Cyanobacterium Sp Research Articles

The Specificities of Lysophosphatidic Acid Acyltransferase and Fatty Acid Desaturase Determine the High Content of Myristic and Myristoleic Acids in Cyanobacterium sp. IPPAS B-1200.

The cyanobacterial strain Cyanobacterium sp. IPPAS B-1200 isolated from Lake Balkhash is characterized by high relative amounts of myristic (30%) and myristoleic (10%) acids. The remaining fatty acids (FAs) are represented mainly by palmitic (20%) and palmitoleic (40%) acids. We expressed the genes for lysophosphatidic acid acyltransferase (LPAAT; EC 2.3.1.51) and Δ9 fatty acid desaturase (FAD; EC 1.14.19.1) from Cyanobacterium sp. IPPAS B-1200 in Synechococcus elongatus PCC 7942, which synthesizes myristic and myristoleic acids at the level of 0.5-1% and produces mainly palmitic (~60%) and palmitoleic (35%) acids. S. elongatus cells that expressed foreign LPAAT synthesized myristic acid at 26%, but did not produce myristoleic acid, suggesting that Δ9-FAD of S. elongatus cannot desaturate FAs with chain lengths less than C16. Synechococcus cells that co-expressed LPAAT and Δ9-FAD of Cyanobacterium synthesized up to 45% palmitoleic and 9% myristoleic acid, suggesting that Δ9-FAD of Cyanobacterium is capable of desaturating saturated acyl chains of any length.

Оптимизация получения полисахаридов из Cyanobacterium sp. IPPAS B-1200

Cyanobacterium sp. IPPAS B-1200 is a cyanobacteria strain that belongs to the rare genus Cyanobacterium, family Cyanobacteriaceae fam. nov. Studies devoted to the isolation of secondary metabolites from this strain concentrate mostly on the fatty acid composition while the issue of isolating and identifying exopolysaccharides remains understudied. However, polysaccharides from cyanobacteria are of scientific and economic interest in the framework of biotechnology, medicine, pharmacology, etc. The research objective was to study the effect of the physicochemical conditions of cultivation and the composition of the cultural medium on exopolysaccharide production.
 Cyanobacterium sp. B-1200 were grown under 7500 ± 50 lux (12 h light/12 h dark). The dry cell weight was determined by gravimetry and a calibration plot that illustrated the dependence of the biomass amount on the degree of absorption at a wavelength of 750 nm. The amount of polysaccharides in the culture liquid was assessed by the Anthrone-sulphate method. The extraction was carried out by alcohol precipitation. The method of ultrasonic dispersion was used to destroy the cell walls of cyanobacteria. 
 The experimental study revealed the optimal parameters for the extraction and purification of exopolysaccharides from the culture medium. Removal of sodium bicarbonate from the medium and a 300%-increase in its concentration raised the yield of polysaccharides. The optimal value of active acidity for the synthesis of polysaccharides was pH = 6 while the optimal temperature for their accumulation was 35°C. The largest amount of biomass was obtained at 25°C. Intense white illumination contributed to the greatest release of exopolysaccharides into the culture medium; red-white illumination affected the morphology of cyanobacteria cells. During the extraction, the concentration, temperature, and nature of the extractant proved to be the most important factors. For example, isopropanol produced the highest yield while butanol triggered the least effective response. 
 The optimal extraction and purification modes for polysaccharides were as follows. For ultrasonic processing, the best results were obtained at a power of 20 W after 5 min. For freeze drying, the rational parameters were 8 h at –15°C.

