EFFECTS OF BACTERIAL EXOPOLYMER ADHESION ON THE ENTRAINMENT OF SAND
EFFECTS OF BACTERIAL EXOPOLYMER ADHESION ON THE ENTRAINMENT OF SAND
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DOI：
10.1080/01490459009377874
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发表时间：
1990-01-01
影响因子：
2.3
通讯作者：
WHITE, DC
中科院分区：
文献类型：
--
作者：
DADE, WB;DAVIS, JD;WHITE, DC
侵蚀酸洗沙床所需的流速由于海底海洋细菌亚特兰蒂斯交替单胞菌的生长而产生的粒间粘连而增加。总体而言，我们发现，无论是单纯的胞外聚合物，还是在原位生长过程中产生的胞外聚合物，都提高了细粒石英砂的耐蚀性。此外，耐腐蚀程度与胞外聚合物组分糖醛酸的浓度成正比，而糖醛酸的浓度又取决于基于蛋白内酯的生长介质的相对氮含量。具体地说，我们观察到，在每克干沉积物中，在富氮条件下原位细菌生长产生的大约100nmoL的外聚体或1.5nmoL的成分糖醛酸，可以有效地使启动传输125-177微米的无粘性石英颗粒所需的海水水槽流速增加一倍。这一最大影响对应于估计的粘附力，该粘附力比淹没的颗粒重量高一个数量级，比颗粒特定的糖醛酸重量高七个数量级。通过气相色谱/质谱联用对从大西洋曲霉培养物中获得的纯化的胞外聚合物进行快速分析，结果表明它是一种多糖，按重量计含有约20%的糖醛酸。在这些实验中产生的最大胞外聚合物和组分糖醛酸浓度比以前报告的河口沉积物的值小一个数量级。这些结果首次将特定的胞外聚合物组分与抗沉积物侵蚀能力联系起来，并进一步证明了微生物渗出物在沉积物结合中的重要性，据信这些沉积物存在于广泛的海洋环境中。
Flow velocity required to erode a bed of acid-washed sand is increased by intergranular adhesion resulting from growth of the benthic marine bacterium Alteromonas atlantica. In general, we find that either pure exopolymer alone or exopolymer generated during in situ growth increases erosion resistance of fine quartz sand. Moreover, the degree of erosion resistance increases in proportion to the concentration of exopolymer-component uronic acids, which in turn is dependent on relative nitrogen content of peptone-based growth media. Specifically, we observe that approximately 100 nmol of exopolymer or 1.5 nmol of component uronic acids generated by in situ bacterial growth under nitrogen-rich conditions per gram of dry sediment can effectively double seawater-flume flow velocity required for initiation of transport of otherwise noncohesive, 125-177-mu-m quartz grains. This maximal effect corresponds to an estimated adhesive force that exceeds submerged particle weight by an order of magnitude and exceeds particle-specific uronic acids weight by seven orders of magnitude. Rapid analysis by gas chromatography/mass spectrometry of purified exopolymer obtained from A. atlantica cultures shows it to be a polysacharide containing approximately 20% uronic acids by weight. Maximal exopolymer and component uronic acid concentrations generated in these experiments are an order of magnitude less than values previously reported for estuarine sediments. These results are the first to correlate specific exopolymer components with sediment erosion resistance and further demonstrate the importance of microbial exudates in sediment binding believed to occur in a wide range of marine environments.