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Bacterial surface components have a major role in the development of biofilms. In the present study, the effect of Escherichia coli O8-antigen on biofilms was investigated using two E. coli K-12 derived strains that differed only in the O8-antigen biosynthesis. In the presence of O8-antigen both bacterial adhesion and biofilm formation slightly decreased under static conditions whereas a substantial increase in adhesion and biofilm formation was observed under agitated conditions. It was noted that, irrespective of the O8-antigen status, the hydrophobic interactions played an important role in bacterial adhesion under both static and agitated conditions. However, under agitated conditions, the extent of bacterial adhesion in the O8-antigen bearing strain was predominantly determined by the electrostatic interactions. Results showed that the presence of O8-antigen decreases the surface hydrophobicity and surface charge. Moreover, O8-antigen facilitates adhesion on hydrophilic and hydrophobic surfaces as revealed through tests with modified substrata. Our results indicate that O8-antigen, which appears dispensable for biofilm formation under static conditions, actually enhances E. coli biofilm formation under agitated conditions.

The development of green composites using different natural fiber reinforcements is an area of active research to reduce the environmental footprint. These composites have serious limitations with high water absorption and reduced mechanical strength. The objective of this work is to develop polymeric green composite form natural reinforcements -jute and rice husk, with improved water resistance and flexural characteristics. Rice husk and jute mat were chemically treated with acrylic acid and sodium hydroxide. The effective treatment conditions such as treatment temperature, time and concentration of the chemical to minimize water absorption, were determined. The effective acrylic acid concentration, temperature and time for acrylic treatment process were 10 volume percent, 60 o C and 4 hours for rice husk and 10 volume percent, 90 o C and 6 hours for jute mat respectively. The flexural properties were also reported for the composites. The surface chemistry, surface morphology and composition (hydroxyl, cellulose and hemicelluloses content) of the treated and untreated natural reinforcements were also analysed. It was observed that the acrylic treatment reduced the water absorption of the composites significantly with marginal reduction on mechanical property. Alkali treatment (using sodium hydroxide) improved the flexural strength of the rice husk reinforced composite, however it exhibits an adverse effect on water resistance properties.

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