Anaerobic digestion of sugar beet – fate of plant pathogens and gas potential
Anaerobic digestion of sugar beet – fate of plant pathogens and gas potential
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甜菜的厌氧消化——植物病原体的命运和产气潜力
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发表时间：
2008
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通讯作者：
Lena Haraldsson
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作者：
Lena Haraldsson
瑞典和欧洲的目标是增加可再生能源的使用。沼气是实现这一目标的一种方式。从有机废物或农作物材料中产生的沼气可用于生产热能和电力，并可用作车辆燃料。沼气过程也是有利的，因为它介导了营养物质从废物产品到耕地的再循环。这可以通过将消化后留下的营养丰富的生物肥料散布在耕地上来实现。在沼气过程中用作底物的有机材料可能含有不同的污染生物，例如不同的真菌。有些真菌是植物病原体，如果它们在沼气过程中存活下来并传播到耕地上，它们可能会感染新作物，从而导致产量下降和对杀真菌剂的需求增加。如果储藏病原体传播，它们可能在地面上的有机碎片上存活，并在储藏期间损害收获的作物。因此，重要的是要评估潜在的风险时，感染植物病原真菌的材料被用作沼气过程中的基质。此外，如果真菌被杀死，沼气工艺提供了一种替代方法，可以使用质量不够好的作物生产食品或饲料。然而，目前还不清楚这种“低质量”材料可以达到什么水平的天然气产量。本研究的目的是调查植物病原体在中温厌氧消化过程中的命运，并调查受感染和未受感染的甜菜，新鲜的甜菜根和储存一年的气体生产潜力。生存研究进行了三种不同的甜菜田间病原菌，丝囊孢菌cochlioides，腐霉和立枯丝核菌，引起出苗疾病，并为两种不同的存储病原体黄色镰刀菌和灰葡萄孢。在分批测试系统中测定产气潜力，所述分批测试系统以来自两个不同的大规模沼气厂的接种物开始。产气潜力的测量表明，未感染的新鲜和储存的甜菜比被不同真菌病原体感染的甜菜材料产生更多的甲烷（每克添加的挥发性固体）。用黄色镰刀菌和灰葡萄孢的孢子进行的存活研究表明存活时间非常短，不到2.5小时。对于两种甜菜病原体，螺旋丝囊霉和终极腐霉，不可能获得最具抗性的存活结构，卵孢子，因此仅用菌丝体和/或卵原细胞进行存活测试。这两种结构都存活了很短的时间。为了预测这些真菌在沼气过程中的命运，需要更多的研究。然而，尽管不可能测试所有感兴趣的真菌结构，但到目前为止的结果表明，真菌不太可能在生物肥料中造成很大的问题。在材料被消化并用作生物肥料之前，它经过几个步骤，卫生，厌氧消化，后消化，有氧储存，不同的环境。因此，真菌似乎不太可能通过所有这些步骤来适应和生存。总之，沼气生产过程可能是一个很好的方式来处理污染的有机材料。然而，在规划沼气厂时，重要的是要考虑较低的甲烷产量。
Sweden and Europe aims at increasing the use of renewable energy. Biogas represents one way to reach this goal. Biogas, produced from organic waste or crop materials, can be used for production of heat and electricity and as fuel for vehicles. The biogas process is also advantageous as it mediate the recirculation of nutrient from waste products to arable fields. This can be achieved by spreading the nutrient rich bio manure, which is left after digestion, on arable fields. Organic material, used as substrate in a biogas process, can contain different contaminating organisms such as different fungi. Some fungi are plant pathogens and if these survive the biogas process and is spread on arable land they might infect the new crop, thus leading to reduced yields and an increased need for fungicides. If storage pathogens are spread they may survive on organic debris on the ground and damage the harvested crop during storage. Therefore it is important to evaluate potential risks when materials infected with plant pathogenic fungi are used as substrate in a biogas process. Furthermore, if fungi are killed, the biogas process offers an alternative way of using crops with not good enough quality for food or feed production. Presently, it is however at unclear what levels of gas production that can be reached with such “low quality” materials. The aim of this study was to investigate fate of plant pathogens during mesophilic anaerobic digestion and also to investigate gas production potential of infected and uninfected sugar beet, both fresh beet roots and those stored for one year. Survival studies were performed for three different sugar beet field pathogens, Aphanomyces cochlioides, Pythium ultimum and Rhizoctonia solani, causing emergence diseases, and for two different storage pathogens Fusarium culmorum and Botrytis cinerea. The gas production potential was determined in a batch test system started with inoculum from two different large scale biogas plants. The measurement of gas production potential showed that both uninfected fresh and stored sugar beets produced more methane (per g added Volatile Solid) than beet material infected by the different fungal pathogens. Survival studies performed with spores of Fusarium culmorum and Botrytis cinerea demonstrated a very short survival time, less than 2.5 hours. For two sugar beet pathogens, Aphanomyces cochlioides and Pythium ultimum, it was not possible to obtain the most resistant survival structure, the oospores, and the survival test was therefore performed with only mycelia and/or oogonia. Both these structures survived for a very short time. In order to predict the fate of these fungi in a biogas process, more studies are needed. However, even though it was not possible to test all fungal structures of interest, the results so far suggest that it is unlikely that fungi would pose a great problem in bio manure. Before the material is digested and used as bio manure it passes several steps, sanitation, anaerobic digestion, post-digestion, aerobic storage, with varied environments. Therefore, it seems unlikely that a fungus can adapt and survive through all of those steps. Conclusively, a biogas production process could be a good way to dispose of contaminated organic material. However, it is important to consider the lower methane yield when planning the biogas plant.