本研究從堆肥中分離一株Bacillus subtilis (B. subtilis YT)，此株B. subtilis YT於液態培養能分泌高濃度iturin A，並證明其具有對抗一些植物病源菌和具有溶磷的能力。本研究將B. subtilis YT加入製作堆肥程序中，探討其對堆肥製作過程之溫度、碳氮比變化的影響，以及B. subtilis YT在最後堆肥成品的含量。堆肥原料分成高碳氮比(HCNR)與低碳氮比(LCNR)試驗。每批試驗分為三組(A、B、CK)，每組有500公斤乾重的堆肥原料，分 別接入不同菌量的B. subtilis YT，A組每公克接入1.5 x 108CFU (colony forming unit)，B組接入1.5 x 107CFU，以 及不接菌的CK組，接種的B. subtilis YT在加入堆肥之前，先用液態培養液活化一天。結果顯示植入B. subtilis YT對於堆肥期間溫度之變化與最後堆肥之碳氮比並無太大影響。HCNR的碳氮比由堆肥初期17.8±0.2到結束時 下降至11.8±0.7，LCNR的碳氮比則是由堆肥初期13.0±0.2到結束期下降至9.5±0.1。B. subtilis YT在三組堆肥成 品中，HCNR試驗A與B，分別含有每公克3.3±2.4 x 107 CFU及1.9 土 0.7 x 107 CFU，LCNR試驗A與B分別為8.4±2.5 x 107CFU及6.5±5.5 x 107CFU。高接菌量的A組堆肥試驗最後B. subtilis YT皆無增加，研判B. subtilis YT的增殖主 要在液態培養液活化階段與堆肥溫度50t以下的階段。從堆肥中選取的B. subtilis YT亦進行16S rDNA與gyrB聚合酶連鎖反應鑑定並將16SrDNA定序，與原菌的基因序列比對，確認相同度達99.9%。

Bacillus subtilis YT, a bacterium isolated from composts, is reported to produce iturin A at high concentrations in liquid culture. B. subtilis YT displays antibiotic activity against some plant pathogenic fungi and phosphate solubilizing activity. This study aimed to investigate the effects on temperature and C/N ratio during inoculation of B. subtilis YT during composting, and the bacterial count of the B. subtilis YT in the final compost. Two tests were performed using the raw material compositions at high initial C/N ratio (HCNR) (C/N, 17.8 ± 0.2) and low initial C/N ratio (LCNR) (C/N, 13.0 ± 0.2). Each individual composting experiment had three heaps (A, B, CK), each comprising 500 kg (dry weight) raw material. B. subtilis YT was inoculated to heap A at 1.5 × 108 CFU/gds (colony forming unit per gram of dry substrate), heap B at 1.5 × 107 CFU/gds, and non-inoculation (CK) as control. B. subtilis YT was cultured in liquid medium for one day before inoculation. There was no significant change in compost temperature during composting and in the final C/N ratio of the compost irrespective of B. subtilis YT inoculation. The C/N ratio of the compost changed from 17.8 ± 0.2 to 11.8 ± 0.7 in the HCNR test and 13.0 ± 0.2 to 9.5 ± 0.1 in the LCNR test. The cell densities of B. subtilis YT in heaps A and B were 3.3 ± 2.4 × 107 CFU/gds and 1.9 ± 0.7 × 107 CFU/gds, respectively, during the HCNR test. However, during the LCNR test, there were 8.4 ± 2.5 × 107 CFU/gds (heap A) and 6.5 ± 5.5 × 107 CFU/ gds (heap B). Cell density did not increase for B. subtilis YT in heap A (high cell density inoculation) during both HCNR and LCNR tests. B. subtilis YT propagated at pre-culture stage in liquid medium or in the compost when the temperature was less than 50oC. B. subtilis (selected from compost) was identified using primer sets for 16S rDNA and gyrB via polymerase chain reaction (PCR) as well as sequenced the PCR products of 16S rDNA and compared to the original lab stock. The data was shown that 99.9% identified to our lab stock, B. subtilis YT.