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A new simple method for estimating the number of individual cells per milliliter in suspensions of filamentous microorganisms is described. This 2-part procedure utilizes a standard microscopic counting chamber and is independent of filament length or individual cell size. A statistical analysis of the method is also presented. [ABSTRACT FROM AUTHOR]

An empirical relation relating specific growth rate in steady state systems to nutrient status with respect to more than one nutrient simultaneously is proposed, based on 3 experimetnally verifiable postulates: (1) that uptake depends on the external substrate concentration; (2) that growth depends on the internal substrate cocnentration; and (3) in a steady state system specific rate of uptake (in the absence of significant excretion) is necessarily the product of the specific growth rate and internal substrate cocnentration. The implications of this model are discussed in particular in respect to the concept of luxury consumption and Liebig's law of minimum. Some aspects of uptake in transient situations are also discussed. [ABSTRACT FROM AUTHOR]

Membrane filters retain [SUP14]C bicarbonate, [SUP14]C glycollate, and other [SUP14]C labeled substances from filtrates of algal cultures and lake water. By refiltering different volumes of the filtrate from algal cultures and from lake water after incubation with [SUP14]C bicarbonate, it was shown that the labeled material retained was not proportional to volume but showed a saturation effect with increasing volume filtered. When the radioactivity retained by a filter is divided by the volume filtered, decreasing values are obtained with increased volume filtered. This radioactivity may represent a significant addition to the radioactivity in particulate material on the filters, resulting in a similar type of curve when different volumes of lake water or cultures are filtered. Values of radioactivity per milliliter were constant using Chlorella in Chu 10 medium. However, the curve could be obtained by increasing pH and bicarbonate concentrations in the medium and on resuspending the algae in Lake Ontario (winter) filtrate. The values of cpm/ml retained from filtrates were low in Cryptomonas cultures and the curve was not obtained unless population density was reduced, thus increasing the relative contribution to the radioactivity on the filters. The curve was not always obtained in lake water. It was significant in 10 out of 14 experiments in Lake Ontario and in 2 out of 5 experiments in Grenadier Pond. Changes in lake water rather than in experimental techniques were probably responsible. On 2 occasions when values of cpm/ml were constant in Lake Ontario, addition of sodium bicarbonate without a pH change resulted in a significant curve. Our experiments do not disprove the possibility of cell damage during Millipore filtration, however, it has been shown that [SUP14]C labeled substances retained from solutions can account for the entire range of decreasing values as a function of volume filtered. [ABSTRACT FROM AUTHOR]

Production of ammonia by urea-grown Chlorella ellepsoidea was investigated. Ammonia was produced during the stationary growth phase ion cultures with urea as sole nitrogen source and glucose as supplementary carbon source. Ammonia was produced only in medium containing excess urea and limiting amounts of glucose. Ammonia production was accompanied by increase in pH. In cultures with nitrate as sole nitrogen source and glucose as supplementary carbon source, growth and pH changes were similar to those in urea-glucose medium, but ammonia was detected. Cultures grown in urea-acetate medium were similar to those grown in urea medium without additional organic carbon source. No ammonia was produced under these circumstances and growth was significantly lower than that achieved in glucose-supplemented cultures. C. ellipsoidea evidently produces an enzyme or enzyme system which forms ammonia from urea. This organism was reportedly urease-free because previous workers did not detect ammonia formation from urea. Our findings indicate that special circumstances are required to produce detectable amounts of ammonia from urea. These findings are in agreement with a recent report of urea-splitting, cofactor-requiring enzyme in cell-free extracts of Chlorella. [ABSTRACT FROM AUTHOR]

A laboratory phenomenon involving autostimulation of growth by filtrates of the green alga Hormotila blennista is described, and stimulation attributed primarily to the secretioin of organic metabolities. Filtrates obtained from actively growing cultures I through 4 weeks old showed maximum growth rate stimulation values in excess of 100%. Stimulatory properties of filtrate were heat labile, were not closely controlled by the starting pH within the limits from depletion of essential nutrients. Concomitant with growth rate stimulation, filtrates characteristically extended the lag phase of culture growth. H. blennista filtrate can support bacterial growth and selectively stimulate or inhibit 2 polanktonic green algae. It was suggested that extracellular organic products secreted by H. blennista during active growth could be of survival value to the organism, and could also play regulatory roles among other microorganisms in nature. [ABSTRACT FROM AUTHOR]

