Search results for "Acetobacter"
showing 4 items of 14 documents
Studies on Two Exoenzymes Which Lyse Wine-Spoiling Bacteria
2014
Microorganisms play an important role in the conversion of grape juice into wine. Different species of yeast are mainly responsible for the production of ethanol. Lactic acid bacteria also occur regularly in must or wine. They are mostly undesirable due to their capacity to produce wine-spoiling compounds. Especially strains of Lactobacillus brevis are able to produce biogenic amines as well as precursors of ethyl carbamate and different off-flavours (N-heterocycles, volatile phenols). By excessive formation of acetic acid some lactobacilli may even induce slow/stuck grape juice fermentations. In conventional winemaking, additions of sulphite or lysozyme are used to inhibit the growth of sp…
Desarrollo de Nanocompuestos de Celulosa Bacteriana para Aplicaciones Biomédicas
2014
La celulosa bacteriana es un polisacárido obtenido a partir de microorganismos de la especie Gluconacetobacter cuando son cultivados en medios que contienen fuentes de carbono y nitrógeno. El material que se obtiene a partir de los procesos bioquímicos que ocurren dentro de la membrana celular de las bacterias se presenta físicamente como un gel que contiene agua y fibras de celulosa de alta pureza, cuyas dimensiones de sección se encuentran en el orden de los nanómetros. Debido a sus buenas propiedades, las aplicaciones de los materiales basados en celulosa bacteriana se incluyen en la industria del papel, alimentaria, farmacéutica y en biomedicina. La mayoría de investigaciones para la fa…
Bacterial Bioconversion of Primary Aliphatic and Aromatic Alcohols into Acids: Effects of Molecular Structure and Physico-chemical Conditions
1997
The biotransformation of four alcohol substrates (butanol, 2-methylbutanol, 3-methylbutanol and 2-phenylethanol) into their acids was studied using a strain of Acetobacter aceti. Bioconversion yields depended on the molecular structure of the alcohol. Biotransformation of high concentrations of alcohols was possible until the precursor reached an inhibiting concentration (3.8 g dm -3 for butanol and 3-methylbutanol, 4.2 g dm -3 for 2-methylbutanol). In contrast, biotransformation of 2-phenylethanol decreased when alcohol concentration was higher than 0.3 g dm -3 . Dissolved oxygen concentrations and pH conditions of the medium were important factors in improving bioconversion. Transformatio…
Morphological Characterisation of Bacterial Cellulose-Starch Nanocomposites
2008
Acetobacter sp. growing medium was modified in order to produce bacterial cellulose (BC) nanocomposites using a bottom-up technique that allowed starch to be introduced into the cellulose network. The BC-starch mats were hot-pressed to obtain nanocomposites sheets. Morphological characterisation was carried out using Atomic Force Microscopy and Environmental Scanning Electron Microscopy. The images obtained from microscopy were then processed using image analysis. Network properties, such as mesh size and fibre orientation were characterised. Fracture surfaces of these new nanocomposites were analysed.