Establishing the Efficacy, Safety and Persistence of biopesticides based on naturally occurring beneficial bacteria

利用天然细菌保护作物和维持农业我们研究的目的是建立有效、安全和环保的非持久性方式使用天然植物保护细菌所需的基础科学知识。目前的农业依赖于使用化学农药来保护作物免受致病微生物的侵害。其中一种被称为“枯萎病”的疾病是农作物在发芽时死亡的主要问题。为了养活不断增长的世界人口，我们将需要加强农业和添加更多的化学农药来保护作物。我们不能继续大量使用农药，特别是在它们损害环境和人类健康的情况下。必须开发可持续的替代方法，天然细菌生物农药为加强未来农业和保护作物免受疾病侵害提供了一个有吸引力的解决方案。伯克霍尔德氏菌-一种天然的植物保护细菌几种天然细菌与植物密切相关，并提供对致病微生物的保护。其中一种细菌，伯克霍尔德菌（B. ambifaria），当用作种皮时，可以很好地保护发芽的作物免受真菌的致命攻击。这使得它们作为生物杀虫剂在美国一直安全使用到1999年，但在20世纪90年代，一组相关的伯克霍尔德氏菌被发现会导致囊性纤维化患者肺部感染。当时，尚不能完全确定双歧杆菌的安全性，因此决定，在证明新的生物农药没有健康风险之前，不允许对其进行登记。虽然登记的伯克霍尔德菌生物农药产品仍然可以使用，但农业工业不再使用它们，而是扩大了化学农药的使用，以维持农业。利用现代研究技术，我们发现双歧杆菌的植物保护能力是由于一组基因，这种细菌用来制造一种叫做cepacin的抗真菌分子。当产生cepacin的基因被移除时，细菌种皮上的植物保护功能就丧失了。通过对双歧双歧杆菌的所有基因进行测序，我们还发现了多个新的基因，这些基因使天然产物有可能被开发为生物农药分子、抗生素或精细化学品。这些新发现使我们能够制定一项研究计划，将双歧杆菌重新用作生物农药，这将作为以下四个研究目标进行：1。我们将绘制出B. ambifaria用来保护植物免受病原体攻击的所有分子和途径，特别是识别出当细菌在作物种子发芽释放的分泌物中生长时开启的那些分子和途径。我们将设计头孢菌素的途径，使其能够进入其他生物技术细菌，并探索它如何能够制造这种生物农药分子的不同寻常的化学结构。我们将通过鉴定其致病基因和探索去除这些基因的不同策略来提高双歧杆菌的安全性。当移除特定基因时，传染性活细菌可以用作疫苗，同样的方法将被用来制造安全的生物杀虫剂。我们将探索当双歧双歧杆菌作为种皮放置在土壤中时会发生什么，以及它如何影响其他土壤微生物，以便我们了解它的环境持久性。总的来说，这一综合研究计划将寻求提供一种有效、安全和环境上不持久的双歧杆菌生物农药，它可以在不需要使用化学农药的情况下显著提高和维持农业生产。

HARNESSING NATURAL BACTERIA TO PROTECT CROPS AND SUSTAIN AGRICULTUREThe aim of our research is to establish the fundamental scientific knowledge required to use naturally occuring plant protective bacteria in an effective, safe and environmentally non-persistent manner. Current agriculture is reliant on the use of chemical pesticides to protect crops from attack by disease-causing microorganisms. One such disease, known as damping off, is a major problem killing crop plants as they germinate. To feed the growing world population we will need to intensify agriculture and adding more chemical pesticides to protect crops. We cannot sustain high usage of pesticides, especially when they damage the environment and human health. Alternative approaches which are sustainable must be developed and natural bacterial biopesticides offer an attractive solution to enhance future agriculture and protect crops from disease.BURKHOLDERIA AMBIFARIA - A NATURALLY PLANT PROTECTIVE BACTERIASeveral natural bacteria live very closely with plants and provide protection against disease causing microbes. One group of bacteria, Burkholderia ambifaria (B. ambifaria), when applied as a seed coat are very good at protecting germinating crops from lethal attack by damping off fungi. This led to their safe use as biopesticides up to 1999 in the US, but during the 1990s, a related group of Burkholderia bacteria were found to cause lung infections in people with cystic fibrosis. At the time, the safety of B. ambifaria could not be fully defined, it was decided that registration of new biopesticides would not be permitted until they were demonstrated to have no health risks. Although the registered Burkholderia biopesticide products could still be used, the agricultural industry moved away from using them and expanded their use of chemical pesticides to sustain agriculture.UNDERSTANDING HOW BURKHOLDERIA AMBIFARIA PROTECTS PLANTS AND ENSURING IT IS SAFE AND ENVIRONMENTALLY NON-PERSISTENTUsing modern research techniques, we found B. ambifaria's plant protective ability was due to a set of genes that the bacterium uses to make an antifungal molecule called cepacin. When the cepacin-making genes were removed, plant protection was lost from the bacterial seed coat. By sequencing all the genes in B. ambifaria bacteria we also identified multiple new genes that make natural products potentially exploitable as biopesticide molecules, antibiotics or fine chemicals. These new findings have allowed us to map out a research program to re-purpose B. ambifaria as a biopesticide which will be carried out as the following four research objectives: 1. We will map all the molecules and pathways B. ambifaria uses to protect plants from attack by pathogens, specifically identifying those which are switched on when the bacteria grow on the exudates released by germinating crop seeds.2. We will engineer the cepacin pathway allowing it to be moved into other biotechnological bacteria and also exploring how it is able to make the unusual chemical structure of this biopesticidal molecule.3. We will improve the safety of B. ambifaria by identifying the genes it uses to cause disease and exploring different strategies to remove these genes. Infectious live bacteria can be used as vaccines when specific genes are removed, and the same approach will be exploited to make a safe biopesticide.4. We will explore what happens to B. ambifaria when it is placed in the soil as a seed coat and how it affects other soil microorganisms, so that we understand it's environmental persistence.Overall this integrated research programme will seek to deliver an effective, safe and environmentally non-persistent B. ambifaria biopesticide, which can significantly enhance and sustain agricultural production without the need to use chemical pesticides.