Techniques are compared for the evaluation of nutrient sources in which the potential mutrients are in contact with algae over their entire culture period versus relatively short-term exposure tests. Different nitrogen and phosphorus compounds were shown to be utilized in darkness as well as in light and were equally available at pH 7 and 9. the availability of relatively insoluble nutrients-ion-phosphorus complounds and teeth for phosphorus, hair for nitrogen, iron phrites for iron, and marble for corbon-indicates that in many cases the equilibrium between soluble and insoluble forms allows algae to compete successfully with insoluble forms for nutrients. Apparently, factors other than mere insolubility prevent algae from obtaining available nitrogen or phosphorus from phosphate rock or lake muds. Live algae or aquatic weeds with adequate or surplus nitrogen or phosphorus were shown to not share their nutrients with nitrogen or phosphorus-limited algae, whereas the nutrients of killed algae or aquatic weeds were readily used by nutrient-limited algae. The fact-(1) that live algae and aquatic weeds do not share their adequate or surplus nutrients with nutrient-limited algae and (2) that lake muds do not provide readily available nitrogen or phosphorus-indicate that once lake waters are stripped of available nutrients by plant production, further plant production will depend upon nutrients from continuous sources of nutrients, such as wastewater effluents. [ABSTRACT FROM AUTHOR]

Planktonic blue-green algae are known to be always associated with bacteria. Earlier work has shown that the addition of a bacteria-assimilable carbon source to a normal Zehnder-Gorham culture medium (No. 11) will produce enhanced growth of these algae when atmospheric CO[sub2] has become the limiting factor. In new work, phosphate-rich culture media were diluted so that they simulate nutrient levels found ion the Great Lakes, e.g., Lake Erie. At these low concentrations and when atmospheric CO[sub2] was not available in a sufficient supply, the addition of sucrose to either a 1/100 or a 1/1000 diluted Z-G medium (10 mg or 2 mg of sucrose, respectively) also produced enhanced growth of the tested blue-green algae. The stimulation of algal growth was apparently due to an increased bacterial production of CO[sub2] and possibly other carbon compounds approaching the composition of the CO[sub2] molecule. The literature suggests that during vigorous algal growth in lakes, atmospheric CO[sub2] will be severely limiting. Productive lakes always contain nonliving organic matter. The presence of bacteria-assimilable matter is probably one of the important factors leading to algal bloom. [ABSTRACT FROM AUTHOR]

A revision of several of the Myrionematacea described by Setchell & Gardner in 1922 from the Pacific Coast of North America has been undertaken. Collections at different seasons, on different substrates, and comparisons with the type and isotype material, as well as culture studies, show that many of these species are merely different stages of a few algae. Twenty-seven species or forms have been grouped into 4 species and several changes of genus have been made. Life histories observed are simple, generally asexual except for Hecatonema streblonematoides, which shows a "Microsyphar"-like gametophyte. [ABSTRACT FROM AUTHOR]

Mature tropical marine algae were transplanted from Jamaica, Bermuda, and Florida to aquaria at Duke University, North Carolina and The Queen's University of Belfast, Northern lreland. Genera cultured included: Caulerpa, Halimeda, Penicillus, Udotea, Acetabularia, Batophora, Cymopolia, Dictyosphaeria, Neomeris, and Valonia. Methods of transport and cultutre are described. The use of adult plants was convenient, as well as essential for those genera and species in which spore or gamete stages are as yet unknown. Since only small amounts of seawater were needed for mainteance of the cultures, studies on these livinng marine algae can be made at institutes far from the sea. The growth of new segments and young plants of Halimeda, Penicillus, and Udotea are described as well as gametangial development, aging and decay in Halimeda. Sequential photographs of Penicillus and Halimeda show development from the time the plants first appeared above the sand to relative maturity. Changes in morphology after a few months' culture are also described. [ABSTRACT FROM AUTHOR]

Several marine algae have been obtained as unialgal cultures in an artificial medium. After treatments with penicillin or streptomycin or both in various combinations Asterocytis ramosa and Polysiphonia urceolata have been obtained in axenic cultures. Trailliella intricata and Nemalion multifidum were obtained in axenic culture after 2 minutes treatment with Jodopax (Ferrosan) in concentrations of 0.01–0.125 per cent. The algae were cultivated under banks of fluorescent tubes (Philips 2 TLF 55, 1 TL 32, 1 TL 5 and 1 TL 17) giving a light intensity of 800-1000 Lux measured with a selenium cell. The optimum light intensity differed in the different species. Several carbohydrates increased growth of Goniotrichum elegans more than 100 per cent in light. There was no growth in darkness with any addition. All species preferred nitrate as a source of nitrogen. Nitrite and ammonium nitrogen in low concentrations could also be utilized, as well as amino and amide nitrogen, but growth was mostly inferior to that with nitrate. An exception was arginine which gave excellent growth of Rhodosorus marinus. The requirement for phosphorus was also investigated and was found to be 4.45–8.9 mg P per litre for several species, but Nemalion preferred a concentration more than twice as high. The availability of some metals in the nutrient medium was investigated. Additions of iron as well as of calcium was necessary for growth. The other metals among the micronutrients seemed to occur in sufficient amounts as impurities among the macronutrients. A description is given of the modified nutrient medium ASP6 F. [ABSTRACT FROM AUTHOR]

