Boron requirement in cyanobacteria : its possible role in the early evolution of photosynthetic organisms

The effect of boron on heterocystous and nonheterocystous dinitrogen fixing Cyanobacteria was examined. The absence of boron in culture media inhibited growth and nitrogenase activity in Nodularia sp., Chlorogloeopsis sp., and Nostoc sp. cultures. Examinations of boron-deficient cultures showed changes in heterocyst morphology. However, cultures of nonheterocystous Cyanobacteria, Gloeothece sp. and Plectonema sp., grown in the absence of boron did not show any alteration in growth or nitrogenase activity. These results suggest a requirement of boron only by heterocystous Cyanobacteria. A possible role for this element in the early evolution of photosynthetic organisms is proposed.     

Bacterial Enhancement of Vinyl Fouling by Algae

The role of bacteria in the development of algae on low-density vinyl was investigated. Unidentified bacterial contaminants in unialgal stock cultures of Phormidium faveolarum and Pleurochloris pyrenoidosa enhanced, by 1 to 2 orders of magnitude, colonization of vinyl by these algae, as determined by epifluorescence microscopy counts and chlorophyll a in extracts of colonized vinyl. Colonization by bacteria always preceded that by algae. Scanning electron microscopy of the colonized Phormidium-bacteria mixture revealed the presence of a slime matrix engulfing both bacteria and algae that may have facilitated algal attachment. Slime was not evident in the Pleurochloris-bacteria mixture, suggesting that the attachment mechanisms differ for the two algae.     

Plankton community and the relationship with the environment in saline lakes of Onon-Torey plain,Northeastern Mongolia

The plankton community of sixteen saline lakes located on Onon-Torey plain (Northeastern Mongolia) during the filling phase and the raising of the water level was investigated in July 2011. Thirty-five taxa of phytoplankton and thirty-one species of zooplankton were found. For phytoplankton, blue-green algae (Merismopedia elegans, Anabaenopsis elenkinii, Arthrospora fusiformis, Spirulina major, Lyngbya sp., Oscillatoria sp.) and green algae (Monoraphidium minutum, Tetrastrum komarekii, Ankyra ocellata, Oocystis sp.) were dominant. For zooplankton, Filinia longiseta, Brachionus plicatilis, B. variabilis, Hexarthra mira (Rotifera), Daphnia magna, Moina brachiata, M. mongolica (Cladocera), Arctodiaptomus bacillifer, Mixodiaptomus incrassatus, Metadiaptomus asiaticus (Copepoda) dominated. Mineralization, active hydrogen ratio, dissolved oxygen and water temperature were the main factors influencing the diversity, structure and distribution of plankton organisms in the steppe lakes during low water level. The RDA analysis for phytoplankton and zooplankton from different lakes was carried out for selected two groups which included lakes and a subset related species. The first group is of oligohaline and mesohaline lakes in which mostly green algae, rotifers and copepods inhabit. The second group is of mesohaline and polyhaline lakes with mainly blue-green algae, some crustaceans and rotifers inhabiting. High abundance and biomass of Spirulina major, Oscillatoria sp. and Brachionus variabilis were observed in lakes with high mineralization, pH and temperature.     

Basis for the Resistance of Several Algae to Microbial Decomposition

The basis for the resistance of certain algae to microbial decomposition in natural waters was investigated using Pediastrum duplex, Staurastrum sp., and Fischerella muscicola as test organisms. Enzyme preparations previously found to convert susceptible algae into spheroplasts had no such effect on the resistant species, although glucose and galacturonic acid were released from P. duplex walls. Little protein or lipid but considerable carbohydrate was found in the walls of the refractory organisms, but resistance was not correlated with the presence of a unique sugar monomer. A substance present in Staurastrum sp. walls was characterized as lignin or lignin-like on the basis of its extraction characteristics, infrared spectrum, pyrolysis pattern, and content of an aromatic building block. Sporopollenin was found in P. duplex, and cellulose in Staurastrum sp. Cell walls of the algae were fractionated, and the fractions least susceptible to microbial degradation were the sporopollenin of P. duplex, the polyaromatic component of Staurastrum sp., and two F. muscicola fractions containing several sugar monomers. The sporopollenin content of P. duplex, the content of lignin or a related constituent of Staurastrum sp., and the resistance of the algae to microbial attack increased with age. It is suggested that resistance results from the presence of sporopollenin in P. duplex, a lignin-like material in Staurastrum sp., and possibly heteropolysaccharides in F. muscicola.     

