黑曲霉C2J6对环己酮的细胞耐受性机制

Tolerance mechanism of Aspergilus niger C2J6 to cyclohexanone

鉴于黑曲霉C2J6在有机溶剂中的菌体生长和酶活性与其细胞耐受性有关,为揭示菌体对有机溶剂的耐受规律和耐受性机制,考察了菌体对15种有机溶剂的耐受性,并从细胞水平上探究了菌体在疏水性较低的环己酮中的耐受性机制。结果表明:黑曲霉C2J6可以在多种有机溶剂中生长产酶,lgP为-0.24~3.0的有机溶剂对菌体生长及产酶有不同程度的抑制作用,而lgP>3.0的有机溶剂则起到相应的促进作用。环己酮胁迫下,细胞膜表面出现破损,胞内细胞器有皱缩现象,细胞表面疏水性下降,胞外核苷酸浓度上升,细胞膜不饱和脂肪酸含量降低,饱和脂肪酸含量增加。说明菌体对环己酮的耐受性涉及多个方面,多种耐受机制同时存在,使环己酮对细胞的毒害大大降低,从而提高了微生物的耐受能力。

The mycelium growth and enzyme activity of Aspergillus niger C2J6 in organic solvent are related to cell tolerance in the solvent. In order to reveal the regulation and mechanism of organic solvent tolerance, fifteen kinds of organic solvents were used to investigate the organic solvent tolerance of Aspergillus niger C2J6. Then the tolerance mechanism for cyclohexanone, which is a less hydrophobic solvent, was studied in the cellular level. The results indicate that Aspergillus niger C2J6 can grow in a variety of organic solvents for enzyme production. Organic solvents whose lgP are between -0.24 and 3.0 will inhibit the cell growth and enzyme production to different degrees, whereas organic solvents whose lgP are greater than 3.0 will promote the growth and production. Under the stress of cyclohexanone, the cell membrane is damaged. The intraceUular organelles shrunk. The hydrophobicity of cell surface decreased. Extracellular nucleotide concentration increased. The content of unsaturated fatty acid decreased while the content of saturated fatty acid increased. These phenomena illustrate that cellular tolerance to cyclohexanone is influenced in many aspects, and there are variety of tolerance mechanisms working together which help to reduce the toxicity of cyclohexanone on the cells, so as to improve the tolerance of the microbes.