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.

基于以下两个核心假设，可以阐明EPS（细胞外聚合物）在农业土壤环境中的EPS（细胞外聚合物）的作用的连续计划：（1）EPS是微生物坏死的重要组成部分，可以从土壤中提取具有阳离子交换树脂的土壤（CER）的重要组成部分。 （2）半乳糖胺（Galn）表明土壤中的微生物EP。在第一个实验中，将在不存在或存在无SOM无菌砂的情况下使用甘油和淀粉作为C来源来研究微生物EPS形成。在第二个实验中，将测试简单（甘油或玉米来源的淀粉）和复杂的（玉米来源的纤维素或玉米稻草）13C标记的底物的13C标记底物，以表明它们在四个土壤中形成细菌和真菌EPS的能力，由于其真菌与细菌与细菌的比例不同，因此由于土壤pH和育肥的差异。在第三个实验中，将监测葡萄糖和纤维素分解，以研究两种土壤中碳的使用效率（CUE）和热力学效率，由于受精史的差异以及由于缺乏或存在EPS，其真菌与细菌的比率不同。在第四次实验中，将通过将微生物EPS形成在一个土壤中诱导，促进一种简单易用的底物（玉米来源的淀粉），促进细菌EPS形成和更顽固的底物（玉米衍生的纤维素），从而促进真菌EPS形成。新鲜形成的EP的持久性和总体稳定效应将被监测70天。实验1中的（NH4）2SO4通常将底物的C/N比率调整为40，在实验2、3和4中（15NH4）2SO4中的C/N。 EPS提取物将进一步检查总有机13C，总碳水化合物，总蛋白质和总脱氧核糖核酸（DNA）。在土壤中，土壤有机13C，微生物生物量13C，总15N，微生物生物量15N，酶活性（N-乙酰基--D-D-葡萄糖酰胺酶和酪氨酸肽酶）和氨基糖将被测量，并与它们的复合特异性Δ13C和δ13N分析一起测量。在土壤大气中，将测量总CO2和13CO2的演变。在实验3中，将使用微钙化法对热生产​​进行进一步监测。