The marine algae of Orkney

Six species are described and compared with related algae. All were isolated in culture from terrestrial habitats on Signy Island, South Orkney Islands, Antarctica. They are: Botrydiopsis constricta sp. nov. (Mischococcales, Xanthophyceae), Heterothrix antarctica sp. nov. (Tribonematales, Xanthophyceae), Sphaerocystis oleifera sp. nov. (Chlorococcales, Chlorophyceae), Sphaerocystis signiensis sp. nov., Sphaerocystis bilobata sp. nov. and Fottea pyrenoidosa sp. nov. (Ulothricales, Chlorophyceae).     

防己抑藻效应及其化感物质的HPLC分析

通过常温水浸提方法获得12种药用植物浸提液,并分别研究其抑藻效应。结果显示：防己水浸提物(相对浓度1 g·L^-1)抑制蛋白核小球藻的效应最强,最大比生长率为-0.28 d^-1。防己甲醇浸提物对蛋白核小球藻的抑藻效应显著,且持续时间长,最低有效抑藻浓度为30 mg·L^-1。HPLC鉴定结果显示：防己水浸提液和甲醇浸提液中主要含有防己诺林碱、粉防己碱等生物碱类化学成分,防己对治理水华发生有较大的应用前景。     

Biomass and oil content of Chlorella sp., Haematococcus sp., Nannochloris sp. and Scenedesmus sp. under mixotrophic growth conditions in the presence of technical glycerol

The growth of algae strains Chlorella sp., Haematococcus sp., Nannochloris sp. and Scenedesmus sp. under mixotrophic conditions in the presence of different concentrations of technical glycerol was investigated with the aim of increasing biomass growth and algae oil content. The highest concentration of lipid obtained in media with 5 g L^?1 glycerol for Chlorella sp., Scenedesmus sp., Nannochloris sp. and Haematococcus sp. was 17.77, 22.34, 27.55 and 34.22 % larger than during the autotrophic growth of these species. Increases in triacylglycerols of up to ten times was observed for Scenedesmus sp. under mixotrophic conditions (using 10 g L^?1 glycerol), whereas an increase of 2.28 times was found for Haematococcus sp. The content of saturated fatty acids of Scenedesmus, Chlorella, Haematococcus and Nannochloris was 67.11, 34.63, 23.39 and 24.23 %, and the amount of unsaturated fatty acids was 32.9, 65.06, 79.61 and 75.78 % of total fatty acids, respectively. Growth on technical glycerol of these strains with light produced higher biomass concentrations and lipid content compared with autotrophic growth. The fatty acid content of oils from these species suggests their potential use as biodiesel feedstock.     

Growth optimization of algae for biodiesel production

Aims: Algae are favourable as a biofuel source because of the potential high oil content and fast generation of biomass. However, one of the challenges for this technology is achieving high oil content while maintaining exponential or high growth of the organism. Introducing a two‐stage reactor to optimize both growth and oil content of the algae could be a solution to this hurdle. The aim of this study was to determine the reactor design parameters of the first‐stage reactor, which would optimize growth of two algal strains, Oocystis sp. and Amphora sp. Methods and Results: Growth kinetics were monitored by in vivo fluorescence and correlated to dry mass for both cultures under several environmental conditions during exponential growth. Temperatures of 25 and 30°C and light intensities of 150 and 80 μmol m^?2 s^?1 provided the most robust growth for Oocystis sp. and Amphora sp., respectively. Both strains showed optimized growth at a light : dark cycle of 16 : 08. At these conditions, the doubling rate for Oocystis sp. was 0·333 d^?1 and for Amphora sp. was 0·179 d^?1. Conclusions: For both cultures, growth rate was more dependent on light : dark cycle and temperature than light intensity. Both strains grew slower in this work than data reported in the literature, however agitation and air/CO₂ sparging were not incorporated in the system under study. The highest doubling rate for Amphora sp. was observed near the maximum tolerable temperature, and it is suggested to grow this strain at 30°C for a consistent high growth rate. Significance and Impact of Study: Optimized growth conditions were determined for two lipid producing strains identified in the Aquatic Species Program summary report. An optimized, first‐stage growth reactor operating at these conditions would thus offer the maximum productivity for an algal biomass feed stream into a lipid‐optimized second‐stage reactor.     

