Search results for "microbiology"

Acetaldehyd als Indicator f�r die Regulation von Atmung und G�rung bei der aeroben Verg�rung von Glucose durch Saccharomyces cerevisiae

1971

Wahrend der aeroben Vergarung von Glucose wurde die Konzentration von Acetaldehyd im Garmedium uber den gesamten Garablauf bei mehreren Stammen von Saccharomyces cerevisiae verfolgt. Die Aldehydkonzentration weist bei Glucosekonzentrationen zwischen 5 und 20% zwei Maxima auf. Damit ist der Konzentrationsverlauf von Acetaldehyd aerob wesentlich anders als bei der anaeroben Garung, mit nur einem meist niedrigen Maximum. 10-3 M Azid hemmt die Bildung von Acetaldehyd ganz oder weitgehend. Das deutet auf die Funktion bzw. Synthese der Cytochrome, die in Gegenwart von Sauerstoff offensichtlich auch bei hohen Glucosekonzentrationen nicht vollstandig reprimiert werden. Der durch die Atmung bedingte…

Dehydration of yeast: Changes in the intracellular content of Hsp70 family proteins

2008

Abstract Yeast is known to experience in natural and industrial conditions cycles of dehydration–rehydration. Several molecular mechanisms can be triggered in response to this and other environmental stressors and to rescue yeast cells of the cytotoxic effect. Since heat shock proteins constitute one of the most important systems of the response to stress we studied whether the pre-induced major stress protein, Hsp70, can cope with yeast cell drying. To induce Hsp70 expression the cells of two yeast species, Saccharomyces cerevisiae and Debaryomyces hansenii , were subjected to non-lethal heat shock. It was found that during yeast culture growth Hsp70 accumulation occurred at the exponentia…

Formation of l(-)malate by Saccharomyces cerevisiae during fermentation

1988

When grown in a synthetic medium most of the 51 strains of the genera Saccharomyces, Saccharomycodes, Zygosaccharomyces and Schizosaccharomyces investigated formed l-malate during fermentation. The quantity varied between 0.1 and 2.6 g malate per liter. Two strains of Saccharomyces cerevisiae synthesized malate at a rate of about 1.5 g/l. Malate was liberated during the growth phase and not metabolized during the stationary phase. Optimum malate formation was observed at a sugar concentration of about 20% (w/v), at pH 5 and at suboptimal nitrogen concentrations of less than 300 mg N/liter. Of the amino acids aspartate and glutamate were most favourable. If ammonium salts were used as the ni…

Enhanced fermentative capacity of yeasts engineered in storage carbohydrate metabolism.

2014

During yeast biomass production, cells are grown through several batch and fed-batch cultures on molasses. This industrial process produces several types of stresses along the process, including thermic, osmotic, starvation, and oxidative stress. It has been shown that Saccharomyces cerevisiae strains with enhanced stress resistance present enhanced fermentative capacity of yeast biomass produced. On the other hand, storage carbohydrates have been related to several types of stress resistance in S. cerevisiae. Here we have engineered industrial strains in storage carbohydrate metabolism by overexpressing the GSY2 gene, that encodes the glycogen synthase enzyme, and deleting NTH1 gene, that …

Protection of living yeast cells by micro-organized shells of natural polyelectrolytes

2015

International audience; Saccharomyces cerevisiae, a eukaryotic model organism, plays a key role in the oxidative stability of fermented products. In order to protect cells against environmental stresses, we report a method of modifying the cell surface architecture while maintaining the internal working properties of the system. The objective was to encapsulate living yeast cells in micro-organized polyelectrolyte shells using layer-by-layer (LbL) assembly. For the first time, the natural polyelectrolytes, β-lactoglobulin and sodium alginate, were alternately deposited on the surface of S. cerevisiae. Transmission electron microscopy coupled with immune-cytochemistry and scanning electron m…

Quorum Sensing effects on Pseudomonas corrugata plant interaction and antagonistic activity

2010

Numerical Taxonomy of Pseudomonads Isolated from Water, Sediment and Eels

1992

Summary A numerical taxonomic study was performed on 129 pseudomonad isolates from aquatic environments. 67 out of 98 field strains were isolated from water and sediment samples from Albufera lake, a hypereutrophic lake near Valencia, and 31 strains came from an eel hatchery. 10 clusters were formed at 84% similarity level when the Sokal-Michener similarity coefficient was used. Five clusters were designated as Pseudomonas putida (16 strains), P. fluorescens biotype I (9 strains), P. pseudoalcaligenes (11 strains), P. stutzen (4 strains) and Shewanella putrefaciens (3 strains). A subcluster of 7 strains (out of 15) was ascribed to the species Xanthomonas maltophilia , while the other strain…

Growth increase of birch seedlings under the influence of earthworms—a laboratory study

1992

The effects of the earthworm Lumbricus rubellus (Hoffm.) on net production and nitrogen content of birch seedlings were studied in laboratory microcosms. Coniferous forest floors with litter, humus and mineral horizons were simulated in transparent plastic cylinders. The materials were partially sterilized by microwaving, and re-inoculated with microflora and -fauna. A young (9 cm) birch seedling (Betula pendula Roth) was planted in each container. Earthworms were added to half of the replicates. The microcosms, through which a constant air flow was maintained, were incubated in a climate chamber. After two growth periods, leaf and stem biomasses of birch in treatments with earthworms incre…

Effects of endogeic earthworms on soil processes and plant growth in coniferous forest soil

1992

The effects of the endogeic earthworm, Aporrectodea caliginosa tuberculata (Eisen) on decomposition processes in moist coniferous forest soil were studied in the laboratory. The pH preference of this species and its effects on microbial activity, N and P mineralization, and the growth of birch seedlings were determined in separate pot experiments. Homogenized humus from a spruce stand was shown to be too acid for A. c. tuberculata. After liming, the earthworms thrived in the humus and their biomass increased (at pH above 4.8). In later experiments in which the humus was limed, the earthworms positively influenced the biological activity in humus and also increased the rate of N mineralizati…

A new species ofPythiumisolated from burgundian vineyards and its antagonism towardsBotrytis cinerea, the causative agent of the grey mould disease

2004

During the course of an investigation on the pythiaceous fungi occurring in burgundian vineyards, three isolates of Pythium were found, all of which were characterised by spherical to lemoniform, proliferating sporangia. Only one out of these three isolates produced sexual characters (S-12) after prolonged incubation, but their asexual structures, temperature growth relationship and molecular characteristics were identical. Saprolegnia-type internal proliferation of the sporangia, and Phytophthora-type lemoniform, papillate sporangia were characteristic of all the three isolates. The type specimen is S-12 which is a medium slow growing saprophyte. The sequence of its ITS region of the rDNA …