Hevea brasiliensis (rubber tree) is well known as the tree of life for its by-products such as wood and latex. The introduction of super clones with high yield potential such as RRIM 3001 is among the efforts to improve latex and timber yields. However, the RRIM 3001 super clone is prone to a disease known as trunk bulges. The appearing of bulging on the tapping panel causes difficulties during the tapping process for harvesting the latex and affects the quality of wood produced. In this study, we aimed to characterize Bacillus pumilus (B. pumilus) causing trunk bulges disease of RRIM 3001 super clone rubber tree isolated from the infected rubber trees in Malaysia. During October to December 2017, samples with trunk bulges symptoms were collected from four rubber plantations with reported outbreaks. Ten bacterial isolates from vascular tissues of rubber tree with trunk bulges symptom were confirmed as Bacillus pumilus species by the production of yellow pigmentation, circular, raised and entire form colonies on Bacillus differentiation agar medium. All of the isolates are Gram-positive, rod-shaped, motile, as well as endospores formers. They were positive for catalase activities and negative in both potassium hydroxide (KOH) and sulfide productions. All bacterial isolates utilized glucose, inositol, mannitol, sucrose, xylose and trehalose, but did not utilize lactose and arabinose. Application of 16S rRNA, species-specific primers; Bsub5F/Bsub3R and UP-1S/UP-2Sr (GyrB gene) successfully identified all isolates as B. pumilus. Phylogenetic analysis of both genes further clustered these isolates into the same cluster to a B. pumilus reference strain in the GenBank database (GenBank Accession Nos. KF158227 and MF968898). The results from this study are useful for developing management strategies of B. pumilus in rubber plantations, since rubber tree has been recognized as important commodity crop with high economic value in Malaysia.

巴西橡胶树（橡胶树）因其副产品如木材和乳胶而闻名于世。引入具有高产量潜力的超级克隆（如RRIM 3001）是提高乳胶和木材产量的努力之一。但是，RRIM 3001超级克隆很容易患上一种称为躯干凸起的疾病。出胶板上出现鼓起的现象在出胶过程中给收获胶乳造成困难，并影响所生产木材的质量。在这项研究中，我们旨在表征芽孢杆菌（B. pumilus）导致从马来西亚受感染的橡胶树中分离出来的RRIM 3001超级克隆橡胶树的树干膨出病。在2017年10月至2017年12月期间，从报告有疫情暴发的四个橡胶园中采集了具有树干凸起症状的样品。从与躯干凸起症状橡胶树的血管组织十细菌分离株被证实为短小芽孢杆菌所生产的黄色色素沉着，圆形的种类，升高和对整个形成菌落芽孢杆菌分化琼脂培养基。所有的分离物都是革兰氏阳性，杆状，能动的，以及内生孢子的。它们的过氧化氢酶活性呈阳性，而氢氧化钾（KOH）和硫化物的产生呈阴性。所有细菌分离物均利用葡萄糖，肌醇，甘露醇，蔗糖，木糖和海藻糖，但未利用乳糖和阿拉伯糖。16S rRNA，物种特异性引物的应用；Bsub5F / Bsub3R和UP-1S / UP-2Sr（GyrB基因）成功鉴定出所有分离株均为短小芽孢杆菌。对这两个基因的系统发生分析进一步将这些分离物聚集到了短小芽孢杆菌的同一簇中GenBank数据库中的参考菌株（GenBank登录号KF158227和MF968898）。这项研究的结果对于制定橡胶人工林中的短双歧杆菌的管理策略很有用，因为橡胶树已被公认为是马来西亚具有高经济价值的重要商品作物。