Enriched Seawater Medium Research Articles

MORPHOGENESIS OF MONOSTROMA OXYSPERMUM (KÜTZ.) DOTY (CHLOROPHYCEAE) IN AXENIC CULTURE, ESPECIALLY IN BIALGAL CULTURE1

ABSTRACTThe typical morphology of Monostroma oxyspermum (Kütz.) Doty is lost in axenic culture. In synthetic media of the ASP type, it grows as a colony‐like mass composed of round cells with numerous rhizoids. Such a mass is a fragile structure which falls apart upon shaking, or slight touch, into small cell‐groups and single cells or cells with a long rhizoid. Only temporary saccate or monostromatic fronds appear and reach 1–2 mm in length when grown in enriched seawater media, but disintegrate and become a colony‐like mass. The typical morphology is easily restored by adding at specific intervals filtrates of bacterial cultures and supernatant medium from axenic brown and red algal cultures to the basal medium (ASP7), or by reinfecting the Monostroma with an appropriate bacterial flora. Furthermore, the typical morphology in also maintained by bialgal cultures between Monostroma and other axenic strains of various species of seaweeds except the species belonging to the Chlorophyceae. Monostroma thus appears to utilize some substances released by most species of brown and red algae for its typical growth. Active substances released by bacteria, brown and red algae have not yet been identified and purified. However, it is demonstrated that in axenic cultures many species of seaweeds produce active extracellular substances which play an important role in growth and Morphogenesis of other species of seaweeds.

Induction of colony formation inOlisthodiscus luteusCarter

Olisthodiscus luteus Carter, a marine member of the Chrysophyceae can be grown in two morphological forms: as motile biflagellated unicells in an inorganic seawater medium and as non-coenobic colonies in an enriched seawater medium. The spherical colonies consisted of from two to 22 cells. The transition from unicells to colonies starts 2 days after the transfer of cells from inorganic seawater into enriched seawater medium while the transformation from the colonial to the unicellular habit of growth is almost completed 2 days after the retransfer of the culture into plain seawater medium.

ROLE OF INORGANIC IONS IN CONTROLLING SEDIMENTATION RATE OF A MARINE CENTRIC DIATOM DITYLUM BRIGHTWELLI1,2

ABSTRACT The settling rates and intracellular levels of K+, Na+, Cl‐, Mg2+ and Ca2+ were measured in Ditylum bright‐welli (West) Grunow, grown axenically in an enriched seawater medium at 20 C at 4,000 lx on an 8:16 LD schedule. Cells at the end of the dark period have high Na+ (118 mM), low K+ (64 mM) and low Cl‐ (117 mM) relative to levels at the end of the light period when K+ (126 mM) and Cl‐ (154 mM) are high and Na+ (101 mM) is low. There is no significant change in Mg2+ (16–18 mM) or Ca2+ (3–4 mM) with time. The net result of the ion changes during the light period is to increase cell density by about 3.4 mg ml‐1. This change can account for the increase in settling rate of ca. 0.3 day‐1 during the same interval. The density of the cell contents, calculated from observed ion concentrations, is 15–18 mg.ml‐1 less than that of the seawater medium. The ion and settling rate changes are light‐dependent and do not persist in the dark or under constant light (ca. 850 lx), but cells do exhibit a free‐running circadian rhythm in cell division under continuous dim illumination. The cell vacuole expands during the light period and contracts during the dark, apparently in response to the net ion fluxes. D. brightwelli appears to regulate its density by active ion selectivity accompanied by trans‐vacuolar water movement.

Medullary tissue culture of the red alga Chondrus crispus

Techniques were developed for the isolation and axenic culture of medullary tissue explants from female gametophytic fronds of Chondrus crispus Stackh. When a strain with narrow thick branches was grown in vitro in a special, enriched seawater medium with added growth regulators, the colourless medullary tissue explants (2-mm cubes) produced fronds exhibiting the normal morphology of the parent plant.

