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. The chlorophyll a and lipid contents predicted by the proposed model are compared with that determined by the standard methods. The good agreement of the model predictions with experimental results is demonstrated with a squared correlation coefficient (R(2)) of 0.99 for chlorophyll a and lipid. The reliability of the RGB model was verified in real cultivations of the microalgae in a photobioreactor. Growth dynamics, contents of chlorophyll a and lipid corresponded very well with previously reported studies.

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. The native lipase showed only 6% conversion.

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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. Fed-batch fermentation with lactose induction yielded a biomass of 18 g/L, and the cells possessed very high transglucosylation activity. In the synthesis of alpha-arbutin by hydroquinone glucosylation, the whole-cell biocatalysts showed a specific activity of 501 nkat/g cell and produced 21 g/L of arbutin, which corresponded to 76% molar conversion. A sixfold increased productivity of whole cell biocatalysts was obtained in the fed-batch culture with lactose induction, as compared to batch culture induced by IPTG.