Enhanced hexadecane degradation and low biomass production by Aspergillus niger exposed to an electric current in a model system

2011 ◽  
Vol 102 (2) ◽  
pp. 1509-1515 ◽  
Author(s):  
Nancy Velasco-Alvarez ◽  
Ignacio González ◽  
Pablo Damian-Matsumura ◽  
Mariano Gutiérrez-Rojas
Keyword(s):  
Aspergillus Niger ◽  
Electric Current ◽  
Biomass Production ◽  
Model System

The use of chemical uncouplers for reducing biomass production during biodegradation

1998 ◽  
Vol 37 (4-5) ◽  
pp. 399-402 ◽  
Author(s):  
Euan W. Low ◽  
Howard A. Chase
Keyword(s):  
Biomass Production ◽  
Cell Mass ◽  
Model System ◽  
Energy Requirements ◽  
Simultaneous Increase ◽  
Maintenance Energy ◽  
Specific Substrate ◽  
Substrate Uptake ◽  
Activated Sludge Process ◽  
Substrate Uptake Rate

Reducing the energy available for anabolism of cell mass was identified as a method to minimise disposal requirements of excess biomass produced in the activated sludge process. A model system consisting of Pseudomonas putida, maintained in a chemostat, was employed to investigate biomass production in the presence of the energy dissipating protonphore, p-nitrophenol (pNP). The efficiency of biomass production was reduced by up to 62% when the feed was supplemented with 100 mg pNP.l−1 with a simultaneous increase in the specific substrate uptake rate. The data obtained have been analysed to reveal maintenance energy requirements and true growth yields. Cells were found to satisfy their maintenance energy requirements prior to utilising energy in anabolism. Decreases in pH alone had no effect on biomass production, but caused additional protonphore induced reduction of biomass production. A pH 6.2 the efficiency of biomass production was reduced by up to 77% when the feed was supplemented with 100 mg pNP.l−1.

Induction and Repression Kinetics of Fungal Beta-Fructofuranosidase in Submerged Culture

2009 ◽  
Vol 5 (2) ◽  
Author(s):  
Armando Robledo-Olivo ◽  
Juan C Contreras-Esquivel ◽  
Raul Rodriguez Herrera ◽  
Cristobal N Aguilar
Keyword(s):  
Aspergillus Niger ◽  
Enzymatic Activity ◽  
Biomass Production ◽  
Submerged Culture ◽  
Enzyme Production ◽  
Maximum Rate ◽  
Sucrose Concentration ◽  
Viable Option ◽  
Initial Concentration ◽  
Kinetics Of

Invertase production by Aspergillus niger in submerged culture was evaluated under different concentrations of sucrose and glucose. When the initial concentration of sucrose was increased from 6.25 to 50 gL-1, a higher biomass production (6.1 gL-1) was observed. The biomass production was increased 4 times more when a glucose-sucrose combination was used as substrate (26.31 gL-1). The strain A. niger produced extracellular beta-fructofuranosidase activity at all test concentrations of the substrate and the highest enzymatic activity (3873 UL-1) was obtained when sucrose was used at 12.5 gL-1. However, with a glucose-sucrose concentration of 25 gL-1 the beta-fructofuranosidase activity was of 23706 UL-1. The maximum rate of invertase enzyme production in presence of sucrose by Aspergillus niger in submerged culture was 3.67 UL-1h-1 at 12.5 gL-1 concentration, while in the case of glucose-sucrose mixture, it was 13.95 UL-1h-1 at a concentration of 25 gL-1. It was observed that the enzyme yield (YE/X) was 1.25 times more in presence of sucrose than with glucose-sucrose combination. In addition, the results suggested that an addition of lower concentration of glucose is a viable option to increase the enzyme secretion by the fungi.

