Bacterial isolation and characterization of Silmondi and Chhiata soil series of Bangladesh

The soil samples were processed through the standard microbiological techniques such as serial dilution, spread plate technique and pure culture preparation, for the isolation, quantification and characterization of the bacterial population of two agricultural soils of Madhupur tract in Bangladesh. The viable bacterial populations by Silmondi and Chhiata in the soil were estimated using plate count method, and the results were 6.4×10⁶ and 7.4×10⁶ CFU/g soil respectively. Colonies were systematically studied for size, pigmentation, shape (form), margin and elevation showing high variation among the isolates. The soil of Chhiata was also more diverse in terms of microorganisms with less homogeneous microbial environment than Silmondi soil. Rod shape/coccoid bushes attached singly or chains were observed by gram, spore staining and capsule staining while acid fast staining was done for common morphological features and staining characteristics observed for gram positive and gram negative bacteria. Many of the isolated strains not only displayed spore- and capsule-forming abilities, but also indicating adaptive survival strategies under environmental stress conditions. The present study, therefore, reaffirms the fact that soils of Madhupur Tract are more diverse in terms of microorganisms and their importance for the soil health in relation to benthic nitrogen cycle. Further molecular and biochemical investigations are required to characterize and validate their function in order to utilize them optimally for sustainable agriculture.