Stabilization of free and immobilized enzymes using hyperthermophilic chaperonin.

Chaperonins suppress the denaturation of proteins and promote protein folding in vivo. Because hyperthermophilic chaperonins are expected to be used as a stabilizer for proteins, the effects of a group II chaperonin from a hyperthermophilic archaeum, Thermococcus strain KS-1 (T. KS-1 cpn), on the stabilization of mesophilic and thermophilic free enzymes and an enzyme co-immobilized with T. KS-1 cpn were studied. T. KS-1 cpn prevented the thermal inactivation of yeast alcohol dehydrogenase (ADH), jack bean urease, and Thermus flavus malate dehydrogenase (MDH) at high temperatures. T. KS-1 cpn also improved the long-term stability of ADH at lower temperatures. Moreover, the residual ADH activity of ADH co-entrapped with T. KS-1 cpn was improved and maintained at a higher level than that of the entrapped ADH without chaperonin. T. KS-1 cpn is useful for the stabilization of free and immobilized enzymes and applicable to various fields of biotechnology.

Biological treatment of wastewater discharged from biodiesel fuel production plant with alkali-catalyzed transesterification.

The biological treatment of wastewater discharged from a biodiesel fuel (BDF) production plant conducting alkali catalysis transesterification was investigated. BDF wastewater has a high pH and high hexane-extracted oil and low nitrogen concentrations, and inhibits the growth of microorganisms. The biological treatment of BDF wastewater is difficult because the composition of such wastewater is not suitable for microbial growth. To apply the microbiological treatment of BDF wastewater using an oil degradable yeast, Rhodotorula mucilaginosa, the pH was adjusted to 6.8 and several nutrients such as a nitrogen source (ammonium sulfate, ammonium chloride or urea), yeast extract, KH2PO4 and MgSO4.7H2O were added to the wastewater. The optimal initial concentration of yeast extract was 1 g/l and the optimal C/N ratio was between 17 and 68 when using urea as a nitrogen source. A growth inhibitor was also present in the BDF wastewater, and this growth inhibitor could be detected by measuring the solid content in an aqueous phase after the hexane extraction of the wastewater. Microorganisms could not grow at solid contents higher than 2.14 g/l in the wastewater. To avoid the growth inhibition, the BDF wastewater was diluted with the same volume of water. Oil degradation in the diluted BDF wastewater was observed and the best result was obtained under the determined optimal conditions. This treatment system is simple because no controllers, except for a temperature, are necessary. These results suggest that the biological treatment system developed for BDF wastewater is useful for small-scale BDF production plants.

Bioprocess monitoring using near-infrared spectroscopy.

Near-infrared spectroscopy (NIR) is a nondestructive analytical technique that has been used for simultaneous prediction of the concentrations of several substrates, products and constructs in mixtures sampled from fermentation processes. In this chapter, we discuss applications of NIR for the monitoring of bioprocesses involving rice vinegar, compost, glycolipid, L-glutamic acid, lactic acid fermentation, mushroom cultivation, and Koji production. This includes detailed discussion of applications of NIR to process management of rice vinegar fermentation and compost fermentation. In the present study, absorbance at wavelengths between 400 and 2500 nm was measured at 2 nm intervals. To obtain calibration equations, multiple linear regression (MLR) was performed on NIR spectral data and conventional analysis values of a calibration sample set. To validate these calibration equations, they were used to calculate concentrations of a prediction sample set, which were then compared with concentrations measured by conventional methods. There was excellent agreement between the results of the conventional method and those of the NIR method, when both were used to analyze culture broth of rice vinegar fermentation and solid-state fermented compost. These results indicate that NIR is a useful method for monitoring and control of bioprocesses.