Algal-bacterial Community Research Articles

Interactions between algal-bacterial populations and trace metals in fjord surface waters during a nutrient-stimulated summer bloom

We examined how variations in algal-bacterial community structure relate to Cu, Zn, and Mn speciation during a diatom-rich bloom that was induced by daily additions of inorganic macronutrients to fjord waters in August 2002. The experiments were carried out in 11-m3 floating mesocosm bags deployed in the Raunefjord, near Bergen, Norway, and operated in a chemostat (flow-through) mode. Copper speciation was controlled by the formation of very strong organic complexes (log K1' = 15.2–15.8; log 1' = 13.0–13.4) whose likely source was the cyanobacterium Synechococcus sp. Strong ligand concentrations were comparable to dissolved Cu levels. This covariation kept the free Cu2+ concentration within the range of 10-12.4 to 10-11.2 mol L-1, i.e., below the toxicity threshold for Synechococcus. Weaker ligands (log 1' = 8.2–9.4) were released during—and up to 4 d following—the exponential 93 growth of algae. During this period, the weaker Cu-binding ligands appeared to have the same source or production process as the proteinlike fluorophores detected in these coastal waters. Zinc speciation was controlled by complexation with a single class of organic ligands that appeared to be released inadvertently upon the death and/or grazing of phytoplankton. Labile manganese fluctuations were inversely synchronized with the abundance of heterotrophic bacteria until the coastal waters experienced a massive rain event on day 17 of the experiment. The rainfall, which was a source of nitrogen and micronutrients, appeared to stimulate the growth of larger cells (diatoms) but to inhibit that of the smaller cells (heterotrophic bacteria and cyanobacteria).

Interaction coefficients in the Lake Shira algal-bacterial community

A new method is proposed to evaluate the interaction coefficients in microbial communities interacting due to physical-chemical environmental factors. This method differs from the classical one suggested by E.P.Odum. Redefinition of the interaction coefficients allows the evaluation of the experimental (actual) and theoretical values of the coefficients for the hypothetical interaction layout. The interaction layout is considered to be a set of factors, the values of their transformation ratios and the form of dependence of a population's specific growth rate on these factors. A comparison of theoretical and experimental values of interaction coefficients enables us to assess the adequacy of the hypothetical interaction scheme in the microbial communities. The aim of the work is to test the suggested method on a natural algal-bacterial community of Shira Lake (Khakasia, Russia), which has been the object of detailed and concerted limnological studies and for which detailed data are available. Feedback coefficients of phyto- and bacterioplankton and the coefficients of influence of phytoplankton on bacterioplankton have been defined. Dominance of negative experimental IC values has been experimentally shown, which is indicative of the negative feedback in bacterio- and phytoplankton links of Shira Lake and of negative interpopulation (phytoplankton on bacterioplankton) interactions. The considerable differences observed between the experimental and theoretical coefficients indicates inadequacy of the assumed interaction layout of the community under study. Further investigations are needed to provide a precise sketch of the interactions.

Proterozoic history and present state of cyanobacteria

The paper delves into the main regularities of the distribution of fossil microorganisms in Precambrian rocks, beginning from the Archean Eon about 3.5 billion years ago and ending in the Cambrian Period about 0.5 billion years ago. The paper analyzes facial peculiarities in the lateral differentiation of microfossils in Proterozoic basins and the main stages of temporal changes in fossil cyanobacterial communities, which are based on the irreversible succession of physicochemical conditions on the Earth and the evolution of eukaryotic microorganisms and their incorporation into prokaryotic ecosystems. To gain insight into Proterozoic fossil records, modern stratified cyanobacterial mats built up from layers of prokaryotes are considered. The analysis of phosphatization, carbonatization, and silification processes in modern algal-bacterial communities suggests that analogous processes took place in Proterozoic microbiotas. A comparison of modern and Precambrian living forms confirms the inference that cyanobacterial communities are very conservative and have changed insignificantly both morphologically and physiologically during the past two billion years.

CALIBRATION OF A STEADY-STATE SEEPAGE MODEL FROM TRANSIENT RECOVERY OF FIELD DATA

ABSTRACT: The South Florida Water Management District (District) constructed three experimental test cells (20 ± 50 feet = 6.1 ± 15.2 m) to determine the seepage influence of a major agricultural canal adjacent to the cells. These three cells represented the first stage of a series of experimental cells to determine the efficiency of algal-bacterial communities (periphyton) to successfully remove phosphorus (P) from the water. This treatment technology is known as Periphyton-based Stormwater Treatment Area (PSTA) and is being considered under the Supplemental Technology Program (Phase II) to comply with the Everglades Forever Act (EFA) of 1994. However, the efficiency of a PSTA in removing nutrients has not been documented yet. To determine the efficiency of PSTA technology to remove phosphorus (P) from the water, it is necessary to quantify all the components of the water budget. The purpose of the cells was to evaluate the potential seepage due to the operational range of stages into and out of the test cells. A steady-state, two-dimensional seepage (FastSEEP/SEEP2D) model was applied and successfully calibrated for that purpose. The model was calibrated using mean seepage flows obtained after drawdowns in each test cell, by pumping water out. These seepage flows as well as the boundary conditions (stages) were estimated by discretizing the recovery data. The recovery data represents the seepage from the agricultural canal into each of the test cells after the drawdowns, since the stages in the canal during the experiment did not change significantly and were high. Each of the three test cells was excavated to different bottom elevations to determine the effect of substrate differences on seepage rates. Values of hydraulic conductivity for five different layers in the models were based on field observations, lithologic descriptions, and slug tests. Modeled seepage produced reasonable results for the three test cells compared with estimated seepage from the recovery data, achieving a satisfactory calibration. The errors of the simulated seepage ranged from −6.1 to 16.8 percent (under and over estimation, respectively).