Degradation ofn-paraffin mixture by marine microorganisms in enriched seawater medium

The ability to degraden-paraffin mixture of two bacterial strains,Caulobacter sp. andFlavobacterium sp., isolated from sea water of Tokyo Bay was studied experimentally in the enriched seawater (ESW) medium. These bacteria degraded actively the mixture ofn-tridecane,n-tetradecane,n-pentadecane andn-hexadecane.

A circular dichroism study of the effects of a hemolytic toxin from gymnodinium breve, the Florida red tide organism, on human erythrocyte membranes

Abstract G.ymnodinium breve, the Florida red tide organism, was cultured in enriched seawater medium; the toxin was extracted and a hemolytic fraction separated by column chromatography on Sephadex LH‐20–100. The circular dichroism spectra of isolated human erythrocyte membranes incubated with and without the hemolytic toxin were taken. No changes in the membranes due to the toxin were detected, indicating that membrane proteins were not affected. It was shown that the hemolytic toxin was removed from solution by the isolated membranes, indicating that the toxin was binding to the membranes.

EFFECTS OF TEMPERATURE AND ILLUMINANCE ON CELL DIVISION RATES OF THREE SPECIES OF TROPICAL OCEANIC PHYTOPLANKTON1

SUMMARY Three species of tropical oceanic phytoplankton were isolated from two locations in the eastern Pacific Ocean. Unialgal cultures were maintained in an enriched seawater medium. The effects of temperature, and, in separate experiments, illuminance, on the exponential cell division rates of those algae were investigated. For 2 isolates of Gymnodinium sp. (probably G. simplex), maximum growth rates were 1.25 and 1.7 divisions/24 hr, the optimum temperature range was 23–29 C, the compensation illuminance was 35 ft‐c, and the saturation illuminance was 750 ft‐c and above. For a small species of Chaetoceros, the maximum growth rate was 6.0 divisions/24 hr, the optimum temperature range was 23–37 C, the compensation illuminance was 10 ft‐c, and the saturation illuminance was 600 ft‐c. For a small Nannochloris species, the maximum growth rate was 4.5 divisions/ 24 hr, the optimum temperature range was 27–37 C, and the saturation illuminance was 800 ft‐c. Nannochloris grew heterotrophically by apparently utilizing organic matter supplied by soil extract.

A SEAWATER MEDIUM FOR DINOFLAGELLATES AND THE NUTRITION OF CACHONINA NIEI1

SUMMARYTwo media have been devised: an enriched seawater medium for culture of dinoflagellates and a defined medium for rapid growth of the dinoflagellate Cachonina niei. A wide range in salinity (10.23–42.38 g/liter NaCl) is tolerated by C. niei. Below 0.6 g/liter MgSO4, 0.19 g/liter KCl, and 0.22 g/liter CaCl2, the generation time greatly increases. Increase in MgSO4 to 7.22 g/liter, KCl to 1.12 g/liter or CaCl2 to 2.22 g/liter has little effect on generation time. The temperature optimum is 19–23 C. Saturating light intensity for growth is 1000 ft‐c and for photosynthesis (determined manometrically) is slightly less than 2000 ft‐c. Cachonina niei requires B12 and thiamin. Neither silicate nor its competitive inhibitor germanate affects generation time or cell yield indicating silicon is not required. Of a variety of buffers tested, Tris is the best. Optimal growth occurs at pHs of 7.5–8.3. Glycerol is inhibitory and does not support dark growth.

