纤维素降解菌的分离及发酵液对大豆种子萌发的影响

Isolation of cellulose-degradation actinomycetes and effects of fermentation broth on soybean seed germination

为提高秸秆还田过程中的腐解效率,采用CMC-Na培养基、刚果红和滤纸平板培养基分离出1株纤维素降解能力强的放线菌菌株,同时利用种子萌发法研究该菌对大豆[Glycine max(Linn.)Merr.]种子的促生作用,并分析了纤维素降解菌发酵液对大豆种子过氧化物酶(POD)、过氧化氢酶(CAT)和超氧化物歧化酶(SOD)活性以及丙二醛(MDA)含量的影响.结果表明,分离出的菌株具有较强的分解纤维素能力,而且不同浓度的发酵液对大豆种子的萌发率和抗氧化酶活性均有影响.当发酵液浓度为100.0%时,大豆种子的萌发率达到最高值,为74.53%,与对照(不加菌液的Mendal's培养基)相比提高了21.96个百分点;大豆种子CAT和SOD活性最强,与对照相比分别提高了291.45%和106.64%;POD活性为25.6U/(mL·min),比对照提高了101.96%,但与纯水培养相比下降了14.65%.MDA含量在发酵液浓度为16.7%时最低,与对照相比降低了21.37%.初步证实了纤维素降解菌发酵液中含有能促进大豆种子萌发和抗氧化酶活性升高的物质,以及保护膜组分的物质.

In order to improve the decomposition efficiency of straw returning to the field,an actinomycete strain with strong cellulose degradability was isolated by using CMC-Na medium,Congo red medium and filter paper plate medium.At the same time,the seed germination method was used to study the growth-promoting effect of the strain on soybean [Glycine max (Linn.) Merr.] seeds.The activities of POD,CAT and SOD and the content of MDA in soybean seeds were also studied.The results showed that the isolated strain had a strong ability to decompose cellulose,and the germination rate and antioxidant enzyme activity of soybean seeds were changed after treated with different concentrations of cellulose-degrading bacteria fermentation broth.When the concentration of fermentation broth was 100.0%,the germination rate of soybean seeds reached the highest,was 74.53%,increasing by 21.96 percent compared with the control(Mendal's medium without bacterial fluid);the activity of CAT and SOD was the strongest,which increased by 291.45% and 106.64% respectively compared with the control;and the POD activity was 25.6 U/(mL·min),101.96% higher than that of the control,but it was 14.65% lower than that of the pure water culture.The content of MDA was the lowest at 16.7%,which was 21.37% lower than that of control.It was preliminarily confirmed that the fermentation broth of cellulose-degrading bacteria contained substances which could promote the germination of soybean seeds and increase the activities of antioxidant enzymes,as well as protective membrane components.