Effect of oxygen on the biosynthesis of flavor compound 3-methylbutanal from leucine catabolism during batch culture in Carnobacterium maltaromaticum LMA 28.

In this study, we demonstrated the effect of different dissolved oxygen concentrations (DOC) on cell growth and intracellular biosynthesis of 3-methylbutanal from leucine catabolism in Carnobacterium maltaromaticum LMA 28 during batch culture. The maximum specific growth rate was obtained in culture when DOC was controlled at 50% of air saturation. The specific consumption rates of glucose and specific production rates of lactate were higher at a DOC at 50 or 90% of air saturation. Carnobacterium maltaromaticum LMA 28 produced high quantities of 3-methylbutanal and 3-methylbutanol during culture with DOC maintained at 90%, suggesting that oxygen had a significant effect of the formation of these flavor compounds. This high formation of flavor compounds in an oxygen-rich environment was attributed to the simultaneous activation and stimulation of both α-ketoacid decarboxylase (KADC) and α-ketoacid dehydrogenase (KADH) pathways. Thus, intracellular biosynthesis of 3-methylbutanal can be controlled by modifying the DOC of the culture or food product during fermentation.

Anterior mediastinal presentation of a giant angiomyolipoma.

Angiomyolipomas are benign, solitary, noninvasive lesions that most often arise in the kidney. Extrarenal manifestations of these tumors include the skin, oropharynx, the abdominal wall, retroperitoneum, gastrointestinal tract, heart, lung, liver, uterus, penis, and spinal cord. We report a patient with a giant angiomyolipoma located in the anterior mediastinum. We believe this is the seventh reported case of mediastinal angiomyolipoma and the largest reported by size. It is the second reported lesion to arise in the anterior mediastinum. Distinction from other pulmonary or thoracic masses relies on the appreciation of the unique and characteristic histologic features of these mediastinal angiomyolipomas. We conclude that, although rare, angiomyolipoma should be considered in the differential diagnosis of a mediastinal tumor.