Studies on the Cellular and Molecular Networks Involved in Hyperswarming Motility in Bacteria

Sarkar, Shukla (2015) Studies on the Cellular and Molecular Networks Involved in Hyperswarming Motility in Bacteria. Masters thesis, Indian Institute of Science Education and Research Kolkata.

PDF (MS dissertation of Shukla Sarkar (10MS49)) MS-thesis_Shukla_Sarkar_10MS49.pdf - Submitted Version Restricted to Repository staff only Download (1MB)

Abstract

Bacteria are one of the most amazing groups of organisms, which portray a wide variety of properties helping them in their sustenance in different environmental conditions. Biofilm formation is one such property in which, group of bacterial cells form a three dimensional network which helps them to sustain under stressed conditions. Within the Biofilm framework, there are group of cells performing specialized tasks. Bacterial swarming or collective cell movement refers to one of such tasks carried out by certain group of cells – preferably found in the periphery of a growing colony of Biofilm framework – commonly known as hyperswarmers. The present study is focused on: 1. Gene expression studies to establish a pathway which is the reason for hyperswarming behaviour 2. Detection and estimation of bio-surfactants during conditions of hyperswarming. 3. To see differences in protein profile of the bacteria. 4. To see differences in flagella in the hyperswarmer versus non-hyperswarmer. The studies were carried on a Bacillus cereus strain, W2.3B which was isolated from a water body near the M.N. Saha hostel. The strain was taxonomically characterized and compared against another B. cereus strain, MSM-S1. Interestingly, it was observed that on semi-solid nutrient agar plate, W2.3B colony moves much faster as a natural hyperswarmer compared to MSM-S1. Confocal laser scanning microscopic studies revealed differences in cellular orientation and morphology between the hyperswarming and non hyperswarming colonies of W2.3B and MSM-S1 respectively. In order to find the contributory factors towards the hyperswarming property of W2.3B, we initially check the aid of bio-surfactant, produced by the growing colony, in such kind of motility by oil-drop and oil-spray assays. Results from these assays indicated possible role of bio-surfactant for hyperswarming. Gene profiling of the hyperswarmer strain W2.3B compared the non-hyperswarmer strain MSM-S1 was done for all common genes involved in cell division, cell motility and quorum sensing. Comparison of expression profile of these genes between the hyperswarmer and non-hyperswarmer strains is underway.

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