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Draw-fill culture was evaluated as a method for xylanase production by Cellulomonas flavigena on sugar cane bagasse. Specific xylanase activity and volumetric xylanase activities were measured by harvesting 50%, 55%, 60% and 70% of fermented broth at the end of each subculture. Maximum specific (64 IU mg–1 protein) and volumetric (166 IU ml–1) xylanase activities were obtained by harvesting 50–55% of broth. Values were 3.4 and 3.8 times greater than those obtained in batch cultures carried out under the same conditions. Enzyme productivity of 4.2 IU ml–1 h–1 was significantly greater than that obtained in continuous cultures (2.4 IU ml–1 h–1) (P<0.05). [ABSTRACT FROM AUTHOR]

The potential of microalgal oil from Scenedesmus incrassatulus as a feedstock for biodiesel production was studied. Cell concentration of S. incrassatulus and lipid content obtained during mixotrophic growth were 1.8 g/L and 19.5 ± 1.5% dry cell weight, respectively. The major components of biodiesel obtained from S. incrassatulus oil were methyl palmitate (26%) and methyl linoleate (49%), which provided a strong indication of high quality biodiesel. Fuel properties were determined by empirical equations and found to be within the limits of biodiesel standard ASTM D6751 and EN 14214. The quality properties of the biodiesel were high cetane number (62), low density (803 kg/m(3)), low viscosity (3.78 mm(2)/s), oxidation stability (9h) and cold filter plugging point (-4°C). Hence, S. incrassatulus has potential as a feedstock for the production of excellent quality biodiesel., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

In the present paper we investigated the effects of sub-lethal concentrations of Cu2+ in the growth and metabolism of Scenedesmus incrassatulus. We found that the effect of Cu2+ on growth, photosynthetic pigments (chlorophylls and carotenoids) and metabolism do not follow the same pattern. Photosynthesis was more sensitive than respiration. The analysis of chlorophyll a fluorescence transient shows that the effect of sub-lethal Cu2+ concentration in vivo, causes a reduction of the active PSII reaction centers and the primary charge separation, decreasing the quantum yield of PSII, the electron transport rate and the photosynthetic O2 evolution. The order of sensitivity found was: Growth>photosynthetic pigments content=photosynthetic O2 evolution>photosynthetic electron transport>respiration. The uncoupled relationship between growth and metabolism is discussed.

The conjugative self-transmissible plasmid pHT73, harbored in Bacillus thuringiensis var. kurstaki, was demonstrated to be transferred to Cellulomonas flavigena, a cellulolytic bacterium. Both conjugation and transformation procedures yielded resistant colonies; however, chromosomal integration was observed only when bacterial conjugation occurred. The efficiency of conjugation was 10% of recipient strain, which is considered a very efficient process. When the plasmid pHT73 was introduced by transformation, erythromycin-resistant cells contained the plasmid as an episome with no arrangements, as assayed by Southern blot analysis. In contrast, conjugated-resistant cells harbor the plasmid integrated into the chromosome. These data suggest a common mechanism of cell communication between nonrelated bacterial species with similar ecological habitats, and also that both electroporation and conjugation can be used to transform C. flavigena efficiently.