Fungal biomass production in response to elevated atmospheric CO2 in a Glomus mosseae–Prunus cerasifera model system

2010 ◽  
Vol 11 (1) ◽  
pp. 17-26 ◽  
Author(s):  
Paola Fortuna ◽  
Luciano Avio ◽  
Stefano Morini ◽  
Manuela Giovannetti
Keyword(s):  
Biomass Production ◽  
Fungal Biomass ◽  
Glomus Mosseae ◽  
Model System ◽  
Atmospheric Co2 ◽  
Elevated Atmospheric Co2 ◽  
Prunus Cerasifera

A Protozoan Model for Golgi-Associated Calcification

1971 ◽  
Vol 29 ◽  
pp. 332-333
Author(s):  
D. C. Williams ◽  
D. E. Outka
Keyword(s):  
Golgi Apparatus ◽  
Organic Matrix ◽  
Model System ◽  
Sequential Formation

Many studies have shown that the Golgi apparatus is involved in a variety of synthetic activities, and probably no Golgi product is more elaborate than the scales produced by various kinds of phytoflagellates. The formation of calcified scales (coccoliths, Fig. 1,2) of the coccolithophorid phytoflagellates provides a particularly interesting model system for the study of biological mineralization, and the sequential formation of Golgi products.The coccoliths of Hymenomonas carterae consist of a scale-like base (Fig. 2 and 4, b) with a highly structured calcified (CaCO3) rim composed of two distinct elements which alternate about the base periphery (Fig. 1 and 3, A, B). Each element is enveloped by a sheath-like organic matrix (Fig. 3; Fig. 4, m).

Existence of DNA in yeast microbodies

1978 ◽  
Vol 36 (2) ◽  
pp. 232-233
Author(s):  
Masako Osumi ◽  
Misuzu Nagano ◽  
Hiroko Kazama
Keyword(s):  
Catalase Activity ◽  
Buoyant Density ◽  
Model System ◽  
Contour Length ◽  
Native State ◽  
Normal Alkane ◽  
Remarkable Increase ◽  
Dna Molecule ◽  
Mitochondrial Dnas

We have found that microbodies appeared profusely together with a remarkable increase in catalase activity in normal alkane-grown cells of hydrocarbon-utilizing Candida yeasts, and that the microbodies multiplied by division in these cells. These features of Candida yeasts seem to provide a useful model system for studies on the biogenesis of the microbody. Subsequently, we have succeeded in isolation of Candida microbodies in an apparently native state, as judged biochemically and morphologically. The presence of DNA in the purified microbody fraction thus obtained was proved by the diphenylamine method. DNA molecule of about 15 urn in contour length was released from an isolated microbody. The physicochemical analyses of the microbody DNA revealed that its buoyant density differed from nuclear and mitochondrial DNAs. All these results lead us to the possibility that there is a novel type of DNA in microbodies.

The coprecipitation of Cr3P and Cr in Cu

1988 ◽  
Vol 46 ◽  
pp. 764-765
Author(s):  
M.J. Witcomb ◽  
U. Dahmen ◽  
K.H. Westmacott
Keyword(s):  
Orientation Relationship ◽  
Interface Structure ◽  
Model System ◽  
Relative Orientation ◽  
Age Hardening ◽  
Precipitation Behavior ◽  
Solution Treated ◽  
Small Needle ◽  
Diffraction Patterns ◽  
Interface Structures

Cu-Cr age-hardening alloys are of interest as a model system for the investigation of fcc/bcc interface structures. Several past studies have investigated the morphology and interface structure of Cr precipitates in a Cu matrix (1-3) and good success has been achieved in understanding the crystallography and strain contrast of small needle-shaped precipitates. The present study investigates the effect of small amounts of phosphorous on the precipitation behavior of Cu-Cr alloys.The same Cu-0.3% Cr alloy as was used in earlier work was rolled to a thickness of 150 μm, solution treated in vacuum at 1050°C for 1h followed by quenching and annealing for various times at 820 and 863°C.Two laths and their corresponding diffraction patterns in an alloy aged 2h at 820°C are shown in correct relative orientation in Fig. 1. To within the limit of accuracy of the diffraction patterns the orientation relationship was that of Kurdjumov-Sachs (KS), i.e. parallel close-packed planes and directions.

