Search results for "Growth medium"

Formation of Variously Shaped Gold Nanoparticles by Anabaena laxa

2017

Anew aspect of this study is the biocatalysis ability of Anabaena laxa—fresh-water strain—which to date has not been studied with respect to the formation of gold nanoparticles. The results of our study have shown that A. laxa is able to form gold nanoparticles (AuNPs) at good yields within 24 h of incubation at all three tested concentrations (0.1, 0.5 and 1 mM) of hydrogen tetrachloroaurate (III). After 24 h, nanoparticles were mostly localized in the growth medium, which significantly facilitates their isolation. However, the elongation of this process is accompanied by their concentration in the exopolysaccharide (EPS) layer of the cyanobacterial cells. There is a correlation between th…

Biogenic iron-silver nanoparticles inhibit bacterial biofilm formation due to Ag+ release as determined by a novel phycoerythrin-based assay

2020

Silver nanoparticles (Ag-NPs) can be considered as a cost-effective alternative to antibiotics. In the presence of Fe(III)-citrate and Ag+, Klebsiella oxytoca DSM 29614 produces biogenic Ag-NPs embedded in its peculiar exopolysaccharide (EPS). K. oxytoca DSM 29614 was cultivated in a defined growth medium–containing citrate (as sole carbon source) and supplemented with Ag+ and either low or high Fe(III) concentration. As inferred from elemental analysis, transmission and scanning electron microscopy, Fourier transform infrared spectrometry and dynamic light scattering, Ag-EPS NPs were produced in both conditions and contained also Fe. The production yield of high-Fe/Ag-EPS NPs was 12 times …

Screening of microalgae and LED grow light spectra for effective removal of dissolved nutrients from cold-water recirculating aquaculture system (RAS…

2019

Popularity of recirculating aquaculture systems (RAS) is increasing. Because of the high water recirculation rate, dissolved nutrients originating from fish feed are concentrated enough in RAS wastewater (WW) to enable growth of primary producers, e.g. microalgae. This study evaluated nitrate-nitrogen (NO3-N) and phosphate-phosphorus (PO4-P) removal efficiency of ten temperate zone freshwater microalgae species during their exponential growth phase in unfiltered RAS WW at 17 ± 0.5 °C. Growth and nutrient uptake efficiency of six green and four non-green microalgae strains were compared between WW and reference growth medium in batch monocultures. The effect of three different LED grow light…

Btn2p is involved in ethanol tolerance and biofilm formation in flor yeast

2008

Flor yeasts are a particular kind of Saccharomyces cerevisiae strains involved in Sherry wine biological ageing. During this process, yeasts form a film on the wine surface and use ethanol as a carbon source, producing acetaldehyde as a by-product. Acetaldehyde induces BTN2 transcription in laboratory strains. Btn2p is involved in the control of the subcellular localization of different proteins. The BTN2 gene shows a complex expression pattern in wine yeast, increasing its expression by acetaldehyde, but repressing it by ethanol. A flor yeast strain transcribes more BTN2 than a first fermentation yeast during growth, but less under different stress conditions. BTN2 deletion decreases flor …

Exploring the diversity of listeria monocytogenes biofilm architecture by high-throughput confocal laser scanning microscopy and the predominance of …

2015

ABSTRACT Listeria monocytogenes is involved in food-borne illness with a high mortality rate. The persistence of the pathogen along the food chain can be associated with its ability to form biofilms on inert surfaces. While most of the phenotypes associated with biofilms are related to their spatial organization, most published data comparing biofilm formation by L. monocytogenes isolates are based on the quantitative crystal violet assay, which does not give access to structural information. Using a high-throughput confocal-imaging approach, the aim of this work was to decipher the structural diversity of biofilms formed by 96 L. monocytogenes strains isolated from various environments. Pr…

Alteration in membrane fluidity and lipid composition, and modulation of H(+)-ATPase activity in Saccharomyces cerevisiae caused by decanoic acid.

1996

Decanoic acid, a lipophilic agent, inhibited in vitro the plasma membrane H+-ATPase of Saccharomyces cerevisiae grown in YPD medium. Conversely, when decanoic acid (35 μM) was present in the growth medium, the measured H+-ATPase activity was four times higher than that of control cells. K m, and pH and orthovanadate sensitivity were the same for the two growth conditions, which indicated that H+-ATPase activation was not due to conformational changes in the enzyme. The activation process was not entirely reversible which showed that plasma membrane H+-ATPase activation is due to several mechanisms. 1,6-diphenyl-1,3,5-hexatriene anisotropy performed on protoplasts from cells grown in YPD rev…

Effect of iron and aeration on superoxide dismutase and catalase activity of PHB-producing Azotobacter chroococcum

2009

Abstract The effect of aeration level and iron concentration on Azotobacter chroococcum 23 growth, PHB accumulation and antioxidative enzyme activities was investigated in shake flask experiments. Biomass yield and carbon source conversation coefficients increased in the presence of iron in the growth medium and under decreased aeration. The highest biomass production was observed for the culture grown in a medium with 36 μM of initial iron concentration and moderate aeration level. The highest PHB accumulation level (70–72% from cell dry weight) under our experimental conditions was observed at decreased aeration in the growth medium with 180 μM of initial iron concentration. Results obtai…

Translational fusion to the Pir4 cell wall protein as a general and efficient method for cell surface immobilization or growth medium secretion of re…

2008

Synthesis and Assembly of Wall Polymers on Regenerating Yeast Protoplasts

1983

Accumulation of chitin and glucan on S. cerevisiae and C. albicans protoplasts begins shortly after resuspension in the regeneration medium, and mannoprotein molecules also appear retained by the regenerating wall after 30–60 minutes in S. cerevisiae or after a longer lag period in C. albicans. Nevertheless, a considerable fraction of the synthesized mannoproteins, which in SDS-acrylamide gels exhibit a different pattern from that of wall mannoproteins of cells, are still released to the growth medium during at least eight hours. De novo synthesis of chitin synthase, but not of glucan synthase, is observed in S. cerevisiae from about 30 minutes after initiation of the regeneration process. …

Wall mannoproteins in cells from colonial phenotypic variants of Candida albicans.

1990

Candida albicans ATCC 26555 switched at high frequency (10(-1) to 10(-3)) between several phenotypes identified by colony morphology on a defined mineral amino-acid-containing agar medium supplemented with arginine and zinc (LAZ medium). When cells taken from colonies exhibiting distinct morphologies were plated directly onto LAZ agar, spontaneous conversion to all the variant phenotypes occurred at combined frequencies of 2.1 x 10(-1) to 9.5 x 10(-3). However, when cells taken from the different colonial phenotypes were plated directly onto an undefined medium (yeast extract/peptone/dextrose; YPD medium), or first incubated in liquid YPD medium and then cloned on YPD agar, all colonies obs…