Autotrophic, sulfur-oxidizing actinobacteria in acidic environments.

Some novel actinobacteria from geothermal environments were shown to grow autotrophically with sulfur as an energy source. These bacteria have not been formally named and are referred to here as "Acidithiomicrobium" species, as the first of the acidophilic actinobacteria observed to grow on sulfur. They are related to Acidimicrobium ferrooxidans with which they share a capacity for ferrous iron oxidation. Ribulose bisphosphate carboxylase/oxygenase (RuBisCO) is active in CO(2) fixation by Acidimicrobium ferrooxidans, which appears to have acquired its RuBisCO-encoding genes from the proteobacterium Acidithiobacillus ferrooxidans or its ancestor. This lateral transfer of RuBisCO genes between a proteobacterium and an actinobacterium would add to those noted previously among proteobacteria, between proteobacteria and cyanobacteria and between proteobacteria and plastids. "Acidithiomicrobium" has RuBisCO-encoding genes which are most closely related to those of Acidimicrobium ferrooxidans and Acidithiobacillus ferrooxidans, and has additional RuBisCO genes of a different lineage. 16S rRNA gene sequences from "Acidithiomicrobium" species dominated clone banks of the genes extracted from mixed cultures of moderate thermophiles growing on copper sulfide and polymetallic sulfide ores in ore leaching columns.

Effects of UV-B radiation on seed yield of Glycine max and an assessment of F1 generation progeny for carryover effects.

Glycine max (L.) Merr plants were grown outdoors in potted sand exposed to elevated ultraviolet-B (UV-B) radiation provided by filtered fluorescent lamps to determine the effects of UV-B on seed yield and UV-B-induced carryover effects in the F1 generation. Increased UV-B radiation had no detectable effects on reproductive parameters except for a reduction on seed number per plant and an increase in the number of unseeded pods per plant and dry weight of unseeded pods per plant in the field supplemental UV-B experiment. Studies on carryover effects in the greenhouse progeny growth trial also showed no effect of parental treatment with UV-B on biomass production, and most symbiotic-N traits and plant metabolite measured. However, the concentrations of N in nodules and starch in roots were significantly increased in the F1 generation progeny from elevated UV-B radiation relative to their F1 counterparts from ambient radiation. Assessing the effects of seed size on plant growth and symbiotic function in the F1 progeny showed that total biomass, dry matter yield of individual organs (leaves, stems, roots and nodules), total plant N and fixed-N rose with increasing seed size. Seed concentration of flavonoids was also enhanced with increasing seed size. These findings suggest that subtle changes did occur in the F1 generation progeny of parental plants exposed to elevated UV-B with potential to accumulate with further exposure to elevated UV-B radiation.