10种蔬菜内生细菌的分离筛选

以抑制植物主要病害病原菌和内生防病相关酶活性为评价标准，从蔬菜作物体内分离筛选植物内生细菌资源。从苦瓜、丝瓜、空心菜、大豆等10种蔬菜体内分离到101株细菌，发现内生细菌在不同种类的蔬菜中出现的频率不同，其中丝瓜叶上的内生细菌数量最多，洋葱体内分离到的内生细菌数量最少。运用平板对峙法从中筛选出了对黄瓜枯萎病菌、番茄青枯病菌、水稻细条病菌、荔枝霜疫霉病菌等有较强拮抗作用的菌株，获得对以上4种病菌均有拮抗作用的内生细菌有41株，占总株数的40．6％。对101株细菌进行纤维素酶、蛋白酶和几丁质酶活性测定表明，同时具有3种酶活性的菌株有32株，占总菌数的31．7％。从中选出13株拮抗效果较好的内生细菌。经初步鉴定均属于芽孢杆菌属（Bacillus sp）。进一步对筛选获得的同时对以上4种病原菌均有拮抗作用，且具有纤维素酶、蛋白酶和几丁质酶活性的13号、14号、59号和82号菌株进行16SrDNA序列分析，表明4个菌株均为枯草芽孢杆菌（B．subtilis）或其近缘种。

LSOLATION AND SCREENING OF ENDOPHYTIC BACTERIA FROM TEN PLANT SPECIES OF VEGETABLE

Endophytic bacteria which could inhibit plant pathogens growth or had enzyme activity were isolated from different species of vegetables. One hundred and one bacterial strains were isolated from balsam pear, snake gourd, water spinach, soybean and so on. The results showed that appearance frequency of endophytic bacteria in different vegetables was different. The bacterial strains which could inhibit Xanthomonas oryzae pv. oryzicola, Ralstonia solanacearum, Peronophythora litchi, Fusarium oxysporum f. sp. , or had cellulase, proteinase, chitinase activity were selected. There were 41 strains, about 40.6%, could inhibit the four plant pathogens and 32 strains, about 31.7%, had three （cellulase, proteinase and chitinase） enzymes activity. Thirteen strains were selected out from the 101 strains and all of them were identified as Bacillus sp by key characteristic tests. The strains 13, 14, 59 and 82 which could inhibit the four plant pathogens and had the three enzymes activity were identified as B. subtilis or the relative species by 16S rRNA gene sequence analysis.