秸稈纖維素降解細菌的篩選及產酶條件優化

王雙，許潔，李浠源，相穎，潘楊楠，夏天

摘要：從富含腐爛秸稈的土壤中分離、篩選出降解纖維素較為有效的細菌，鑒定其類別，并對其產酶條件進行優化研究。利用羧甲基纖維素鈉水解圈法、濾紙崩解法、酶活測定法篩選菌株，并對秸稈液體產酶培養基中不同秸稈長度、培養時間、氮源、氮源投加量和培養基初始pH對酶活性的影響進行了研究。結果篩選出秸稈纖維素降解能力較強的兩株菌株XY2和XY6。經鑒定XY2屬于伯克霍爾德菌屬（Burkholderia mimosarum），XY6屬于腸桿菌屬（Enterobacter）。菌株XY2的最優產酶條件為：溫度30 ℃，培養基初始pH為6.0，碳源為4 cm長度的水稻秸稈或小麥秸稈，氮源為0.5%硫酸銨；菌株XY6的最優產酶條件為：溫度30 ℃，4 cm長度秸稈段為碳源，而在以水稻秸稈為惟一碳源時，最適氮源為0.5%的硫酸銨、培養基初始pH為6.0，以小麥秸稈為惟一碳源時最適氮源為0.5%的硝酸鈉、培養基初始pH為8.0，氮源為5‰硝酸鈉或硫酸銨，且在一周之內酶活性變化較小。

關鍵詞：秸稈；纖維素降解細菌；篩選；酶活性；產酶條件

中圖分類號：Q939.96；X712 文獻標識碼：A 文章編號：0439-8114（2013）05-1121-04

Screening of Cellulose-Degrading Bacteria and Optimization of Enzyme-Production Conditions

WANG Shuang，XU Jie，LI Xi-yuan，XIANG Ying，PAN Yang-nan，XIA Tian

（Taizhou Institute of Science and Technology， Nanjing University of Science and Technology，Taizhou 225300， Jiangsu， China）

Abstract： Bacteria， which could effectively degrade the cellulose， was isolated and screened from the rotting straw soil. The classification of this bacteria and its optimal enzyme production conditions were determined. The sodium carboxymethyl cellulose hydrolysis circle method， filter paper disintegration， enzyme activity determination method were used to screen bacteria strains. The effects of straw length， incubation time， nitrogen sources， nitrogen dosage and pH value on enzyme production were inverstigated in straw enzyme production medium. Two strong degradation ability strains were isolated， which were named XY2 and XY6 respectively. Through the 16 S rRNA sequence analysis， strain XY2 belongs to the Burkholderia mimosarum； strain XY6 belongs to the Enterobacter. The optimal enzyme production conditions for strain XY2 is 30 ℃， pH 6.0， 4 cm straw segment as the carbon source， 0.5% ammonium sulfate as the nitrogen source； for strain XY6， the optimal enzyme production conditions is 30 ℃， pH 6.0 for rice straw or 8.0 for wheat straw， 4 cm straw segment as the carbon source. And 5‰ sodium nitrate for rice straw or ammonium sulfate as the nitrogen source for wheat straw. The enzyme activities changed a little in a week.

Key words： straw； cellulose-decomposition bacteria； screen； enzyme activities； enzyme production conditions