Microbial ecology of high-temperature compost and its usefulness as genetic resource

高温堆肥系统的堆肥上部温度达到90 ℃以上。平板法测得的活菌数约为镜检法的1/100 ~ 1/1000，说明不可培养菌在高温堆肥过程中起着重要作用。在堆肥初期，芽孢杆菌占优势，占总细胞数的36%，而嗜热Melghirimyces thermohalophilus占63%，说明堆肥过程中细菌植物群发生了剧烈的变化。从堆肥中分离的DNA中直接克隆了嗜热酶基因，并从堆肥中分离到了产细胞壁降解酶的嗜热菌，表明高温堆肥是分离嗜热酶和嗜热菌的良好遗传资源。

Temperature reached over 90 degrees centigrade in the upper position of the compost of the high-temperature composting system. Viable cell numbers by surface plate method was about 1/100 to 1/1000 of those by microscopic observation method, suggesting that unculturable bacteria were important in the high-temperature composting process. Bacillus species dominated in the early stage of composting, accounting for 36% of the total cell numbers, but Melghirimyces thermohalophilus accounted for 63%, indicating that bacterial flora drastically changed in the process of the composting. Genes encoding thermophilic enzymes were directly cloned from DNA isolated from the compost and thermophilic bacteria producing bacterial cell wall-degrading enzymes were isolated from the compost, indicating that the high-temperature compost was quite useful as the genetic resource for isolating thermophilic enzymes and bacteria.