Effect of oxygen on ethanol fermentation in packed-bed tapered-column reactor

Summary In ethanol production with immobilized yeast a major problem is the provision of nutrients to these highly concentrated cells. O₂ being one of the nutrients of utmost importance to yeast cells, was fed into a column packed with beads with a cell loading of more than 40 g/l. Since addition of large volume of air or O₂ to a cylindrical column reactor would aggravate the problems of pressure build up and channelling caused by the evolving CO₂ gas, a tapered-column reactor and pulsed flow of oxygen gas was used. The supplement of O₂ gas to the tapered column increased the productivity from 21.1 g ethanol x (l gel x h)^-1 to 26.7 g x (l gel x h)^-1, when the ethanol concentration at the outlet was about 80 g/l. The yield coefficient of ethanol was also increased from 0.41 g ethanol/g glucose to 0.43 after O₂ supplement was started. The effects of frequency and duration of O₂ supplement were also determined.     

Enzymatic synthesis of two ginsenoside Re-beta-xylosides.

Two new beta-xylosyl derivatives of ginsenoside Re, 20(S)-protopanaxatriol 6-O-alpha-L-rhamnopyranosyl-(1 --> 2)-[beta-D-xylopyranosyl-(1 --> 4)]-beta-D-glucopyranosyl-20-O-beta-D-glucopyranoside and 20(S)-protopanaxatriol 6-O-alpha-L-rhamnopyranosyl-(1 --> 2)-[beta-D-xylopyranosyl-(1 --> 6)]-beta-D-glucopyranosyl-20-O-beta-D-glucopyranoside, were respectively synthesized from p-nitrophenyl beta-D-xylopyranoside and phenyl beta-D-xylopyranoside as donors and ginsenoside Re as the acceptor in 25% acetone and acetonitrile by a cellulase preparation from Trichoderma viride and a beta-galactosidase preparation from Aspergillus oryzae. The latter enzyme preparation also catalyzed the hydrolysis of ginsenoside Re to the minor saponin, ginsenoside Rg2.     

Mycolactone toxin induces an inflammatory response by targeting the IL-1β pathway: Mechanistic insight into Buruli ulcer pathophysiology

Mycolactone, a lipid-like toxin, is the major virulence factor of Mycobacterium ulcerans, the etiological agent of Buruli ulcer. Its involvement in lesion development has been widely described in early stages of the disease, through its cytotoxic and immunosuppressive activities, but less is known about later stages. Here, we revisit the role of mycolactone in disease outcome and provide the first demonstration of the pro-inflammatory potential of this toxin. We found that the mycolactone-containing mycobacterial extracellular vesicles produced by M. ulcerans induced the production of IL-1β, a potent pro-inflammatory cytokine, in a TLR2-dependent manner, targeting NLRP3/1 inflammasomes. We show our data to be relevant in a physiological context. The in vivo injection of these mycolactone-containing vesicles induced a strong local inflammatory response and tissue damage, which were prevented by corticosteroids. Finally, several soluble pro-inflammatory factors, including IL-1β, were detected in infected tissues from mice and Buruli ulcer patients. Our results revisit Buruli ulcer pathophysiology by providing new insight, thus paving the way for the development of new therapeutic strategies taking the pro-inflammatory potential of mycolactone into account.     

Functional significance of manganese catalase in Lactobacillus plantarum.

A strain of Lactobacillus plantarum which was unable to produce manganese (Mn)catalase (ATCC 8014) grew somewhat more rapidly and to a slightly higher plateau density than did an Mn catalase-positive strain (ATCC 14421), and this was the case during aerobic or anaerobic growth. However, when maintenance of viability was measured during the stationary phase of the growth cycle, the advantage provided by Mn catalase was obvious. Thus, the viability of ATCC 14431 was undiminished over 21 h of aerobic incubation, during the stationary phase, whereas that of ATCC 8014 decreased by seven orders of magnitude. Addition of catalase to the medium or growth in the presence of hemin, which allows catalase synthesis, protected ATCC 8014 against this loss of viability. Suppression of Mn catalase within ATCC 14431 by treatment with NH2OH caused the cells to lose viability when exposed to 4 mM H2O2.     

Morphological and histological study of castration-induced degeneration and androgen-induced regeneration in the mouse prostate

Degenerative and regenerative changes in the ductal architecture of the ventral and dorsolateral prostates (VP and DLP) of the adult mouse were investigated in microdissected specimens over a time-course of 14 days following castration and subsequently during 14 days of administration of testosterone propionate. After castration, about 35% of the ductal tips and branch-points were lost in distal regions (usually near the capsule) in both prostatic lobes. By contrast, in more proximal regions of the prostate (closer to the urethra), the ducts survived in an atrophic condition. The ductal morphology that had been lost in the distal regions completely regenerated after testosterone propionate was administered to the castrated males. In the VP, androgen replacement simply returned the gland to its former size with moderate ductal distension; in the DLP, excessive epithelial infoldings and ductal distension were elicited in the distal regions of the ducts after 14 days of treatment with testosterone propionate. These results suggest that androgenic responsiveness and dependency are different in distal versus proximal ducts. Distal ducts are exquisitely androgen-dependent and androgen-sensitive; in proximal regions, androgen-dependency is not as strict.