Inhibitory effect of ACC deaminase‐producing bacteria on crown gall formation in tomato plants infected by Agrobacterium tumefaciens or A. vitis

This study showed that various rhizosphere bacteria producing the enzyme 1‐aminocyclopropane‐1‐carboxylate (ACC) deaminase (ACCD), which can degrade ACC, the immediate precursor of ethylene in plants, and thereby lower plant ethylene levels, can act as promising biocontrol agents of pathogenic strains of Agrobacterium tumefaciens and A. vitis. Soaking the roots of tomato (Solanum lycopersicum) seedlings in a suspension of the ACCD‐producing Pseudomonas putida UW4, Burkholderia phytofirmans PsJN or Azospirillum brasilense Cd1843 transformed by plasmid pRKTACC carrying the ACCD‐encoding gene acdS from UW4, significantly reduced the development of tumours on tomato plants injected 4–5 days later with pathogenic Agrobacterium strains via wounds on the plant stem. The fresh mass of tumours formed by plants pretreated with ACCD‐producing strains was typically four‐ to fivefold less than that of tumours formed on control plants inoculated only with a pathogenic Agrobacterium strain. Simultaneously, the level of ethylene evolution per amount of tumour mass on plants pretreated with ACCD‐producing bacteria decreased four to eight times compared with that from tumours formed on control plants or plants pretreated with bacteria deficient in ACCD production. Moreover, transgenic tomato plants expressing a bacterial ACCD were found to be highly resistant to crown gall formation relative to the parental, non‐transformed tomato plants. The results support the hypothesis that ethylene is a crucial factor in Agrobacterium tumour formation, and that ACCD‐produced rhizosphere bacteria may protect plants infected by pathogenic Agrobacteria from crown gall disease.     

洋葱伯克霍尔德菌0107产脂肪酶发酵条件优化研究

[目的]对洋葱伯克霍尔德菌（Burkholderia cepacia）0107产脂肪酶发酵条件进行优化。[方法]探讨碳源、氮源、诱导物和pH值等条件对产脂肪酶的影响。[结果]较为合适的培养基组成为玉米粉1.50%,蛋白胨1.50%,橄榄油1.00%,K2HPO40.20%,MgSO40.05%。较优化的培养条件为：起始pH值9.0,30℃培养60h,酶活达9.15U/ml,与初始相比酶活提高1.7倍。酶的最适pH值和温度分别为8.5和所60℃,70℃保温2h酶活稳定,这些性质都有利于对动植物油脂的转酯化。[结论]该研究为洋葱伯克霍尔德菌0107所产酶的广泛应用奠定了基础。     

一株香蕉拮抗内生细菌的分离及鉴定

从健康的香蕉组织内分离获得22株内生细菌,从中获得1株对香蕉枯萎病菌(Fusarium oxysporum f. sp. cubense）1号与4号小种具有抑制作用的拮抗菌(编号为BEB9）,经形态学、生理生化及16S rDNA序列鉴定等方面研究,确认为伯克霍尔德菌。研究还发现NA和YE培养基是其抑菌作用最适培养基。     

解磷细菌 Burkholderia 的分离鉴定及对香草兰生长和 P 吸收 的影响

香草兰为喜磷作物,从香草兰种植园中分离筛选到一株解磷微生物——伯克霍尔德氏菌 V-29。在 NBRIP 液体 培养基中摇床振荡培养 5 d 后可溶性磷含量达 475.3 μg/mL,培养基 pH 下降。通过大田试验研究了接种绿色荧光蛋白 标记后的解磷菌株 V-29 及其与有机肥发酵制得的微生物有机肥对香草兰生长和磷素吸收的影响。结果表明：单独接种 V-29 或施用微生物有机肥可显著增加香草兰植株干重、土壤有效磷含量;移栽 4 个月后,标记菌株 V-29 在香草兰根际 土壤中的含量可达 106 cfu/g 土壤。由此可见,伯克霍尔德氏菌 V-29 可单独作为生物菌剂或与有机肥发酵制得微生物有 机肥后用于农业生产中,以减少化肥施用量。     

Effect of injection site on the bioavailability of an oxytetracycline formulation in ruminant calves

The oxytetracycline (OTC) disposition was studied in a group of six calves following the administration of an oxytetracycline‐10 per cent formulation (i) intravenously (i.v.), (ii) subcutaneously (s. c.) in the lateral neck, and intramuscularly (i. m.) in (iii) the lateral neck, (iv) the shoulder (M. triceps brachii), and (v) the buttock (M. semitendineus). The dose levels used for the intravenous route and other routes were respectively 17.0 ± 2.3 and 18.3 ± 1.25 mg OTC/kg. The peak OTC concentrations (Cmax) were achieved with the s. c. and i. m. routes between 4 and 8 hours after injection, the highest being found after application in the shoulder (Cmax:6.9 ± 0.82 μg/ml plasma). The Cmax for the s.c. and other i.m. routes of application was similar to each other, ranging from 5.0 to 5.5 μg/ml plasma. For different points in time after injection the partial bioavailability was calculated. At 52 h post injection (p.i.) maximal bioavailability was observed for the i.m. shoulder route, viz. 98.1 ± 7.0 per cent of the administered dose, while at 76 h p.i. similar bioavailabilities were achieved for the i.m. neck and shoulder route, namely 93.3 ± 8.9 and 99.4 ± 4.2 per cent, respectively. The lowest bioavailability (83.1 ± 13.4 per cent) was obtained following the i.m. buttock route at 76 p.i.