A suggested standardised method for testing photocatalytic inactivation of aeroterrestrial algal growth on TiO2-coated glass

Aeroterrestrial green algae form conspicuous biofilms on man-made surfaces. The self-cleaning properties of photocatalytic coatings prevent their growth and can probably replace biocides. The aim of this study was to develop a laboratory method to investigate the efficiency of photocatalytic materials against algal growth. Two algal isolates (“Chlorella” luteoviridis, SAG 2196, and Coccomyxa sp., SAG 2040) functioned well as model organisms because they grew on almost all test specimens at 100% humidity and low UVA radiation. With these species, we examined algal growth prevention using photocatalytic glass. No effects on algal growth were detected, although the coated surfaces were photocatalytically active and degraded methylene blue. Because their cells are protected well against photocatalytically generated hydroxyl radicals, aeroterrestrial algae survive various stress factors. Nevertheless, the newly developed experimental design may be useful for assessing the biological function of other photocatalytic materials or stress factors.     

Bacterial communities of some brown and red algae from Peter the Great Bay, the Sea of Japan

The structure of microbial communities of brown algae, red algae, and of the red alga Gracilaria verrucosa, healthy and affected with thallus rot, were comparatively investigated; 61 strains of heterotrophic bacteria were isolated and characterized. Most of them were identified to the genus level, some Vibrio spp., to the species level according to their phenotypic properties and the fatty acid composition of cellular lipids. The composition of the microflora of two species of brown algae was different. In Chordaria flagelliphormis, Pseudomonas spp. prevailed, and in Desmarestia viridis, Bacillus spp. The composition of the microflora of two red algae, G. verrucosa and Camphylaephora hyphaeoides, differed mainly in the ratio of prevailing groups of bacteria. The most abundant were bacteria of the CFB cluster and pseudoalteromonads. In addition, the following bacteria were found on the surface of the algae: Sulfitobacter spp., Halomonas spp., Acinetobacter sp., Planococcus sp., Arthrobacter sp., and Agromyces sp. From tissues of the affected G. verrucosa, only vibrios were isolated, both agarolytic and nonagarolytic. The existence of specific bacterial communities characteristic of different species of algae is suggested and the relation of Vibrio sp. to the pathological process in the tissues of G. verrucosa is supposed.     

Algicidal effects of yellow clay and the thiazolidinedione derivative TD49 on the fish-killing dinoflagellate Cochlodinium polykrikoides in microcosm experiments

In order to evaluate the potential to control the fish-killing dinoflagellate Cochlodinium polykrikoides, we compared the algicidal effects of the thiazolidinedione derivative TD49 with those of yellow clay in 10-L microcosms. The responses of higher trophic level marine organisms and microbial loop communities to the algicide were also evaluated. In the yellow clay treatments, the concentration of C. polykrikoides was slightly reduced at day 1 of the experiment but remained higher than that of the control, suggesting that the reduction ratio of C. polykrikoides was <20 %. In the 0.8-μM TD49 treatment, the abundance of C. polykrikoides declined by 98 % 1 day following the addition of the algicide. The algicide did not affect nontarget algae including Chaetoceros spp., Skeletonema spp., Cylindrotheca spp., and other species. In all microcosms, bacterial abundance increased abruptly after day 1, then declined over the next 2 days as a result of predation by heterotrophic nanoflagellates and the small protozoan Uronema sp. Predation by the large protozoan species Euplotes sp. on Uronema sp. gradually increased with increasing incubation time in the TD49 treatment. Zooplankton were particularly affected by the environmental changes that occurred in the microcosms following collapse of the C. polykrikoides populations. Striped beak perch were not affected by the yellow clay treatments and concentrations of TD49?C. polykrikoides, whereas the algicide TD49 is effective in controlling the harmful alga. The results imply that the algicide has positive effects on natural microbial communities and is not toxic to nonharmful algae and higher trophic level marine organisms.     

