在酵母粉或Cu^(2+)胁迫下古菌Ferroplasma thermophilum与两种中度嗜热细菌的协同作用

Synergies between archaea Ferroplasma thermophilum and two moderately thermophilic bacteria under stress of yeast extract or Cu^(2+)

本研究目的为考察在酵母粉或Cu2+胁迫下,古菌Ferroplasma thermophilum在分别与其他两种中度嗜热细菌(Leptospirillum ferriphilum和Acidithiobacillus caldus)混合培养体系中的生态功能。实验在250 mL摇瓶中进行,采用纯培养与混合培养对照的方法,结合荧光定量PCR(Quantitive PCR,Q-PCR)技术考察F.thermophilum分别与其他两种中度嗜热菌之间的协同作用。结果表明:在0.04%(w/v)酵母粉胁迫下,L.ferriphilum YSK纯培养物的生长受到完全抑制,而At.caldus s2纯培养物的生长不受抑制。F.thermophilum L1与L.ferriphilum YSK混合培养减轻了酵母粉对L.ferriphilum YSK的抑制作用且促进其生长;F.thermophilum L1/At.caldus s2混合培养体系中,F.thermophilum L1的加入能够促进平稳期At.caldus s2的生长。在5 g/L Cu2+胁迫下,F.thermophilum L1与L.ferriphilum YSK混合培养时,F.thermophilum L1生长被促进,而L.ferriphilum YSK的生长受到抑制;F.thermophilumL1与At.caldus s2混合培养能够有效地促进彼此生长,且协同促进铁/硫氧化代谢。

The purpose of this study was to explore the ecological functions of Ferroplasma thermophilum when it was mixed with Leptospirillurn ferriphilum or Acidithiobacillus caldus under the stress of yeast extract or Cu2＋. Population dynamics of pure culture and mixed culture were compared by using Quantitative PCR, and synergies between Ferroplasma thermophilum and the other two moderately thermophilic bacteria were evaluated. The results show that the growth of pure L. ferriphilum YSK is inhibited under the stress of 0.04% （w/v） yeast extract. Yet, L. ferriphilurn YSK grows well in the presence ofE thermophilum L1, which indicates that the toxicity of yeast extract to L. ferriphilum YSK is reduced in the mixed culture. The results also show that there is no influence of yeast extract on the growth of At. caldus s2 in the pure culture, and compared with the pure culture, the cell density of At. caldus s2 at the stationary phase increases in the mixed culture. Under the stress of 5 g/L Cu2＋, when iv.. thermophilum L1 and L. ferriphilurn YSK are mix-cultured, the growth of E thermophilum L1 can be promoted, while the growth of L. ferriphilum YSK is inhibited. The mixed cul^xe of E thermophilum and At. caldus has a positive effect on the growth of each other, and can mutually promote ferrous or sulfur oxidation under the stress of 5 g/L Cu2＋.