Sequestration of Reactive Blue 4 by free and immobilized Bacillus subtilis cells and its extracellular polysaccharides.

Bacillus subtilis a gram positive bacteria and its extracellular polysaccharide were used in free form as well as immobilized form as biosorbent for sequestration of an anionic dye, Reactive Blue 4 (RB) in aqueous phase. The dye uptake enhanced with decrease in pH. Extracellular polymeric substances (EPS) and free cells were found to be better adsorbents when compared to alginate immobilized cells (IC) and EPS (IEPS). The presence of functional groups in free cells and EPS was confirmed by FT-IR analysis. Immobilization resulted in poor adsorption performance due to increase in mass transfer resistance by the polymeric matrix. High Q(max) and b values were noted in the case of free cells and free EPS in contrast to IC and IEPS. From the kinetic experiments, the adsorption system was found to be a pseudo-first-order reaction at low dye concentration. Desorption of RB was found to be 100% in 1N NaOH. However, the alginate beads were found to be unstable under high alkaline conditions of NaOH.

Preservation of kombucha tea-effect of temperature on tea components and free radical scavenging properties.

Kombucha tea is sugared black tea fermented with a consortium of acetic acid bacteria and yeasts (tea fungus) for 14 days. The tea tastes slightly sweet and acidic. The formation of tea fungal biofilms during storage is a big problem when kombucha tea is being stored and commercialized. Various thermal treatments have been tried for long-term storage of kombucha tea. The present study revealed the influence of heat on the biochemical constituents and the free radical scavenging properties of kombucha tea. Heat treatment at 60, 65, and 68 degrees C for 1 min controlled biofilm formation in kombucha tea without changing its clarity, taste, and flavor. However, tea polyphenols and black tea quality parameters showed varying stability during the storage period. A decrease in free radical scavenging properties was also found during the storage period. Because the biological activities of kombucha tea depended on the biochemical constituents, it was concluded that heat treatment was not a suitable method for kombucha tea preservation.