共存甲烷短杆菌Methanobrevibacter thaueri F1提高梨囊鞭菌Piromyces sp. F1对硝呋烯腙的耐受性

【背景】硝呋烯腙能够抑制厌氧真菌。共存甲烷菌可以促进厌氧真菌的生长以及对木质纤维素的降解,然而关于共存甲烷菌对厌氧真菌抗逆性影响的研究较少。【目的】旨在研究甲烷菌共存对厌氧真菌耐受硝呋烯腙的影响。【方法】采用体外批次培养,以稻草为底物,添加不同浓度的硝呋烯腙(0、5、10、25 mg/L),分别接种厌氧真菌纯培养和厌氧真菌与甲烷菌共培养悬浮液,于39°C静置培养96 h。测定不同时间点的产气量和甲烷产量,结束后测定p H、干物质降解率(DMD)、中性洗涤纤维消失率(NDFD)、半纤维素消失率(ADSD)、酸性洗涤纤维消失率(ADFD)以及上清液中甲酸、乳酸和乙酸的浓度。【结果】添加5、10和25 mg/L硝呋烯腙皆显著降低了厌氧真菌纯培养的发酵活性(P0.05);添加5 mg/L硝呋烯腙没有显著降低厌氧真菌与甲烷菌共培养的发酵活性(P0.05),添加10和25 mg/L硝呋烯腙则显著降低了共培养发酵活性(P0.05);比较5、10 mg/L硝呋烯腙对纯培养和共培养发酵活性影响的结果表明,共培养发酵活性显著高于纯培养发酵活性(P0.05)。【结论】硝呋烯腙对厌氧真菌纯培养和厌氧真菌与甲烷菌共培养的抑制作用都存在剂量效应,在一定添加浓度范围内(25 mg/L),甲烷菌共存可以显著提高厌氧真菌对硝呋烯腙的耐受性。

Enhancing the resistance of anaerobic fungus Piromyces sp. F1 to nitrovin by co-culture with Methanobrevibacter thaueri F1

[Background] Anaerobic fungi can be inhibited by nitrovin. The presence of associated methanogens enhances the growth of anaerobic fungi and the decomposition of lignocellulose by anaerobic fungi. However, few studies have investigated the effect of the co-cultured methanogens on stress resistance of anaerobic fungi. [Objective] The objective of this study was to investigate the effect of associated methanogen on the resistance of anaerobic fungus to nitrovin. [Methods] Mono-culture of anaerobic fungus Piromyces sp. and co-culture of Piromyces sp. and Methanobrevibacter thaueri were inoculated into fresh media with rice straw as substrate, respectively. Nitrovin hydrochloride was added to the final concentrations of 0, 5, 10 and 25 mg/L-nitrovin. Bottles were incubated at 39 °C for 96 h without shaking. Gas production and methane production were measured at intervals. At the end of fermentation, the pH was determined immediately upon removing crimp-seals and stoppers. Samples were collected for the analysis of in vitro digestibility of dry matter, digestibility of neutral detergent fiber, digestibility of acid detergent solution and digestibility of acid detergent fiber. The water-soluble end-products including formate, lactate and acetate were measured as well. [Results] In the mono-culture, nitrovin (5, 10 and 25 mg/L) significantly reduced the fermentation activity of anaerobic fungus (P<0.05). In the co-culture, no significant difference was observed when adding 5 mg/L nitrovin (P>0.05). However, the fermentation activity was significantly depressed at the concentrations of 10 and 25 mg/L. At the concentrations of 5 and 10 mg/L nitrovin, the fermentation activity of the co-culture was significantly higher than the mono-culture (P<0.05). [Conclusion] A dose effect of nitrovin on the fermentation of anaerobic fungal mono-culture and co-culture was observed. The presence of associated methanogen enhanced the resistance of anaerobic fungus to nitrovin when the concentration of nitrovin was less than 25 mg/L.