Membrane-associated microtubular areays induced in proximal myelinated processes of dorsal root ganglia by large doses of vitamin B6

1986 ◽  
Vol 44 ◽  
pp. 368-369
Author(s):  
V.J. Montpetit ◽  
S. Dancea ◽  
L. Tryphonas ◽  
D.F. Clapin
Keyword(s):  
Animal Model ◽  
Endoplasmic Reticulum ◽  
Dorsal Root Ganglia ◽  
Rough Endoplasmic Reticulum ◽  
Dorsal Root ◽  
Vitamin B6 ◽  
Morphological Changes ◽  
Model System ◽  
Sensory Nerves ◽  
Peripheral Sensory

Very large doses of pyridoxine (vitamin B6) are neurotoxic in humans, selectively affecting the peripheral sensory nerves. We have undertaken a study of the morphological and biochemical aspects of pyridoxine neurotoxicity in an animal model system. Early morphological changes in dorsal root ganglia (DRG) associated with pyridoxine megadoses include proliferation of neurofilaments, ribosomes, rough endoplasmic reticulum, and Golgi complexes. We present in this report evidence of the formation of unique aggregates of microtubules and membranes in the proximal processes of DRG which are induced by high levels of pyridoxine.

An Ultrastructural Comparison of Hepatocytes from ADH+ and ADH−Peromyscus Maniculatus

1996 ◽  
Vol 54 ◽  
pp. 30-31
Author(s):  
J. T. Ellzey ◽  
D. Borunda ◽  
B. P. Stewart
Keyword(s):  
South Carolina ◽  
Adult Male ◽  
Uranyl Acetate ◽  
Model System ◽  
Deer Mice ◽  
En Bloc ◽  
Genetic Stock ◽  
Hepes Buffer ◽  
Transmission Electron ◽  
Color Scanner

Genetically alcohol deficient deer mice (ADHN/ADHN) (obtained from the Peromyscus Genetic Stock Center, Univ. of South Carolina) lack hepatic cytosolic alcohol dehydrogenase. In order to determine if these deer mice would provide a model system for an ultrastructural study of the effects of ethanol on hepatocyte organelles, 75 micrographs of ADH+ adult male deer mice (n=5) were compared with 75 micrographs of ADH− adult male deer mice (n=5). A morphometric analysis of mitochondrial and peroxisomal parameters was undertaken.The livers were perfused with 0.1M HEPES buffer followed by 0.25% glutaraldehyde and 2% sucrose in 0.1M HEPES buffer (4C), removed, weighed and fixed by immersion in 2.5% glutaraldehyde in 0.1M HEPES buffer, pH 7.4, followed by a 3,3’ diaminobenzidine (DAB) incubation, postfixation with 2% OsO4, en bloc staining with 1% uranyl acetate in 0.025M maleate-NaOH buffer, dehydrated, embedded in Poly/Bed 812-BDMA epon resin, sectioned and poststained with uranyl acetate and lead citrate. Photographs were taken on a Zeiss EM-10 transmission electron microscope, scanned with a Howtek personal color scanner, analyzed with OPTIMAS 4.02 software on a Gateway2000 4DX2-66V personal computer and stored in Excel 4.0.

Elemental analysis of human erythrocytes

1989 ◽  
Vol 47 ◽  
pp. 242-243
Author(s):  
S. A. Livesey ◽  
A. A. del Campo ◽  
E. S. Griffey ◽  
D. Ohlmer ◽  
T. Schifani ◽  
...  
Keyword(s):  
Sample Preparation ◽  
Elemental Analysis ◽  
Human Erythrocyte ◽  
Spectroscopic Analysis ◽  
Model System ◽  
Human Erythrocytes ◽  
List Type ◽  
Chemical Fixation ◽  
Ethanol Dehydration ◽  
Lowicryl K4m

The aim of this study is to compare methods of sample preparation for elemental analysis. The model system which is used is the human erythrocyte. Energy dispersive spectroscopic analysis has been previously reported for cryofixed and cryosectioned erythrocytes. Such work represents the reference point for this study. The use of plastic embedded samples for elemental analysis has also been documented. The work which is presented here is based on human erythrocytes which have been either chemically fixed and embedded or cryofixed and subsequently processed by a variety of techniques which culminated in plastic embedded samples.Heparinized and washed erythrocytes were prepared by the following methods for this study :(1). Chemical fixation in 4% paraformaldehyde/0.25% glutaraldehyde/0.2 M sucrose in 0.1 M Na cacodylate, pH 7.3 for 30 min, followed by ethanol dehydration, infiltration and embedding in Lowicryl K4M at -20° C.

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