Some physiological aspects of the autecology of the suspension-feeding protozoanTetrahymena pyriformis

Feeding, growth, and reproductive responses of the suspension-feeding protozoanTetrahymena pyriformis to shifts up or down of the density of its bacterial food were observed. The rates of feeding, growth, and reproduction were determined by measuring the rates of uptake of viable bacterial cells, of change of mean volume of the protozoan cells, and of change of number of protozoan cells, respectively. The effects of the nutritional status of the protozoans at the time of shifting were observed also. Results are interpreted in terms of the limited polymorphism exhibited in the life cycle of this organism. Responses in all cases seem to reflect a strategy for exploiting a patchy, transient environment, a conclusion already reached by several earlier investigators.     

In situ imaging of microorganisms in geologic material.

In order to fully delineate the interactions of microorganisms with geological substrates, unequivocal identification of intact microbial cells within geologic samples is required without the disruption of either the rock texture or the relationship of the microorganisms to the mineral fabric. To achieve this objective we developed a protocol that enables the visualization of intact microbial cells in petrographic thin sections, avoids detaching the cells from their host mineral surfaces and avoids microbial contamination during the lapidary process. Propidium iodide and POPO-3, nucleic acid stains that specifically target double-stranded DNA and RNA were utilized for in situ visualization of cells in surface and subsurface basalts from northeastern Idaho. Additionally, examination of samples incubated with acetic acid-UL-14C via phosphor imagining facilitated the in situ visualization of 14C labeled biomass. Biomass observed was low (<10(7) cells/g). These observations indicate that the microbial distribution in these rocks exhibits a high degree of spatial heterogeneity at the sub-centimeter scale.     

Biosolubilization of low-rank coal by aTrametes versicolor siderophore-like product and other complexing agents

Summary A heat stable, low molecular weight (<1000) extracellular product inTrametes versicolor (=Coriolus versicolor=Polyporous versicolor) cultures was demonstrated to be a principal factor in the solubilization of leonardite and other low-rank coals. The solubilization of leonardite byT. versicolor cell-free cultures and active fractions was inhibited by Fe³⁺ and was mimicked by the siderophore desferal mesylate and the iron chelating agents EDTA and 8-hydroxyquinoline. Leonardite solubilization by these later compounds was also inhibited by Fe³⁺. The ferrated and unferrated form of the partially purified active component fromT. versicolor cultures demonstrated absorption spectra that were similar to the ferrated and unferrated form of desferal mesylate.