Assessment of Bacterial Isolation and Characterization of Chhiata and Silmondi Soil Series of Madhupur Tract

Abstract

This study investigated the bacterial diversity in two agricultural soils of Bangladesh, Chhiata and Silmondi. Soil samples were collected aseptically from the top 0–15 cm layer and subjected to isolation, purification, and enumeration of bacterial populations. Colony morphology, cellular characteristics, and staining properties were systematically examined to assess microbial diversity. The bacterial counts were 7.6×10^6 CFU/g soil for Chhiata and 6.5×10^6 CFU/g soil for Silmondi, reflecting active microbial communities. The isolates displayed considerable phenotypic heterogeneity, with variations in colony size, pigmentation, form, margin, and elevation. Morphological analysis revealed both Gram-positive and Gram-negative bacteria, including rod-shaped and cocci forms with single and chain arrangements. Several isolates exhibited spore- and capsule-forming abilities, indicative of adaptive survival strategies under environmental stress. The findings corroborate previous studies from Bangladesh, highlighting the dominance of Bacillus spp., along with other Gram-negative, spore-forming bacteria such as Enterobacter spp., Klebsiella spp., and Azospirillum spp. This study underscores the rich microbial diversity of Bangladeshi soils and emphasizes the ecological importance of soil bacteria in nutrient cycling, soil fertility, and sustainable agriculture.