真菌和细菌防治根结线虫的研究进展

根结线虫是一类重要的植物病原物,其防治一直是学者们研究的热点.综述了近几年植物根结线虫生防真菌和生防细菌的开发利用现状,介绍了有应用前景的菌属,并对存在的问题进行了讨论.     

Partial Characterization of Chitinolytic Extract from Endophytic Streptomyces sp. and Its Effects on the Boll Weevil

The present study achieves the biochemistry partial characterization of the chitinolytic extract produced by an endophytic Streptomyces sp. strain （A8）. This extract was also tested against Anthonomus grandis, the cotton boll weevil aiming its control. The chitinase crude extract from the A8 strain was cultured for five days in a minimum liquid media supplemented with chitin. The extract was partially characterized by standard methods. The chitinolytic extract had an optimum temperature of 66 ＂C and an optimum pH between 4 to 9 （around 80% of relative activity）. We also characterized the temperature and pH stability and measured the effects of enzyme inhibitors. The filtered chitinolytic extract was added to an artificial boll weevil diet. Boll weevil development from the egg stage to the adult stage was prolonged, and the percentage of adults that emerged was approximately 66% less than on control diet. This study showed that the.larval development of A. grandis was inhibited by the presence of characterized chitinolytic extract in artificial diet. This work provides an experimental basis for using the chitinase from an endophytic bacterium Streptomyces sp. as a biocontrol alternativeto controlling the plant pest A. grandis.     

茶叶内生菌的分离鉴定及其生防功能初探

对采自福建宁德地区的大白毫和福云六号茶叶进行内生菌的分离和脂肪酸鉴定.从7份样品中共分离到16株细菌、1株真菌.老叶中均未检测到内生菌,芽叶中内生菌数量为26.5×106-139.5×106cfu.g-1.有机种植的福云六号芽叶含菌量是大白毫的1.94倍.常规种植的大白毫芽叶含菌量为97.5×106-139.5×106cfu.g-1,明显高于有机种植的26.5×106-28.3×106cfu.g-1.大白毫带有红杆菌属、微杆菌属、根瘤菌属和贪噬菌属的内生细菌,福云六号仅含有根瘤菌属和贪噬菌属.有11株茶叶内生菌对10种供试病原菌表现出拮抗活性,其中放射根瘤菌Eb659菌株抑菌谱最广,具有作为生防菌防治植物病害的潜质.     

植酸对生防细菌L-227-03生长、发酵及抑菌能力的影响

研究了植酸(PA)对生防细菌L-227-03生长、发酵及抑菌能力的影响。结果表明:(1)在发酵6 h添加0.006%PA,18 h添加0.004%PA对L-227-03菌株细胞生长的促进作用最强,达到最佳的添加效果。(2)添加PA能提高L-227-03菌株细胞增殖速度,促进菌株提前6 h进入对数生长期,稳定期延长6 h。(3)添加PA发酵后,生防细菌L-227-03的抑菌活性增强,皿内抑菌圈直径最大达24 mm,较对照大6 mm,萝卜块根防效试验和盆栽防效试验的最高防效分别为82.34%和82.37%,较对照提高了13.39%和12.26%;菌体发酵液的耐保藏能力也有所提高,发酵液的有效期限延长3~6个月。(4)PA能缓和pH变化对菌体生长的影响,提高菌体对盐的耐受力。     

War on foot and mouth disease in the UK, 2001: Towards a cultural understanding of agriculture

This article applies some ofthe insights from framing studies in policyresearch, metaphor analysis, and the history ofmedicine to a cultural understanding ofagriculture, using the 2001 outbreak of footand mouth disease in the UK as a case study.The article will show how metaphors of war wereused as a rhetorical frame by the media andas an implicit action frame by policy makers.It will be argued that although the war framemight initially have been useful in rallyingsupport for the slaughter policy, the metaphorlater backfired, when a metaphorical war turnedinto a literal holocaust. This might haveencouraged the public to perceive the policy asmedieval, brutal, and misguided, thuspotentially undermining the willingness ofsections of the public to support the slaughterpolicy in future outbreaks. If, on the otherhand, a vaccination policy were adopted in thefuture, care would need to be taken to avoidmetaphorical linkages with other controversiesover vaccination in other domains.