10.22376/ijpbs.2019.10.1.p1-12 Volume 6 Issue 2 2015 (April - June) The Sundarbans are the largest and unique wetland mangrove ecological niches in the world which support different microbes, recycle the nutrients and perform various environmental activities. Analysis of the soil microbial diversity from this ecosystem would help in isolation of potent micro-organisms having high specificity for various applications. Therefore, microbial analysis in the soils of five locations namely Bakkhali, Henry's Island, Patharpratima, Purba Amarabati, Namkhana of the Sundarbans, West Bengal was undertaken. The population dynamics (cfu/g dr. soil) of the aerobic heterotrophic (4.4 - 7.5 ×10 lessThan sup greaterThan 6 lessThan /sup greaterThan ), spore forming (2.6 - 5.4 ×10 lessThan sup greaterThan 4 lessThan /sup greaterThan ), nitrifying (3.7 - 5.4 ×10 lessThan sup greaterThan 3 lessThan /sup greaterThan ), gram (-)ve (3.3 – 6.1 ×10 lessThan sup greaterThan 3 lessThan /sup greaterThan ), phosphate solubilizing (1.9 - 3.6×10 lessThan sup greaterThan 3 lessThan /sup greaterThan ) and nitrogen fixing bacteria(2.1 - 3.9×10 lessThan sup greaterThan 3 lessThan /sup greaterThan ) were variable in different soils. Population of different bacterial groups were higher in Bakkhali due to more organic carbon level than the other areas and lower in Purba Amarabati due to its lower organic carbon and water holding capacity. Soil physico-chemical properties like soil pH (6-7.8), organic carbon (0.39-0.79%), nitrogen (5.2-8.1), phosphorus (6.1-9.2) and potassium (3.8-6.2) were also higher in Bakkhali. SOUMENDRANATH CHATTERJEE , PRIYANKA MUKHOPADHYAY AND TUSHAR KANTI DANGAR The Sundarbans, mangrove ecosystem, soil microbial diversity, physico-chemical and biochemical properties, Scanning Electron Microscopy (SEM) 353-361