檸條木質素降解菌的篩選及其降解條件優化

崔家榮 段開紅

摘要 [目的]將檸條轉化為可被牲畜高效利用的優良飼料。[方法]采用檸條作為單一碳源的篩選培養基、苯胺藍篩選培養基從牲畜糞便以及檸條腐質中分離篩選出對檸條木質素具有降解作用的菌株D-11。[結果]經微生物形態學和16S rDNA鑒定，D-11為地衣芽孢桿菌，同時對D-11降解條件進行優化。菌株D-11的最佳降解條件如下：最佳氮源為蛋白胨;溫度為28～32 ℃;pH為7;添加誘導劑Mn2+的濃度為0.6 mmol/L。在最優條件下，菌株D-11對檸條木質素降解率為18.21%，半纖維素的降解率為16.11%，纖維素的降解率為13.19%。[結論]采用菌株D-11對檸條進行發酵降解，使其轉化為可被牲畜利用的優良飼料。

關鍵詞 檸條;木質素;木質素降解菌;篩選;發酵降解;降解條件優化

中圖分類號 S816.6文獻標識碼 A

文章編號 0517-6611（2019）19-0107-03doi：10.3969/j.issn.0517-6611.2019.19.031

Abstract [Objective] To convert Caragana korshinskii into a good feed efficiently utilized by livestock.[Method]C.korshinskii was used as a single carbon source for screening medium and aniline blue screening medium was used to separate and screen out lignin degrading strain D11 from livestock manure and C.korshinskii humus.[Result] Strain D11 was identified by microbial morphology and 16S rDNA as Bacillus licheniformis，and the degradation conditions of D11 were optimized.The optimal degradation conditions of strain D11 were as follows：optimal nitrogen source was peptone，temperature was 28-32 ℃，pH was 7，the concentration of added inducer Mn2+ was 0.6 mmol/L.Under the optimal conditions，the degradation rate of strain D-11 to C.korshinskii lignin was 18.21%， the degradation rate of hemicellulose was 16.11%，the degradation rate of cellulose was 13.19%.[Conclusion] Strain D-11 can be used to ferment and degrade C.korshinskii，which can be transformed into an excellent feed utilized by livestock.

Key words Caragana korshinskii;Lignin;Lignindegrading bacteria;Screening;Fermentation and degradation;Optimization of degradation conditions

檸條是多年生豆科灌木，作為一種非競爭性資源，在我國北方地區具有數量大、分布廣、價格低廉的特點，由于其枝繁葉茂、營養豐富，含有10多種生物活性物質，尤其是氨基酸含量豐富[1]，因此也是良好的飼用植物，但其木質纖維素含量高，且收獲干燥后莖稈粗硬，并具有脫葉刺也成為影響牲畜對其高效利用的關鍵問題[2]。筆者從微生物豐富的糞便及其檸條腐殖質中分離篩選出具有高效降解檸條木質素的菌株，將檸條中難以被牲畜直接消化利用的木質素，通過生物處理的方式降解為可被生物利用的小分子物質，提高檸條的飼料營養價值和利用率，來發揮檸條潛在的飼用價值。

1 材料與方法

1.1 樣品來源及處理方法 試驗所用樣品采自市區周邊郊區農戶的牲畜糞便、腐質檸條，分別裝入無菌袋帶回并保存于4 ℃冰箱中。……