Galactosamine can be used as an indicator for microbial extracellular polymeric substances (EPS), an important source of stable organic matter in agricultural soils

半乳糖胺可用作微生物胞外聚合物（EPS）的指示剂，EPS是农业土壤中稳定有机质的重要来源

• 批准号: 464850637
• 负责人: Dr. Jens Dyckmans
• 金额: --
• 依托单位: Kompetenzzentrum Stabile Isotope
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/464850637?language=en
• 关键词: Galactosamine; used; indicator; microbial; extracellular

Four experiments form a consecutive programme for elucidating the role of EPS (extracellular polymeric substances) in agricultural soil environments, based on the following two central hypotheses: (1) EPS are an important component of microbial necromass, which can be extracted from soil with cation exchange resins (CER). (2) Galactosamine (GalN) indicates microbial EPS in soil. In the first experiment, microbial EPS formation will be investigated by cultivating soil bacteria and soil fungi, using glycerol and starch as a C source in the absence or presence of SOM-free sterile sand. In the second experiment, simple (glycerol or maize-derived starch) and complex (maize-derived cellulose or maize straw) 13C labelled substrates will be tested for their ability to form bacterial and fungal EPS in four soils, differing in their fungi to bacteria ratio due to differences in soil pH and fertilization history. In the third experiment, glucose and cellulose decomposition will be monitored to investigate carbon use efficiency (CUE) and thermodynamic efficiency in two soils, differing in their fungi to bacteria ratio due to differences in fertilization history and due to the absence or presence of EPS. In the fourth experiment, microbial EPS formation in soil will be induced by applying to one soil a simple and easily available substrate (maize-derived starch) that promotes bacterial EPS formation and a more recalcitrant substrate (maize-derived cellulose) that promotes fungal EPS formation. The persistence and aggregate stabilizing effect of the freshly formed EPS will be monitored for 70 days. The C/N ratio of the substrates will be generally adjusted to 40, using (NH4)2SO4 in experiment 1 and (15NH4)2SO4 in experiments 2, 3, and 4. In all experiments, CER extracted EPS will be analysed for their concentration of amino sugars, combined with their compound-specific δ13C and δ13N analysis. EPS extracts will be additionally checked for total organic 13C, total δ15N, total carbohydrates, total protein, and total deoxy-ribonucleic acid (DNA). In the soil, soil organic 13C, microbial biomass 13C, total 15N, microbial biomass 15N, enzyme activity (N-acetyl--D-glucosaminidase and tyrosine-peptidase) and amino sugars will be measured, combined with their compound-specific δ13C and δ13N analysis. In the soil atmosphere, the evolution of total CO2 and 13CO2 will be measured. In experiment 3, heat productions will be additionally monitored using microcalorimetry.

通过4个连续的实验，阐明了胞外聚合物（EPS）在农业土壤环境中的作用，主要基于以下两个假设：（1）EPS是微生物坏死物质的重要组成部分，可以用阳离子交换树脂（CER）从土壤中提取。(2)半乳糖胺（GalN）表示土壤中的微生物EPS。在第一个实验中，微生物EPS的形成将通过培养土壤细菌和土壤真菌，使用甘油和淀粉作为C源，在不存在或存在SOM的无菌砂的情况下进行研究。在第二个实验中，简单的（甘油或玉米衍生的淀粉）和复杂的（玉米衍生的纤维素或玉米秸秆）13 C标记的基板将被测试的能力，形成细菌和真菌的EPS在四种土壤中，不同的真菌细菌的比例，由于土壤pH值和施肥历史的差异。在第三个实验中，葡萄糖和纤维素分解将被监测，以调查碳利用效率（CUE）和热力学效率在两种土壤中，不同的真菌细菌的比例，由于施肥历史的差异，由于存在或不存在EPS。在第四个实验中，将通过向一种土壤施用促进细菌EPS形成的简单且容易获得的基质（玉米衍生的淀粉）和促进真菌EPS形成的更难消化的基质（玉米衍生的纤维素）来诱导土壤中微生物EPS的形成。将对新形成的EPS的持久性和聚集体稳定作用进行70天的监测。在实验1中使用（NH 4）2SO 4，在实验2、3和4中使用（15 NH 4）2SO 4，通常将基质的C/N比调节至40。在所有实验中，将分析CER提取的EPS的氨基糖浓度，并结合其化合物特异性δ 13 C和δ 13 N分析。将额外检查EPS浸提液的总有机13 C、总δ 15 N、总碳水化合物、总蛋白质和总脱氧核糖核酸（DNA）。在土壤中，将测量土壤有机13 C、微生物量13 C、总15 N、微生物量15 N、酶活性（N-乙酰-β-D-氨基葡萄糖苷酶和酪氨酸肽酶）和氨基糖，并结合其化合物特异性δ 13 C和δ 13 N分析。在土壤大气中，将测量总CO2和13 CO2的演变。在实验3中，将使用微量热法额外监测产热。