ABSTRACT

The commercial production of paclitaxel; the most potent anti-cancer drug, is based on its extraction from Taxus spp (yews) or microbial fermentation from yews’ endophytes. The present study investigated the capability of local endophytes that have been isolated from ecologically altered Taxus baccata (host tree) to produce this diterpenoid secondary metabolite and improve its production and stability. Results revealed the ability of three endophytes; Acremonium, Colletotrichum and Fusarium spp, to produce paclitaxel up to 116.19 μg l⁻¹. The challenge of their production instability away from their host is overcome by two strategies; the addition of unusual elicitor (0.0001% crushed bark of T. baccata) and induction of mutagenesis using ultraviolet irradiation which stimulated the production to higher levels (reach four folds for parent strain Acremonium sp. MK). Produced paclitaxel has a strong cytotoxic effect on human breast cancer cell line (MCF-7). The molecular analysis of the endophyte; Acremonium sp. showed the presence of BAPT gene that responsible for paclitaxel production and encoding C-13 phenylpropanoid side chain-acetyl coenzyme A acetyl-transferase. Therefore, the selected endophyte has an individual metabolic system that can be activated in the absence of the host or changing its ecology.

摘要

紫杉醇的商业化生产；最有效的抗癌药物是基于从红豆杉（紫杉）中提取或从紫杉的内生菌中发酵而来。本研究调查了从生态改变的红豆杉（寄主树）中分离出来的本地内生菌产生这种二萜类次生代谢产物并提高其产量和稳定性的能力。结果揭示了三种内生菌的能力。种植顶孢，炭疽菌和镰刀菌，可产生高达116.19μgl ^-1的紫杉醇。通过两种策略可以克服其远离主机的生产不稳定的挑战；添加异常引发剂（0.0001％的碎树皮T. baccata）和使用紫外线照射诱变，将其刺激到更高的水平（亲本菌株Acremonium sp。MK达到四倍）。产生的紫杉醇对人乳腺癌细胞系（MCF-7）具有很强的细胞毒性作用。内生菌的分子分析；顶头孢霉。结果表明BAPT基因的存在与紫杉醇的产生有关，并编码C-13苯基丙烷侧链-乙酰辅酶A乙酰转移酶。因此，选择的内生菌具有可以在没有宿主或改变其生态的情况下被激活的单个代谢系统。