Chase Van Baalen

Hydrocarbons of Blue-Green Algae: Geochemical Signfficance

The hydrocarbon compositions of 11 species of blue-green algae are simple and qualitatively similar. Three marine coccoids contain only monoenoic and dienoic C19 hydrocarbons. Hydrocarbons of the remaining eight species are C15 to C18. Hydrocarbons of higher molecular weight (C20 or more) were not detected. Blue-green algae do not appear to be the source material for the longchain (greater than 20 carbons) hydrocarbons found in ancient sediments.

Maximum carbon isotope fractionation in photosynthesis by blue-green algae and a green alga

Abstract The maximum carbon isotope fractionation occurring in photosynthetic fixation of carbon dioxide in pure cultures of blue-green algae was −23.9%. and for a green alga was −22.6%., Maximum fractionations were obtained where cell densities were low and carbon dioxide concentrations were greater than 0.5%. Fractionation was reduced at higher temperatures using a thermophilic blue-green alga. For filamentous blue-green algae wherein clumping occurs and localized cell concentrations were high, fractionation was also lower. Fractionations reported in literature for Precambrian organic materials are comparable to the maximum fractionations reported here. This suggests that the early photosynthetic organisms developed under conditions of high carbon dioxide availability, i.e. slow growth rates and/or low population densities.

FURTHER OBSERVATIONS ON GROWTH OF SINGLE CELLS OF COCCOID BLUE‐GREEN ALGAE

Initiation of growth (lag) and subsequent growth to visible colonies was examined for single cells of several coccoid blue-nreen algae under controlled incuba-tion conditions. At 30 or 39 C, with tungsten or fluorescent illumination, organisms such as Agmenel-lum quadruplicatum, strains PR-6 and strain BG-J, showed no evidence of lag associated with initiation of growth. The final colony count was within 20% of the expected number derived from cell counts and serial dilutions. For Anacystis nidulnns, Tx 20, a new medium C, 10 with EDTA as chelator was developed. In this medium groiuth of single cells at 39 C was excellent with quantitative recovery and no evidence of lag. At 30 C, however, Tx 20 showed anomalous behavior, lag and nonquantitative cell recovery. This behavior at 30 C is not yet understood.Initiation of growth (lag) and subsequent growth to visible colonies was examined for single cells of several coccoid blue‐nreen algae under controlled incuba‐tion conditions. At 30 or 39 C, with tungsten or fluorescent illumination, organisms such as Agmenel‐lum quadruplicatum, strains PR‐6 and strain BG‐J, showed no evidence of lag associated with initiation of growth. The final colony count was within 20% of the expected number derived from cell counts and serial dilutions.

Oxidation of biphenyl by the Cyanobacterium, Oscillatoria sp., strain JCM

The oxidation of biphenyl by Cyanobacterium, Oscillatoria sp., strain JCM was studied. The organism grown photoautotrophically in the presence of biphenyl oxidized biphenyl to form 4-hydroxybiphenyl. The structure of the metabolite was elucidated by ultraviolet and mass spectra and shown to be identical to authentic 4-hydroxybiphenyl. In addition this metabolite had properties indentical to 4-hydroxybiphenyl when analyzed by thin-layer and high-pressure liquid chromatography. Experiments with [14C]-biphenyl showed that over a 24 h period the organism oxidized 2.9% of the added biphenyl to ethyl acetate-soluble products.

Isolation and characterization of heterocysts from Anabaena sp. strain CA

A comparative study has been made on the pigment composition and nitrogenase activity of whole filaments and isolated beterocysts from a mutant strain of Anabaena CA. The whole cell absorption spectra of intact filaments and isolated heterocysts showed close resemblance especially between 550–700 nm region. On a quantitative basis the chlorophyll a content was found almost equal between the vegetative cell and heterocyst but the c-phycocyanin content in the heterocyst was about 1/2 that of the vegetative cell. The purification of the phycobiliprotein on DEAE-cellulose showed the presence of c-phycocyanin (γmax 615 nm) and allophycocyanin (γmax 645 nm, shoulder 620 nm). Isolated heterocysts under H2 showed acetylene reduction rates of 57 nmol C2H4/mg dry wt·min (342 μmol C2H4/mg chl a·h), whereas intact filaments reduced at the rate of 18 nmol C2H4/mg dry wt·min (108 μmol C2H4/mg chl a·h). This rate accounts for 30% recovery of nitrogenase activity in isolated heterocysts compared to whole filaments. The activity was strictly light dependent and was linear under H2 for more than 3 h. Addition of as little as 5% H2 under argon stimulated the C2H2 reductionseveral fold. The acetylene reduction (nitrogenase activity) also showed tolerance to 5% added O2 either under H2 or argon. The results suggest that the heterocyst of Anabaena CA-V is different in some characteristics (viz., higher endogenous C2H2 reduction rate, prolonged activity and higher levels of phycobiliproteins) than those reported in other Anabaena species.

