微生物學

Inhibitory effects of the secondary metabolite of actinomycete were examined on cell cycle of the yeasts of S. pombe and S. cerevisiae. The secondary metabolite was obtained from cultivation of the actinomycete isolated from the soil of Owakudani in Hakone, Japan. The fifth fraction of the secondary metabolite by ODS column separation (HK-T5), which was soluble to pure methanol, was used in the present experiments. The HK-T5 brought about the delay of forming colonies of S. pombe for about 11 days compared to that cultivated without the HK-T5. The delay of the colony formation was longer for the S. pombe cultivated with more amount of the HK-T5. The cultivation with HK-T5 also brought about the extension of the lifespan of the S. pombe for more than 10 weeks in a liquidus medium. The cell life recovered the ordinary manner by removal of the HK-T5, meaning that the activities of the HK-T5 is reversible. These facts confirm the suppression of cell cycle, and the delay of cell growth by the HK-T5. These phenomena were similarly observed for S. cerevisiae. Comparison of the action of HK-T5 with hydroxyurea, which is an anticancer drug inhibiting the cell cycle at S phase, clarified that the inhibitory action of HK-T5 worked at the phase earlier than S phase. The combined effects of HK-T5 on the cell cycle were evaluated with triamcinolone acetonide (TA), or aspirin, the former of which is a drug synchronizing cancer cells in S phase, and the latter keeping human cells in G1/G0 phases. The combined use of HK-T5 with TA synchronized the cells at the phase slightly proceeding from G1 to S phase without toxicity. On the other hand, the combined use with aspirin made the inhibitory effect of HK-T5 inactive. Hence, the HK-T5 is attractive as a drug for the extension of cell lifespan, and anticancer therapy.

乳酸菌（Lactic acid bacteria）是生活中常接觸到的菌種，除了製作食品，也有研究指出部分乳酸菌菌株可抑止造成齲齒的「變異鏈球菌」生長，目前已有牙膏等產品號稱添加乳酸菌。但乳酸菌發酵產生的乳酸，會分解牙齒的琺瑯質，所以我們從發酵乳食品中分離出9株乳酸菌，並進行氫氧基磷灰石的分解實驗與對變異鏈球菌的抑菌實驗。經過實驗，1號、5號、6號與8號乳酸菌株對氫氧基磷灰石的分解能力較弱，而6號、8號與15號對變異鏈球菌的抑制效果較明顯，實驗結果交互比較後，得出6號和8號菌作為牙齒保健的應用價值較高。未來若能進一步研究，可嘗試以離心將乳酸菌各部位分離，研究其真正有抑菌作用的物質，並加以純化，應用於保健食品中。

Inhibitory effects of the secondary metabolite of actinomycete were examined on cell cycle of the yeasts of S. pombe and S. cerevisiae. The secondary metabolite was obtained from cultivation of the actinomycete isolated from the soil of Owakudani in Hakone, Japan. The fifth fraction of the secondary metabolite by ODS column separation (HK-T5), which was soluble to pure methanol, was used in the present experiments. The HK-T5 brought about the delay of forming colonies of S. pombe for about 11 days compared to that cultivated without the HK-T5. The delay of the colony formation was longer for the S. pombe cultivated with more amount of the HK-T5. The cultivation with HK-T5 also brought about the extension of the lifespan of the S. pombe for more than 10 weeks in a liquidus medium. The cell life recovered the ordinary manner by removal of the HK-T5, meaning that the activities of the HK-T5 is reversible. These facts confirm the suppression of cell cycle, and the delay of cell growth by the HK-T5. These phenomena were similarly observed for S. cerevisiae. Comparison of the action of HK-T5 with hydroxyurea, which is an anticancer drug inhibiting the cell cycle at S phase, clarified that the inhibitory action of HK-T5 worked at the phase earlier than S phase. The combined effects of HK-T5 on the cell cycle were evaluated with triamcinolone acetonide (TA), or aspirin, the former of which is a drug synchronizing cancer cells in S phase, and the latter keeping human cells in G1/G0 phases. The combined use of HK-T5 with TA synchronized the cells at the phase slightly proceeding from G1 to S phase without toxicity. On the other hand, the combined use with aspirin made the inhibitory effect of HK-T5 inactive. Hence, the HK-T5 is attractive as a drug for the extension of cell lifespan, and anticancer therapy.

組蛋白脫乙醯基酶 (HDAC) 會調節染色體結構，提升基因表現。除了調控基因表現以外，HDAC基因家族中的 I 類已知有調節細胞週期的功能，但 II 類調節細胞週期之研究甚少。而癌症臨床用藥HDAC抑制劑會同時阻斷 I 和 II 類之功能而產生副作用。因此本研究以釀酒酵母為對象，分析 I 類的RPD3、 II 類的HDA1基因對細胞週期之影響，以及HDAC基因剔除菌株在面臨DNA複製壓力時的變化。結果顯示同時失去 RPD3 、HDA1 基因的菌株 S 期檢查點功能損壞、細胞滯留於 G2/M 期，且在DNA複製壓力環境下死亡。爲釐清此菌株死亡的原因，實驗剔除在S期和G2/M期皆具調節功能的 MAD2 基因。得知 HDAC 基因和 MAD2 在S期的DNA複製起步期分別調控不同路徑；在DNA複製衝刺期則調控同一路徑。也發現RPD3 基因在維持細胞S期檢查點正常作用扮演較重之角色，而 HDA1 則扮輔助的功能。

塑膠對環境危害甚深，雖已有研究證實部分昆蟲可降解塑膠類的聚苯乙烯（PS），但關於聚丙烯（PP）的生物降解研究很少，也沒有進一步透過腸道菌相分析，鑑定出負責降解的菌種。因此我們希望利用麵包蟲生物降解PP，透過16S rRNA定序分析找出可降解PP的潛力菌種，解決塑膠垃圾對環境造成的傷害。我們的實驗結果顯示，麵包蟲能攝食PP並生長，且加入濕料及利用糞便移植腸道菌相能增加麵包蟲對PP的消耗量，證明麵包蟲能攝食PP與腸道菌相有關。利用次世代基因定序分析腸道菌相，麵包蟲攝食PP後腸道菌相有極為顯著的變化，其中腸道菌Pseudomonas stutzeri顯著增多，經實驗證實此菌可降解PP，且在37oC、中性環境的降解效果較佳，一星期約降解3.4 %的PP。我們所使用的方法可快速篩選出能降解PP的菌種。