The impact of bacterial activity on decay and fossilization of arthropods: An experimental approach

细菌活动对节肢动物腐烂和石化的影响：一种实验方法

• 批准号: 396704301
• 负责人: Professorin Dr. Gabriele Bierbaum
• 金额: --
• 依托单位: Abteilung Paläontologie
• 依托单位国家: 德国
• 项目类别: Research Units
• 财政年份: 2018
• 资助国家: 德国
• 起止时间: 2017-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/396704301?language=en
• 关键词: impact; bacterial; activity; decay; fossilization

Arthopods represent the highest biodiversity among metazoa. Insights into evolution and phylogeny of arthropods are mainly derived from exceptionally well-preserved fossils from so called conservation deposits (Konservatlagerstätten). These fossils were formed by a complex sequence of biological, chemical and geological processes that starts immediately after the death of the organism. Between the death and the embedding of the carcass into the sediment, decay (aerobic) or/and putrefaction (anaerobic)- catalyzed by microorganisms that originate from the gut flora of the arthropod and/or its environment – may lead to a partial loss of characteristic features that are important for phylogenetic interpretations. This bacterial decay, which is not equally fast in different tissues, has led to serious misinterpretation in the fossil record of vertebrates, because fossils of partially decomposed organisms were incorrectly classified. In addition to the decay of organisms, bacteria have also been shown to contribute to the formation of fossils, by synthesizing biofilms which later fossilize by precipitation of minerals and yield casts or pseudomorphs of the hard and fine tissues of the carcass. Also the precipitation of minerals may be a product of bacterial activity.The overall goal of this project is to improve the general understanding of decay processes in the context with microbial activity in arthropods. To this end we will start monitoring the disarticulation of whole arthropods and characterize the developing microbial communities on the carcass over the time. The goal of the decay monitoring will not only be to observe the physical disarticulation, but also to understand the influence of chemical and physical parameters and to identify the best conditions for mineralization. The microbiome of decaying arthropods under different environmental conditions will be characterized by 16S rRNA sequencing and correlated to its sources (gut, environment), the speed of the decay and morphological changes. On the other hand, bacterial strains which are characterized by the production of biofilms and exoenzymes will be isolated from the decaying cadavers and characterized. To prove or disprove the hypotheses that the formation of biofilms favors the formation of fossils, and that on the other hand the secretion of exoenzymes, however, leads to an accelerated degradation, different tissue types of arthropods will be incubated with the isolated bacterial strains in the second part of the project. Decay or fossilisation will be recorded and yield systematic insights into the influence of bacterial activity on the fossilisation process. Thus, finally the experiments shall contribute to a better understanding of the conditions that determine the occurrence of exceptional preservation of arthropods in different environmental settings through geological time.

节肢动物是后生动物中生物多样性最高的动物。对节肢动物进化和系统发育的洞察主要来自保存异常完好的化石，这些化石来自所谓的保护性沉积物(Konservatlagerstätten)。这些化石是由生物体死亡后立即开始的一系列复杂的生物、化学和地质过程形成的。在身体死亡和将身体埋入沉积物之间，由节肢动物肠道菌群和/或环境中的微生物催化的腐烂(需氧)或/和腐烂(厌氧)可能导致对系统发育解释重要的特征特征的部分丧失。这种细菌腐烂在不同组织中的速度并不相同，这导致了对脊椎动物化石记录的严重误解，因为部分分解生物的化石被错误地归类。除了生物体的腐烂，细菌也被证明有助于化石的形成，因为细菌合成的生物膜后来通过矿物的沉淀而石化，并产生身体坚硬和精细组织的铸型或假象。此外，矿物质的沉淀可能是细菌活动的产物。该项目的总体目标是在节肢动物微生物活动的背景下提高对腐烂过程的总体理解。为此，我们将开始监测整个节肢动物的脱节情况，并确定随着时间的推移身体上正在发育的微生物群落的特征。衰变监测的目标将不仅是观察物理脱节，而且还要了解化学和物理参数的影响，并确定成矿的最佳条件。对不同环境条件下腐烂节肢动物的微生物群进行16S rRNA测序，并与其来源(肠道、环境)、腐烂速度和形态变化相关联。另一方面，从腐烂的身体中分离出以产生生物膜和外源酶为特征的细菌菌株并对其进行鉴定。为了证明或反驳这样的假设，即生物膜的形成有利于化石的形成，另一方面，外源酶的分泌会导致加速降解，在项目的第二部分，不同组织类型的节肢动物将与分离的细菌菌株培养。腐烂或化石作用将被记录下来，并对细菌活动对化石过程的影响产生系统的见解。因此，这些实验最终将有助于更好地理解决定节肢动物在不同环境背景下通过地质时间异常保存的条件。