Effects of salinity on synthesis of DNA, acidic polysaccharide, and ichthyotoxin in Gymnodinium breve

A Florida red tide organism, Gymnodinium breve Davis, an unarmored dinoflagellate, was grown in enriched sea water media at salinities 20–43% and constant illumination. Use of lowest (23%) and highest (43%) salinities resulted in death within 24 hr of inoculation, though good growth was obtained at all intermediate salinities (29–39%), in accord with field observation. Rates of synthesis of DNA, acidic polysaccharide and ichthyotoxin were determined as a function of salinity and growth constant (K 10). The relative rate of' synthesis of DNA or polysaccharide increased linearly with growth constant. Mean cell volumes, determined during log-phase growth, showed a positive correlation with doubling time. Hemolytic activity was detected in cell extracts only at high toxin concentrations (0.35–2.05 mg of ichthyotoxin). No significant difference was noted in hemolytic activity of extracts of cells grown in high (34%) or low (26%) salinity. The rate of toxin synthesis showed a linear decrease with the rate of DNA or polysaccharide synthesis.

The life history ofPetrocelis franciscana

Tetraspores from Petrocelis franciscana Setch. et Gardn. collected at Rockaway Beach, San Mateo County, California, 11 January 1971 were isolated into unialgal culture with Provasoli's enriched seawater medium at 10° and 15° C, 16:8 daily photoregime, 2000–2500 lx cool white fluorescent lighting. The germlings developed as crustose discs with marginal meristems until about 300–500 µm in diameter when erect multiaxial blades were established. The erect plants grew to reproductive maturity in 15° C but not in 10° C. By the fifth month of growth the erect axes flattened and branched dichotomously. At the end of 7 months the plants were reproductively mature. These cultured plants were morphologically similar to Gigartina agardhii Setch. et Gardn. (subgenus Mastocarpus) which occurs abundantly at Rockaway Beach. Male plants were non-papillate with spermatangia forming on the entire blade surface except at the growing tip and near the stipe. The female plants developed papillae which bore many procarps. Many o...

The culture of four species of Fucus under laboratory conditions

Mature thalli of Fucus distichus, F. edentatus, F. serratus, and F. vesiculosus were obtained in unialgal culture from zygotes and were grown in an enriched seawater medium. The two former species were maintained in culture for more than 2 years, in which time the length of thalli of F. edentatus never exceeded 4 cm. The other species grew reasonably well with a maximum rate of elongation of about 1 cm per month for F. serratus. In all species the rates of growth were less than that observed in nature. Fertile receptacles with viable gametes were formed in F. distichus, but the other species never attained reproductive maturity. All specimens retained their characteristic morphology under identical conditions of culture, and it is suggested that morphological variation amongst Fucus spp. is due mainly to hybridization rather than to environmental conditions. There was no indication that any of these species required intertidal conditions, and no unique nutritional requirements were identified.

LABORATORY STUDIES OF A GREEN NOCTILUCA FROM NEW GUINEA1,2

SUMMARYA strain of Noctiluca miliaris Suriray, containing in the vacuole a motile green flagellate, was collected off the north shore of New Guinea and maintained in culture in autoclaved seawater or an enriched seawater medium. In light, this green Noctiluca survived for at least a month and divided, without added food; while in darkness the symbiotic flagellate disappeared and the Noctiluca died within a few days, unless the food organism Dunaliella tertiolecta was present. Long‐continued growth in light required the presence of Dunaliella, since the symbiotic flagellate was gradually lost under all the culture conditions assayed.All green Noctiluca assayed were luminescent. The light emitted per cell varied with the nutritional state of the host, and was as bright as a Japanese strain without symbionts when the Noctiluca was feeding on Dunaliella. In the absence of Dunaliella, the light emitted per Noctiluca depended on the light intensity in which cultures were maintained. The luminescent flash followed the same time course as that of other strains of Noctiluca without symbionts. No circadian rhythm of luminescence was present.Observations on both the growth and luminescence show that the flagellate symbiont contributes to the nutrition of the green Noctiluca. The symbiosis, however, is unstable in culture.

