5种优势腐生真菌降解华山松针叶的酶活测定

Enzyme activities on decomposing needle litter of Pinus armandii by five dominant saprophytic fungi

摘要:

【目的】分析腐生真菌降解华山松落针过程中各种酶活性变化与酶间关系，探索真菌对华山松落针的降解能力。【方法】通过形态学观察和转录间隔区 ITS序列分析，鉴定分离自华山松凋落物的5种优势菌株。以此为供试菌株，华山松落针为底物，通过发酵纯培养方法，测定底物总有机物质(total organic matter，TOM)质量损失率及在发酵过程中产生的内切葡聚糖酶(Endoglucanase，EG)、木聚糖酶(Xylanase，Xyl)、木质素过氧化物酶(Lignin peroxidase，LiP)、锰过氧化物酶(Manganese peroxidase，MnP)和酸性磷酸酶(Acid phosphatase，AP)活性。【结果】5种菌株分别为Mucor sp.、Pestalotiopsis sp.、Allantophomopsis sp.、Phoma sp.和Hypocrea sp.。5种菌引起的针叶TOM质量损失率在6.63%?15.77%之间，Pestalotiopsis sp.具有最高的AP酶活性，且EG酶、Xyl酶和LiP酶3种酶活性较高。Allantophomopsis sp.的LiP酶活性最高，并具有很高的MnP酶活。Hypocrea sp.分泌的EG酶、Xyl酶活性低，但能产生LiP酶且有较高的AP酶活。相关性分析表明菌株分泌的AP酶活性与TOM质量损失率负相关，EG酶、Xyl酶及AP酶3种酶之间存在协同作用，特别是EG与AP之间。【结论】5种腐生真菌对华山松针叶均有降解作用，降解能力：Pestalotiopsis sp.>Allantophomopsis sp.>Hypocrea sp.>Phoma sp.>Mucor sp.。酶活大小及酶协同作用共同影响针叶降解，Pestalotiopsis sp.、Allantophomopsis sp.和Hypocrea sp.能产生木质纤维素降解酶并能引起较高的质量损失率，因此这3株菌为木质纤维素降解真菌。

Abstract:

[Objective] The purpose of this research was to analyze the changes of enzyme activities and relationships amony enzymes on decomposing needle litter of Pinus armandii by saprophytic fungi and explore fungal decomposition capacities of the litter. [Methods] Basing on morphological characteristics and sequence alignment analysis of rDNA-ITS region, five dominant strains isolated from Pinus armandii needle litter from Erlang Mount were identified. These five isolates were used as the fungal strains and the needle litter was used as the natural substrate. The fungi abilities to degrade the needle in terms of the loss in total organic matter (TOM) and the enzyme activities of endoglucanase (EG), xylanase (Xyl), lignin peroxidase (LiP), manganese peroxidase (MnP) and acid phosphatase (AP) by fermentation were tested. [Results] The five isolates were identified as Mucor sp., Pestalotiopsis sp., Allantophomopsis sp., Phoma sp. and Hypocrea sp., respectively. The loss in TOM caused by the five fungi was between 6.63%?15.77%. AP activity in the case of Pestalotiopsis sp. was the highest and the activities of EG, Xyl, LiP were relatively high. LiP activity was the highest in Allantophomopsis sp., which had high activity of MnP. Whereas EG and Xyl activities were low for Hypocrea sp. which can secrete LiP and higher AP. The results of correlation analysis showed that AP activity was negatively correlated with the loss in TOM. Moreover, there was a certain synergy between EG, Xyl and AP, especially between EG and AP. [Conclusion] In the present study, the five saprophytic fungi can degrade needle litter of Pinus armandii and the ability from highest to lowest was as followed: Pestalotiopsis sp., Allantophomopsis sp., Hypocrea sp., Phoma sp., Mucor sp.. Enzyme activities and enzymes synergy had an influence on decomposition of the needle litter. Pestalotiopsis sp., Hypocrea sp. and Allantophomopsis sp. were found to not only be capable of producing lignocelluloses-degrading enzymes but cause higher loss in TOM. These three strains were regarded as lignocelluloses-degrading fungi.