S.A., cyanobacteria (primarily Oscillatoria ) first appeared at 6-m depth and then became abundant throughout the epilimnion.
3. During the May field experiment, D. lumholtzi , D. parvula and D. mendotae all consumed a similar diet of algae, showing positive selection for small greens (chlorophytes and cryptophytes <20 μm). During the July experiment, when the epilimnion exceeded 25 °C and cyanobacteria were common in the lake, D. lumholtzi consumed significantly more total algae and more cyanobacteria than the two native species. Although the Daphnia selected against cyanobacteria, all three species consumed about 25% of this food in their diet.
4. A life table experiment compared the responses of D. lumholtzi and D. parvula with variation in density of high-quality food ( Ankistrodesmus ) and concentration of a toxic strain of cyanobacteria ( Anabaena flos-aquae ). Both Daphnia species showed reduced survivorship, fertility and intrinsic rates of increase in response to elevated concentrations of cyanobacteria, particularly at the higher food level.
5. The results suggest that D. lumholtzi shows similar inhibition from cyanobacteria as does the native Daphnia . However, their continued high in situ feeding rates imply that D. lumholtzi is less affected by midsummer conditions in warm-water reservoirs than are native Daphnia .     

微囊藻毒素在滇池鱼体内的积累水平及分布特征

为了解富营养化水体中鱼体内微囊藻毒素(MC)的积累水平及其分布特征,2003年4月和9月份两次在滇池试验区采集了鲢、鳙和草鱼等鱼种,用ELISA方法对鱼体中肝、肾、空肠、胆、肌肉等不同组织中MC的含量进行了检测。结果表明,MC在所有样品中均能检测到,且主要分布在鱼体的肝肾脏和消化道等器官,而肌肉和非消化道器官中毒素含量相对较低。不同鱼种不同组织对MC的富集程度也明显不同,鲢鳙中肝脏和肾脏这两个主要的靶器官对MC的蓄积能力就远高于草鱼。同时,不同季节MC在鱼体内的积累水平也明显不同,4月份鱼样中MC的含量普遍低于9月份鱼样中MC的含量。最后按照WHO生活饮用水安全标准的建议进行推算,所有鱼肉中的MC均没有超过其推荐的人体每日可允许摄入量(≤0.04μg/kg人体重),初步推断鱼肉中MC暂时还未危及到人体健康,但仍具有潜在的风险性。     

Screening of different algae for green synthesis of gold nanoparticles

The cyanobacteria Phormidium valderianum, P. tenue and Microcoleus chthonoplastes and the green algae Rhizoclonium fontinale, Ulva intestinalis, Chara zeylanica and Pithophora oedogoniana were exposed to hydrogen tetrachloroaurate solution and were screened for their suitability for producing nano‐gold. All three cyanobacteria genera and two of the green algae (Rhizoclonium fontinale and Ulva intestinalis) produced gold nanoparticles intracellularly, confirmed by purple colouration of the thallus within 72?h of treatment at 20°C. Extracted nanoparticle solutions were examined by UV‐vis spectroscopy, transmission electron microscopy (TEM) and X‐ray diffractometry (XRD). XRD confirmed the reduction of Au (III) to Au (0). UV‐vis spectroscopy and TEM studies indicated the production of nanoparticles having different shapes and sizes. Phormidium valderianum synthesized mostly spherical nanoparticles, along with hexagonal and triangular nanoparticles, at basic and neutral pHs (pH 9 and pH 7, respectively). Medicinally important gold nanorods were synthesized (together with gold nanospheres) only by P. valderianum at acidic pH (pH 5); this was initially determined by two surface plasmon bands in UV‐vis spectroscopy and later confirmed by TEM. Spherical to somewhat irregular particles were produced by P. tenue and Ulva intestinalis (TEM studies). The UV‐vis spectroscopy of the supernatant of other algal extracts indicated the formation of mostly spherical particles. Production of gold nanoparticles by algae is more ecofriendly than purely chemical synthesis. However, the choice of algae is important: Chara zeylanica and Pithophora oedogoniana were found to be unable to produce nanoparticles.     