DISCOVR strain pipeline screening – Part I: Maximum specific growth rate as a function of temperature and salinity for 38 candidate microalgae for biofuels production

To identify high productivity strains for microalgal biofuels generation, the maximum specific growth rate of 38 strains was measured as a function of salinity (i.e., 5, 15, and 35 PSU) and temperature (i.e., at 8 temperatures along a linear gradient from ca. 5 to 45 °C) to determine the most suitable growth medium salinity and best growing season, respectively, for outdoor raceway pond cultivation. The following strains were evaluated: Agmenellum quadruplicatum UTEX 2268, Anabaena sp. ATCC 33081, Arthrospira fusiformis UTEX 2721, Arthrospira platensis UTEX 3086, Chlorella vulgaris NREL 4-C12, Chlorella autotrophica CCMP 243, Chlorella sorokiniana DOE1044, Chlorella sorokiniana DOE 1116, Chlorella sorokiniana DOE 1412 (UTEXB3016), Chlorella vulgaris LRB AZ-1201, Chlorococcum littorale UTEX 117, Chlorococcum sp. UTEX-B P7, Chloromonas reticulata CCALA 870, Coelastrella sp. DOE 0202, Cyanobacterium sp. AB1, Micractinium reisseri NREL 14-F2, Microchloropsis gaditana CCMP1894, Microchloropsis salina CCMP 1776, Monoraphidium sp. MONOR1, Monoraphidium minutum 26B-AM, Nannochloropsis oceanica CCAP 849/10, Oscillatoria cf. priestleyi CCMEE 5020.1-1, Picochlorum celeri TG2-WT-CSM/EMRE, Picochlorum oklahomensis CCMP 2329, Picochlorum renovo NREL 39-A8, Picochlorum soloecismus DOE 101, Porphyridium cruentum CCMP 675, Scenedesmus acutus LRB-AP-0401, Scenedesmus obliquus DOE 0152.z, Scenedesmus obliquus UTEX393,Scenedesmus rubescens NREL 46B-D3, Scenedesmus sp. IITRIND2, Stichococcus minor CCMP 819, Stichococcus minutus CCALA 727, Synechococcus elongatus UTEX2973.1, Tetraselmis striata LANL 1001, Tisochrysis lutea CCMP 1324, and Tribonema minus UTEXB3156. For each strain, the identity and the presence of bacterial cohorts was determined using 18S and 16S rDNA sequencing, respectively. The maximum specific growth rate versus temperature data were also used to determine the activation energies (Arrhenius equation) for most strains. For all strains, the measured salinity and temperature tolerance data were compared to those reported in the literature. The fastest growing strains were down-selected for subsequent biomass productivity measurements in climate-simulation photobioreactors, as reported in the next paper in the issue.

A newly isolated alkaliphilic cyanobacterium for biomass production with direct air CO2 capture

Large-scale microalgal biomass production usually relies on concentrated CO2 as the carbon source which is a major logistical and economic challenge because of the required infrastructure and geospatial constraints of siting large algal production facilities close to concentrated CO2 sources. By taking advantage of enhanced CO2 mass transfer within alkaline media due to the reaction between CO2 and OH-, carbon can be directly captured from the ambient air and used by the algae. Achieving such goal requires algal strains that can grow fast under alkaline conditions. In this study, a newly isolated alkaliphilic cyanobacterial strain Cyanobacterium sp. PNNL-SSL1 was characterized for its temperature, pH, and salinity tolerance. The result shows that PNNL-SSL1 could sustain grow at pH above 11.2 but exhibited the highest growth rates at pH below 10.5. The strain is a warm season strain and grows the best at 10 PSU (practical salinity unit). The strain was then evaluated in indoor climate simulation ponds under outdoor-relevant pond cultivation conditions with carbon supplied only through direct air CO2 capture at the culture surface. Two batch culture runs, at slightly different initial pH, exhibited average biomass productivity of 15.2 g m-2 day-1 on ash-free dry weight basis. CO2 was directly captured from the air at an average rate of 21.6 g CO2 m-2 day-1 (78.8 tons ha-1 yr-1), contributing 74% of the carbon fixed in the biomass. The results demonstrated that PNNL-SSL1 is a promising strain for biomass production using air CO2 as the carbon source.

