Immobilized thermophilic bacteria as a source of respiratory chain for the recycling of NAD+

Immobilization of thermophilic bacterium strain PS3 has been performed by crosslinking with 0.4% glutaraldehyde in the presence of 4.6% bovine serum albumin at ? 20°C. After immobilization of bacteria the plasma membrane became permeable to NADH. The yield of NADH respiration of the immobilized strain was ～10%. The apparent K_m for NADH with the immobilized thermophilic strain was $\text{6 × 10}{}^{\mathrm{?4}}\text{m}$. After immobilization of this strain no variations of activities were observed between pH 4.5 and 9.5. Recycling of NAD⁺ is at least 10 times better with the thermophilic strain compared to Escherichia coli. In a preliminary experiment at 45°C the half life obtained with Escherichia coli was 1 h and with PS3 was 12 h. This temperature increased the rate of respiration by a factor of ～4 (compared to 20°C) and may avoid most of bacterial contaminations (most bacteria are not able to grow above 42°C).