Preparation of volatile fatty acid (VFA) calcium salts by anaerobic digestion of glucose.

Many potentially useful intermediates such as hydrogen and volatile fatty acids (VFAs) are formed during the complex anaerobic digestion processes that produce methane from biomass. This study recovers VFAs from an anaerobic digester by a combination of gas stripping and absorption with calcium carbonate slurry. Glucose was used as the model substrate because it is readily available, inexpensive, and easily digested.

Estimation of fungal biomass and lipid production by morphological characteristics of Mucor rouxii.

This study presents methodology for estimating biomass and lipid production by Mucor rouxii via image analysis. Morphological variations in M. rouxii in relation to its biomass and lipid production were investigated using image analysis.

High cell density cultivation of Escherichia coli with surface anchored transglucosidase for use as whole-cell biocatalyst for alpha-arbutin synthesis.

A fed-batch culture strategy for the production of recombinant Escherichia coli cells anchoring surface-displayed transglucosidase for use as a whole-cell biocatalyst for alpha-arbutin synthesis was developed. Lactose was used as an inducer of the recombinant protein. In fed-batch cultures, dissolved oxygen was used as the feed indicator for glucose, thus accumulation of glucose and acetate that affected the cell growth and recombinant protein production was avoided.

Production of ascorbic acid glucoside by alginate-entrapped mycelia of Aspergillus niger.

The mycelia of Aspergillus niger, cultivated in a medium containing 45 g l(-1) maltose, 66 g l(-1) yeast extract, and 5 g l(-1) K(2)HPO(4) at 30 degrees C and 200 rpm, were used as a biocatalyst in the glucosylation of ascorbic acid. Free mycelia from 3-day-old culture, when used in a 6-h reaction with maltose as the acyl donor, gave 16.07 g l(-1) ascorbic acid glucoside corresponding to a volumetric productivity of 2.

Simultaneous estimation of chlorophyll a and lipid contents in microalgae by three-color analysis.

A method of rapid determination of chlorophyll a and lipid contents of microalgae based on colorimetric analysis of the digital images of the microalgae is proposed. The color variation of microalgae during cultivation is evaluated by the brightness of the three primary colors (red, green, and blue). The brightness values of the three primary colors are modeled as two linear correlation functions (RGB model) for microalgal chlorophyll a and lipid contents, respectively.

Production of ascorbyl palmitate by surfactant-coated lipase in organic media.

The surface of a lipase from Burkholderia cepacia was coated with a nonionic surfactant, propylene glycol monostearate, and was used as a biocatalyst in the production of ascorbic acid in tert-butyl alcohol. The influence of various factors such as the type of surfactant, the pH of the buffer used for coating, the amount of surfactant in the coating, the organic solvent, and the temperature and molar ratio of the substrates used in the reaction on the conversion of ascorbyl palmitate were studied. After 24 h of reaction at 50 degrees C, a conversion of 47% was obtained using an ascorbic acid to palmitic acid molar ratio of 1:6.

Productivity improvement in l-sorbose biosynthesis by fedbatch cultivation of Gluconobacter oxydans.

The effect of increased (100, 200 and 300 gl(-1)) initial sorbitol concentrations (S0) was investigated in the sorbitol to sorbose bioconversion process. Batch cultivations with a S0 of 100, 200 and 300 gl(-1) were completed at 10, 14 and 24 h with a corresponding overall sorbose productivity of 10.1, 14.