NOVELTY - Determining (M1) number of microorganisms of proteolysis bacteria in an environmental sample, comprising performing quantitative PCR using primer pair comprising SEQ ID No. 5 and 6, in which the 16S rRNA gene of proteolysis microorganism that exists in the environmental sample is the target, measuring the amount of nucleic acid amplified by the PCR, and determining the number of microorganisms based on the measured value, is new.    USE - (M1) is useful for determining number of microorganisms of proteolysis bacteria in an environmental sample. (M1) is useful for evaluating protein decomposability of the environmental sample, which involves utilizing the value obtained by carrying out (M1) (claimed).    ADVANTAGE - (M1) enables efficient and specific detection of high temperature anaerobic proteolysis bacteria, quantitatively, in a reliable manner.    DETAILED DESCRIPTION - Determining (M1) number of microorganisms of proteolysis bacteria in an environmental sample, involves performing quantitative PCR using primer pair comprising SEQ ID No. 5 and 6 or their substantially homologous base sequences, SEQ ID No. 6 and 7 or their substantial homologous base sequences, or SEQ ID No. 8 and 9 or their substantial homologous base sequences, in which the 16S rRNA gene of proteolysis microorganism that exists in the environmental sample is the target, measuring the amount of nucleic acid amplified by the PCR, and determining the number of microorganisms based on the measured value.    INDEPENDENT CLAIMS are also included for:    (1) oligonucleotides comprising one of SEQ ID No. 5-9 or their substantial homologous base sequence;    (2) processing organic waste, involves degrading organic waste under anaerobic conditions at 45-70degreesC, using the strain belonging to Coprothermobacter genus having base sequence of 16S rRNA comprising one of SEQ ID No. 1-4 or base sequence showing 99% or more homology to one of SEQ ID No. 1-4; and    (3) primer pair comprising SEQ ID No. 5 and 6 or their substantially homologous base sequences, SEQ ID No. 6 and 7 or their substantially homologous base sequences, or SEQ ID No. 8 and 9 or their substantially homologous base sequences.