不同植被土壤产淀粉酶放线菌的分离与筛选

Isolation and Screening of Amylase-producing Actinomycetes from the Soil under Different Vegetations

为了从土壤中获得产淀粉酶放线菌,对陕西省洛南县7种植被下不同土层土壤中的产淀粉酶放线菌进行了分离纯化,研究了化学抑制剂K2Cr2O7质量浓度和土壤稀释液浓度对放线菌分离效果的影响,并通过菌落形态特征和生理生化指标对产淀粉酶放线菌进行了综合分析。结果表明,当土壤稀释液为10-5～10-4 g/mL、K2Cr2O7质量浓度为50mg/L时,最有利于放线菌的分离;同一植被下表层土壤(5～20cm)中放线菌数量显著多于深层土壤(20～30cm);从7种不同植被下土样中共筛选出10株放线菌菌株,其中有8株是产淀粉酶放线菌菌株,从槐树下土壤中分离出的M4菌株对淀粉的水解能力最强,u0为14.27,并初步被判定为诺卡氏菌属放线菌;8株产淀粉酶放线菌均能利用葡萄糖进行糖酵解,6株能利用乳糖,7株不能利用蔗糖,6株不能利用麦芽糖,仅2株能够产生色氨酸酶,并且所有菌株均具有较强的耐碱性(pH值7.0～7.5),6株具有较强的耐盐性(10%),6株具有柠檬酸盐利用能力。

To obtain amylaseproducing actinomycetes from soil, amylaseproducing actinomycetes were isolated and purified from different soil layers under seven vegetations in Luonan county of Shanxi province. The effects of chemical inhabitor K2Cr207 concentration and soil diluted concentration on the isolation of actinomycetes were studied, and a comprehensive analysis of amylaseproducing actinomycetes was done with the morphological characteristics and physiologi cal and biochemical index. The results showed that the effective concentration of soil diluent was 10^（-5）- 10^（-4） g/mL, and the effective concentration of K2Cr2O7 was 50 mg/L for isolating actinomycetes;the amount of actinomycetes in the surface soil （5-20 cm） was more than those in deep soil（20-30 cm） under the same vegetation;a total of 10 actinomycete strains were isolated from the soil under seven different vegetations, eight of them were amylaseproducing actinomycetes, the strain M4 exhibited the strongest ability of starch hydrolysis（u0 = 14. 27）,which was isolated from the soil under locust tree, and was preliminarily identified as Nocardia spp.. Eight amylaseproducing actinomycetes strains all involved in glycolytic pathway, all of them could ferment glucose, six strains of them could ferment lactose, seven strains of them could not ferment sucrose, and six strains of them could not ferment maltose; two strains of them could produce tryptophanase;eight stains all showed the strong alkali resistance（pH 7.0-7.5）;six strains of them had good salt tolerance（10%）, and six strains of them could make good use of acarbon source.