Lake Shira, a Siberian salt lake: ecosystem structure and function. 2. Brachionus plicatilis (Rotatoria) growth and development

The growth and development of Brachionus plicatilis (Muller), a rotifer and one of the most abundant zooplankton species in Lake Shira, a saline lake at low temperature in the Republic of Khakassia, was studied in cultures at different trophic conditions. Growth indices were evaluated at natural (lake) concentrations of bacteria, Chlorella vulgaris, a microalga, and Candida utilis, a yeast. The negative effect on rotifer reproduction in the algal-bacterial community by blue-green algae was demonstrated. The ratio of ontogenetic periods was shown to be in accord with species and food concentration. Base values required to calculate B. plicatilis population simulation model parameters were defined.

Clostridium thermosulfurogenes sp. nov., a New Thermophile that Produces Elemental Sulphur from Thiosulphate

A new Clostridium species is described that was isolated from a thermal, volcanic, algal-bacterial community via selective enrichment procedures with pectin as energy source. Clostridium thermosulfurogenes sp. nov. deposits elemental sulphur on the cell surface and in the culture medium from thiosulphate transformation. This species stained Gram-negative, but electron micrographs revealed a double-layered wall without the presence of an outer membranous layer. Thin sections displayed numerous internal membranes and sulphur granules were not discernible. The organism was motile and formed distinctly swollen sporangia with terminal, white-refractile, spherical spores. The temperature range for growth was >35 °C and <75 °C, the pH range was between 4·0 and 7·5. The DNA base composition was 32·6 ± 0·04 mol% guanosine plus cytosine. Fermentable carbohydrates included pectin, starch, xylose, glucose, mannose, cellobiose, maltose, arabinose and sucrose. The doubling time on glucose or pectin was about 2 h. The production of ethanol, H2/CO2, acetate and lactate accounted for a balanced fermentation of glucose, whereas methanol and isopropanol were also produced during pectin fermentation. The taxonomic relationships of C. thermosulfurogenes to other thermophilic Clostridia and its biological role in a thermal microbial community are discussed.

Nutritional relationships among microorganisms in an epilithic biofilm community

Previous studies of an epilithic algal-bacterial community in a pristine mountain stream suggested that heterotrophic bacteria were responding to the metabolic activities of the phototrophic population. Subsequent studies were performed to follow the flow of labeled carbon, from its initial inorganic form, through the trophic levels of the mat community. A majority of primary production metabolites were excreted by the algal population during active growth; this shifted to an incorporation into cellular material as phototrophic activity declined. Results suggest that there was a direct flux of soluble algal products to the bacterial population, with little heterotrophic utilization of dissolved organics from the overlying stream water. Both phototrophic productivity and bacterial utilization of algal products peaked at approximately the same time of year. Activity of the diatom-dominated algal population declined as silica concentrations in the stream water dropped, leading to a situation in which the sessile bacteria were substrate limited. These events resulted in an almost complete disappearance of the community in early September.

The Ecology of a Biotic Community Consisting of Algae and Bacteria

Two important areas for the application of biological processes are the reclamation of water and organic nutrients from waste waters and the complete control of enclosed environments. The former may be accomplished through the agency of communities consisting of algae and bacteria grown in especially designed lagoons known as oxidation ponds. These ponds have been described by Oswald and his colleagues (1954, 1957, and 1958). The biological control of enclosed environments, such as in atomic submarines or in space vehicles, may also be brought about through the collective activity of algae and bacteria and has been described by Golueke and Oswald ( 1958). The successful application of a biological process to such widely divergent and, paradoxically? closely related functions as the control of the environment in a space vehicle and the treatment of wastes in a high-rate oxidation pond requires an extensive knowledge of the ecology of the organisms involved in the process. This is true because effective biological control requires an optimum relationship between the environment and the community concerned, and this can be accomplished only by providing proper environmental conditions. To establish such a relationship, it is necessary to know the nature and extent of the influence of the principal environmental factors involved. Among the key factors to which an algal-bacterial community is subject, whether in an oxidation pond or in a space ship, are carbon dioxide concentration, light intensity and length of duration of light per day, length of growth period, and temperature. In a space ship these factors can be regulated mechanically, and in an oxidation pond, by engineering and geographical location. Although much has been written on the effect of the key environmental factors on individual algal species, there is a paucity of information in thle literature on the effect of these environmental factors, either individually or collectively, on such organisms when living as members of a community. Inasmuch as the influence of these factors are modified by the collective action of different types of organisms living together in the same and by the nature of the action of one group upon the other, information gained from studies of an organism grown as a pure cannot be applied unequivocally to the same organisms when living as a member of a community. This paper treats that part of an investigation on the biological control of enclosed environments which deals with the influence of certain environmental factors in determining the nature and over-all activity of climax associations of algae and bacteria resulting from the application of a given set of factors. In the description to follow, the term culture will he used synonymously with biotic community, inasmuch as the microorganisms were grown in a prepared nutrient medium under controlled conditions. The author wishes to express his appreciation for counsel given him by Dr. WV. J. Oswald, Dept. of Civil Engineering and School of Public Health, University of California, Berkeley.