L-J van den Berg

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The results of morphological, base ratio, nutritional, temperature, and pH studies on a strain of Methanospirillum hungatii, isolated from an anaerobic pear waste digester, are described. The isolate, designated as strain GP 1, was compared with some of the characteristics of type-strain M. hungatii JF 1. Strain GP 1 is Gram-negative, weakly motile, and a(More)
A stable enrichment culture converting acetic acid to methane was successfully obtained from a pear waste digester, using a synthetic substrate solution with acetic acid as the main carbon source. This enrichment culture converted up to 10 mmol of acetic acid per litre per day at 35 degrees C and did not use hydrogen or formic acid in appreciable amounts as(More)
A new hybrid reactor, the upflow blanket filter (UBF), which combined on open volume in the bottom two-thirds of the reactor for a sludge blanket and submerged plastic rings (Flexiring, Koch Inc., 235 m(2)/m(3)) in the upper one-third of the reactor volume, was studied. This UBF reactor was operated at 27 degrees C at loading rates varying from 5 to 51 g(More)
Nuclear genome size, as measured by flow cytometry with propidium iodide, was used to investigate the relationships within the genus Gagea (Liliaceae), mainly from the Netherlands. The basic chromosome number for Gagea is x = 12. The inferred ploidy in the Dutch and German accessions varies from diploid to decaploid. Consequently there is a large range of(More)
The ultrastructure of the cells of the major component of an enriched culture of a presumed methanogen which utilized acetic acid was studied by transmission and scanning electron microscopy. The filaments were composed of Gram-positive, rod-shaped cells, 1--2 micrometer in length and about 0.5 micrometer in breadth, attached end to end. Septa between cells(More)
Tests to determine the mixing characteristics of the anaerobic downflow stationary fixed film (DSFF) reactor during startup showed that mixing characteristics affected performance. Different mixing profiles were obtained by keeping the same flow distribution system and by varying the number of clay channels (1, 4, and 25) in the DSFF reactors (2-32 L).(More)
Studies with a methanogenic culture enriched for use of acetic acid showed that this culture had an optimum growth temperature of 35 degrees C, with only small differences for other temperatures between 30 and 40 degrees C. The optimum temperature was the same when determined on the basis of biomass production rate during the exponential (log) phase of(More)
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