The distribution and abundance of algae in saline lakes of Saskatchewan,Canada

Collections of algae, mainly planktonic, were made from 41 saline lakes in southern Saskatchewan ranging in salinity from 3.2 to 428 g l^-1. Algae in 7 phyla, 8 classes, 42 families, 91 genera and 212 species and varieties were identified. Fourteen species were restricted to hypersaline (50 g l^-1) waters and eleven of these were diatoms. In general, species diversity was inversely related to lake salinity. Algae that were important community constituents over a broad spectrum of salinities were the green algae Ctenocladus circinnatus, Dunaliella salina and Rhizoclonium hieroglyphicum, the blue-green Lyngbya Birgei, Microcystis aeruginosa, Oscillatoria tenuis, O. Utermoehli and Nodularia spumigena and the diatoms Melosira granulata, Stephanodiscus niagarae and Chaetoceros Elmorei. In general green algae were dominant when lake salinity exceeded 100 g l^-1 although diatoms played important roles in most of these highly saline lakes except for Patience Lake.     

The influence of macrophytes on a phytoplankton community in experimental conditions

The impact of submerged macrophytes or their extracts on planktonic algae was studied under experimental conditions. Live Ceratophyllum demersum L., its extract, and extracts of four other plant species induced modifications in the phytoplankton dominance structure. These modifications were: a decline in the number of Oscillatoria limnetica Lemm., which was the most numerous cyanobacterian species, and a decline in biomass and percentage contribution of all cyanobacteria to total algal biomass. This was accompanied by an increase in biomass and percentage contribution of green algae, especially Chlorella sp. and Chlamydomonas sp. Also, there was an increase in biomass and percentage contribution of nanoplankton (under 50 µm) to total phytoplankton biomass.The isolation of planktonic algae from direct influence of C. demersum by means of dialysis membranes caused an increase in number, biomass and percentage contribution of cyanobacteria. Release of organic compounds of over 3000 daltons by macrophytes apparently contributed to a decline of cyanobacteria by changing the phytoplankton dominance structure.     

Early stages of biofilm succession in a lentic freshwater environment

Initial events of biofilms development and succession were studied in a freshwater environment at Kalpakkam, East Coast of India. Biofilms were developed by suspending Perspex (Plexiglass) panels for 15 days at bimonthly intervals from January 1996 to January 1997. Changes in biofilm thickness, biomass, algal density, chlorophyll a concentration and species composition were monitored. The biofilm thickness, biomass, algal density and chlorophyll a concentration increased with biofilms age and colonization was greater during summer (March, May and July) than other months. The initial colonization was mainly composed of Chlorella vulgaris, Chlorococcum humicolo (green algae), Achnanthes minutissima, Cocconeis scutellum, C. placentula (diatoms) and Chroococcus minutus (cyanobacteria) followed by colonial green algae such as Pediastrum tetras, P. boryanumand Coleochaete scutata, cyanobacteria (Gloeocapsa nigrescens), low profile diatoms (Amphora coffeaeformis, Nitzschia amphibia, and Gomphonema parvulum) and long stalked diatoms (Gomphoneis olivaceumand Gomphonema lanceolatum). After the 10th day, the community consisted of filamentous green algae (Klebshormidium subtile, Oedogonium sp., Stigeoclonium tenue and Ulothrix zonata) and cyanobacteria (Calothrix elenkinii, Oscillatoria tenuis and Phormidium tenue). Based on the percentage composition of different groups in the biofilm, three phases of succession could be identified: the first phase was dominated by green algae, the second by diatoms and the third phase by cyanobacteria. Seasonal variation in species composition was observed but the sequence of colonization was similar throughout the study period.     

The combined effects of treated sewage discharge and land use on rivers

Freshwater ecosystems are increasingly threatened by multiple anthropogenic stressors. Release of treated sewage effluent and pollution from agricultural or urban sources can independently reduce water quality with implications for ecological communities. However, our knowledge of the combined effects of these stressors is limited. We performed a field study to quantify the combined effect of treated sewage discharge and land use on nutrient concentrations, sewage fungus presence and communities of macroinvertebrates and benthic algae. Over three seasons in four rivers we found that a model which included an interaction between sewage pollution and time of the year (i.e. months) was the best predictor of nutrient concentrations and the abundance of algae and sewage fungus. Both macroinvertebrate and algae communities shifted downstream of sewage input. Specifically, more tolerant groups, such as cyanobacteria and oligochaetes, were more abundant. The EPT (Ephemeroptera, Plecoptera and Tricoptera) water quality score was best explained by an interaction between month and agriculture in the surrounding landscape. Overall, our results show that sewage discharge has a significant impact on water quality and benthic riverine communities, regardless of the surrounding land uses. Agricultural inputs, however, could be more important than treated sewage discharge in reducing the abundance of sensitive invertebrate taxa. We need both improvements to wastewater treatment processes and reductions in agricultural pollution to reduce threats to vulnerable freshwater communities.     