New cyanobacterial strains for biohydrogen production

Under certain conditions, cyanobacteria can switch from photosynthesis to hydrogen production, which is a good energy carrier. However, the biological diversity of hydrogen-releasing cyanobacteria has a great unexplored potential. This study is aimed to investigate the ability of new strains of cyanobacteria Cyanobacterium sp. IPPAS B-1200, Dolichospermum sp. IPPAS B-1213, and Sodalinema gerasimenkoae IPPAS B-353 to release H2 and to evaluate the effects of photosystem II inhibitor 3-(3,4-dichlorphenyl)-1,1-dimethylurea (DCMU) on H2 production under light and dark conditions. The results showed that cultures treated with DCMU produced several times more H2 than untreated cells. The highest rate of H2 photoproduction of 4.24 μmol H2 (mg Chl a h)−1 was found in a Dolichospermum sp. IPPAS B-1213 culture treated with 20 μM DCMU.

Assessment of novel halo- and thermotolerant desert cyanobacteria for phycobiliprotein production

Four indigenous cyanobacteria isolates identified as QUCCCM 34: Chroococcidiopsis sp., QUCCCM 54: Pleurocapsa sp., QUCCCM 77: Euhalothece sp., and QUCCCM 129: Cyanobacterium sp. were investigated during this study. Temperatures and salinities observed in outdoor were reproduced indoor, using small-scale photobioreactors, and culture conditions were optimized for maximum biomass and phycobiliprotein productions. The strains showed their halo and thermotolerance capacity. The highest biomass productivity was 125 ± 1.1 mg x L−1 d−1 for Pleurocapsa sp.at 30 °C–40 ppt. The major phycobiliproteins were phycocyanin, and the content was strain and age dependent. Pleurocapsa sp., Euhalothece sp., and Cyanobacterium sp reached their highest phycocyanin content (up to 160 ± 2.6 mgPC gx-1) after 4, 8, and 10 days, respectively, while it was only up to 100 ± 3.5 mgPC gx-1 for Chroococcidiopsis sp. at day 4, 40 °C–60 ppt. Increasing temperature and salinity stimulated the phycocyanin synthesis in Chroococcidiopsis sp, Pleurocapsa sp. and Euhalothece sp., whereas only salinity increment enhanced the pigments production(both phycoerythrin and phycocyanin) for Cyanobacterium sp. Finally, all the pigment extracts exhibited an antioxidant and radical scavenging activity which were maximal for the extracts from Pleurocapsa sp., with ≈ 60 mM Trolox equivalent gx−1 and 50%, respectively.

Assessment of the Biotechnological Potential of Cyanobacterial and Microalgal Strains from IPPAS Culture Collection

A search for strains capable of the simultaneous production of high amounts of several biologically valuable compounds and/or high biomass productivity has been carried out. The growth characteristics and biochemical composition of 12 microalgal and cyanobacterial strains from the IPPAS Collection were studied at the exponential and stationary growth phases. All of the strains had high growth rates (a doubling time of 6–22 h). The strains Cyanobacterium sp. IPPAS B-1200, Chlorella sp. IPPAS C-1210, Nannochloris sp. IPPAS C-1509, Cyanidium caldarium IPPAS P-510, and Vischeria sp. IPPAS H-242 demonstrated the highest biotechnological potential and can be used for the production of various types of biofuel, pigments, and feed and food additives, including those with a high content of eicosapentaenoic acid (20 : 5 Δ5, 8,11, 14, 17).

Prospects for the creation of a waste-free technology for wastewater treatment and utilization of carbon dioxide based on cyanobacteria for biodiesel production

Current fresh water and energy shortage determines the need to study the possibilities of using living objects in bioenergy and environmental purification technologies. The development of waste-free technologies allows waste recycling, which saves raw materials and energy, in turn, reducing waste generation. The effect of different carbon dioxide concentrations and wastewater from households on the growth of cyanobacteria was studied in order to determine their capabilities in the purification processes. It was found that the optimal CO2 concentration for the cultivation of cyanobacteria Cyanobacterium sp. IPPAS B-1200 and Desertifilum sp. IPPAS B-1220 was 10 %, and for the Cyanobacterium aponinum IPPAS B-1201 – 5%. It was revealed that the cultivation of the cyanobacterium Cyanobacterium sp. IPPASB-1200 on wastewater from the water storage reduces the concentration of organic pollutants and, accordingly, improves the physicochemical properties of water. The cleaning percentage for selected pollutants was 68–100 %. It was shown that the most optimal ratio of wastewater to nutrient media for cyanobacteria cultivation were 25:75 and 50:50. The lipid content (%/dry weight) in the biomass of the studied strains of cyanobacteria ranges from 15 to 22% after cultivation in wastewater. It was determined that the strains of Cyanobacterium genus were the most suitable for the production of biodiesel according to their fatty acids composition. It was determined that lipids were composed of only saturated and monounsaturated fatty acids. As a result of the studies, the optimal conditions for the growth of Cyanobacterium sp. IPPAS B-1200 were determined. This microorganism has a good potential to produce biodiesel as a producer of saturated and monounsaturated middle-chain-length fatty acids.