Food quality effects on life history traits and fitness in the generalist herbivore Daphnia

Summary Life table experiments were conducted on the generalist suspension feeder Daphnia galeata, using as food the two green algae (Chlorophyta) Scenedesmus acutus and Oocystis lacustris. Oocystis was hypothesized to be a lower quality food because it is convered with a thick sheath, believed to reduce digestibility. Results showed that Oocystis is a lower quality food for Daphnia, but only at relatively low food concentrations (0.15 mg C/L) and not at higher concentrations (1.0 mg C/L). At 0.15 mg C/L, Daphnia intrinsic rate of increase (r) when grown on Oocystis was only half that when grown on Scenedesmus. Daphnia r was similar at 0.15 mg C/L Oocystis and 0.075 mg C/L Scenedesmus, indicating that Daphnia requires twice as much Oocystis as Scenedesmus to achieve the same fitness. Intrinsic rate of increase was lower on Oocystis mainly because age at first reproduction was greatly delayed compared to that on Scenedesmus (13.6 vs 7.3 d). In addition, juvenile growth and survivorship were reduced on Oocystis compared with Scenedesmus. Clutch sizes were similar on the two foods, indicating that once individuals reached adulthood, the two foods were similar in quality. In contrast, at high food concentrations (1.0 mg C/L), the two algae were similar in quality for both juveniles and adults, and r was not significantly different on the two foods. Ingestion and assimilation rate experiments whowed that Daphnia consumes the two algae at identical rates, and that adults assimilate the two algae at similar rates. However, juveniles assimilate Oocystis at much lower rates than Scenedesmus, possibly accounting for reduced juvenile growth and delay in age at maturity at low concentrations. Thus, Daphnia exhibits an ontogenetic shift in its ability to utilize Oocystis, and this can result in juvenile bottlenecks in which survival and growth of young age classes are of critical importance in determining population dynamics. Because food quality effects were manifested primarily in juveniles and at low concentrations, food quality effects in nature will depend on phytoplankton abundance and age-structure of Daphnia populations.     

Upper Triassic (Carnian) reef biota from the Sambosan Accretionary Complex, Kyushu, Japan

Calcified sponges, algae, and reef problematica are abundant yet poorly known from the Triassic of Japan. They are abundant in shallow-water carbonate, redeposited blocks of the Sambosan Accretionary Complex, Konosé Group, and southern Kyushu. Based on study of thin-sections from reef limestone exposed along the Kuma River, some important organisms and reef microfacies are described, which seem typical of Upper Triassic reef complexes. The most abundant reef organisms are hypercalcified sponges, including sphinctozoans, inozoans and chaetetids, followed by cyanophycean algae (including “Tubiphytes”-like organisms), and solenoporacean red algae. Loose sponge spicules in one thin-section also indicate the occurrence of rare hexactinellid sponges. Chambered demosponges described from the Konosé carbonate rocks include Solenolmia manon manon (Münster), Colospongia sp., Jablonskyia andrusovi (Jablonsky), several unidentified chambered sponges as well as the inozoid Permocorynella sp. 1 and Permocorynella sp. 2. Also present are chaetetid sponges and solenoporacean red algae belonging to Parachaetetes cassianus (Flügel) and Parachaetetes? sp. or Solenopora? sp. Especially abundant in thin-sections are cyanophyceans and “Tubiphytes”-like organisms. Among the organisms is Cladogirvanella Ott and Hedstroemia sp. The composition of the biota and presence of typical problematic organisms increases our knowledge of shallow-water Upper Triassic carbonate rocks in a remote setting in western Panthalassa. The composition of the biota indicates a mostly Carnian age. Most comparable organisms are known from both the northeastern and southern Tethys.     

