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Activation energies of suspended and immobilized nitrifying bacteria were determined and compared to determine if diffusion limitation results in decreased sensitivity for temperature. The activation energy for the respiration activity of suspended Nitrosomonas europaea and Nitrobacter agilis was found to be 86.4 and 58.4 kJ mol(-1), respectively. The activation energy for oxygen diffusion in the support material, kappa-carrageenan, determined from the effect of temperature on the effective diffusion coefficient (D), was 17.2 kJ mol(-1). Consequently, the apparent actvation energy of diffusion limited cells should be lower. It was indeed shown that due to the effect of diffusion limitation and to temperature effects on the Monod constant K(s), the immobilized-cell activity was less sensitive to temperature. The apparent activation energy for immobilized Ns. europaea was between 28.6 and 94.2 kJ mol(-1) and for immobilized Nb. agilis between 1.4 and 72.9 kJ mol(-1), depending on the oxygen concentration and temperature. (c) 1995 John Wiley & Sons, Inc.

In this study, Norwalk-like virus (NLV) RNA was detected by reverse transcriptase PCR (RT-PCR) in sewage water concentrates. Sequence analysis of the RT-PCR products revealed identical sequences in stools of patients and related sewage samples. In 6 of 11 outbreak-unrelated follow-up samples, multiple NLV genotypes were present. Levels as high as 107 RNA-containing particles per liter were found. These data show that high loads of NLVs may be present in sewage and warrant further studies addressing the efficacy of NLV removal by sewage water treatment processes.