Effects of various CO 2 concentrations on the productivity of cyanobacterial strains

The accumulation of carbon dioxide (CO2) in the atmosphere, as well as pollution ofwater objects with heavy metals, are environmental problems associated with numerous impacts onecosystems. The cultivation of photosynthetic microorganisms that efficiently absorb CO2 is a promisingsolution, since the biomass of cyanobacteria can be used to produce valuable bioproducts. Interest inthe effect of high concentrations of CO2 on the activity of cyanobacteria is growing in connection withstudies of cleaning the atmosphere from industrial pollution using cyanobacteria as biofilters, due totheir ability to grow rapidly in conditions of high CO2 content in the atmosphere. Cyanobacteria are aconvenient object for research due to the high growth rate and controllability of their biosynthesis. Thisarticle presents the results of the influence of different concentrations of carbon dioxide on the productivity of strains of cyanobacteria. Resistance to inhibitory concentrations of CO2 is species-specific andvaries over a wide range of values. The effect of carbon dioxide at a concentration of 2%, 4%, and 8%on the growth rate of cyanobacteria was studied, and a comparative assessment of the effect of increasedcarbon dioxide concentrations on biomass growth from the readings of optical density and fluorescenceactivity was carried out. It was determined that carbon dioxide concentrations of 2-4% have a positive effect on the productivity of the studied cultures of cyanobacteria. It was found that increasing the concentration of CO2 to 8% leads to a decrease in growth rates of cyanobacteria. It was determined that thestrain Cyanobacterium sp. IPPAS B-1200 was selected as the most productive strain from the studied cyanobacteria according to the yield of dry biomass, fluoresce activity and characterized by active growthat a concentration of CO2 in air – 4%.Key words: Carbon dioxide, cyanobacteria, biomass productivity, fluorescence activity

Характеристика биотехнологического потенциала штаммов цианобактерий и микроводорослей коллекции IPPAS

As a result of screening of spore-forming bacteria, a B-13186 strain with a wide spectrum of antagonistic activity identified as Brevibacillus laterosporus by the analysis of sequences of variable sites of 16S rRNA was selected. Morphological, cultural and biochemical characteristics of the strain were studied. A distinctive feature of the strain is the presence of a canoe-like inclusion formed in sporangia and attached to the mature spore, as well as the ability to synthesize round-shaped crystalline inclusions. The strain was shown to be active against various species of gram-positive bacteria including A search for strains capable of simultaneously producing high amounts of several biologically valuable compounds and/or having high biomass productivity has been carried out. The growth characteristics and biochemical composition of 12 microalgae and cyanobacteria strains from the IPPAS Collection in the exponential and stationary growth phases were studied. All the strains had high growth rates (doubling time 6-22 h). The strains of Cyanobacterium sp. IPPAS B-1200, Chlorella sp. IPPAS C-1210, Nannochloris sp. IPPAS C-1509, Cyanidium caldarium IPPAS P-510 and Vischeria sp. IPPAS H-242 demonstrated the highest biotechnological potential and can be used for the production of various types of biofuel, pigments, feed and food additives, including those with high content of eicosapentaenoic (20:5 Δ5,8,11,14,17) acid content. microalgae, cyanobacteria, biochemical composition, fatty acids, valuable metabolites, growth characteristics This work was supported by a grant from the Russian Science Foundation [no. 14-14-00904]