自养和兼养条件下蛋白核小球藻昼夜节律的响应

【目的】研究自养和兼养两种培养方式对蛋白核小球藻(Chlorella pyrenoidosa)生长、细胞分裂和生化组分积累的影响,探讨人工培养蛋白核小球藻的昼夜节律响应机制和优化技术。【方法】小球藻自养培养采用BG11培养基,兼养培养基在BG11培养基中添加4种不同浓度(1、5、10、20 g/L)的葡萄糖,培养周期为10 d。血球板计数法测定藻细胞浓度,干重法测定藻细胞生物量。显微观察藻细胞大小和分裂情况。脂染色法测定小球藻总脂的含量,藻细胞的叶绿素、蛋白和淀粉分别采用甲醇、氢氧化钠、硝酸钙浸提后通过紫外分光光度法定量测定。【结果】葡萄糖兼养培养对蛋白核小球藻具有显著的促生长效应,最适浓度为10 g/L。10 d收获时,兼养组(10 g/L葡萄糖)藻细胞浓度和干重分别是自养组的2.57倍和6.73倍。分析一昼夜中的藻细胞增殖规律可知,第2天和第5天时自养组中增殖的新生子细胞约有76.00%在黑暗期分裂产生,而兼养组中第2天和第5天光照期的新细胞增殖量占比分别达到40.90%和67.50%。一昼夜内藻细胞大小的迁移动态监测表明,第2天自养组藻细胞的体积变化静息期为8 h,兼养组只有4 h;第5天两组藻细胞大小迁移动态的昼夜节律明显,但兼养组黑暗结束后较大细胞(D6μm)占比显著高于自养组。第8天时,兼养组藻细胞已处于稳定期,总脂和蛋白含量均显著高于自养组,藻细胞总脂和色素含量在一昼夜中相对稳定,但蛋白和淀粉含量分别在光照8 h和12 h左右达到峰值。从第2天开始,对兼养组细胞每天进行2 h光延长,收获时藻细胞浓度和干重分别比对照组提高13%和11%。【结论】葡萄糖兼养培养能大幅提高蛋白核小球藻的生物量。蛋白核小球藻生长增殖与生化组分积累均受昼夜节律调控,自养条件下藻细胞以光照期生长黑暗期增殖为主。兼养培养提高藻细胞生物量的机制在于缩短藻细胞生长静息期,在昼夜节律中加速藻细胞生长并显著提高通过细胞周期检查点的细胞比例,光照期效应尤其明显。藻细胞蛋白和淀粉含量昼夜节律明显,最佳收获时间分别在光照8 h和12 h后。     

Relationship between the Unicellular Red Alga Porphyridium sp. and Its Predator, the Dinoflagellate Gymnodinium sp

Contamination of algae cultivated outdoors by various microorganisms, such as bacteria, fungi, algae, and protozoa, can affect growth and product quality, sometimes causing fast collapse of the cultures. The main contaminant of Porphyridium cultures grown outdoors in Israel is a Gymnodinium sp., a dinoflagellate that feeds on the alga. Comparison of the effects of various environmental conditions, i.e., pH, salinity, and temperature, on Gymnodinium and Porphyridium species revealed that the Gymnodinium sp. has sharp optimum curves, whereas the Porphyridium sp. has a wider range of optimum conditions and is also more resistant to extreme environmental variables. The mode of preying on the alga was observed, and the specificity of the Gymnodinium sp. for the Porphyridium sp. was shown. In addition, Gymnodinium extract was shown to contain enzymatic degrading activity specific to the Porphyridium sp. cell wall polysaccharide.     

SOME FACTORS IN THE COMPETITION OR ANTAGONISM AMONG BACTERIA, ALGAE, AND AQUATIC WEEDS

Field observations of changes in the populations of aquatic weeds and phytoplankton have confirmed that aquatic weeds have antagonistic activity toward phytoplankton. Nutritional studies in the laboratory indicate that cultures of the aquatic weeds, Myriophyllum sp., Ceratophyllum sp., and duckweed (Lemma minor L.); liquid cultures of barley (Hordeum vulgare L., Dickson variety); and cultures of the filamentous green algae, Cladophora sp. and Pithophora oedogonium (Mont.) Withrock, will remain relatively free of epiphytes or competing phytoplankton if the cultures are nitrogen-limited. Field observations of Cladophora sp. have confirmed that the growth of epiphytes on the Cladophora is related to conditions of surplus available nitrogen compounds. It is proposed that this antagonistic activity may be due to a “nitrogen sink” effect in which the aquatic weeds or filamentous green algae prevent the growth of contaminating algae by competition for the limited nitrogen compounds available. However, the presence of bacteria-sized organisms which have selective toxicity to certain algae indicates that perhaps multiple factors exist. Discussed are the ecological implications of associations of certain algae with bacteria that have selective toxicities for other species of algae under certain environmental conditions such as nitrogen-limited growth.     

