TECHNOLOGY FOCUS - BIOTECHNOLOGY - Preferred Method: The step of determining half-saturation constant, involves measuring the fluctuation of the distribution coefficient of IM originating in substrate by each microorganism in the presence of hydrogen. The distribution coefficient is determined using concentration of microorganism, and substrate or IM and is calculated by using specific equation involving a predetermined parameters such as k, K, S, Y, X, SH2, Kiasyn, and Fa, where k is maximum substrate velocity, K is half saturation constant, S is substrate concentration, Y is microorganisms, X is microorganism concentration, SH2 is hydrogen concentration, Kiasyn is biosynthesis inhibition constant of IM such as sugar, organic acid, alcohol or hydrogen, and Fa is distribution coefficient of IM. The microorganism is detected by determining the DNA and RNA of microorganism using the (a) primer set targeting Clostridium sp. JC3, Clostridium sp. clone 6-2-K and clone 5-1-N having 16S rRNA gene of SEQ ID No. 1, 2 and 3 respectively, comprising oligonucleotide having the base sequence of fully defined 19 nucleotides (SEQ ID No. 11) sequence given in the specification or its homolog, and oligonucleotide of base sequence having a fully defined 18 nucleotides (SEQ ID No. 12) sequence given in the specification or its homolog, where the above 3 strains are cellulose decomposing bacteria, (b) primer set targeting Clostridium sp. JC94 clone having 16S rRNA gene of SEQ ID No. 4, comprising oligonucleotide having base sequence of fully defined 23 nucleotides (SEQ ID No. 13) sequence given in the specification or its homolog and oligonucleotide of SEQ ID No. 12 or its homolog, where the above strain is cellulose decomposing bacteria, (c) primer set targeting Coprothermobacter proteolyticus P1, P2, P3 or P4 strain having 16S rRNA of SEQ ID No. 5-8 respectively, comprising oligonucleotide having a fully defined 20 nucleotides (SEQ ID No. 14) sequence given in the specification or its homolog, and oligonucleotide of base sequence having a fully defined 16 nucleotides (SEQ ID No. 15) sequence given in the specification or its homolog, or oligonucleotide having a fully defined 20 nucleotides (SEQ ID No. 16) sequence given in the specification or its homolog, and oligonucleotide having a base sequence of SEQ ID No. 15 or its homolog, or oligonucleotide having a fully defined 19 nucleotides (SEQ ID No. 17) sequence given in the specification or its homolog, and oligonucleotide having a fully defined 19 nucleotides (SEQ ID No. 18) sequence given in the specification or its homolog, where the above strain is proteolytic microorganism, (d) primer set targeting S1 strain having 16S rRNA gene of SEQ ID No. 9, comprising oligonucleotide having a fully defined 20 nucleotides (SEQ ID No. 20) sequence given in the specification or its homolog, and oligonucleotide having a fully defined 22 nucleotides (SEQ ID No. 19) sequence given in the specification or its homolog, where the above strain degrades saccharides other than cellulose, (e) primer set targeting S2 strain having 16S rRNA gene of SEQ ID No. 10, comprising oligonucleotide having a fully defined 24 nucleotides (SEQ ID No. 21) sequence given in the specification or its homolog, and oligonucleotide having a fully defined 23 nucleotides (SEQ ID No. 22) sequence given in the specification or its homolog, where the above strain degrades saccharides other than cellulose, (f) primer set targeting Methanosarcina, comprising oligonucleotide having a fully defined 21 nucleotides (SEQ ID No. 23) sequence given in the specification or its homolog, and oligonucleotide having a fully defined 17 nucleotides (SEQ ID No. 24) sequence given in the specification or its homolog, where the above strain is methane producing bacteria using acetic acid and/or hydrogen as substrate, (g) primer set targeting Methanosaetaceae family, comprising oligonucleotide having a fully defined 18 nucleotides (SEQ ID No. 25) sequence given in the specification or its homolog, and oligonucleotide having a fully defined 23 nucleotides (SEQ ID No. 26) sequence given in the specification or its homolog, where the above strain is methane producing bacteria using acetic acid as substrate, (h) primer set targeting Methanoculleus and Methanogenium genus of Methanomicrobiaceae family, comprising oligonucleotide having a fully defined 23 nucleotides (SEQ ID No. 27) sequence given in the specification or its homolog, and oligonucleotide having a fully defined 23 nucleotides (SEQ ID No. 28) sequence given in the specification or its homolog, where the above strain is methane producing bacteria using hydrogen as substrate,(i) primer set targeting Methanomicrobiales texture of Methanospirillaceae family, comprising oligonucleotide having a fully defined 22 nucleotides (SEQ ID No. 29) sequence given in the specification or its homolog, and oligonucleotide having a fully defined 24 nucleotides (SEQ ID No. 30) sequence given in the specification or its homolog, where the above strain is methane producing bacteria using hydrogen as substrate, and (j) primer set targeting Methanobacteriaceae family, comprising oligonucleotide having a fully defined 22 nucleotides (SEQ ID No. 31) sequence given in the specification or its homolog, and oligonucleotide having a fully defined 22 nucleotides (SEQ ID No. 32) sequence given in the specification or its homolog, where the above strain is methane producing bacteria using hydrogen as substrate. Preferred Microorganisms: The microorganisms are chosen from (a) microorganisms producing volatile organic acid other than saccharides, acetic acid and propionic acid or acetic acid, propionic acid, alcohol and hydrogen by making cellulose/protein/saccharides other than cellulose/lipid as substrate, (b) microorganisms producing methane by making acetic acid/acetic acid and/or hydrogen/hydrogen as substrate. The cellulose, proteolytic and saccharide degrading microorganism described in (a) has 16S rRNA gene showing 90% homology with respect to base sequence having a fully defined 1623, 1617, 1610 and 1628 nucleotides (SEQ ID No. 1-4), 1528 nucleotides (SEQ ID No. 5-8), and 962 or 1494 nucleotides (SEQ ID No. 9 or 10) sequence given in the specification. The microorganisms in (b) is methane producing bacteria belonging to Methanosaetaceae family, Methanosarcina, and Methanoculleus and Methanogenium of Methanomicrobiaceae family, respectively.