Abstract: A survey on screening and identification of gram-positive bacteria was conducted during 1998-2004. Seven hundred and fifty-six rice samples were collected from Zhejiang, Jiangsu, Fujian and Yunnan Provinces, China. Over 1000 bacterial isolates were isolated and tested with colony morphology, pathogenicity, and some characteristics of bacteriology including Gram staining, fluorescent pigment on Kings medium B and microscopic observation for endospore. Together with 5 standard reference strains, 74 representative gram-positive bacterial isolates were confirmed by Biolog and gas chromatographic analysis of fatty acid methyl esters. Five bacterial species of Bacillus and other 3 genera were identified and the isolates from Bacillus sublitis and Bacillus megaterium exhibited the most effective inhibition against the pathogens of sheath blight and bakanae disease of rice. A few isolates from Bacillus pumilus and Bacillus megaterium showed weak virulent on rice together with some virulent isolates, risk should be considered when isolates from these species were screened for biocontrol agents.

Key words: bacterial identification, bacterial population, antagonistic bacteria, sheath blight, bakanae disease

摘要： 于1998~2004年对采自浙江、江苏、福建和云南省的756份稻株和稻种样本进行了革兰氏阳性细菌的分离、鉴定研究。被分离的1015个菌株经致病性测定、菌落形态及部分细菌学特征（革兰氏染色、KMB培养基上的荧光色素及芽孢的染色镜检等）测定后，选出代表菌株74个连同5个对照菌株用Biolog及脂肪酸分析法(FAME)进行测试, 鉴定出Bacillus属5个种及其他3属的革兰氏阳性细菌，并发现枯草芽孢杆菌和巨大芽孢杆菌菌株具有很好的纹枯病和恶苗病拮抗能力,但来自短小芽孢杆菌和巨大芽孢杆菌的极少数菌株在条件适宜时能与其他病原菌一起引起水稻褐斑，从这些种筛选生防菌株时应充分考虑其风险。

关键词: 细菌鉴定, 细菌种群, 拮抗细菌, 纹枯病, 恶苗病