Substrate Specificity of Acyl-Lipid Δ9-Desaturase from Cyanobacterium sp. IPPAS B-1200, a Cyanobacterium with Unique Fatty Acid Composition

Cyanobacterium sp. IPPAS B-1200 is characterized by a high content of rare fatty acids (FAs), both myristic (14:0–30%) and myristoleic (14:1Δ9–10%) in the membrane lipids. Thus, short-chain FAs reach 40% of the sum of all FAs in cells, which is unusual for Cyanobacteria. Monounsaturated palmitoleic acids (16:1Δ9) also reach 40% of the sum of the FAs. We determined the complete nucleotide sequence of the genome of this cyanobacterium and found the only gene for the acyl-lipid Δ9-desaturase, desC1. We cloned this gene and characterized its specificity to the length of the substrate using heterologous expression in Escheriсhia coli. The results show that DesC1 nonspecifically generates olefin bond in FAs with a length of 14, 16, and 18 carbon atoms. This finding confirms that all monoesterifed FAs in Cyanobacterium sp. IPPAS B-1200 are generated by one acyl-lipid Δ9-desaturase.

Screening of isolated and collection strains of cyanobacteria on productivity for determining their biotechnological potential

Cyanobacteria produce a wide range of metabolites, such as proteins, carbohydrates, carotenoids,vitamins and lipids which can be used as potential food sources for human and animals, in pharmaceutical and cosmetic industries and also as energy source. It is known that the technology of using cyanobacteria as fuel raw materials makes one of the central places among the approaches of modern alternativeenergy. To date, the possibility of using cyanobacteria in wastewater treatment with the further use ofbiomass for obtaining biodiesel fuel is being considered. For their application in biotechnology the strainscreening for producers is needed. Prospectivity of types and species for use in biotechnology is firstlydetermined by their productivity. The article presents data of screening of collection and isolated strainsof cyanobacteria: Cyanobacterium sp. B-1200, Cyanobacterium aponium IPPAS B-1201, Synechococcuselongatus 7942, Anabaena variabilis R-I-5 and Nostoc calsicola RI-3. Comparative analysis of constantfluorescence indices, cell growth rate and accumulation of dry weight in cyanobacteria was carriedout. Thus, as a result of investigations, the greatest optical density was noted in Anabaena variabilisR-I-5 strains (1,191) and Cyanobacterium sp. B-1200 (1,281). Fluorescence indices also confirmed thehigh photosynthetic activity of cyanobacteria Cyanobacterium sp. B-1200 (26101 rel.un.) and Anabaenavariabilis R-I-5 (25054 rel.un). Also, investigated strains Anabaena variabilis R-I-5 and Cyanobacteriumaponium IPPAS B-1201 were characterized by relatively high biomass accumulation – 1,19 g/l и 1,36g/l correspondingly. According to obtained data, it was established that cyanobacteria Cyanobacteriumsp. B-1200 and Anabaena variabilis R-I-5 have a relatively high values of growth rate, fluorescence andbiomass yield which determine their high productivity. Thus, in the result of screening strains Cyanobacterium stanieri B-1 and Anabaena variabilis R-I-5 were selected for further investigations of theirphysiological and biochemical properties with the purpose to determine potential producers of valuablemetabolites for biotechnology.Key words: screening, cyanobacteria, biomass, fluorescence, biotechnological potential

Determination of Storage (Starch/Glycogen) and Total Saccharides Content in Algae and Cyanobacteria by a Phenol-Sulfuric Acid Method.

This is a protocol for quantitative determination of storage and total carbohydrates in algae and cyanobacteria. The protocol is simple, fast and sensitive and it requires only few standard chemicals. Great advantage of this protocol is that both storage and total saccharides can be determined in the cellular pellets that were already used for chlorophyll and carotenoids quantification. Since it is recommended to perform the pigments measurement in triplicates, each pigment analysis can generate samples for both total saccharide and glycogen/starch content quantification. The protocol was applied for quantification of both storage and total carbohydrates in cyanobacteria Synechocystis sp. PCC 6803, Cyanothece sp. ATCC 51142 and Cyanobacterium sp. IPPAS B-1200. It was also applied for estimation of storage polysaccharides in Galdieria (IPPAS P-500, IPPAS P-507, IPPAS P-508, IPPAS P-513), Cyanidium caldarium IPPAS P-510, in green algae Chlorella sp. IPPAS C-1 and C-1210, Parachlorella kessleri IPPAS C-9, Nannochloris sp. C-1509, Coelastrella sp. IPPAS H-626, Haematococcus sp. IPPAS H-629 and H-239, and in Eustigmatos sp. IPPAS H-242 and IPPAS C-70.