It has been shown in previous experiments under different sterile and unsterile conditions that (1) no nitrogen fixation takes place under sterile conditions. (2) substantial nitrogen fixation takes place under unsterile conditions in sand, even with no organic substance supplied. In further experiments carried out in a synthetic substrate nitrogen fixation was obtained when inoculation was made with Nostoc calcicola. If Nostoc was combined with other microorganisms (bacteria or actinomycetes) a substantially larger nitrogen fixation was obtained in certain cases. Of the bacterial strains tested, especially B. megaterium and another, not yet identified strain, together with Nostoc, caused a relatively rapid and large nitrogen fixation. But also other microorganism, such as Rhizobium. Agrobacterium radiobacter, and Streptomyces albus increased the nitrogen fixation. Particular attention has been given to the co-operation of Nostoc and Rhizobium. [ABSTRACT FROM AUTHOR]

1The author describes an arrangement for cultivation of algae in fluorescent light under constant temperature conditions and continuous aeration by means of shaking.2 Different types of fluorescent lamps were tested. In a light rich in short waves (daylight type) the algae lost all pigmentation during the course of a few weeks. The growth rate was very irregular. 3 In a light rich in long waves the pigment formation was normal. The differences in the growth rate between parallel cultures were slight. It is obvious that fluorescent lamps rich in long wave light are more suitable for the cultivation of algae than those of the daylight type. 4 As the spectral composition of sunlight agrees closely with that of daylight lamps, the well known injurious effects on algae cultures caused by sunlight may be assumed to be connected with too great an excess of light of short wave lengths. [ABSTRACT FROM AUTHOR]

The article reports on a two-year study of the ability of algae to survive in dry conditions. The data gathered for the study included the water's levels, temperatures and pH levels, and the mud and litter's moisture and organic content. Through culturing and observation, it was found that certain algae survived lengthy exposure through cell wall thickening, a gelatinous covering, and the cell's accumulation of oil. The test also revealed that the vegetative stages' ability to resist exposure and drying is the major controlling factor of algal zonation..

The effects of different concentrations of salinity, pH, and nutritional and growth-promoting substances on the production of proliferations in Gelidiella acerosa were investigated, with a view of increasing the production rate of the alga in its aqriculture. [ABSTRACT FROM AUTHOR]

Desmotrichum undulatum (J. Agardh) Reinke (Phaeophyta) was found in the winter months in the littoral zone of a tidal marsh in Virginia. When field collections were maintained in culture media at 21 C, most cells of the thallus developed into plurilocular sporangia. Released zoospores developed into microthalli from which clonal cultures were established. At 21 C microthalli produced sporangia which releaseld zoospores, subsequently developing into more microthalli. However, microthalli at 6 C formed filaments which subsequently developed into thalloid plants when the thalloid plants of Desmotrichum formed in culture were sunjected to 21 C, plurilocular sporangia were formed. These results support the proposition that the seasonal periodicity of Desmotrichum is due to a temperature-regulated phenomenon in the development of macrothalli. [ABSTRACT FROM AUTHOR]

It has long been a practice, in culturing photosynthesizing unicellular green algae, to enhance growth by bubbling with air enriched with carbon dioxide. Although various concentrations of CO[sub2] have been employed, it has been demonstrated that 1 % is sufficient to sustain maximum growth under most conditions. Many effects of supraoptimal amounts of CO[sub2] are known; among them, a delay in the release of autospores in synchronous cultures has been demonstrated. Using "Chlorella I," they reported that 3 percent CO[sub2] induced a 1 1/2 hour delay in autospore release, compared to air, and 6 percent, a 2 1/2 hour delay.

After the death of Dr. Gilbert M. Smith on July 11, 1959, the strains of Chlamydomonas maintained in his collection were sent to the Culture Collection of Algae at Indiana University. Axenic cultures of 29 strains were investigated to determine the nature of their sexual behavior. Mating types for 6 species (C. elliptica var. britannica, C. frankii, C. minutissima, C. moewusii f. microstigmata, C. reinhardtii, C. smithii) produced zygotes when agar cultures were harvested with sterile distilled water or low nitrogen medium and the complementary mating types for each species were mixed. Three species, C. moewusii f. microstigmata, C. reinhardtii, and C. smithii, produced sufficient zygotes to be of value in experimental work. G. smithii is an undescribed species interfertile with C. reinhardtii. The description of C. smithii will be published in a separate paper. Fourteen mating types of Chlamydomonas originally isolated and maintained by Smith are now maintained in the Culture Collection. [ABSTRACT FROM AUTHOR]

Dry 3.5-yr-old akinetes of Oedocladium packed with carotenoid pigments, fact and starch, became green and reproduced like ordinary vegetative cell when they were placed in a defined mineral medium. [ABSTRACT FROM AUTHOR]

A simple method is described to demonstrate zoospore formation in a chlorococcalean alga. [ABSTRACT FROM AUTHOR]