外生菌根真菌Xerocomus chrysenteron对DDT胁迫的耐受性及酶响应研究

Tolerance and Enzyme Response of Ectomycorrhizal Fungi Xerocomus chrysenteron to DDT Stress

在纯培养条件下,研究了外生菌根真菌红绒盖牛肝菌(Xerocomus chrysenteron)对不同浓度DDT的生长效应、耐受性和氧化酶活性,测定了在DDT浓度为80.0 mg.L-1液体培养条件下菌种生物量积累和漆酶活性随培养时间的变化.结果表明,不同浓度DDT处理并不会改变被试菌种的生长模式,所有处理组均为典型的Logistic增长;Xerocomus chrysenteron对DDT胁迫有很好的耐受性,其半抑制浓度可达139.75 mg.L-1;在80.0 mg.L-1液体培养条件下,Xerocomus chrysenteron生长正常,且36 d后培养液中DDT残留率仅为初始添加量的3.5%;在高浓度DDT胁迫下,被试菌种的漆酶和过氧化物酶活性显著增强,但液体培养条件下漆酶从第16 d开始出现,36 d后培养液中漆酶活性和比活力分别达到107.24 U.L-1和61.77 U.g-1.外生菌根真菌Xerocomus chrysenteron通过不同方式来响应DDT胁迫,显示出生物降解甚至矿化DDT的巨大潜力.

The growth effect, tolerance and oxidative enzymes activities of Xerocomus chrysenteron under different concentrations of DDT were studied at the condition of pure culture. The changes of biomass accumulation and laccase activity were also examined along with the liquid medium period under the DDT concentration of 80.0 mg· L^-1 . The results show that various DDT concentrations don＇t change the growth mode of the studied ectomycorrhizal fungi, which are all in the mode of classic Logistic growth. Xerocomus chtysenteron has a good tolerant ability to the DDT stress, whose hemi-inhibit concentration reaches 139.75 mg· L^-1 . Under the liquid medium of 80.0 mg· L^-1 of DDT, Xerocomus chrysenteron grows normally and after 36 days and the residue of DDT in the liquid medium is only 3.5 % of the original concentration. Under the high concentration of DDT, the laccase and peroxidase activities significantly increase. The laccase is detected since the 16th day. After 36 days＇ culture, the laccase activity and specific activity in liquid medium reach 107.24 U·L^-1 and 61.77 U·g^-1 respectively. The ectomycorrhizal fungi Xerocomus chrysenteron responses to the DDT stress in various ways, which suggests large potential of biodegradation or mineralization of DDT.