Effect of high compost temperature on enzymatic activity and species diversity of culturable bacteria in cattle manure compost

To clarify the characteristics of thermophilic bacteria in cattle manure compost, enzymatic activity and species diversity of cultivated bacteria were investigated at 54, 60, 63, 66 and 70 °C, which were dependent on composting temperature. The highest level of thermophilic bacterial activity was observed at 54 °C. Following an increase in temperature to 63 °C, a reduction in bacterial diversity was observed. At 66 °C, bacterial diversity increased again, and diverse bacteria including Thermus spp. and thermophilic Bacillus spp. appeared to adapt to the higher temperature. At 70 °C, bacterial activity measured as superoxide dismutase and catalase activity was significantly higher than at 66 °C. However, the decomposition rate of protein in the compost was lower than the rate at 66 °C due to the higher compost temperature.