Two new taxa of phototrophic heliobacteria are described: Heliobacterium gestii sp. nov. and Heliophilum fasciatum gen. nov. sp. nov. Both organisms were isolated from dry paddy soils. Cells of H. gestii were motile spirilla; cells of H. fasciatum formed cell bundles that were motile as units. Both organisms produced endospores; H. gestii endospores contained dipicolinic acid and elevated levels of calcium. As with other heliobacteria, bacteriochlorophyll g was produced in both organisms and no intracytoplasmic photosynthetic membranes were observed. Growth of H. gestii and H. fasciatum occurred under both photoheterotrophic and chemotrophic conditions; nitrogen fixation also occurred in both organisms. H. gestii and H. fasciatium showed a phylogenetic relationship to the "low GC" line of gram-positive Bacteria, but H. fasciatum was distinct from H. gestii and all other heliobacteria. The ability of H. gestii and H. fasciatum to form endospores might be a significant ecological advantage for survival in their rice soil habitat.

The green sulfur bacterium Chlorobium vibrioforme contains two types of bacteriochlorophyll (Bchl). The minor pigment, Bchl a, is associated primarily with the cell membrane and its reaction centers; and the major light-harvesting antenna pigment, Bchl d, is found primarily in the chlorosomes, which are attached to the inner surface of the cell membrane. Anesthetic gases, such as N20, ethylene, and acetylene, were found to inhibit the synthesis of Bchl d, but not of Bchl a, thus allowing the cells to grow at high light intensities with a greatly diminished content of antenna pigment. Chlorosomes were absent or sparse in inhibited cells. Porphyrins accumulated in the inhibited cells. The major one was identified as the Bchl precursor magnesium-protoporphyrin IX monomethyl ester (Mg-PPME) by comparative absorption and fluorescence spectroscopy and thin-layer chromatography of the porphyrin and its derivatives with those of authentic protoporphyrin IX. Small amounts of Mg-PPME were present in control cells, but the addition of inhibitor caused a rapid increase in the Mg-PPME concentration, accompanying the inhibition of Bchl d synthesis. Cells grown in the presence of ethephon (as a source of ethylene) and allowed to stand in dim light for long periods accumulated large amounts of PPME and other porphyrins and excreted or released porphyrins, which accumulated as a brown precipitate in the culture. Inhibition of Bchl d synthesis was relieved upon removal of the inhibitor. These results suggest that the gases act at a step in pigment biosynthesis that affects the utilization of Mg-PPME for isocyclic ring formation. Synthesis of Bchl d and Bchl a may be differentially affected by the gases because of compartmentation of their biosynthetic apparatus or because competition for precursors favors Bchl a synthesis. An ethephon-resistant mutant strain was isolated by selection for growth in dim, long-wavelength light. The mutant cells were also resistant to acetylene, but not to N20. The ability to reversibly generate viable Chlorobium cells that lack antenna pigments may be useful in photosynthesis research. The ethephon-and acetylene-resistant strain may be useful in the study of the enzymes and genes that are involved in the biosynthetic step that the gases affect.The green sulfur bacterium Chlorobium vibrioforme contains very large amounts of bacteriochlorophyll (Bchl) provided they receive sufficient light. Cells from such cultures appeared to contain few or no chlorosomes (Ormerod and Nesbakken, Proc. IV Int. Symp. Photosynthetic Prokaryotes).These observations are significant in several respects. First, the experimental system should be useful for investigating chlorophyll synthesis; second, the inhibition may also be related to the mechanism of action of gaseous anesthetics in animals, which is poorly understood at present; third, since the inhibition appears to be quite specific, it provides a method of growing cultures of C. vibrioforme with drastically reduced amounts of antenna Bchl, thus permitting spectrosc...

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The efficacy of a commercial inoculant, Natuferm, which contains multiple strains of lactic acid bacteria, was examined in seven experiments using 6 m3 pilot-scale silos. Samples taken during the fermentation period were analysed and compared with samples @om untreated controls and formic acid silages. Good quality silages were obtained with crops of low dry matter content (12)(13)(14) %)and with a water soluble carbohydrate content of 1.5 % related to jkesh weight. The addition of Natuferm resulted in increased lactic acid levels (50-90%) during the initial fermentation, and p H dropped faster compared with the untreated controls. Compared with the formic acid silages the level of enterobacteria declined rapidly in both the inoculated and untreated silages. I n two of the experiments a pronounced difference in enterobacterial count was observed between the Natuferm and control silages on day 2. The effluent volumes were recorded, and the pH and the dry matter content of the effluents were determined. Compared with the formic acid silages, a 40% average reduction of the efluentflow was observed from Natuferm silages, and in most experiments there was also a reduced effluent volume compared with the controls. Analyses of 174 Natuferm silages and 73 formic acid silages )om full scale (farm) silos revealed no signijcant differences in silage quality between the two additives. Natuferm silages with a dry matter content below 20 % were not signijcantly different )om silages with a dry matter content above 20 %.

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