Natural diet of herbivorous zooplankton in Lake Xolotlán (Managua)

The natural diet of herbivorous zooplankton was analyzed for a better understanding of the trophic relationships in Lake Xolotlán (Managua). Gut content of the most common zooplankton species (Arctodiaptomus dorsalis, Moina micrura andDiaphanosoma fluviatile) were analyzed. The quality and the relative abundance of ingested algae was studied. The most consumed algae during the dry season (February) wereCyclotella, Oocystis andLyngbya, and during the rainy season (November)Cyclotella, Oocystis andChroococcus. The kind of food ingested byA. dorsalis andM. micrura was similar in both periods. There was no similarity with the diet ofD. fluviatile. During the dry season, when algal biomass in the lake was high,A. dorsalis andM. micrura ingested a higher proportion of diatoms. During the rainy season, when food was scarce, the diet was more diverse and bluegreen algae (Chroococcus) were ingested in a larger proportion.Diaphanosoma fluviatile ingested predominantly tiny particles (bacteria and detritus) and algal food consisted mainly of green algae (Oocystis) and probably (not studied) nanoplanktonic algae. The results were consistent with those obtained in other lakes, indicating the importance of diatoms and green algae for zooplankton nutrition.     

Fatty acid composition of ten marine algae from australian waters

Detailed fatty acid analyses are reported for ten benthic algae from Australian waters of which the data for Cladophora fascicularis (Chlorophyta); Polysiphonia pungens, Porphyra sp., Centroceras clavatum (Rhodophyta); Hormosira banksii, Ralfsia sp., and Dictyota dichomota (Phaeophyta) are presented for the first time. The analyses report the exact molecular structure of component acids which is essential for taxonomic and food chain studies. The acid 16:4ω3 could be taxonomically distinguishing for species of the Chlorophyta. The occurrence of cis-vaccenic acid (18:1ω7) in the algae reported here suggests a distribution in marine benthic algae which is wider than hitherto realised, with particular taxonomic importance for Chlorophyta species in which it occurs in high levels. Corallina officinalis was found to contain the non-methylene interrupted acids 20:2 and 22:2.     

Grazers and Phytoplankton Growth in the Oceans: an Experimental and Evolutionary Perspective

The taxonomic composition of phytoplankton responsible for primary production on continental shelves has changed episodically through Earth history. Geological correlations suggest that major changes in phytoplankton composition correspond in time to changes in grazing and seawater chemistry. Testing hypotheses that arise from these correlations requires experimentation, and so we carried out a series of experiments in which selected phytoplankton species were grown in treatments that differed with respect to the presence or absence of grazers as well as seawater chemistry. Both protistan (Euplotes sp.) and microarthropod (Acartia tonsa) grazers changed the growth dynamics and biochemical composition of the green alga Tetraselmis suecica, the diatom Thalassiosira weissflogii, and the cyanobacterium Synechococcus sp., increasing the specific growth rate and palatability of the eukaryotic algae, while decreasing or leaving unchanged both parameters in the cyanobacteria. Synechococcus (especially) and Thalassiosira produced toxins effective against the copepod, but ciliate growth was unaffected. Acartia induced a 4-6 fold increase of Si cell quota in the diatom, but Euplotes had no similar effect. The differential growth responses of the eukaryotic algae and cyanobacteria to ciliate grazing may help to explain the apparently coeval radiation of eukaryophagic protists and rise of eukaryotes to ecological prominence as primary producers in Neoproterozoic oceans. The experimental results suggest that phytoplankton responses to the later radiation of microarthropod grazers were clade-specific, and included changes in growth dynamics, toxin synthesis, encystment, and (in diatoms) enhanced Si uptake.     

Photosynthetic Light Reactions in Chemically Fixed Anacystis nidulans, Chlorella pyrenoidosa, and Porphyridium cruentum

The photochemical activities of various species of unicellular algae (Anacystis nidulans, Chlorella pyrenoidosa, and Porphyridium cruentum) were studied following chemical fixation. Fixation with formaldehyde and glutaraldehyde yielded cells which retained their ability to perform photosystem I and photosystem II reactions. The photochemical efficiencies of some fixed algae are as great as those of unfixed spinach chloroplasts. Fixed algae containing accessory pigments appear to be useful models for further studies of the light reactions of photosynthesis.