Autoselection of Cyanobacterium sp. IPPAS B-1200 strain – Potential producer of biodiesel

Autoselection of Cyanobacterium sp. IPPAS B-1200 strain – Potential producer of biodiesel

Characterization of Function of the GlgA2 Glycogen/Starch Synthase in Cyanobacterium sp. Clg1 Highlights Convergent Evolution of Glycogen Metabolism into Starch Granule Aggregation.

At variance with the starch-accumulating plants and most of the glycogen-accumulating cyanobacteria, Cyanobacterium sp. CLg1 synthesizes both glycogen and starch. We now report the selection of a starchless mutant of this cyanobacterium that retains wild-type amounts of glycogen. Unlike other mutants of this type found in plants and cyanobacteria, this mutant proved to be selectively defective for one of the two types of glycogen/starch synthase: GlgA2. This enzyme is phylogenetically related to the previously reported SSIII/SSIV starch synthase that is thought to be involved in starch granule seeding in plants. This suggests that, in addition to the selective polysaccharide debranching demonstrated to be responsible for starch rather than glycogen synthesis, the nature and properties of the elongation enzyme define a novel determinant of starch versus glycogen accumulation. We show that the phylogenies of GlgA2 and of 16S ribosomal RNA display significant congruence. This suggests that this enzyme evolved together with cyanobacteria when they diversified over 2 billion years ago. However, cyanobacteria can be ruled out as direct progenitors of the SSIII/SSIV ancestral gene found in Archaeplastida. Hence, both cyanobacteria and plants recruited similar enzymes independently to perform analogous tasks, further emphasizing the importance of convergent evolution in the appearance of starch from a preexisting glycogen metabolism network.

Bio-optical characterization of selected cyanobacteria strains present in marine and freshwater ecosystems.

The optical properties, i.e., absorption and scattering spectra of ten strains of cyanobacteria from the Baltic Sea and Pomeranian lakes (Aphanizomenon flos-aquae KAC 15, Microcystis aeruginosa CCNP 1101, Anabaena sp. CCNP 1406, Synechocystis salina CCNP 1104, Phormidium sp. CCNP 1317, Nodularia spumigena CCNP 1401, Synechococcus sp. CCNP 1108, Nostoc sp. CCNP 1411, Cyanobacterium sp. CCNP 1105, Pseudanabaena cf. galeata CCNP 1312) grown under low light conditions were investigated. Moreover, the chlorophylls, carotenoids, and phycobilin composition as well as the size structure of chosen cyanobacteria were measured. Studied species revealed high diversity both in optical properties with the absorption spectra similarity index ranging from 0.67 to 0.94 and the pigment composition. The chlorophyll-specific absorption coefficient at 440 nm aph*(440) varied between 0.017 and 0.065 m2 mg−1. The influence of the package effect was only observed in the case of large filamentous cyanobacteria like N. spumigena or Nostoc sp. Interestingly, the package effect factor Qa*(675) for large-celled Anabaena sp. was 0.92. Besides chlorophyll a, only echinenone, β-carotene, and phycocyanin were present in all analyzed cyanobacteria strains. Zeaxanthin, which is widely used as a marker pigment for cyanobacteria, was absent in the toxic N. spumigena and Anabaena sp., which are the species that occur in the Baltic Sea most frequently causing summer cyanobacterial blooms. The investigation also showed that the sample preservation technique can introduce some major errors within the absorption band affected by the phycocyanin absorption.

