尖叶胡枝子青贮微生物数量变化及发酵特性

Fermentation characteristics and changes of lactic acid bacteria isolated from ensiling Lespedeza hedysaroides

以尖叶胡枝子(Lespedeza hedysaroides)为原料,对其表面附生的2株乳酸菌(LH29、LH33)的生化特性、生长特性、产酸速率进行了研究,经传统鉴定方法及16SrRNA分析方法鉴定,LH29为戊糖片球菌,LH33为植物乳杆菌;发酵初期戊糖片球菌产酸速率优于植物乳杆菌,发酵中后期后者产酸速率优于前者;将SNOW LACT-L(SL)和纤维素酶(AC)2种添加剂添加至尖叶胡枝子中,研究了不同发酵时间微生物数量的动态变化及发酵品质。发酵初期,各种微生物的数量较青贮原料上的数量有较大的增长,发酵第2天,添加AC处理组的乳酸菌数量最高,SL+AC添加组的乳酸菌的数量显著高于对照组(P<0.05),发酵第30天,乳酸菌、好氧细菌、酵母菌、霉菌及大肠杆菌的数量有所减少,大肠杆菌减少更明显;各添加组与对照组相比,氨态氮及丁酸含量显著降低(P<0.05),乳酸含量明显提高(P<0.05)。通过Flieg青贮饲料评分方案得出直接青贮饲料的发酵品质较差,等级为劣,而添加AC及SL+AC处理的青贮饲料发酵品质Flieg等级为优。

Two strains of lactic acid bacteria（LAB） were isolated from fresh Lespedeza hedysaroides,and Pediococcus pentosaceus（LH29﹚and Lactobacillis plantarum（LH33） were obtained by 16S rRNA method and traditional identification methods.This study showed that the acid-production rate of LH29 was better than that of LH33 in the early stage of ensiling,but the LH33 was better than LH29 in the later stages.SNOW LACT-L（SL） and Acremonium cellulose（AC） were used as additives to L.a hedysaroides silage.During the fermentation process,LAB in SL＋AC treatments was bigger significantly than that in the control silage（CK） after two days of ensiling（P0.05）.On the thirtieth day,the numbers of aerobic bacteria,yeasts,molds and E.coli in all treatments decreased,in which E.coli declined significantly（P0.05）.Compared to CK,all the silages with additives had significantly lower pH,NH3-N,butyric acid concentration and significantly higher lactic acid content（P0.05）.The improvement in silage quality was graded basing on Flieg score： ACSL＋ACSLCK.The highest Flieg point was obtained from tests with AC and SL＋AC.