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Paja Brava is a native South American grass with a high carbohydrate content. In the current work, the potential of using this feedstock for ethanol production using a simultaneous saccharification and fermentation (SSF) process with the xylose-fermenting yeast Pichia stipitis (Scheffersomyces stipitis) CBS6054 was investigated. The straw material was subjected to SO2 catalyzed steam pretreatment at 200°C and 5 min residence time, which resulted in a solubilization of pentose sugars (mainly xylose) of 64% with only minor amounts of degradation products. The obtained material, including the pretreatment liquid, was subsequently hydrolyzed and fermented in an SSF process at microaerobic conditions using either a batch or a fed-batch process at a total water-insoluble solids loading of 10%. Overall yields of ethanol based on all available sugars of 0.24 g/g and 0.27 g/g were obtained for batch and fed-batch mode of operation, respectively. The higher yield in the fed-batch process coincided with a higher degree of conversion of the sugars in the liquid medium, in particular of arabinose, for which the conversion was doubled (from 48% to 97%).
Global steady-state optimization of Zymomonas mobilis fermentation process problems is performed to demonstrate the existence of multiple optimum solutions necessitating the use of a global optimization strategy. It is shown that the steady-state equations for the Zymomonas mobilis fermentation process can be reduced to a single equation which when used as a constraint results in yielding only one optimum solution, the global one.
Gut Fermentation Syndrome also known
as Auto-Brewery Syndrome is a relatively unknown phenomenon in modern medicine.
Very few articles have been written on the syndrome and most of them are
anecdotal. This article presents a case study of a 61 years old male with a well documented case
of Gut Fermentation Syndrome verified with glucose and carbohydrate challenges.
Stool cultures demonstrated the causative organism as Saccharomyces cerevisiae. The patient was treated with antifungals
and a low carbohydrate diet and the syndrome resolved. Helicobacter pylori was also found and could have been a possible confounding variable
although the symptoms resolved post-treatment of the S. cerevisiae.