Microbial ecology of sourdough fermentations: diverse or uniform?

Sourdough is a specific and stressful ecosystem inhabited by yeasts and lactic acid bacteria (LAB), mainly heterofermentative lactobacilli. On the basis of their inocula, three types of sourdough fermentation processes can be distinguished, namely backslopped ones, those initiated with starter cultures, and those initiated with a starter culture followed by backslopping. Typical sourdough LAB species are Lactobacillus fermentum, Lactobacillus paralimentarius, Lactobacillus plantarum, and Lactobacillus sanfranciscensis. Typical sourdough yeast species are Candida humilis, Kazachstania exigua, and Saccharomyces cerevisiae. Whereas region specificity is claimed in the case of artisan backslopped sourdoughs, no clear-cut relationship between a typical sourdough and its associated microbiota can be found, as this is dependent on the sampling, isolation, and identification procedures. Both simple and very complex consortia may occur. Moreover, a series of intrinsic and extrinsic factors may influence the composition of the sourdough microbiota. For instance, an influence of the flour (type, quality status, etc.) and the process parameters (temperature, pH, dough yield, backslopping practices, etc.) occurs. In this way, the presence of Lb. sanfranciscensis during sourdough fermentation depends on specific environmental and technological factors. Also, Triticum durum seems to select for obligately heterofermentative LAB species. Finally, there are indications that the sourdough LAB are of intestinal origin.

Acute myelomonocytic leukemia (M4) with eosinophilia: problems concerning chromosome 16 abnormality.

A case of acute myelomonocytic leukemia is reported which was hematologically classified as M4 (FAB), because the patient had a high count of immature eosinophils with typical histochemical features in the bone marrow. An abnormal chromosome #16 was found besides a trisomy 22 or a monosomy 18 in part of the cultured bone marrow cells and unstimulated blood cells but not in directly prepared bone marrow. The structural aberration of chromosomes #16, which was demonstrated best by CBG-banding, was more likely due to a partial deletion of the long arm than to an inversion. The difficulties involved in correct cytogenetic diagnosis of such cases are discussed.

Tetraploidy and Y chromosome loss in acute mixed-lineage leukemia.

An unusual case of acute leukemia with mixed phenotype was followed up from diagnosis to death for about 12 months. The first cytogenetic examination revealed about 80% of the bone marrow cells in the diploid and 20% in the tetraploid range. After two courses of induction therapy, complete remission was achieved within 2 months. At this time the tetraploid cells were reduced to 3%, but 50% of the mitoses showed a Y chromosome loss, while the other mitoses had a diploid karyotype. Early intensification therapy was given 6 weeks later with slow recovery of blood counts. After four months a sharp decrease of the number of Y-missing mitoses was observed, while the marrow remained in full remission. Two months later a relapse occurred and the patient died. At this time the -Y clone had dropped to 2% and the tetraploid clone was totally absent. We conclude from these findings that the diploid clone was the most malignant one, whereas the -Y cells were probably not directly involved in the leukemic process.

Long term cultivation of Namalva cells for interferon production: stable cytogenetic markers for identification of cells in spite of drastic chromosomal variation.

Namalva cells were propagated continuously over a period of up to 18 months. During this period the chromosomal status of the cell populations were investigated cytogenetically. The ability of the cells to produce interferons after induction with Sendai virus was monitored. In contrast to the drastic chromosomal variation observed, interferon production was remarkably stable. Comparison of the various cytogenetic data revealed the presence of marker chromosomes and chromosomal constellations which were excluded from the drift. Some of these are useful for unequivocal identification of Namalva cells during long term cultivation.