Isolation, Morphological and Biochemical Characterization of Rhizobacteria from Arsenic Contaminated Paddy Soils in Bangladesh: An In vitro Study

Soil-plant–microbes relations within the plant rhizosphere are the determinants of plant and soil health, which is important for soil ecological environment for plant-microbe interactions. Plant growth-promoting rhizobacteria (PGPR) are considered to encourage plant growth and development directly or indirectly in soil. PGPR can demonstrate a diversity of characteristics responsible .for influencing plant growth and development. During this study, Twenty four different bacterial isolates were isolated, and detailed morphological, biochemical, and physiological characterizations of those isolates were accomplished. This experiment was performed with the 24 bacterial isolates to see their gram stain test, KOH test, catalase activity, cellulose degradation capability, in dole acetic acid (IAA) production, and phosphate solubilization activities, and also tested for growth within the different arsenic and salt stress conditions and 37°C temperature. Results revealed that among the rhizobacterial isolates, fifteen bacterial isolates were negative and nine was positive in gram reaction, while some were showed high IAA production ability, phosphate solubility capability, and cellulose degradation capacity within the culture media. The isolates were isolated from paddy soils and a few were characterized by a yellow color, flat elevation, and gram-positive, while some were characterized because of the yellowish color with round colony shape, raised elevation, gram-negative, and every one the isolates were positive in catalase production capacity and phosphate solubilization activity which is able to increase the available phosphorus within the soil for plants and also produced indole acetic acid that may use as a hormone to be used in growth enhancement of plants. Hence, these isolates need to be tested further for their effect on arsenic dynamics at the plant rhizosphere, selection of suitable plant species for the bacterial association, bacterial effect on arsenic uptake by plants, and potentials for field applications for sustainable agriculture.