An obvious irritating effect was observed after s.c. application in the neck an di.m. injection in the buttock, which had disappeared at 5 days p.i. It is assumed that the longer persistence of OTC in plasma resulting with the latter two routes of administration was due to this irritation effect.     

多噬伯克霍尔德氏菌WS-FJ9对草甘膦降解特性的研究

长期或不当施用草甘膦会对非靶标生物和环境造成破坏作用。微生物是生物修复的重要生物资源,利用微生物及其产生的降解酶处理环境中有机磷农药的方法,已显示出良好的应用前景,是近年来研究有机磷农药降解的主要发展方向。本文目的在于研究分离于松树根际土壤的高效解磷细菌多噬伯克霍尔德氏菌（Burkholderia multivorans）WS-FJ9菌株对草甘膦的降解特性及其降解条件的优化。采用添加不同浓度草甘膦NA平板接种WS-FJ9菌株观察其对草甘膦的耐受性;分别以草甘膦为唯一碳源、氮源或磷源,探讨WS-FJ9菌株对草甘膦的利用状况;采用低进水量间歇式反应器法（FBR）测定了WS-FJ9菌株降解草甘膦动力学参数;利用Plackett-Burman（PB）、Central Composite Design（CCD）试验设计及响应面分析法（RSM）筛选与优化影响WS-FJ9菌株降解草甘膦的主要因素。WS-FJ9菌株有效降解草甘膦的最大耐受浓度为0.4%; WS-FJ9菌株在以草甘膦为唯一碳源、氮源或磷源培养基上均能正常生长;WS-FJ9菌株对草甘膦的亲和性常数（Ks值）为65 μL?mL-1,对草甘膦降解的极限浓度（Smin）为21.9 μL?mL-1;通过PB试验,筛选出3个影响菌株降解草甘膦的关键因素为培养温度、葡萄糖及硫酸铵的加入量,通过CCD设计及响应面法优化分析得到影响草甘膦降解率的关键因素的二阶模型,确定了WS-FJ9菌株降解草甘膦的最优实验操作条件为：培养温度27.7℃,葡萄糖和硫酸铵的加入量分别为0.67、0.50 g?L-1。实验条件下WS-FJ9菌株对草甘膦的降解率最高为72.83％。     

一种高效降解阿特拉津的混合菌发酵配方优化

前期降解试验表明2株能够高效降解阿特拉津的菌株:伯克霍尔德氏菌(Burkholderia sp.)LH-ZY01和丛毛单胞菌(Comamonas sp.)A2混合后降解效果明显提高,因此共降解具有重要的应用价值。为节约生产成本,通过响应面设计,利用2株能够高效降解阿特拉津的菌株,通过一系列显著因素优化设计,最终获得高密度培养上述2株菌的发酵培养基配方(g/L):蔗糖6.72,葡萄糖6.75,豆粕粉6.34,K_2HPO_4·3H_2O 0.6,KH_2PO_42.5,MgSO_4·7H_2O 0.3,NaCl 0.4,酵母粉3,pH 7.0~7.2。通过优化发酵配方和发酵方法,获得发酵液的总菌数为102亿/m L,其中伯克霍尔德氏菌菌数为62亿/m L,丛毛单胞菌菌数为40亿/m L。高密度发酵的优化配方为高效降解阿特拉津复合微生物的生产应用提供了重要依据。     

Isolation and Identification of Burkholderia glumae from Symptomless Rice Seeds

A survey on isolation and detection of the casual organism of bacterial grain rot of rice was conducted during 1997–2006. In 2006, six pathogenic bacterial strains were isolated from two symptomless seed samples of rice (Oryza sativa L.) originally produced in Hainan Province and then planted in Zhejiang Province, China. They were identified as Burkholderia glumae which is the causal organism of bacterial grain rot of rice by physiological characteristics, colony morphology, pathogenicity test, Biolog, fatt...     

一株分离自含羞草的β-根瘤菌的生物学特性研究

从海南尖峰岭自然保护区巴西含羞草的根瘤中分离到一株根瘤菌,编号为caf324,经过16S rDNA全序列测定和系统发育分析,发现caf324与β-根瘤菌含羞草伯克霍尔德菌PAS44(AY752958)的亲缘关系很近,相似度达到99.7%。通过部分生理生化测定发现,caf324接触酶、氧化酶和硝酸盐还原试验均为阳性,不能利用明胶和淀粉,不能利用葡萄糖发酵产酸,不能水解酪素,不能产生吲哚和3-酮基乳糖;抗逆性研究表明,caf324的生长范围广,可耐2%的NaCl,耐酸碱(pH4～11),最高生长温度45℃。     

洋葱伯克氏菌无细胞培养物的生防及促生活性研究

为了防止洋葱伯克氏菌在农业环境中对人类的危害,采用离心和过滤的方法获得洋葱伯克氏菌无细胞培养物,并研究其在平板上对植物病原真菌的拮抗作用和对水稻的促生作用。结果表明：洋葱伯克氏菌对植物病原真菌具有明显的拮抗作用,其中菌株R。、R。,、R。R~o．R：．、R。、R28的抑菌效果显著,在这7株菌中R。表现出对灰霉菌的强烈抑制作用和对稻瘟菌的较强抑制作用,并且表现出明显的促生作用。