Reduction of RNA and DNA in Methylococcus capsulatus by endogenous nucleases

 A method for reducing RNA and DNA in the bacterium Methylococcus capsulatus (Bath) has been developed. Endogenous RNase and DNase were activated by a 10 s heat shock at 90°C. Cells were then incubated at 60°C for 20 min to allow degradation of the nucleic acids. The optimum pH for the process was 7.0. The protein loss was less than 10% and occurred during the initial heat shock. No protein loss was found during incubation. The total dry-weight loss in connection with an 80% reduction of the nucleic acid content was 20%–25%, giving a final product with a raw protein content of approximately 75%. Reduction of both RNA and DNA was inhibited by CuSO₄ and ZnSO₄. DNA reduction was stimulated by other minerals. Optimal stimulation was found at 1 mM FeSO₄. Reduction of RNA was not increased by any of the minerals tested. Received: 29 June 1995/Received last revision: 2 October 1995/Accepted: 16 October 1995