Engineering analysis of the high-density heterotrophic cultivation of mung bean sprouts.

This study investigated the heterotrophic growth behavior of mung beans cultivated in an individual bed under water supply. The fresh weight of mung beans in the bed was estimated, and changes in temperature, and oxygen and carbon dioxide concentrations were recorded during the cultivation period. The specific growth rate, oxygen uptake rate, and carbon dioxide evolution rate, based on the fresh weight in the bed, were calculated. Growth under heterotrophic cultivation can be classified into the following three stages. Reductions in specific oxygen uptake rate, specific carbon dioxide evolution rate, and specific energy production rate corresponded to that of specific growth rate. Indicators of biological activity related to oxygen and carbon dioxide were evaluated quantitatively for beds under high-density heterotrophic cultivation. Moreover, the results obtained from this study successfully demonstrate that there is a relationship between the growth of mung beans and indicators of biological activity.

StHsp14.0, a small heat shock protein of Sulfolobus tokodaii strain 7, protects denatured proteins from aggregation in the partially dissociated conformation.

The small heat shock protein (sHsp), categorized into a class of molecular chaperones, binds and stabilizes denatured proteins for the purpose of preventing aggregation. The sHsps undergo transition between different oligomeric states to control their nature. We have been studying the function of sHsp of Sulfolobus tokodaii, StHsp14.0. StHsp14.0 exists as 24meric oligomer, and exhibits oligomer dissociation and molecular chaperone activity over 80°C. We constructed and characterized StHsp14.0 mutants with replacement of the C-terminal IKI to WKW, IKF, FKI and FKF. All mutant complexes dissociated into dimers at 50°C. Among them, StHsp14.0FKF is almost completely dissociated, probably to dimers. All mutants protected citrate synthase (CS) from thermal aggregation at 50°C. But, the activity of StHsp14.0FKF was the lowest. Then, we examined the complexes of StHsp14.0 mutants with denatured CS by SAXS. StHsp14.0WKW protects denatured CS by forming the globular complexes of 24 subunits and a substrate. StHsp14.0FKF also formed similar complex but the number of subunits in the complex is a little smaller. These results suggest that the dimer itself exhibits low chaperone activity, and a partially dissociated oligomer of StHsp14.0 protects a denatured protein from interacting with other molecules by surrounding it.