尼龙袋法研究燕麦草茎杆在瘤胃中降解超微结构的动态变化  

In Situ Degradation of Oat Grass Stem and Ultrastructure Changes by Rumen Microorganism

作　　者：徐俊[1] 侯玉洁[1] 杨宏波[1] 邬彩霞[1] 霍永久[1] 赵国琦[1] 

机构地区：[1]扬州大学动物科学与技术学院,江苏扬州225009

出　　处：《中国畜牧杂志》2014年第7期35-39,共5页Chinese Journal of Animal Science

基　　金：十二五国家科技支撑计划(2011BAD17B03);江苏省研究生科研创新计划(CXLX12_0933)

摘　　要：通过半体内法研究燕麦草茎杆在奶牛瘤胃微生物作用下的超微结构变化。选用长势和株高相近的燕麦草,剥离出茎杆后纵切为6份投入奶牛瘤胃内降解,分别在6、12、24、48 h和72 h后取出样品并按扫描电子显微镜(SEM)和透射电子显微镜(TEM)要求制片观察。结果表明:细菌通过胞外酶优先降解薄壁组织和韧皮部中较薄的细胞壁,这一过程并不依赖细菌与纤维的紧密粘附,然而维管束鞘中厚壁细胞的降解则需要细菌与细胞壁的紧密粘附;维管束中的导管组织不能被微生物降解,它通常伴随薄壁组织的降解而脱落下来;当降解到72 h后,表皮和厚壁组织细胞仍保持完整;从超微结构图可知某些细菌通常是通过类似于纤维状的胞外物质和电子致密层与细胞壁中的纤维相连进而发生作用,尤其是对那些细胞壁加厚组织的降解。结果显示,不同组织瘤胃内的降解程度存在明显差异,低木质化的薄壁组织优先降解,而表皮和厚壁细胞难以降解;降解纤维的细菌通常借助类似于纤维状的胞外物质或电子致密层与细胞壁粘附进行降解作用。This study was conduc ted to investigate the uhrastructure changes of oat grass stem degraded by rumen microorganisms. Stems bared from the oat grass with similar growth and plant height were choosed and then longitudinally cut to six parts, which were incubated for 6, 12, 24, 48 and 72 h in the rumen. The samples were prepared for scanning electron microscope （SEM） and transmission electron microscope （TEM）. Bacteria degraded the thin cell walls of parenchyma and phloem apparently by extracellular enzymes and without prior attachment, thick wailed bundle sheath were degraded after bacteria attachment. Vascular tissues were resistant to degradation but could shed following parenchyma degraded. However, bacterial degradation of the lignified cells of the epidermis and sclerenchyma did not occur after 72 h of incubation. Ultrastructural features apparently involved in the adhesion of bacteria to cell walls were observed by scanning and transmission electron microscope. Attachment of bacteria to the plant cell wall was mediated by the extracellular rod-like appendages and the electron dense, especially to the resistant tissues. In conclusion, the degradation characteristics of tissues were significant differences, and the low lignified parenchyma degraded faster than high lignified epidermis and sclerencyma tissues. Bacterias appered to be joined by the extracellular rod-like appendages or electron-dense extracellular substance to degrade the cell walls.

关 键 词：燕麦草茎杆 电子显微镜 微生物 细胞壁 

分 类 号：S816.5[农业科学—饲料科学]