The unicellular green alga Dunalielia acidophila grows optimally at pH 1.0 while maintaining a neutral cytoplasmic pH and a positive membrane potential. To study the mechanism of K+ uptake in this organism and in the acidophilic yeast Metschnikowia reukaufii, 86Rb was trapped in plasma membrane vesicles of these organisms, by freezing and thawing with phospholipid vesicles. Both preparations possess K+-stimulated, vanadate-sensitive H+-ATPases. ATP stimulates 86Rb efflux from the reconstituted vesicles, and the stimulation is abolished by vanadate. The protonophore SF-6847 also inhibits the ATP-dependent 86Rb efflux. In contrast, the lipophilic anion SCN-, which abolishes the ATP-induced membrane potential, does not inhibit 86Rb efflux. An artificial pH difference, acid inside, stimulates 86Rb efflux in reconstituted D. acidophila plasma membranes and the stimulation is not affected by vanadate but is inhibited by SF-6847. These results suggest the existence of a K+/H+ cotransport system acting in parallel to the H+-ATPase in the plasma membranes of these organisms. It can explain how acidophiles accumulate K+ against a large electrochemical potential gradient.

Ziel der Untersuchung war es, fuer verschiedene Mikroorganismenkulturendie optimalen Fuehrungsbedingungen zu finden, die fuer den Betrieb eines kontinuierlich arbeitenden Sauerteigfermenters erforderlich sind. Die Sauerteige wurden mit vier verschiedenen Starterkulturen herangefuehrt und danach kontinuierlich weitergefuehrt. In den Sauerteigen entwickelten sich Mikrofloren, die sich in Abhaengigkeit von den in den Sauerteigen enthaltenen Mikroorganismen erheblich voneinander unterschieden. Die Sauerteige erstellten unter konstanten Fuehrungsbedingungen unterschiedliche Stoffwechselleistungen. Die Vermehrung und die Stoffwechselleistung konnten durch die Arbeitsparameter Fermentationstemperatur und Anstellgutmasseanteil in weiten Grenzen veraendert werden. Die Fermentationstemperatur uebte darauf den groessten Einfluss aus. Die Milchsaeurebakterien vermehrten sich am besten bei 35 Grad C und die Hefen bei 30 Grad C. Auf der Grundlage der dargestellten Ergebnisse ist es moeglich, die Leistung des Fermentationssystems im Hinblick auf die Vermehrung der Mikrofloraund Saeurebildung in Abhaengigkeit von den spezifischen physiologischen Leistungen der Mikroorganismen zu optimieren. [S-90-04325]

DEUTSCH: Ziel der Untersuchung war es, fuer verschiedene Mikroorganismenkulturendie optimalen Fuehrungsbedingungen zu finden, die fuer den Betrieb eines kontinuierlich arbeitenden Sauerteigfermenters erforderlich sind. Die Sauerteige wurden mit vier verschiedenen Starterkulturen herangefuehrt und danach kontinuierlich weitergefuehrt. In den Sauerteigen entwickelten sich Mikrofloren, die sich in Abhaengigkeit von den in den Sauerteigen enthaltenen Mikroorganismen erheblich voneinander unterschieden. Die Sauerteige erstellten unter konstanten Fuehrungsbedingungen unterschiedliche Stoffwechselleistungen. Die Vermehrung und die Stoffwechselleistung konnten durch die Arbeitsparameter Fermentationstemperatur und Anstellgutmasseanteil in weiten Grenzen veraendert werden. Die Fermentationstemperatur uebte darauf den groessten Einfluss aus. Die Milchsaeurebakterien vermehrten sich am besten bei 35 Grad C und die Hefen bei 30 Grad C. Auf der Grundlage der dargestellten Ergebnisse ist es moeglich, die Leistung des Fermentationssystems im Hinblick auf die Vermehrung der Mikrofloraund Saeurebildung in Abhaengigkeit von den spezifischen physiologischen Leistungen der Mikroorganismen zu optimieren. [S-90-04325].

