玉米秸秆纤维素降解菌的筛选及复合菌系的构建

Screening of cellulose-degrading bacteria for corn straw and construction combined strains

研究从内蒙古东部地区采集样品并从中分离筛选可降解纤维素的兼性厌氧细菌,构建高效玉米秸秆降解复合菌系。经过分离纯化最终获得57株兼性厌氧菌。通过DNS法测定酶活后复筛出10株具有较高CMC酶活的菌株。经形态学及分子生物学鉴定,10株菌分别属肠球菌属(Entero-bacter,1-3、6-2、8-2)、芽孢杆菌属(Bacillus,2-4、3-4、6-9、14-1)、非脱羧勒克菌属(Leclercia adecar-boxylata,5-2)、柠檬酸菌属(Citrobacter,10)和泛菌属(Pantoea,11-2)。经过拮抗验证后,将所筛菌株混合构建为5个复合菌系A:1-3、5-2、6-2、11-2;B:3-4、6-9、5-2、8-2;C:2-4、5-2、8-2、11-2;D:10、2-4、8-2;E:14-1、3-4、8-2,其中菌系B的CMCase相较于单一菌株最高提高了105.07%。进一步玉米秸秆发酵实验表明,复合菌系B处理后的秸秆粗纤维降解率达到48.6%,表现出较高的降解玉米秸秆纤维素的能力。研究的结果为进一步构建玉米秸秆微贮菌剂,提高内蒙古自治区玉米秸秆饲用价值奠定基础。

In order to improve the feed rate of corn straw in Inner Mongolia Autonomous Region, a co- culture system which had high degradation rate of corn straw was constructed by the faeultative anaero- bic bacteria. The results showed that a total of 57 faeultative anaerobic bacteria were obtained from the samples that collected from the eastern part of Inner Mongolia and ten of them with higher CMCase were selected finally by DNS mathod. In addition, the selected isolates were identified by method of morphological observation and molecular biology and found that they were belong to five dif- ferent genera of Enterobacter（1-3, 6-2, 8-2）, Bacillus（2-4, 3-4, 6-9, 14-1）, Leclercia （5-2）, Citrobac- tet（10） and Pantoea（11-2）. Moreover, the isolates were constructed into five co-culture system as A： 1- 3, 5-2, 6-2 and 11-2; B：3-4, 6-9, 5-2 and 8-2; C：2-4, 5-2, 8-2 and 11-2; D：10, 2-4 and 8-2; E： 14-1, 3-4 and 8-2 after antagonistic validation. Finally, the CMCase of B co-culture system was in- creased by 105.07% compared with the single strain and the corn stalk fermentation experiment showed that the degradation rate of crude straw of corn stalk was 48.6% in the B co-culture system. This study laid the foundation for further improving the corn straw feeding in Inner Mongolia Autono- mous Region.