Effects of food type on the life history of Daphnia clones from lakes differing in trophic state. II. Daphnia cucullata feeding on mixed diets*

1. The effects of feeding on suboptimal foods were investigated in Daphnia cucullata a zooplankton common in many types of lakes. Eleven clones of D. cucullata were collected from four lakes of varying trophic levels and fed a high (1 mg C l^–1) concentration of one of two diets: (i) a 1 : 9 mixture of the cryptophyte Cryptomonas pyrenoidifera with the green alga Scenedesmus obliquus ; and (ii) a 1 : 9 mixture of the cryptophyte C. pyrenoidifera with the filamentous cyanobacterium Oscillatoria limnetica.
2. As expected, the diet dominated by Oscillatoria was found to be significantly poorer compared with the diet dominated by Scenedesmus. All D. cucullata clones were, however, able to achieve positive population growth rates on both diets, supporting the view that daphnids can grow and reproduce on a diet dominated by filamentous cyanobacteria.
3. Clones originating from different types of lakes differed in their responses to the two diets. On the Scenedesmus -dominated diet, clones originating from moderately eutrophic lakes had lower population growth rates than clones from hypertrophic lakes. In contrast, on the Oscillatoria -dominated diet, the clones from moderately eutrophic lakes had higher population growth rates than clones from hypertrophic lakes. Contrary to expectation, clones originating from lakes dominated by filamentous cyanobacteria had more difficulty utilizing filamentous cyanobacteria as food than clones from less eutrophic lakes which contain less filamentous cyanobacteria.
4. As the reactions of clones originating from same type of lake resembled each other, it is hypothesized that the life histories of D. cucullata populations are locally adapted to environmental factors other than abundance of filamentous cyanobacteria, which are correlated with trophic levels.     

Herbivory in the tilapia Oreochromis niloticus: a comparison of feeding rates on phytoplankton and periphyton

A quantitative comparison of the grazing behaviour of young Oreochromis niloticus feeding on the planktonic cyanobacterium Microcystis aeruginosa and a periphytic community dominated by the cyanobacterium Oscillatoria sp., determined that biomass ingestion rates of fish filter-feeding on planktonic cyanobacteria were significantly lower than those surface-grazing on periphyton. Comparisons of published laboratory data on filter-feeding with field data on algal ingestion rates suggest that filter-feeding may be a relatively unimportant method of ingesting algae.     

Determination of cyanobacterial diversity during algal blooms in Daechung Reservoir, Korea, on the basis of cpcBA intergenic spacer region analysis

The detection and prevention of cyanobacterial blooms are important issues in water quality management. As such, the diversity and community dynamics of cyanobacteria during cyanobacterial bloom in the Daechung Reservoir, Korea, were studied by analyzing the intergenic spacer (IGS) region between phycocyanin subunit genes cpcB and cpcA (cpcBA IGS). To amplify the cpcBA IGS from environmental samples, new PCR primers that could cover a wider range of cyanobacteria than previously known primers were designed. In the samples taken around the bloom peak (2 September 2003), seven groups of cpcBA IGS sequences were detected, and none of the amplified cpcBA IGSs was closely related to the cpcBA IGS from chloroplasts. Apart from the Microcystis-, Aphanizomenon (Anabaena)-, Pseudanabaena-, and Planktothrix (Oscillatoria)-like groups, the three other groups of cpcBA IGS sequences were only distantly related to previously reported sequences (<85% similarity to their closest relatives). The most prominent changes during the bloom were the gradual decrease and eventual disappearance of the Aphanizomenon (Anabaena)-like group before the bloom peak and the gradual increase and sudden disappearance of Planktothrix (Oscillatoria)-like groups right after the bloom peak. The community succession profile obtained based on the cpcBA IGS analysis was also supported by a PCR-denaturing gradient gel electrophoresis analysis of the 16S rRNA genes.     

Screening of marine cyanobacteria for high palmitoleic acid production

Abstract Screening of fatty acid composition in 150 strains of marine microalgae, cyanobacteria and green algae was carried out, and 20 strains showed relatively high contents of palmitoleic acid. Among them, two cyanobacteria, Phormidium sp. NKBG 041105 and Oscillatoria sp. NKBG 091600, showed an unusually high cis -palmitoleic acid content (54.5% and 54.4% of total fatty acid, respectively). Phormidium sp. NKBG 041105 had the highest cis -palmitoleic acid content per biomass (46.3 mg (g dry cell weight)⁻¹), and cis -palrnitoleic acid composition was found to be constant with varying temperature. These results indicate that this cyanobacterium could be considered as a new source for palmitoleic acid.