Functional characterization of three (GH13) branching enzymes involved in cyanobacterial starch biosynthesis from Cyanobacterium sp. NBRC 102756

Starch and glycogen are widespread storage polysaccharides in bacteria, plants, and animals. Recently, some cyanobacteria were found to accumulate water-insoluble α-glucan similar to amylopectin rather than glycogen, the latter of which is more commonly produced in these organisms. The amylopectin-producing species including Cyanobacterium sp. NBRC 102756 invariably have three branching enzyme (BE) homologs, BE1, BE2, and BE3, all belonging to the glycoside hydrolase family 13. Multiple BE isoforms in prokaryotes have not been previously studied. In the present work, we carried out functional characterization of these enzymes expressed in Escherichia coli. The recombinant enzymes were all active, although the specific activity of BE3 was much lower than those of BE1 and BE2. After the incubation of the enzymes with amylopectin or amylose, the reaction products were analyzed by fluorophore-assisted carbohydrate capillary electrophoresis method. BE1 and BE2 showed similar chain-length preference to BEIIb isoform of rice (Oryza sativa L.), while the catalytic specificity of BE3 was similar to that of rice BEI. These results indicate that starch-producing cyanobacteria have both type-I BE (BE3) and type-II BEs (BE1 and BE2) in terms of chain-length preferences, as is the case of plants. All BE isoforms were active against phosphorylase limit dextrin, in which outer branches had been uniformly diminished to 4 glucose residues. Based on its catalytic properties, BE3 was assumed to have a role to transfer the glucan chain bearing branch(es) to give rise to a newly growing unit, or cluster as observed in amylopectin molecule.

Isolation and Characterization of a New Cyanobacterial Strain with a Unique Fatty Acid Composition

A new cyanobacterial strain was isolated and purified from salt Lake Balkhash, Kazakhstan. According to its morphological and ultrastructural characteristics, 16S rRNA sequence and the fatty acid profile, the strain has been classified as Cyanobacterium spp. and assigned as Cyanobacterium sp. IPPAS B-1200. The strain is characterized by a non-temperature inducible Δ9-desaturation system, and by high relative amounts of myristic (14:0—30%) and myristoleic (14:1Δ9—10%) acids. The total amount of C14 fatty acids reaches 40%, which is unusually high for cyanobacteria, and it has never been reported before. The remaining fatty acids are represented mainly by palmitic (16:0) and palmitoleic (16:1Δ9) acids (the sum reaches nearly 60%). Such a fatty acid composition, together with a relatively high speed of growth, makes this newly isolated strain a prospective candidate for biodiesel production.

Physicochemical Variation of Cyanobacterial Starch, the Insoluble α-Glucans in Cyanobacteria

Unicellular, diazotrophic species of cyanobacteria, Cyanobacterium sp. NBRC 102756, Cyanothece sp. ATCC 51142 and Cyanobacterium sp. CLg1, accumulate insoluble α-glucan inside the cells as the storage polysaccharide. The purified polysaccharides showed granular morphology, with a diameter of 0.2-0.7 µm. The three α-glucan preparations all showed A-type allomorph in X-ray diffraction analysis. Distinct thermal gelatinization temperatures were observed for these polysaccharides. The α-glucans from NBRC 102756 and ATCC 51142 strains consisted solely of branched α-glucans, or semi-amylopectin, while CLg1 contained semi-amylopectin as the primary component as well as linear or scarcely branched glucan (amylose). Separation of the debranched glucan chains by gel filtration chromatography explicitly showed the presence in the semi-amylopectin molecule of long chains corresponding to B2 chains, which connect clusters in amylopectin of plants. The relative proportions of short and long glucan chains in the branched polysaccharides differed depending on the species, and the variation was intimately correlated with the physical properties of the α-glucans. The results suggested that semi-amylopectin of the three cyanobacteria exhibit essentially similar organization with a tandem cluster structure. The polysaccharides of these strains are therefore referred to as 'cyanobacterial starch', distinct from glycogen.

Cyanobacterium sp. NBRC 102756 株のデンプン生産能に及ぼす鉄栄養、光照射条件の検討

Cyanobacterium sp. NBRC 102756 株のデンプン生産能に及ぼす鉄栄養、光照射条件の検討