Comparison of growth kinetics in Pseudomonas using two different sets of conditions

The aim of this study was to compare the growth kinetic responses to two different sets of conditions by investigating the growth kinetic response of Pseudomonas sp. which was isolated by an enrichment technique using a shaking water bath and a biosimulator. The viable count of the Pseudomonas sp. was initially determined on a small scale using sterile nutrient broth alone, plus broth supplemented with malathion (8.55 mg ml^-1) incubated in a shaking water bath. A biosimulator was used on a larger scale to compare the growth kinetics of the Pseudomonas sp. using sterile undiluted and diluted (1:10) nutrient broth. The viable count was measured by the standard plate count (SPC) technique for both the sets of conditions (shaking water bath; biosimulator) and reported as colony forming units (CFU ml^-1). In the shaking water bath experiments, the culture grew very well in the presence of 8.55 mg ml^-1 malathion, as indicated by good growth response in comparison to that of nutrient broth alone. Similar studies were also performed using the same culture in the biosimulator, using undiluted and diluted (1:10) nutrient broth, results of which revealed, that at each sampling hour the viable population density was greater in the presence of undiluted nutrient broth, than in the presence of diluted (1:10) nutrient broth. A critical evaluation of data presented indicated that the growth performance of Pseudomonas sp. was better in the biosimulator when compared to the shaking water bath. As the Pseudomonas sp. is highly aerobic, it performed better in the biosimulator, where a greater quantity of oxygen (DO 4.0 mg l^-1) was more readily available in comparison to the shaking water bath. The total quantity of nutrients available also affected the total viable population density. The study revealed that the wild isolate, when studied on a laboratory scale, could be effective in bioremediation of environmental pollution caused by pesticides.