Karmakar Kapudeep, Roy Dipankar, Pal Srija, Chowdhury Bratati, Choudhury Ashok
Regional Research Station, Terai Zone, Uttar Banga Krishi Viswavidyalaya, Pundibari, Coochbehar, West Bengal, 736165, India.
Department of Soil Science and Agricultural Chemistry, Uttar Banga Krishi Viswavidyalaya, Pundibari, Coochbehar, West Bengal, 736165, India.
Curr Microbiol. 2025 May 26;82(7):307. doi: 10.1007/s00284-025-04295-x.
Leaching loss of nutrients from the agricultural field is a major concern in areas receiving excessive rainfall. The water-soluble nutrients are therefore lost due to leaching and runoff water. This leads to excessive dependence on chemical fertilizers. In this regard, the role of indigenous exopolysaccharide (EPS) producing bacteria in stabilizing the nutrient-holding capacity is far greater than conceived. The sub-Himalayan terai region, located at Cwa zone (monsoon type with dry winter, Köppen's classification) in India, which receives heavy rainfall (> 3000 mm), is a suitable location to study the role of such bacteria. A culture-dependent analysis of EPS-producing bacteria showed their comparatively lower abundance throughout the year. The EPS-associated bacterial microenvironment on vermiculite particles under aerobic and anaerobic conditions was visualized using a Confocal Laser Scanning Microscope (CLSM). The cells of EPS producers were found distributed within the EPS matrix, pushing each other away, showing a higher organic matter secretion (EPS) per unit of the bacterial cells. Since EPS has adhesive properties, the indigenous EPS-producing bacteria were amended to the soil, and the formation of macroaggregates was analyzed. Two in-house EPS-producing bacteria were used to monitor if they can reduce the leaching loss of nutrients. In vitro, assays on nutrient-holding capacity by soil-column-flow-through revealed that these bacteria-treated soil retained more nutrients. Till now, there were no reports on the role of the genus Serratia in improving the nutrient-holding capacity. For the first time, we have shown that using such soil-dwelling genera can improve the formation of stable aggregates and prevent nutrient loss.
在降雨过多的地区，农田养分的淋失是一个主要问题。因此，水溶性养分因淋溶和径流而流失。这导致对化肥的过度依赖。在这方面，本地产胞外多糖（EPS）细菌在稳定养分保持能力方面的作用远比想象的要大。位于印度Cwa区（柯本分类法中的冬季干燥季风型）的喜马拉雅次山脉台地地区，年降雨量超过3000毫米，是研究此类细菌作用的合适地点。对产EPS细菌的培养依赖性分析表明，它们全年的丰度相对较低。使用共聚焦激光扫描显微镜（CLSM）观察了蛭石颗粒在好氧和厌氧条件下与EPS相关的细菌微环境。发现EPS生产者的细胞分布在EPS基质中，相互推开，表明每单位细菌细胞分泌的有机物（EPS）较高。由于EPS具有粘附特性，将本地产EPS细菌添加到土壤中，并分析了大团聚体的形成。使用两种内部产EPS细菌来监测它们是否能减少养分的淋失。通过土壤柱流通法对养分保持能力进行的体外测定表明，这些经细菌处理的土壤保留了更多养分。到目前为止，关于沙雷氏菌属在提高养分保持能力方面的作用尚无报道。我们首次表明，使用此类土壤栖居菌属可以改善稳定团聚体的形成并防止养分流失。