Microorganisms have been implicated in causing cytoplasmic incompatibility in a variety of insect species, including mosquitoes, fruitflies, beetles and wasps. The effect is typically unidirectional: incompatible crosses produce no progeny or sterile males, whereas the reciprocal crosses produce normal progeny. The parasitic wasp Nasonia vitripennis is one of the few species in which the cytogenetic mechanism of incompatibility is known. In this species the paternal chromosome set forms a tangled mass in a fertilized egg and is eventually lost. Here we report that cytoplasmic microorganisms are associated with complete bidirectional incompatibility between N. vitripennis and a closely related sympatric species. N. giraulti. Microorganisms can be seen in the eggs of both species. Hybrid offspring are normally not produced in crosses between the two species, but do occur after elimination of the microorganisms by antibiotic treatment. A cytogenetic and genetic study shows that bidirectional interspecific incompatibility is due to improper condensation of the paternal chromosomes. Microorganism-mediated reproductive isolation is of interest because it could provide a rapid mode of speciation. The mechanism of incompatibility in Nasonia is also of interest as a potential tool for studying chromosome imprinting and chromosome condensation.

The importance of microniches for the survival of introduced Rhizobium leguminosarum biovar trifolii cells was studied in sterilized and recolonized sterilized loamy sand and silt loam. The recolonized soils contained several species of soil microorganisms but were free of protozoa. Part of these soil samples was inoculated with the flagellate Bodo saltans, precultured on rhizobial cells. The introduced organisms were enumerated in different soil fractions by washing the soil, using a standardized washing procedure. With this method, free organisms and organisms associated with soil particles or aggregates greater than 50 micromoles were separated. The total number of rhizobia was influenced slightly (silt loam) or not at all (loamy sand) by the recolonization with microorganisms or by the addition of flagellates alone. However, when both flagellates and microorganisms were present, numbers of rhizobia decreased drastically. This decrease was more than the sum of both effects separately. Nevertheless, populations of rhizobia were still higher than in natural soil. In the presence of flagellates, higher precentages of rhizobia and other microorganisms were associated with soil particles or aggregates greater than 50 micromoles than in the absence of flagellates. In recolonized soils, however, the percentages of particle-associated rhizobia were lower than in soils not recolonized previous to inoculation. Thus, the presence of other microorganisms hindered rhizobial colonization of sites where they are normally associated with soil particles or aggregates.

Forest products industries usually debark trees by machine, but the bark also loosens naturally and there are some cases in which it is desirable that the bark remain attached. The bond of bark to wood varies seasonally. Under suitable conditions, microorganisms dissolve the bond, consuming the barely visible cambial sheath that bonds bark to wood. The cambium is not lignified and therefore is ready food for fungi and bacteria. The microorganisms decompose cambium much faster than they do the main constituents of wood and bark, thus they separate the bark from the tree stems long before they weaken the wood and bark. This article reviews information related to the conditions under which microorganisms separate bark from wood, and the rate of this microbiological debarking. Under optimal conditions, bark may come off within a few days. Delayed loosening of the bark following "chemical debarking" is explained by the action of microorganisms. Seasonal variations of bark adhesion are included, since they occur not only on standing live trees but also on felled trees. Drying enforces the bark/wood bond, and steaming loosens it.

A relatively new analytical technique, Fourier transform infrared-photoacoustic spectroscopy (FTIR-PAS), provides spectra of bacteria, fungi, and other microorganisms in solid states not suitable for conventional absorption spectroscopy. In this paper the feasibility of quantitative measurement of protein biomass on solid substrates by FTIR-PAS is examined and discussed. By measuring photoacoustic absorption bands from amide groups in the protein of microorganisms, the increase in biomass that occurs during growth was monitored directly and accurately. Incorporation of polyacrylonitrile into the sample as an internal standard was shown to be a convenient method for improving both the reliability and the range of detection by photoacoustic spectroscopy. Results of FTIR-PAS measurements of known quantities of microbial mass in simulated growth experiments suggest that the technique may be especially suitable for assays of microorganisms used in solid-state biosyntheses of drugs, hormones, and other biological agents.