Search results for "substrate"

Optimization of acetate production from citrus wastewater fermentation

2021

Abstract Citrus wastewater is a sugar-rich waste stream suitable for the recovery of energy of material from its treatment. In this study, fermentation of citrus wastewater was carried out to assess the optimal conditions to maximize the bioconversion of the organic substrate into acetate. Unbalanced nutrient (C: N: P 200:0.1:0.1) enabled the highest acetate production. The presence of the particulate organic fraction enabled to obtain a higher acetate concentration regardless the initial COD concentration. Initial pH values higher than 5 did not cause substantial differences on the maximum bioconversion of COD into acetate in Trial 3, whereas pH lower than 5 hindered the hydrolysis process…

A thermo-alkaline lipase from a new thermophileGeobacillus thermodenitrificansAV-5 with potential application in biodiesel production

2015

BACKGROUND A thermophilic lipase-producing Geobacillus thermodenitrificans strain AV-5 was isolated from the Mushroom Spring of Yellowstone National Park in WY, USA and studied as a source of lipase for transesterification of vegetable oils to biodiesel. RESULTS A maximum activity of 330 U mL−1 was produced on 2% (v/v) waste cooking oil at 50 °C, pH 8, aeration rate of 1 vvm and agitation speed of 400 rpm. However, the higher lipase productivity (14.04 U mL−1 h−1) was found at a volumetric oxygen transfer coefficient (kLa) value of 18.48 h−1. The partially purified lipase had a molecular weight, temperature and pH optimum of 50 kDa, 65 °C and pH 9, respectively, and was thermo-alkali stable…

New evidence for the multiplicity of ubiquinone- and inhibitor-binding sites in the mitochondrial complex I.

2000

Determination of the number of ubiquinone- and inhibitor-binding sites in the mitochondrial complex I (NADH:ubiquinone oxidoreductase) is a controversial question with a direct implication for elaborating a suitable model to explain the bioenergetic mechanism of this complicated enzyme. We have used combinations of both selective inhibitors and common ubiquinone-like substrates to demonstrate the multiplicity of the reaction centers in the complex I in contrast with competition studies that have suggested the existence of a unique binding site for ubiquinone. Our results provide new evidence for the existence of at least two freely exchangeable ubiquinone-binding sites with different specif…

Structural analysis and biochemical properties of laccase enzymes from two Pediococcus species

2021

Summary Prokaryotic laccases are emergent biocatalysts. However, they have not been broadly found and characterized in bacterial organisms, especially in lactic acid bacteria. Recently, a prokaryotic laccase from the lactic acid bacterium Pediococcus acidilactici 5930, which can degrade biogenic amines, was discovered. Thus, our study aimed to shed light on laccases from lactic acid bacteria focusing on two Pediococcus laccases, P. acidilactici 5930 and Pediococcus pentosaceus 4816, which have provided valuable information on their biochemical activities on redox mediators and biogenic amines. Both laccases are able to oxidize canonical substrates as ABTS, ferrocyanide and 2,6‐DMP, and non‐…

Biogeochemical responses to nutrient, moisture and temperature manipulations of soil from Signy Island, South Orkney Islands in the Maritime Antarctic

2014

AbstractWe have investigated how the microbially-driven processes of carbon (C) mineralization (respiration) and nitrogen (N) mineralization/immobilization in a soil from the northern Maritime Antarctic respond to differences in water availability (20% and 80% water-holding capacity) and temperature (5°C and 15°C) in the presence and absence of different organic substrates (2 mg C as either glucose, glycine or tryptone soy broth (TSB) powder (a complex microbial growth medium)) in a controlled laboratory experiment over 175 days. Soil respiration and N mineralization/immobilization in the presence of a C-rich substrate (glucose) increased with increases in water and temperature. These facto…

Mycelium Growth and Biological Efficiency of Ganoderma lucidum on Substrate Supplemented with Different Organic Additives

2015

Plant colonization of bare peat surface - relative importance of seed availability and soil

1992

A field survey on two former peat harvesting sites of similar successional age revealed a marked difference in species composition and a 30-fold difference in biomass of the established vegetation Based on this observation, a field experiment in which the substrate was changed between sites was conducted to examine whether the differences in revegetation were mainly a consequence of differences in seed supply or in substrate quality After three growing seasons, a many hundred-fold difference in plant biomass existed between the transplanted and control plots with the same substrate, but only a small difference between the plots with a different substrate within the site Biological activity …

Templating: Substrate Templating upon Self-Assembly of Hydrogen-Bonded Molecular Networks on an Insulating Surface (Small 19/2012)

2012

UDP-glucosyltransferase activity toward exogenous substrates in Drosophila melanogaster.

1991

To investigate the capacity of Drosophila extracts to glucosylate exogenous substrates we have developed a fast and sensitive method for the detection of UDP-glucosyltransferase activity using 4-nitrophenol, 1-naphthol, or 2-naphthol as substrates. High-performance liquid chromatography was used to separate and quantitate the reaction products, allowing detection of activities that produced as little as 1 pmol of 2-naphthol glucoside (fluorescence detection) or 16 pmol of 4-nitrophenol glucoside (absorbance detection). Optimal activity was found at 43 degrees C and alkaline pH. The affinity of the Drosophila enzyme was 250-fold higher for 1-naphthol or 2-naphthol (Km approximately 4 microM)…

Mucolipidosis I: increased sialic acid content and deficiency of an alpha-N-acetylneuraminidase in cultured fibroblasts.

1977

Abstract Extracts of fibroblasts derived from a patient with mucolipidosis I exhibited a fivefold increase in sialic acid content as compared to those of normal cells. About 80% of this sialic acid was linked to other molecules. Using neuraminlactose as a substrate, mucolipidosis I fibroblasts were found to be severely deficient in an “acid” α-N-acetylneuraminidase. Since other lysosomal hydrolase activities were normal, we hypothesize that the basic metabolic lesion in mucolipidosis I lies in a defective degradation of sialic acid-containing compounds due to the genetic deficiency of a neuraminidase.