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Bacterial-foraging optimization algorithm (BFOA) attempts to model the individual and group behavior of E. Coli bacteria as a distributed optimization process. Since its inception, BFOA has been finding many important applications in real-world optimization problems from diverse domains of science and engineering. One key step in BFOA is the computational chemotaxis, where a bacterium (which models a candidate solution of the optimization problem) takes steps over the foraging landscape in order to reach regions with high-nutrient content (corresponding to higher fitness). The simulated chemotactic movement of a bacterium may be viewed as a guided random walk or a kind of stochastic hill climbing from the viewpoint of optimization theory. In this paper, we first derive a mathematical model for the chemotactic movements of an artificial bacterium living in continuous time. The stability and convergence-behavior of the said dynamics is then analyzed in the light of Lyapunov stability theorems. The analysis indicates the necessary bounds on the chemotactic step-height parameter that avoids limit cycles and guarantees convergence of the bacterial dynamics into an isolated optimum. Illustrative examples as well as simulation results have been provided in order to support the analytical treatments. Index Terms--Bacterial foraging, biological systems, computational chemotaxis, limit cycles, stability analysis.

A comparative analysis of the bacterial diversity of freshwater sediment of a shallow eutrophic lake on the basis of 16S rRNA gene analysis and modified cultivation techniques that improved the culturability of hitherto known species present in the ecosystem is conducted. The effectiveness of using gellan gum as a gelling reagent in a culture-dependent analysis of bacterial diversity in freshwater sediment is also demonstrated.

The multicopper oxidase CueO had previously been demonstrated to exhibit phenoloxidase activity and was implicated in intrinsic copper resistance in Escherichia coli. Catecholates can potentially reduce Cu(II) to the prooxidant Cu(I). In this report we provide evidence that CueO protects E. coli cells by oxidizing enterobactin, the catechol iron siderophore of E. coli, in the presence of copper. In vitro, a mixture of enterobactin and copper was toxic for E. coli cells, but the addition of purified CueO led to their survival. Deletion of for resulted in copper hypersensitivity that was alleviated by additional deletion of entC, preventing synthesis of enterobactin. In addition, copper added together with 2,3-dihydroxybenzoic acid or enterobactin was able to induce a [PHI](cueO-lacZ) operon fusion more efficiently than copper alone* The reaction product of the 2,3-dihydroxybenzoic acid oxidation by CueO that can complex Cu(II) ions was determined by gas chromatography-mass spectroscopy and identified as 2-carboxymuconate.

Amplified Ribosomal DNA (rDNA) restriction analysis and rDNA sequencing was used for identifying the cultivable bacterial community of maple sap coming out of the taphole. The results derived from the study provide information on the maple sap microflora, which will assist in investigations concerning microbial contamination and quality of maple products and guide in the development of new strategies related to taphole contamination control.

The expression of htrA is completely dependent on the rpoE gene in vivo and is essential for bacterial growth at high temperature. This is so because the reconstituted RNA polymerase containing EsigmaE projects htrA in vitro. Construction of an rpoE-defective strain by gene disruption by using cloned rpoE gene is also reflected.

Byline: Yu Tian Extracellular Polymeric Substances (EPS) are the predominant constituents of activated sludge and dramatically affect its properties. As EPS constitute as much as 5090% of the solid phase of sludge, the use of EPS may bring a great reduction in sludge volume and mass, which have been great environmental interest. In this paper, results of over 60 publications related to structure, composition, storing condition, extraction and characteristics of EPS and their influences on behaviours of EPS is analysed. Possible application of EPS in heavy metal contamination is also discussed, together with a brief consideration of possible research interests.