THE GROWTH AND MORPHOLOGY OF THE SILICOFLAGELLATE DICTYOCHA FIBULA EHRENBERG IN CULTURE1,2

SUMMARY Dictyocha fibula was cultured in an enriched seawater medium from collections taken at Edmonds, Washington. The optimum temperature for growth is 10 C at salinity 24% and 160 ft‐c illumination in Provasoli enriched seawater at the concentration of 7.5 ml/liter seawater. Average generation time is 49 hr. In addition to swimming cells with skeletons, swimming cells without skeletons and nonswimming coenocytes were observed in clonal cultures at 15 C.

EFFECTS OF TEMPERATURE AND ILLUMINANCE ON CELL DIVISION RATES OF THREE SPECIES OF TROPICAL OCEANIC PHYTOPLANKTON(1).

Three species of tropical oceanic phytoplankton were isolated from two locations in the eastern Pacific Ocean. Unialgal cultures were maintained in an enriched seawater medium. The effects of temperature, and, in separate experiments, illuminance, on the exponential cell division rates of those algae were investigated. For 2 isolates of Gymnoclinium sp. (probably G. simplex), maximum growth rates were 1.25 and 1.7 divisions/24 hr, the optimum temperature range was 23-29 C, the compensation illuminance was 35 ft-c, and the saturation illuminance was 750 ft-c and above. For a small species of Chaetoceros, the maximum growth rate was 6.0 divisions/24 hr, the optimum temperature range was 23-37 C, the compensation illuminance was 10 ft-c, and the saturation illuminance was 600 ft-c. For a small Nannochloris species, the maximum growth rate was 4.5 divisions/ 24 hr, the optimum temperature range was 27-37 C, and the saturation illuminance was 800 ft-c. Nannochloris grew heterotrophically by apparently utilizing organic matter supplied by soil extract.

SOME CONSIDERATIONS OF THE GROWTH OF MARINE ALGAE IN ARTIFICIAL MEDIA.

Growth of 10 species of unicellular marine algae, representative of seven classes, in an enriched seawater medium was compared with growth in several artificial media. All media were buffered with glycylglycine, which was found to be less inhibitory than tris(hydroxymethyl)aminomethane. Growth of most species in natural seawater was superior to that in the artificial media examined, but the addition of 2 mM bicarbonate to these media resulted in improved growth comparable to that in the enriched seawater medium. All organisms were euryhaline and grew well in at least 50% seawater. Although considerable variation in the concentration of the major cations was tolerated, the concentration at which a particular cation limited growth was not the same for each species. Large changes in the magnesium-to-calcium ratio did not appear to affect growth, but a relation between sodium and magnesium and calcium was indicated for several organisms.

A MICROBIOLOGICAL ASSAY FOR BIOTIN IN SEAWATER

A method is described for the direct bioassay of biotin in seawater samples. The assay organism is an unidentified marine bacterium that shows a growth response, in enriched seawater medium, proportional to dissolved biotin concentration in the range 3–12 μμg/ml. The growth was measured turbidimetrically with a spectrophotometer. The effective assay range was extended successfully to higher biotin levels by making appropriate dilutions in synthetic seawater.

THE GROWTH OF UNICELLULAR ALGAE IN ARTIFICIAL AND ENRICHED SEA WATER MEDIA

The growth of pure cultures of Dutialiella euchlora strains WHOI-1 and WHOI-2, Platymonas subcordiformis, Phaeodactylum tricormitum, Chlorella vulgaris, and Cyclotella meneghiniana was compared in two enriched sea water media and two artificial marine media. Three general patterns of growth were observed; the green flagellates grew the same in all media, Phaeodactylum and Chlorella grew more slowly in the artificial media, and Cyclotella did not grow in the artificial medium without organic supplements. The addition of vitamin B12 to the artificial medium promoted good growth of Cyclotella, and of the species studied this alga was the only auxotroph. Growth in the enriched sea water medium was not affected by a precipitate, but removal of the precipitate markedly affected the rate of growth and the total number of cells obtainable.