Metabolism and toxicity of 1- and 2-methylnaphthalene and their derivatives in cyanobacteria

Agmenellum quadruplicatum strain PR-6, Oscillatoria sp. strain JCM and Anabaena sp., strain CA grown photoautotrophically in the presence of either 1- or 2-methylnaphthalene oxidized both compounds at the methyl group to form 1-hydroxymethylnaphthalene and 2-hydroxymethylnaphthalene, respectively. Ring hydroxylated metabolites were not detected. The metabolites were isolated by thin-layer, high performance liquid and gas chromatography and identified by comparison of chromatographic and mass spectral properties with those of authentic compounds. The extent of 1- and 2-methylnaphthalene metabolism to ethyl acetate soluble metabolites ranged from 0.7 to 3.2%.Incubation of Agmenellum quadruplicatum strain PR-6 with 2-methylnaphthalene and molecular oxygen-18 led to the isolation of 2-hydroxymethylnaphthalene that contained oxygen-18. The toxicity of naphthalene, 1- and 2-methylnaphthalene and their derivatives on the growth of Agmenellum quadruplicatum strain PR-6 was investigated using the algal lawn technique. Phenol and quinone derivatives of naphthalene, 1- and 2-methylnaphthalene were most inhibitory. Alkyl side chain hydroxylation products, such as the hydroxymethyl derivatives of 1- and 2-methylnaphthalene were more toxic than the parent methylnaphthalenes. 1- and 2-Naphthoic were not toxic to the cyanobacterium.

Biotransformation and toxicity of aniline and aniline derivatives in cyanobacteria

Agmenellum quadruplicatum strain PR-6 and Oscillatoria sp. strain JCM grown photoautotrophically in the presence of aniline metabolized the aromatic amine to formanilide, acetanilide and p-aminophenol. The metabolites were isolated by either thin-layer, gas-liquid or high pressure liquid chromatography and identified by comparison of their chromatographic, ultraviolet absorbance and mass spectral properties with those of authentic compounds. The toxicity of aniline derivatives towards Agmenellum quadruplicatum strain PR-6 indicated that the cyanobacterium was extremely sensitive to o-, m- and p-aminophenols, and phenylhydroxylamine.

Isolation and characterization of rapidly-growing, marine, nitrogen-fixing strains of blue-green algae

Five strains of heterocystous blue-green algae capable of high rates of growth and nitrogenase activity were isolated from shallow coastal environments. Growth of the organisms was characterized with respect to temperature, NaCl concentration in the medium, and nitrogen source. The temperature optima ranged from 35–42°C, and all but one of the strains displayed a requirement for added NaCl. The generation times under N2-fixing conditions were 5.1–5.9 h, and were as low as 3.4 h for growth on NH4Cl. Nitrogenase activity (C2H2 reduction) was high throughout the logarithmic growth phase of each strain. The maximum value observed for one strain was 65.5 nmoles C2H4 produced/mg protein x min, and the average values for the five strains ranged from 24.5–46.7 nmoles C2H4/mg protein x min. The organisms all belong to the genusAnabaena. The growth and nitrogenase activity of these strains are much higher than those of the heterocystous blue-green algae commonly used for investigation of nitrogen metabolism, and they thus should prove to be useful physiological tools. Their prevalence, as judged by the ease of their enrichment and isolation, in bay and estuarine environments suggests that they are important contributors of combined nitrogen.

PURIFICATION OF RIBULOSE 1,5‐BISPHOSPHATE CARBOXYLASE AND CARBON ISOTOPE FRACTIONATION BY WHOLE CELLS AND CARBOXYLASE FROM CYLINDROTHECA SP. (BACILLARIOPHYCEAE.)1,2,3

Ribulose 1,5‐biphosphate carboxylase has been purified to homogeneity from extracts of Cylindrotheca sp. (strain N‐1), a marine, pennate diatom. The carboxylase has a molecular weight and structural composition similar to the enzyme from higher plants. When assayed in the presence of 1 mM NaHCO3 the enzyme was stimulated nearly 40% by 1 mM aspartate and over 20% by 1 mM malate, and was inhibited to over 60% by 1 mM phosphoenolpyruvate. Similar experiments, using spinach carboxylase, failed to show activation by these metabolites. When assayed in the presence of 20 mM NaHCO3, 6‐phosphogluconate (1 mM) inhibited activity of ribulose bisphosphate carboxylase from Cylindrotheca by 60%, and higher concentrations of maiate (10 mM) inhibited activity by 25% Carbon isotope fractionation by ribulose bisphosphate carboxylase was ‐32.6% (ppt) when measured under N2 using homogeneous enzyme, whereas maximum carbon isotope fractionation by the whole alga grown in 1% ‐C02‐in air averaged ‐ 16.8%. Carbon isotope fractionation by the whole alga varied with the density of the culture and was maximum at a low cell density (1.7 ± 106 cellslml). At higher densities, the fractionation decreased by 4.0%. Carbon isotope fractionation has been used previously to determine the pathway of carbon metabolism in other organisms; the results of this investigation seem to indicate that this strain uses both the reductive pentose phosphate pathway and the C4 carbon pathway for primary CO2 fixation.

Growth requirements of blue-green algae under blue light conditions

Abstract1.Growth requirements of blue-green algae containing only the c-phycocyanin + chlorophyll a pigment system have been studied under blue light (380–540 nm) which approximates light conditions existing in subsurface waters in nature.2.While a few species were capable of very slow photosynthetic growth on minimal medium with NO3- as nitrogen source, most species were dependent on organic compounds for comparable growth under this condition. Some organisms did quite well with only Casamino Acids as a supplement, others did well with only glucose. One species, Agmenellum quadruplicatum strain PR-6, grew only when glucose and Casamino Acids were supplied simultaneously.3.Inhibitory effects of blue light on CO2 fixation and nitrogen metabolism are noted as possible explanations of these responses.