摘要
【背景】在我国北方地区玉米秸秆还田时期地温低、秸秆降解慢,如何加速玉米秸秆低温腐解成为研究热点。【目的】从冷凉地区土壤中筛选具有高效降解纤维素能力的低温菌株,为秸秆的有效利用奠定基础。【方法】在低温培养条件下,采用稀释涂布平板法、羧甲基纤维素钠(sodium carboxymethyl cellulose,CMC-Na)水解圈测定法、胞外酶活测定法、秸秆失重法进行低温秸秆降解菌株的初筛、复筛和秸秆降解性能的测定;根据菌株形态学特征及ITSrDNA序列分析对筛选菌株进行鉴定;利用3,5-二硝基水杨酸(3,5-dinitrosalicylic acid,DNS)法和秸秆失重法对菌株在不同接种量、培养基初始pH、温度情况下的纤维素酶活力和玉米秸秆降解能力进行研究。【结果】以16°C为筛选温度,获得一株在刚果红-羧甲基纤维素钠平板上D/d值为2.17、CMC酶活力为703 U/mL的高产纤维素酶低温真菌SDF-25;该菌株在4°C可以生长,10-16°C为最适生长温度,37°C条件下仍能生长;综合菌株的形态学和分子生物学测定结果,菌株SDF-25为草酸青霉菌(Penicillium oxalicum);该菌株最佳产纤维素酶的培养条件为接种量2%、初始pH为7.0、培养温度为10°C,在该培养条件下菌株SDF-25的CMC酶活为993.3 U/mL。失重法测定接种SDF-25于10°C培养15 d时秸秆降解率为39.5%,16°C时为44.9%。【结论】草酸青霉菌SDF-25可在低温条件下生长并具有较强的纤维素酶生产能力,在秸秆还田方面具有良好的应用前景。
[Background] Due to the low-temperature at maize straw returning time, the straw degradation is slow in the northern part of China. The acceleration of straw decomposition is thus important.[Objective] To isolate strains with high cellulose degradation ability at low temperature from soil sample collected from cold region. [Methods] Dilution and plating method was used to isolate strains from soil sample at low temperature culture. The sodium carboxymethyl cellulose(CMC-Na) hydrolysis circle assay, extracellular enzyme activity assay and straw weight loss method were used to screen fungi with cellulose degradation ability at low cultural temperature. Strains were identified based on method of morphological characteristics and ITS rDNA sequence analysis. Using the reducing sugar method of DNS, the cellulase activity of the strains under different inoculation volumes, initial pH of the medium and culture temperature was studied. The straw degradation ability of the strain was studied by sandbag method. [Results] A cold adapted fungus SDF-25 with higher cellulose activity was screened and identified as Penicillium oxalicum. It could grow from 4 to 37 °C. The optimal cultural condition for cellulase production was determined as follow: inoculation quantity 2%, initial pH 7.0, the optimal temperature 10 °C. The enzyme activity at the optimal cultural condition was 993.3 U/mL. The straw degradation rate of SDF-25 was 39.5% and 44.9% with cultural temperature at 10 °C and 16 °C respectively. [Conclusion] P. oxalicum SDF-25 is a fungus with strong cellulase production ability at low temperature and has a good application prospect in straw returning.
作者
邢慧珍
宋水山
黄媛媛
黄亚丽
XING Hui-Zhen;SONG Shui-Shan;HUANG Yuan-Yuan;HUANG Ya-Li(College of Chemical Engineering,Hebei University of Technology,Tianjin 300131,China;Institute of Biology,Hebei Academy of Sciences,Shijiazhuang,Hebei 050051,China;Hebei University of Science and Technology,Shijiazhuang,Hebei 050018,China)
出处
《微生物学通报》
CAS
CSCD
北大核心
2020年第9期2923-2933,共11页
Microbiology China
基金
国家重点研发计划(2017YFD0300905)。
关键词
纤维素降解真菌
低温
秸秆还田
产酶特性
菌株鉴定
Cellulose-degrading fungi
Low temperature
Straw returning
Enzyme production characteristics
Identification
