盐胁迫下耐盐性木霉菌的筛选与鉴定

Screening and Identification of Salt-tolerant Trichoderma Species under Salt Stress

对分离于甘肃省民勤县的6株木霉菌进行耐盐性筛选和鉴定。结果表明,随着NaCl浓度(0 to 150 mmol/L)增加显著降低6株木霉菌(TG1 to TG6)的菌落直径。与其他5株木霉菌相比,不同浓度NaCl胁迫下菌株TG1具有较强耐盐性。当NaCl浓度为50 mmol/L时,培养2 d后菌株TG1产孢量和菌落直径与对照相比无显著差异,但是其孢子萌发率增加10.59%。菌株TG1在PDA培养基上菌落正面呈暗绿色,菌落背面呈暗黄色,分生孢子球形至椭圆形。分生孢子梗直角分枝,结合其形态特征将菌株TG1鉴定为T.longibrachiatum。构建菌株TG1的TEF和ITS系统发育树,结果表明菌株TG1的TEF和ITS序列分别与T.longibrachiatum IMI 297702(EU401578.1)和T.longibrachiatum(MT889709.1)序列相似性为99.22%和100.00%。因此,结合形态特征和分子生物学分析将菌株TG1鉴定为T.longibrachiatum TG1。与对照相比,菌株TG1在50、100和150 mmol/L NaCl胁迫下产生IAA浓度分别为1.25、1.35和1.56μg/mL,而对照为0.92μg/mL。同时,在50、100和150 mmol/L NaCl胁迫下,TG1菌株ACC脱氨酶活性分别为0.1、0.16和0.17μmolα-ketobutyrate mg/h,而对照为0.09μmolα-ketobutyrate mg/h。

This study focused on the screening and identification of salt-tolerant Trichoderma species from six strains that were isolated from Minqin County,Gansu Province,China.The results showed that increasing NaCl concentrations(from 0 to 150 mmol/L)reduced the colony diameter in all the six Trichoderma strains(TG1 to TG6).The strain of TG1 presented higher salt-tolerant ability under different NaCl concentrations in comparison to the other five strains.At 50 mmol/L NaCl-stress,there was no significant difference at the spore concentration and the colony diameter across the two days compared to the control.However,the spore germination of TG1 was increased by 10.59%at 50 mmol/L NaCl stress,compared to the control.Morphologically,TG1 strain showed dull green mycelial growth on potato dextrose agar medium with slightly dull yellow in revise colony,conidia were spherical to ellipsoidal,conidiophores having a more or less distinct central axis and five layers of phialides extending across the terminal parts of the conidiophores.According to the morphology of TG1,it was identified as T.longibrachiatum.Phylogenetic analysis based on TEF and ITS revealed that TG1 strain was 99.22%and 100.00%closely related to T.longibrachiatum IMI 297702(EU401578.1)and T.longibrachiatum(MT889709.1),respectively.Thus,TG1 strain was identified as T.longibrachiatum TG1 according to the morphological characteristics and molecular analyses.The activity and concentration of 1-aminocyclopropane-1-carboxylate(ACC-deaminase)and indole-3-acetic acid(IAA)of TG1 strain were increased significantly under salt stress.The IAA concentrations of TG1 strain were 1.25,1.35 and 1.56μg/mL at 50,100 and 150 mmol/L NaCl stress as compared to the control 0.92μg/mL,respectively.Similarly,the activities of ACC deaminase of TG1 were 0.1,0.16 and 0.17μmolα-ketobutyrate mg/h at 50,100,and 150 mmol/L NaCl stress compared to the control 0.09μmolα-ketobutyrate mg/h,respectively.